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  • 1
    ISSN: 1570-7458
    Keywords: Vitis vinifera ; Empoasca vitis ; leafhopper ; photosynthesis ; transpiration ; stomatal conductance ; mesophyll conductance ; growth ; yield ; fruit quality ; starch ; carbohydrate reserves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The impact of the grape leafhopper,Empoasca vitis, on leaf gas exchange, plant growth, yield, fruit quality and carbohydrate reserves of the grapevines,Vitis vinifera L., was studied. Gas exchange was measured on the discolored (red) and the green parts of infested main leaves and on leaves from uninfested vines. Photosynthesis and mesophyll conductance were severely reduced on main leaves showing leafhopper feeding symptoms. The stomatal conductance of the red leaf section of infested main leaves was lower than on undamaged control leaves. Additionally, the red leaf section of infested main leaves showed lower transpiration rates when compared to the green parts of the same leaves and to undamaged control leaves. Gas exchange processes of lateral leaves were not affected by leafhopper feeding. Leafhopperload on main leaves was correlated to visual damage symptoms. At 71.8 leafhopper-days per leaf up to 40% of the main leaf area of the infested plants was discolored from the borders towards the center. Lateral leaves showed no feeding symptoms. Shoot diameter, pruning weight and carbohydrate reserves in the wood were not affected by leafhoppers. Lateral leaf area growth was significantly stimulated on plants infested by leafhoppers. No decrease in yield and fruit quality with leafhopper-loads up to 71.8 leafhopper-days per leaf were observed.
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  • 2
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    Entomologia experimentalis et applicata 71 (1994), S. 201-209 
    ISSN: 1570-7458
    Keywords: Hypothenemus hampei ; coffee berry borer ; abiotic mortality ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mortality of the coffee berry borer was studied under controlled laboratory conditions in Tapachula, Mexico. For adult female borers subjected to a range of relative humidities (RH) without food at 25°C, the longest mean survival time (20 days) was obtained at 93.5% RH. Adult borer survival was also studied at a range of temperatures for a fixed relative humidity (93.5% RH); at 20°C mean survival time was 28 days. Fecundity and mortality of borer stages in berries was studied for a range of humidities at 25°C. Maximum fecundity was obtained at 90 and 93.5% RH. Immature stages were ejected from the berry at 84% RH and above, which is interpreted as a form of brood hygiene.
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  • 3
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    Entomologia experimentalis et applicata 72 (1994), S. 255-263 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; Leptinotarsa decemlineata ; behavior ; thermal biology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In short-term field trials at combinations of ambient temperature (°C) and insolation (W·m−2), larval Colorado potato beetles (Leptinotarsa decemlineata [Say] [Coleoptera: Chrysomelidae]) were observed after their release on the adaxial surface of leaflets on potato plants (Solanum tuberosum L. Solanaceae). The larvae either began feeding or moved under the leaflet; mean interval from release to expression of these behaviors (2.9±0.05 min [n =358]) was independent of air temperature and insolation. Proportion of larvae moving under the leaflet increased logistically with both air temperature and insolation. A 1 W·m−2 change in insolation (P) evoked the same effect on this proportion as a 0.0838 °C change in air temperature (T a ), so the two quantities were combined as T*=T a +P·0.0838 °C/(W·m−2), which has units of °C. The proportion of larvae moving under the leaflet increased logistically with T*. In 1-day field trials we monitored air temperature, insolation and proportion of larvae under the leaflet, and compared the latter to predictions from the logistic regression derived from the short-term trials. Consistently more larvae occurred under leaflets than predicted from the logistic regression; this bias diminished as T* increased until at T*≥40 °C, observed and predicted proportions were equal. This pattern of deviation from the predictions of the logistic regression is consistent with a thermoregulatory strategy in which larvae move away from hostile conditions, rather than seek optimal conditions.
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  • 4
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    Entomologia experimentalis et applicata 69 (1993), S. 13-20 
    ISSN: 1570-7458
    Keywords: Artificial diets ; Coccinellidae ; rearing ; biological control ; Chilocorus spp. ; Coleoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Promising diets were screened and the most successful modified with additives used in artificial diets for other entomophagous insects. Two suitable diets were obtained, one for adults and one for larvae ofChilocorus nigritus (Fabricius) (Coleoptera: Coccinellidae). They were still inferior to natural prey and not adequate as the sole food source for rearing consecutive generations. They are valuable as substitute food in the insectary during shortages of natural prey. Oleander scaleAspidiotus nerii Bouché andAsterolecanium miliaris (Boisduval) were evaluated as natural prey forC. nigritus and two other potential biocontrol agents in southern Africa,C. bipustulatus (Linnaeus) andC. infernalis Mulsant.A. nerii andA. miliaris were suitable for all life stages ofC. nigritus and adults ofC. bipustulatus andC. infernalis. A. miliaris was inadequate for larvae ofC. bipustulatus andC. infernalis.
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  • 5
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    Entomologia experimentalis et applicata 71 (1994), S. 177-180 
    ISSN: 1570-7458
    Keywords: aflatoxin ; Carophilus ; Zea mays ; corn ; plant resistance ; Coleoptera ; Nitidulidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 6
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    Entomologia experimentalis et applicata 63 (1992), S. 115-121 
    ISSN: 1570-7458
    Keywords: Pea weevil ; Bruchus pisorum ; Bruchidae ; Coleoptera ; flower feeding ; nectar robbing ; pea ; Pisum sativum ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pea flower feeding by adult pea weevils, Bruchus pisorum (L.) (Coleoptera: Bruchidae), with special emphasis on nectar feeding, was investigated in a series of laboratory experiments. Male and female adults robbed nectar from flowers of the garden and field pea, Pisum sativum L., and females which fed on the nectar, petals, and female organs of pea flowers lived significantly longer than those denied food and water and those that fed on water only. The results of other experiments suggested that pea flower qualities other than pollen influenced the reproductive success of female B. pisorum. It is hypothesized that pollen seeking B. pisorum effected cross-pollination in the wild progenitor of the modern-day autogamous pea, and adult pea weevils of both sexes rob pea nectar to obtain a readily available source of energy to sustain flight.
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  • 7
    ISSN: 1570-7458
    Keywords: Ceutorhynchus inaffectatus ; Coleoptera ; Curculionidae ; Hesperis matronalis ; Dame's violet ; Brassicaceae ; Cruciferae ; glucosinolates ; feeding stimulants ; host plant specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ceutorhynchus inaffectatus Gyllenhal (Coleoptera: Curculionidae:Ceutorhynchinae) is a monophagous species feeding only onHesperis matronalis L. (Cruciferae) in North-western Europe. Feeding responses of this weevil to five glucosinolates from its host plant were compared with the responses to four glucosinolates from non-host plants. The major glucosinolates in the host plant were isolated and identified: 6-methylsulphinylhexylglucosinolate (glucohesperalin), 3,4-dihydroxybenzylglucosinolate (glucomatronalin), 3-O-apiosylglucomatronalin, a 3,4-dihydroxybenzoylester and a 3,4-dimethoxybenzoylester of 3-O-apiosylglucomatronalin. The three glucosinolates containing apiose were powerful feeding stimulants forC. inaffectatus while the other host plant compounds and allyglucosinolate (sinigrin), 3-methylsulphinylpropylglucosinolate (glucoiberin), benzylglucosinolate (glucotropaeolin) and p-hydroxybenzylglucosinolate (sinalbin) were weaker stimulants. The role of glucosinolates in host plant selection ofC. inaffectatus and related monophagous crucifer feeders is discussed.
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  • 8
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    Entomologia experimentalis et applicata 70 (1994), S. 217-225 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; Leptinotarsa decemlineata ; Colorado potato beetle ; Solanaceae ; Solanum berthaultii ; plant resistance ; glandular trichomes ; host preference ; behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Choice and no-choice studies were conducted to determine how the glandular trichomes of the wild potato,Solanum berthaultii Hawkes, affect host preference of the Colorado potato beetle,Leptinotarsa decemlineata (Say). Given a feeding choice betweenS. tuberosum andS. berthaultii, larvae and adults preferred the foliage ofS. tuberosum, but adults were more discriminating. When foliage ofS. berthaultii was appressed toS. tuberosum leaflets, fewer adults fed on the appressed leaflets. When given a choice between ‘trichome-intact’ and ‘trichome-removed’S. berthaultii foliage, adults preferred to feed on the latter. The preference for ‘trichome-removed’ foliage and the percent of adults initiating feeding, increased with the degree of trichome removal. These studies provide evidence that the resistance ofS. berthaultii is associated with feeding deterrents localized in the glandular trichomes, thatS. berthaultii possesses more than one mechanism of resistance to the Colorado potato beetle, and that the expression of resistance is dependent on the developmental stage of the insect.
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  • 9
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    Entomologia experimentalis et applicata 63 (1992), S. 101-102 
    ISSN: 1570-7458
    Keywords: Cnaphalocrosis medinalis ; rice leaffolder ; Oryza sativa ; rice ; photosynthesis ; transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 10
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    Entomologia experimentalis et applicata 63 (1992), S. 81-86 
    ISSN: 1570-7458
    Keywords: Laboratory bioassay ; olfactometer ; olive bark beetle ; Phloeotribus scarabaeoides ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bioassay conditions with a glass olfactometer for the olive bark beetle, Phloeotribus scarabaeoides Bern. (Coleoptera: Scolytidae), have been investigated. The best temperatures and light intensities were between 17 and 28° C and 1000 and 1500 lux, respectively. The best response was obtained with newly emerged individuals from reproduction galleries with no feeding period.
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  • 11
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    Entomologia experimentalis et applicata 65 (1992), S. 129-140 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Carabidae ; Bembidion lampros ; Pterostichus cupreus ; P. melanarius ; diet ; egg production ; egg size variation ; pirimicarb ; fat reserves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Egg size was measured at different rates of egg laying in three polyphagous carabid species, known to be useful predators of cereal aphids; the small Bembidion lampros Herbst and the medium-sized Pterostichus cupreus L. and P. melanarius Illiger. Variations in fecundity, as well as the ability of the medium-sized species to also build up fat reserves, were obtained when beetles were subjected to different dietary regimes consisting of aphids, or foods with a lower or higher protein content. Egg size was found to be dependent on the rate of egg laying within a species. A diet of cereal aphids appeared to be adequate for egg production in these polyphagous carabids, but female P. cupreus were unable to build up fat reserves when they ingested aphids contaminated with the aphicide pirimicarb. Beetles were able to devote resources to more and larger eggs (B. lampros), or to larger eggs and/or fat reserves (P. melanarius/P. cupreus) when given access to a carbohydrate-rich food with low protein content. The highest rate of egg laying was obtained when female P. cupreus and P. melanarius were given a more varied diet at frequent intervals; including regular shifts between unsprayed aphids, carbohydrate-rich food and protein-rich maggots. Within the varied diet treatment a negative relationship was obtained between egg size and egg number among similar-sized individuals of P. cupreus and P. melanarius; females producing the largest number also laid the smallest eggs. Egg size affected larval survival, since first instars hatching from large eggs were found to survive longer than those hatching from small eggs. The influence of differences in food intake on reproduction, maintenance metabolism, and survival of fieldinhabiting carabids is discussed.
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  • 12
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    Entomologia experimentalis et applicata 65 (1992), S. 235-240 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Tenebrionidae ; Pterohelaeus darlingensis ; Gonocephalum macleayi ; false wireworms ; sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Counts of adults of the false wirewormsGonocephalum macleayi (Blackburn) andPterohelaeus darlingensis Carter in pitfall traps in burnt, mulched and sorghum treatments conformed to Taylor's power law. Within a species there were no significant differences in distributions of counts of either sex in any habitat butG. macleayi were more aggregated thanP. darlingensis (Taylor'sb 1.35 and 1.26, respectively). Relationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines for sequential sampling are developed for each species using Taylor's parameters for combined data over all habitats.
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  • 13
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    Entomologia experimentalis et applicata 65 (1992), S. 247-257 
    ISSN: 1570-7458
    Keywords: Population genetics ; microgeographic differentiation ; leaf-beetles ; Chrysomelinae ; Coleoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We usedF-statistics to quantify the population structure of two sympatric species of leaf beetles,Oreina cacaliae andO. speciosissima (Chrysomelinae, Coleoptera), which share the same microhabitat since they feed on the same herbaceous host plants. We measured genetic differentiation at six allozyme loci 1) among populations separated by relatively small distances (40 to 250 kilometers), 2) within each population, and 3) between sexes within populations. For both species, the populations studied are not panmictic. For each population, heterozygosities are relatively high, but the observed heterozygosities are generally lower than the expected values. Overall, within-population differentiation is high and similar for both species (F is=0.326 forO. cacaliae and 0.332 forO. speciosissima). Additionally, populations of both species are highly differentiated (F st=0.234 versus 0.051 forO. speciosissima). ForO. cacaliae,F is andF st are greater among females than among males, while forO. speciosissima,F st is sustantially greater among the males whileF is is slightly greater among males. Differences in gene frequency among the sexes were statistically tested using a modifiedF st with sex as the defining category, and the sexes differed significantly with the exception of one population inO. cacaliae. Possible explanations for this difference are discussed.
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  • 14
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    Entomologia experimentalis et applicata 66 (1993), S. 161-169 
    ISSN: 1570-7458
    Keywords: avoidance behaviour ; capture efficiency ; Coleoptera ; time-lapse video ; visual recording
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pitfall trap capture forSitophilus oryzae (L.),S. zeamais (Motschulsky),S. granarius (L.),Tribolium confusum (Duval),T. castaneum (Herbst);Oryzaephilus surinamensis (L.),Cryptolestes pusillus (Schonherr),Rhyzopertha dominica (Fabr.), andProstephanus truncatus (Horn) in millet was assessed by visual and time-lapse video recordings. The behaviour of different beetle species in arenas containing millet was monitored over 24 h and the frequency of encounters with the trap rim resulting in capture recorded. The capture efficiency of four types of pitfall traps (i.e. polystyrene, polythene, glass and tin-plated steel can) with rims exposed or submerged below the millet surface level were compared. Capture was related to beetle size, locomotory rate, and beetle behaviour at the trap rim as well as trap design and placement. The lighter and smaller species were least captured. Glass jars were more effective than plastic and metal containers. Traps placed with their rims submerged below the grain surface level were more efficient than those with rims exposed. Capture rate was unrelated to trap size. The frequency of encounters with trap rims was not correlated with capture rate. Three types of avoidance behaviours at the trap rims i.e. probing, skirting and spontaneous retreat, were related to capture rate, spontaneous retreat being the most effective escape mechanism and probing least.
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  • 15
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    Entomologia experimentalis et applicata 65 (1992), S. 39-47 
    ISSN: 1570-7458
    Keywords: Development ; fecundity ; geographical variation ; Coleoptera ; Bruchidae ; ecology ; Phaseolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zabrotes subfasciatus (Boheman) (Coleoptera:Bruchidae) is native to parts of Central and South America but has now been spread to many others areas. It commonly infests the seeds of both Lima beans, Phaseolus lunatus, and common beans, Phaseolus vulgaris. Five geographic populations were found to differ in fecundity, patterns of egg distribution, times of development and adult sizes when they were kept under the same conditions. Each population also differed unpredictably from the others in its response to different cultivars of host seed. These differences have been shown to be of considerable importance in determining the potential pest status of the populations and should also promote caution in making predictions about the responses of different populations to new cultivars of bean for agricultural use.
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  • 16
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    Entomologia experimentalis et applicata 66 (1993), S. 191-196 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata (Say) ; Coleoptera ; Chrysomelidae ; distribution ; diapause ; overwintering ; mortality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 17
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    Entomologia experimentalis et applicata 70 (1994), S. 201-208 
    ISSN: 1570-7458
    Keywords: Sitophilus oryzae ; S. zeamais ; Coleoptera ; Curculionidae ; flight activity ; symbiosis ; vitamin ; amino acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les performances de vol de nombreuses souches deSitophilus oryzae L. etS. zeamais Mots. (Coleoptera, Curculionidae) ont été comparées sur blé. Il s’avère que les mâles sont plus actifs que les femelles et queS. zeamais possède une meilleure aptitude au vol queS. oryzae. De plus, dans les deux espèces élevées sur blé, seuls les charançons normalement symbiotiques sont capables de voler, tandis que les aposymbiotiques ont perdu ce pouvoir. En complémentant la nourriture avec des vitamines (acide pantothénique et riboflavine) et certains acides aminés (phénylalanine et proline), cette activité a pu être restaurée en partie. L’influence de la symbiose sur l’aptitude au vol du charançon du genreSitophilus est commentée en fonction du métabolisme énergétique (coenzymes, proline) et du rôle joué par la symbiose dans ce comportement qui permet d’augmenter la dissémination de l’espèce.
    Notes: Abstract The flight activity (take-off) of various strains ofSitophilus oryzae L. andS. zeamais Mots. (Coleoptera, Curculionidae) have been compared on wheat. It was shown that males are more active than females and thatS. zeamais, is more active thanS. oryzae. Furthermore, in the two species, when reared on wheat kernels, only symbiotic weevils were able to fly, while aposymbiotic insects did not. By supplementation of the diet with vitamins (pantothenic acid, riboflavin) and amino acids (phenylalanine and proline), this activity could be restored in part. The influence of symbiosis on the flight ability ofSitophilus weevil is discussed in relation to the energy metabolism (coenzymes, proline), the role played by symbiosis in this behaviour and its possible effect on the dissemination of the species.
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  • 18
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    Entomologia experimentalis et applicata 73 (1994), S. 39-50 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata ; Coleoptera ; Chrysomelidae ; distribution ; overwintering ; diapause ; cultural control ; trap cropping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Overwintering Colorado potato beetles (Leptinotarsa decemlineata (Say)) were concentrated primarily within woody borders, and mortality was lower in borders than in potato fields. After overwintering, only 15–44% of live beetles were in the potato fields. In experiments with small plots, colonization of fields from woody borders was reduced ∼60% by a trap crop, either treated with adulticide or with beetles collected daily. Such trap crops, or simply pitfall traps to prevent colonization from woody borders, could significantly reduce early-season adult numbers and subsequent larval populations. However, success is dependent on the local densities of overwintered beetles, and the prevalence of arrestment behavior in the case of trap crops.
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  • 19
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; Leptinotarsa decemlineata ; Colorado potato beetle ; Solanaceae ; Solanum berthaultii ; potato ; plant resistance ; selection ; adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thirty cohorts of the Colorado potato beetle (CPB) were reared for ten consecutive generations on the cultivated potato,Solanum tuberosum, and on two accessions (PI 473331 and PI 473334) of the resistant wild species,S. berthaultii. At each generation, selection was imposed for increased survival, decreased development time, and for increased fecundity. Although several parameters responded to selection, net replacement rate (R0) onS. berthaultii was consistently less than 1/3 that on cultivated potato. At the tenth generation, eachS. tuberosum strain female replaced herself with 110 daughters, whereas females from strains reared on PI 473334 and PI 473331 produced an average of 30 and 7 daughters, respectively. Slopes of the R0 regression lines for populations reared onS. tuberosum andS. berthaultii did not differ from zero, indicating no significant response to selection. Our findings suggest that populations of the Colorado potato beetle may have genetic variability in some performance traits for adaptation toS. berthaultii, but that adaptation is unlikely to occur as rapidly as previously reported.
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  • 20
    ISSN: 1570-7458
    Keywords: Pterostichus melanarius ; Coleoptera ; Carabidae ; pitfall traps ; insecticides ; prey ; hunger ; activity ; Rhopalosiphum padi ; Fenitrothion ; Sumicidin (Fenvalerate) ; spring barley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Au cours d'essais à grande échelle, effectués en 1981 et 1982, sur orge de printemps, pour évaleur l'effet des insecticides Fenitrothion et Sumicidine (fenvalerate) sur les arthropodes utiles, un accroissement significatif des captures, dans des trappes pièges de Barber, de Pterostichus melanarius (Illiger) a été observé plusierus semaines après le traitement dans les lots traités par rapport aux lots témoins. Significativement plus de femelles de P. melanarius ont été capturées dans les parcelles traitées pendant cette période d'accroissement après traitement. Une diminution correspondante dans les populations de proies a été observée à la suite des traitements. Chaque femelle de P. melanarius des parcelles traitées avait une fraction significativement moins importance de son intestin remplie d'aliments solides (arthropodes) que celles des parcelles non traitées. Des auteurs précédents avaient observé des taux de capture plus rapides dans les trappes et ne plus grande mobilité des carabes affamés. La réduction des populations proies par l'application d'insecticides affamerait les carabes dont l'activité serait par suite plus élevée. Comme le taux de captures dans les trappes est dû à la fois à la taille de la population et à son activité, on en déduit que la capture par trappes seule ne peut donner une image exacte de l'effet des insecticides sur les populations de carabes dans les champs.
    Notes: Abstract During large-scale field experiments in 1981 and 1982, designed to assess the effects of the insecticides Fenitrothion and Sumicidin (Fenvalerate) on beneficial arthropods in spring barley, significant increases in pitfall-trap catches of Pterostichus melanarius (Illiger) were observed in treated plots compared to untreated controls, several weeks after treatment. Significantly more female P. melanarius were caught in treated plots during these post-treatment increases. Corresponding decreases were observed in prey populations following treatments. Individual female P. melanarius from treated plots had significantly fewer of their gut areas full of solid (arthropod) food when compared to those from untreated control plots. Earlier workers observed both faster recapture rates in pitfalls and higher mobility in hungry carabid beetles. The following hypothesis is suggested: reducing prey populations by the application of insecticides results in hungrier carabid beetles with consequently higher activity. Since pitfall-trap catch is determined not only by population size but also activity, it is argued that pitfall-trap catches alone cannot give a true measure of the effects of insecticides on carabid populations in the field.
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  • 21
    ISSN: 1572-8889
    Keywords: firefly ; entrainment ; insect communication ; Coleoptera ; aggressive mimicry ; bioluminescence ; Lampyridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract FemalePhoturis versicolor fireflies attempt to capture males by responding to heterospecific flash patterns. A mating-dependent switch occurs which affects response timing and frequency of female flashes. We examined the switch using females of known age, mating status, and flash experience to assess how accurate mimicry is, what factors influence it, and what mechanism produces it. Presentations of simulated male flash patterns before and after mating revealed elements of an entrainment mechanism controlling female responsiveness. Unmated females preferentially answered conspecific patterns with variable latencies, averaging 1 s. Mating induced changes in both response frequency and response latency: Females answered heterospecific patterns more frequently, and latencies elicited by conspecific patterns shifted away from the unmated range. Heterogeneity in mean and variance of response latency among individuals indicates that females do not share a discrete reply to a given pattern. Little correspondence exists between latencies of sympatric species andP. versicolor females, suggesting that the flash response mechanism produces entriainment to any rhythmic pattern, not a one-to-one matching between prey and predator latencies. Different selective scenarios underlie strict mimicry versus entrainment mimicry.
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  • 22
    ISSN: 1572-8889
    Keywords: Coleoptera ; Scarabaeidae ; Cotinis nitida (L.) ; beetle flight ; pheromone bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 23
    ISSN: 1572-8773
    Keywords: Chorella vulgaris ; acid tolerance ; ATPase ; nickel toxicity ; nutrient uptake ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract This study concerns the inhibitory effects of acid pH and nickel on growth, nutrient (NO3 - and NH4 +) uptake, carbon fixation, O2 evolution, electron transport chain and enzyme (nitrate reductase and ATPase) activities of acid tolerant and wild-type strains of Chlorella vulgaris. Though a general reduction in all these variables was noticed with decreasing pH, the tolerant strain was found to be metabolically more active than the wild-type. A reduced cation (NH4 +, Na+, K+ and Ca2+) uptake, coupled with a facilitated influx of anions (NH4 +, PO4 3- and HCO3 -), suggested the development of a positive membrane potential in acid tolerant Chlorella. Nevertheless, a tremendous increase in ATPase activity at decreasing pH revealed the involvement of superactive ATPase in exporting H+ ions and keeping the internal pH neutral. A difference in Na+ and K+ efflux of the two strains at decreasing pH suggests there is a difference in membrane permeability. The low toxicity of Ni in the acid tolerant strain may be due to the low Ni uptake brought about by a change in membrane potential as well as in permeability. Hence, the development of superactive ATPase and a change in both membrane potential and permeability not only offers protection against acidity, but also co-tolerance to metals.
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    Entomologia experimentalis et applicata 59 (1991), S. 75-78 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata Say ; Coleoptera ; Chrysomelidae ; female sex pheromone ; screening method ; mating behaviour ; tactile stimuli
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    Entomologia experimentalis et applicata 54 (1990), S. 219-224 
    ISSN: 1570-7458
    Keywords: Diabrotica virgifera virgifera ; Coleoptera ; Chrysomelidae ; corn ; life-stage occurrence ; planting date
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    Topics: Biology
    Description / Table of Contents: Résumé Dans les conditions de l'est du Sud Dakota (USA), 3 dates de semailles de maïs et 3 dates de contamination avec des œufs de D. virgifera virgifera LeConte ont servi à imposer ou à empêcher la synchronisation des éclosions des œufs et par conséquent des développements ultérieurs. Les dates médianes d'apparition de chacun des 3 stades larvaires et des imagos ont été déterminées en relation avec les unités de température et le nombre de jours depuis la contamination. Aucune différence significative entre les dates médianes d'apparition n'a été mise en évidence par utilisation des unités de température; par contre, ces différences deviennent significatives lorsque l'on utilise le nombre de jours depuis la contamination. Des paramètres fiables sont nécessaires pour prédire la présence des différentes stades de cet insecte. En dépit des différentes conditions imposées pour cette étude, la méthode la moins capricieuse pour prédire l'apparition d'un stade larvaire et l'émergence des adultes est la somme de températures avec une base de 11°C.
    Notes: Abstract Under field conditions in eastern South Dakota, USA three different planting dates of corn and three times of egg infestation were used to imposed synchronous and asynchronous timing of corn growth and Diabrotica virgifera virgifera LeConte egg hatch and subsequent development. Median occurrence of each of the three larval stages and of the adult stage for each of the infestation-planting treatments was determined by relating occurrence to thermal units and to days after infestation. No significant differences were found among the treatments for median occurrence of each life stage when the thermal unit approach was used. However, significant differences were found among treatments for median occurrence when the day after infestation approach was used. Consistent parameters are needed for prediction of the occurrence of life stages of this insect. Despite the various imposed conditions, this study indicates that the least variable method of predicting life stage occurrence and adult emergence of D. v. virgifera was the use of thermal unit accumulations (base 11°C).
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    Entomologia experimentalis et applicata 68 (1993), S. 9-13 
    ISSN: 1570-7458
    Keywords: bioassay ; behavioural response ; Coleoptera ; carob extract ; stored product
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    Topics: Biology
    Notes: Abstract The behavioural responses ofCryptolestes pusillus Oryzaephilus surinamensis andProstephanus truncatus to different doses of carob extract were assessed in a two-choice pitfall bioassay and in plastic grain probe traps. The extract evoked a quick directional response and induced high beetle attraction to treated pitfall arenas compared with the controls. Overall, the extract improved probe trap efficiency by about 50% compared to unbaited probes. Beetle response was dose-dependent with the medium dose of 10 μl probably eliciting optimum response.
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    Aquatic sciences 53 (1991), S. 263-272 
    ISSN: 1420-9055
    Keywords: Lake ecosystem ; chl-a ; phosphorus ; nitrogen ; river flow ; thermocline ; simulation model ; multiple regression
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    Topics: Biology
    Notes: Abstract The management variables which primarily affect phytoplankton biomass (as chl-a) in Lake Mjøsa, Norway, are total phosphorus loading (TP) and the timing and volume of water through flow (by active storage reservoirs). The response of the lake to changes in these factors is studied using a simulation model of the lake ecosystem. Chl-a responses from both observed data and the simulated results are extracted by multiple regression. Results show that decreasing TP load decreases chl-a, but less at low TP levels (〈 10 mg TP · m−3). There is also a certain time period for peak river flow which gives the least yield of chl-a per unit TP. This time period occurs in early summer (i.e., around June 10) if the total phosphorus load is low, and later if the load is high. Both observations and simulation results show that a high water flow increases chl-a at low epilimnion depths (〈 15 m), but that the same high water flow decreases chl-a when epilmnion is deep.
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    Cellular and molecular life sciences 46 (1990), S. 700-704 
    ISSN: 1420-9071
    Keywords: Coleoptera ; Tenebrionidae ; Tribolium confusum ; defesive secretion ; biosynthesis of 1-alkenes ; oxidative decarboxylation ; anti-elimination
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    Topics: Biology , Medicine
    Notes: Summary The terminally unsaturated hydrocarbons of the defensive secretion ofTribolium confusum are biosynthesized from fatty acids by oxidative decarboxylation. The process involves an enantiospecific cleavage of the C−H bond of thepro-(S) C(3)−H atom and simultaneous decarboxylation of the acid into an 1-alkene and carbon dioxide via ananti-periplanar transition state geometry (anti-elimination). The stereochemistry of this biotranformation is identical in all respects with the same reaction in higher plants. The mechanism seems to be of general importance for the biosynthesis of many vinylic substructures of natural products from oxygen-containing precursors.
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    Cellular and molecular life sciences 49 (1993), S. 171-174 
    ISSN: 1420-9071
    Keywords: Coleoptera ; Meloidae ; Epicauta funebris ; chemical defense ; biosynthesis ; terpenoid
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    Topics: Biology , Medicine
    Notes: Abstract Cantharidin, a potent defensive chemical, is present in all ten life stages of the blister beetleEpicauta funebris. The first five larval stages accumulate cantharidin as they feed and grow in size. When disturbed, they exude cantharidin in a milky oral fluid, not in hemolymph which adult beetles reflexively discharge from leg joints. Two subsequent larval stages and the pupa do not feed, grow, regurgitate, or change in their defensive reserves (110 μg cantharidin/insect, regardless of sex). Adult beetles kept in isolation for 60–90 d exhibit a pronounced sexual dimorphism in cantharidin production: the male biosynthesizes about 17 mg of the toxin, representing 10% of his live weight, whereas the female actually loses most of her defensive reserves. But in the wild a female beetle repeatedly acquires cantharidin as copulatory gifts from her mates.
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    Cellular and molecular life sciences 49 (1993), S. 272-275 
    ISSN: 1420-9071
    Keywords: Semiochemical ; pheromone ; host selection ; competition ; Coleoptera ; Scolytidae
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    Topics: Biology , Medicine
    Notes: Abstract Bark beetles,Ips typographus andPityogenes chalcographus, attracted by synthetic or natural pheromone to Norway spruce logs,Picea abies, preferred to colonize uninfested logs rather than logs occupied by these beetles, probably as a means of avoiding intra-and interspecific competition. The aggregation pheromone components ofP. chalcographus, chalcogran and methyl (E, Z)-2,4-decadienoate, inhibited the attraction response ofI. typographus to its pheromone components (methyl butenol andcis-verbenol), while the converse was not true. However, verbenone released from colonized bark inhibited pheromonal response ofP. chalcographus.
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  • 31
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    Aquatic sciences 52 (1990), S. 199-220 
    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; ecosystem ; chlorophyll-a ; mathematical modelling
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    Topics: Biology
    Notes: Abstract We compare results of a new model for predicting the short term inter annual changes in chlorophyll-a (chl-a) in lakes after reductions in total phosphorus (TP) to predictions made by least squares regression models. In the new method, slopes of chl-a/TP graphs (both axes in mg · m−3) are depicted in frequency diagrams and used to extract information on the expected, short term chl-a/TP response. The short term response for nine shallow (〈 10 m deep) and nutrient rich lakes to changes in TP was found to be: Chl-a = 0.49 · TP + 17.3, and for nine deep, P-limited lakes: Chl-a = 0.08 · TP + 3.5. If the TP-reduction is known to be greater than 10 mg · m−3, the expected slope increases to 0.58 for shallow lakes and to 0.26 for deep lakes. The slope, 0.58, is 8% lower than the slope for the long term response calculated by regression for the shallow lakes. For deep lakes the slope, 0.26, is 2 to 3 times higher than that calculated by regression, indicating that reductions in TP for deep lakes give greater effects than least squares regression equations suggest. We have also calculated the reduction in TP which will give about 80% probability that a reduction in chl-a will be observed next year. For shallow, P-limited lakes this reduction is about 30 mg · m−3 (5% of average initial in-lake TP concentration), and for deep lakes about 14 mg · m−3 (35% of average initial in-lake TP concentration).
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    Aquatic sciences 52 (1990), S. 256-268 
    ISSN: 1420-9055
    Keywords: Vertical mixing ; stratification ; phosphorus ; Lake Constance
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    Notes: Abstract Depth variable vertical eddy diffusion coefficients for heat (K z) were calculated from continuously measured temperature profiles in Überlinger See (western part of Lake Constance). The temperatures were averaged over vertical intervals of 10 m yielding 14 discrete values (maximum depth of Überlinger See: 147 m). A linear fit from 10 June to 29 September 1987 was used to smooth the significant temperature fluctuations caused by internal seiches of Lake Constance. Assuming horizontal homogeneity for the smoothed data the Gradient-Flux-Method was applied to compute vertical diffusion coefficientsK z at different depths using the depth variable volumes and surfaces of the 14 layers. The resulting mean diffusion coefficients for the period from June to September are 0.04 cm2/s near the thermocline and up to 0.8 cm2/s in deeper strata (accuracy: ± 50%). It is shown that horizontal mixing between Überlinger See and Obersee (main lake) alters the computation ofK z by less than 50%. A relationship betweenK z and stability (Brunt-Väisälä) frequencyN is found which corresponds well to the theory of internal wave induced turbulence. Combining the diffusion coefficients with measured phosphorus profiles, a phosphorus flux from the hypolimnion to the epilimnion of (0.7 ± 0.4) mg P m−2 d−1 was calculated, corresponding to about 20% of the average external loading per area of Lake Constance in 1986.
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  • 33
    ISSN: 1420-9055
    Keywords: Phytoplankton ; primary production ; photosynthesis ; optics ; adaptation
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    Notes: Abstract This tutorial was designed for nonbiologists requiring an introduction to the nature and general timescales of phytoplankton responses to physical forcing in aquatic environments. As such, an effort was made to highlight biological markers which might assist in identifying, measuring and/or validating physical processes controlling the variability in the distribution, abundance, composition and activity of phytoplankton communities. Given the recent advances in environmental optics and remote sensing capabilities, a special emphasis was placed on the nature and utility of phytoplankton optical properties in current bio-optical modelling efforts to predict temporal and spatial variability in phytoplankton productivity and growth.
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  • 34
    ISSN: 1420-9055
    Keywords: Sediment ; interstitial water ; phosphorus ; iron ; persulfate digestion
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    Notes: Abstract It is shown that sorption of orthophosphate to iron compounds, formed during persulfate digestion, can cause a significant underestimation of total dissolved phosphorus in interstitial waters rich in iron and poor in phosphorus. Labelling the samples with carrier free32PO4 before digestion allows to correct for these losses.
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    Entomologia experimentalis et applicata 30 (1981), S. 151-156 
    ISSN: 1570-7458
    Keywords: Xyleborus ferrugineus ; pupae ; ecdysteroids ; pharate adult ; radioimmunoassay ; Coleoptera ; Scolytidae
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    Topics: Biology
    Description / Table of Contents: Zusammenfassung Der Ecdysteroidtiter weiblicher Puppen von Xyleborus ferrugineus (Fabr.) wurde geschätzt, indem ganze Tiere homogenisiert und radioimmunologisch untersucht wurden. Ein ausgeprägtes Maximum an Ecdysteroiden wurde bei 36 Stunden Puppenent-wicklung beobachtet (743 pg/mg Körpergewicht). Der Titer nahm ab auf 299 pg/mg im Pharatstadium und auf 193 pg/mg unmittelbar vor Schlüpfen der Adulten. Qualitative Studien mit HPLC ergaben in frischen Puppen ein Verhältnis von 3:1 Ecdyson zu 20-Hydrooxyecdyson. Pharatstadien enthielten vor allem 20-Hydrooxyecdyson. Das beobachtete einzige Maximum im Titer stimmt überein mit den Resultaten bei andern untersuchten Coleopteren.
    Notes: Abstract Ecdysteroid titers were estimated on the whole body homogenates of Xyleborus ferrugineus (Fabr.) female pupae during development by radioimmunoassay. A distinct peak of ecdysteroids was observed at 36-hr pupal development (743 pg/mg body wt). Titer declined to 299 pg/mg by the pharate adult stage and to 193 pg/mg body wt just before adult emergence. Qualitative studies by HPLC revealed a ratio of 3:1 ecdysone to 20-hydroxyecdysone in the initial pupal stage. Pharate adults had mainly 20-hydroxyecdysone. The observed single peak in ecdysteroid titer agrees with findings in other studied coleopteran species.
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    Entomologia experimentalis et applicata 34 (1983), S. 291-296 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Curculionidae ; Cyrtobagous ; Salvinia weevil ; Feeding characteristics of larvae ; Development of larvae ; Plant nutrition ; Temperature effects on development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Après leur naissance, les larves de Cyrtobagous sp. passent de 1 à 4 jours à brouter les racines, et de 0 à 9 jours dans les bourgeons de la plante hôte, Salvinia molesta, avant d'y creuser une galerie dans le rhizome. Bien que les larves aient été capables de survivre jusqu'à 38 jours en broutant les racines, quant elles furent privées de rhizome, elle ne purent achever leur développement. Quand les galeries furent commencées, le développement larvaire, entre 21° et 31°, dépendit de la température et de la teneur en azote de l'hôte. Les larves ne se développèrent pas à 17°. Une haute valeur nutritive de l'aliment consommé par les larves réduisit la durée du développement, mais n'influença pas la durée ultérieure de leur développement nymphal. Les lieux de prise de nourriture et les dégâts produits par des larves isolées furent précisés.
    Notes: Abstract Newly-emerged larvae of a salvinia weevil, Cyrtobagous sp. spent from 1–4 days browsing on the roots and from 0–9 days in the buds of the host plant, Salvinia molesta, prior to tunnelling into the rhizome of this aquatic weed. Although larvae were able to survive up to 38 days browsing on roots when rhizomes were withheld, they were unable to complete development. After tunnelling began, larval development between 21° and 31° was dependent on temperature and nitrogen levels in the host. Larvae failed to develop at 17°. High nutritional intake by the larvae reduced larval development time but did not influence duration of their subsequent pupal development. The feeding sites and plant damage produced by individual larvae were assessed.
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    Entomologia experimentalis et applicata 56 (1990), S. 15-21 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; corn rootworms ; age-specific survival ; age-specific fecundity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé D. virgifera virgifera LeConte a été placé sur des régimes nutritifs mimant l'évolution des tissus du maïs disponsibles dans le champ lorsque les insectes éclosent est aux stades suivants du maïs: 1) après émergence de l'épi mâle, mais avant l'apparition des barbes et l'émission du pollen; 2) lors de la présence de barbes et de l'émission de pollen; 3) après la pollinisation et quand les barbes ont bruni. Un quatrième régime a été fourni pendant toute l'expérience comprenant des barbes vertes, du pollen et des feuilles. Les pontes moyennes des femelles pendant les 12 semaines de l'étude on été 125, 235, 179 et 441 pour les régimes 1, 2, 3 et 4. Les dates de mort de la moitié des adultes a été 7,2, 7,2, 6,7 et 8,8 semaines pour respectivement les mêmes régimes. Les femelles du régime 1 pondent à un âge plus avancé que les femelles des régimes 2 et 3. L'influence des changements de la qualité alimentaire du maïs au fur et à mesure du vieillissement des plantes et deDiabrotica, a été déterminée par la survie au bout de 48 heures d'insectes éclos depuis peu et d'autres maintenus en cage sur des lots de maïs à différents stades poussant en serre depuis des temps plus ou moins longs. Plus les plantes sont âgées, plus la survie des 2 groupes deDiabrotica diminue, mais plus vite chez les lots d'insectes âgés.
    Notes: Abstract Adult corn rootworm beetles,Diabrotica virgifera virgifera LeConte, were maintained on three dietary regimes which mimicked the progression of corn tissues that would be available in the field for beetles eclosing when corn was in the following growth stages: (A) after tassels had emerged but prior to silking and pollen shed; (B) while plants were silking and shedding pollen; and (C) after pollination was complete and silks had turned brown. A fourth regime (D) was established in which green corn silks, pollen, and leaves were provided throughout the study. The mean number of eggs laid per female over the 12-week duration of the study was 125, 235, 179, and 441 for regimes A, B, C, and D, respectively. Median length of life was 7.2, 7.2, 6.7, and 8.8 weeks for regimes A, B, C, and D respectively. Beetles in regime A laid a greater proportion of their eggs at an older age than did beetles from regimes B and C. To further investigate the influences on survival of changes in food quality of corn as plants and beetles aged, newly-eclosed beetles and beetles that had been maintained in caged plots of corn growing in a greenhouse for various lengths of time were caged on corn at different stages of growth, and the proportion of beetles surviving for 48 h was determined. Survival decreased as plants aged for both groups of beetles, but decreased at a faster rate for old than for young beetles.
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    BioMetals 5 (1992), S. 149-156 
    ISSN: 1572-8773
    Keywords: Hg2+ toxicity ; cyanobacterium ; Nostoc calcicola ; growth ; photopigments ; nucleic acids ; photosynthesis ; membrane integrity ; nutrient uptake ; enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Toxicological responses of the filamentous N2-fixing cyanobacteriumNostoc calcicola Bréb. towards Hg2+ were studied to enumerate the decisive lethal events. In low-dose, long-term experiments (0.05–0.25 μm Hg2+, 10 days), photoautotrophic growth was severely inhibited with concurrent loss of photosynthetic pigments (phycocyanin〉chlorophyll α〉carotenoids) and nucleic acids. The termination of growth after a day 4 exposure to 0.25 μm Hg2+ has been attributed to the complete inhibition ofin vivo photosynthetic activity in the cyanobacterium (O2 evolution〉14CO2 incorporation). The elevated Hg2+ concentrations irreversibly damaged the cell membrance as observed under light microscopy, and as indicated by the leakage of intracellular electrolytes and phycocyanin. In high-dose, short-term experiments (0.5–20.0 μm Hg2+, up to 6 h), thein vivo activities of selected enzymes (glutamine synthetase 〉 nitrate reductase 〉 nitrogenase) were less inhibited by Hg2+ than the uptake of nutrient ions (NH 4 + 〉NO 3 − 〉PO 4 3− ).
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  • 39
    ISSN: 1570-7458
    Keywords: Coleoptera ; Curculionidae ; Cylas formicarius elegantulus ; sweetpotato weevil ; sweet potato ; digestion ; enzyme distribution ; trypsin-inhibitors ; resistance
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    Topics: Biology
    Description / Table of Contents: Résumé L'activité endoprotéinase était limitée au liquide de la lumière des régions ventriculaires antérieure et postérieure de l'intestin moyen des larves deCylas formicarius elegantulus Summers. Les aminopeptidases ont été trouvées dans le liquide de la lumière (18%), mais étaient principalement associées avec les fractions insolubles des cellules du ventricule postérieur (82%). Suivant le substrat, l'activité carboxypeptidase était à peu près également répartie entre le liquide de la lumière et les fractions insolubles des cellules du ventricule postérieur. L'amylase, enzyme secrétée, a été observée à la fois dans la lumière antérieure et postérieure. Cinq bandes d'activité amylase ont été révélées sur zymogrammes d'amidon après électrophorèse d'intestins moyens entiers. Trois des bandes d'amylase pouvaient provenir de la plante. Il y avait au moins 2 α-glucosidases, une secrétée et une liée aux cellules du ventricule antérieur. L'activite β-glucosidase était liée aux cellules du ventricule antérieur, fandis que l'activité α-galactosidase était limitée au fluide de la lumière. Les activités β-galactosidase et cellulase ont été trouvées à la fois dans le liquide de la lumière et dans la fraction cellulaire insoluble. Ainsi, la digestion initiale des grosses protéines et des polymères de carbohydrates se produit dans le liquide de la lumière dans les régions ventriculaires antérieure et postérieure. Cependant, l'achèvement de la digestion des oligopeptides se produit principalement dans le ventricule postérieur, tandis que la fin de la digestion des oligosaccharides se produit dans le ventricule antérieur. Les concentrations en inhibiteurs de trypsine de 5 cultivars d'I. batatas L. diffèrent de 1 à 20. Les endoprotéinases deC. formicarius elegantulus ont été inhibées par des extraits de cultivars, mais les cultivars avec des concentrations relativement élevées d'inhibiteur avainent antérieurement montré être susceptibles d'être attaqués par le coléoptère dans des essais en champs.
    Notes: Abstract Endoproteinase activity was confined to luminal fluid from anterior and posterior ventricular regions of midguts of larvae of the sweetpotato weevil,Cylas formicarius elegantulus (Summers). Aminopeptidase was found in luminal fluid (18%) but was primarily associated with insoluble fractions from cells of the posterior ventriculus (82%). Depending on substrate, carboxypeptidase activity was about equally distributed between luminal fluid and insoluble fractions from posterior ventriculus cells. Amylase was found in luminal fluid in both the anterior and posterior ventriculus. Five bands of amylase activity were detected on starch zymograms following electrophoresis of whole midgut samples. Three of the amylase bands may be plant-derived. At least two α-glucosidases were present, one secreted and one bound to anterior ventriculus cells. β-Glucosidase activity was bound to anterior ventriculus cells whereas α-galactosidase activity was confined to luminal fluid. β-Galactosidase and cellulase activities were found in both luminal fluid and the insoluble cell fraction. Thus, initial digestion of large protein and carbohydrate polymers occurs in luminal fluid in both anterior and posterior ventriculus regions. However, terminal digestion of oligopeptides occurs primarily in the posterior ventriculus while terminal digestion of oligosaccharides occurs in the anterior ventriculus. A 20-fold difference in trypsin-inhibitor concentration was found among five sweetpotato cultivars. Endoproteinases from sweetpotato weevil larvae were inhibited by extracts from the cultivars but cultivars with relatively high concentrations of inhibitor were previously shown to be susceptible to weevil attack in field trials.
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    Entomologia experimentalis et applicata 34 (1983), S. 124-126 
    ISSN: 1570-7458
    Keywords: Negret ; Melanic mutant ; X-linked mutation ; Flour Beetle ; Tribolium confusum ; Coleoptera
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  • 41
    ISSN: 1570-7458
    Keywords: Storage pests ; Coleoptera ; Bostrichidae ; Prostephanus truncatus ; (±)-1-methylbutyl (E)-2-methyl-2-pentenoate ; Rhyzopertha dominica ; (±)-1-methyl-butyl (E)-2,4-dimethyl-2-pentenoate ; Dominicalure ; Aggregation pheromone ; Monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les réponses de Prostephanus truncatus Horn (Coleoptera: Bostrichidae) à deux constituants de la phéromone d'agrégation de Rhyzopertha dominica Fabricius (Coleoptera: Bostrichidae), le (±)-1-méthylbutyl (E)-2-méthyl-2-penténoate et le (±)-1-méthylbutyl (E)-2,4-diméthyl-2-pentéoate, connus comme “Dominicalure 1” et “Dominicalure 2”, ont été étudiées au laboratoire et au champ. Auslaboratoire ces composés ont été essayés individuellement et en mélange 1:2. Une membrane de caoutchouc imprégnée de phéromone a été utilisée comme émetteur lent, et une courbe de réponse en fonction de la dose a été établie. P. truncatus répondait plus vigoureusement à la Dominicalure 2 seule. Tous ces traitements ont été comparés dans un essai aux champs en Tanzanie, dans lesquels des pièges en carton ondulé contenant des diffuseurs de phéromone étaient placés dans des entrepôts de maïs dans les fermes. La Dominicalure 1 et le mélange de 1 et 2 étaient tous deux efficaces pour piéger R. dominica. La Dominicalure 2 a piégé plus de P. truncatus que les autres traitements et était à peu près aussi efficace que le contrôle visuel pour détecter la présence de cet insecte dans les stocks. On peut envisager que la Dominicalure 2 pourrait servir de base à un programme pour lutter contre P. truncatus en Afrique de l'Est.
    Notes: Abstract Laboratory and field studies have been made of the responses of Prostephanus truncatus (Horn) to two components of the aggregation pheromone of Rhyzopertha dominica (Fabricius) — (±)-1-methylbutyl (E)-2-methyl-2-pentenoate and (±)-1-methylbutyl (E)-2,4-dimethyl-2-pentenoate, known as “Dominicalure 1” and “Dominicalure 2” respectively. In the laboratory, these compounds were tested individually and as a 1:2 mixture; P. truncatus responded most strongly to Dominicalure 2 alone. All three treatments were compared in a field trial in Tanzania to monitor both R. dominica and P. truncatus in farm stores. Dominicalure 1 or a mixture of 1 and 2 were both highly effective for trapping R. dominica. In contrast, Dominicalure 2 trapped more P. truncatus than the other treatments and was about as effective as visual inspection at demonstrating the presence of the beetle in stores. Dominicalure 2 could form the basis of a monitoring programme for P. truncatus in East Africa.
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    Entomologia experimentalis et applicata 61 (1991), S. 255-263 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Bruchidae ; Bruchidius atrolineatus ; larval crowding ; post-embryonic development ; intracotyledonary mortality ; weight of emerging adults ; reproductive diapause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Chez Bruchidius atrolineatus, l'accroissement de la densité larvaire à l'intérieur de la graine entraîne une augmentation de la mortalité alors que la réduction de poids des individus à l'émergence est relativement limitée. L'accroissement de la densité larvaire provoque une augmentation du taux d'adultes en diapause reproductrice, dans certaines conditions thermopériodiques. Dans d'autres conditions, permenttant l'émergence d'un fort taux d'adultes diapausants, l'effet de la densité larvaire est nul. Lorsque l'on analyse l'effet de la densité chez les individus d'une souche ne présentant pas de phénomène de diapause, il n'y a pas de corrélation entre la durée de développement et le poids des adultes. Par contre, lorsqu'il y a émergence d'adultes sexuellement actifs et diapausants, il existe une corrélation entre la durée de développement et le poids des adultes émergeants. Cette corrélation est due au fait que les adultes diapausants, qui présentent les durées de développement les plus longues, sont ceux qui ont les poids les plus faibles.
    Notes: Abstract In Bruschidius atrolineatus (Pic), an increase in larval density inside the seed led to a reduction in the survival rate during post-embryonic development, with only a limited decrease in the weight of adults. A high larval density increased the proportion of adults in reproductive diapause under certain thermoperiodic conditions. Under other conditions that already promote the emergence of a high proportion of diapausing beetles, an increase in larval density had no effect on diapause. There was no correlation between the larval developmental time and the weights of adults in a strain with a very low incidence of diapause. However, such a correlation was observed when both sexuallyactive and diapausing beetles emerged. This correlation was explained by the longer developmental times and lower weights of diapausing beetles.
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    Microchimica acta 101 (1990), S. 273-279 
    ISSN: 1436-5073
    Keywords: aluminium analysis ; phosphorus ; sulfur ; chlorine
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Multi-step procedures for the determination of phosphorus, sulfur and chlorine are described and tested against established methods and on reference materials. Phosphorus is separated as hydrogen phosphide, extracted as phosphomolybdic acid, reduced to molydenum blue and measured photometrically (detection limit 0.05 μg/g). Sulfur is separated after reduction as hydrogen sulfide or by means of pyrohydrolysis and measured by ICP-OES (detection limit 0.1 μg/g). Chloride can be measured by ion chromatography after pyrohydrolytic separation (detection limit 0.1 μg/g). The determination of sulfur was also successfully tested on copper and steel samples.
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    Microchimica acta 109 (1992), S. 201-209 
    ISSN: 1436-5073
    Keywords: phosphonate base scale inhibitor ; brine ; direct current plasma ; inductively coupled plasma atomic emission spectrometry ; phosphorus
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The determination of phosphonate base scale inhibitors in brines by direct current plasma (DCP) and inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. The first method is based on a direct nebulization of the brine samples and plasma using the phosphorus line at 213.618 nm. The second method involves extraction of phosphorus as phospho-antimonyl molybdate complex into methylisobutyl ketone (MIBK) phase and analysis of the extract for molybdenum using the Mo 313.260 nm line. Comparison between the proposed methods and an established recommended method [1] shows excellent agreement between the results in addition to the sensitivity and ease of automation provided by AES.
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  • 45
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
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    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
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    Nutrient cycling in agroecosystems 1 (1980), S. 95-101 
    ISSN: 1573-0867
    Keywords: soil fertility ; phosphorus ; potassium ; green manure ; crop rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Changes in the soil phosphorus and potassium status on three farming systems in the Northeast Polder during 25 years are related to the fertilizer regime over this period. The changes in the nutrient status of the soil are reflected in fertilizer policy. High rates of phosphate dressings markedly increased the phosphate status of the soil and built up a reserve of phosphate. In contrast, the potassium status decreased by about half, because only potatoes in the rotation were dressed with potassium. Methods of fertilization are discussed and suggestions are made with regard to possible improvements.
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    Nutrient cycling in agroecosystems 36 (1993), S. 127-133 
    ISSN: 1573-0867
    Keywords: hydrology ; water balance ; phosphorus ; Streamflow ; Peel-Harvey
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper discusses the land types, hydrologic characteristics and processes, and the major modification of these, in relation to mechanisms and magnitude of phosphorus losses to drains and riverine systems which discharge to the Peel-Harvey estuary. About 75% of the coastal plain part of the catchment is cleared of native vegetation and used for dryland, dairy and beef grazing. There are small areas devoted to irrigated pasture and commercial horticulture. Seventy-five percent of the soils of the catchment are sandy surfaced with a poor capacity to retain phosphorus. Though the area is flat, catchment water yields are high because of a large winter rainfall excess and low soil storage capacity. Drainage schemes have been constructed in much of the catchment to remove excess water quickly. This was required initially to allow agricultural expansion and is now important for protecting a growing infrastructure which serves the most populous region of Western Australia.
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    Nutrient cycling in agroecosystems 37 (1994), S. 1-22 
    ISSN: 1573-0867
    Keywords: animal slurries and manures ; applications to soils ; carbon- ; nitrogen- ; phosphorus ; contamination ; crop production ; dissemination ; hazardous organics ; heavy metals ; inputs ; macro- and micronutrients ; pathogens ; sewage sludges ; survival- ; transfer- ; transport and adsorption rates in soils
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The European Community is producing annually about 300 × 106 tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM−1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg−1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg−1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha−1 a−1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes. Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.
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    Nutrient cycling in agroecosystems 27 (1991), S. 107-111 
    ISSN: 1573-0867
    Keywords: Liming ; phosphorus ; heathland ; copper ; fertilization ; forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Forest fertilization in the Netherlands has played an important role in the phase of afforestation of former heathlands. Research started in the early fifties, but results were not applied in practical forestry. A review is presented on forest fertilization in practice, and on the main results of the activities of De Dorschkamp on NPK fertilization, liming and micronutrients application. Attention is paid to problems which have developed during the past ten years.
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    Nutrient cycling in agroecosystems 26 (1990), S. 253-269 
    ISSN: 1573-0867
    Keywords: Nitrogen ; phosphorus ; sulphur ; nutrient balances ; surface waters ; North Sea ; Baltic Sea ; eutrophication ; hypertrophication ; primary production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dissolved inorganic nitrogen and phosphorus, their relationship to each other (DIN/DIP) as predisposing (nutrient) factors, as well as prevailing weather as a triggering factor all work together to induce the primary production and hence the eutrophication (hypertrophication) process in surface waters. Sulfate likewise is a decisive predisposing factor influencing the eutrophication process by reducing N availability but increasing P availability and thus acting towards an N limitation of the primary production. This is one of the reasons why marine (coastal) waters and estuaries often exhibit N limitation with respect to primary production, while freshwater ecosystems often tend to exhibit P limitation. Within the N and P balance of agriculture of some countries of Western Europe (Netherlands, Denmark, Switzerland, FRG, UK and Sweden for N, resp. Netherlands, FRG and GDR for P) more the level than the efficiency of the N and P applications indicates the extent of the nutrient surplus. Despite 59–73% N utilization in plant production, the rate of 13–23% for agriculture as a whole equals to the 12–21% efficiency of N use in animal production. The varying N surplus in agriculture in the separate countries of 124 to 465 kg N ha−1 a−1 is determined almost exclusively by the level of the N application and not by its efficiency. The situation is similar for P: In spite of P utilization in plant production of 59–76%, P utilization in total agriculture is only 11–38%, or comparable to the P efficiency within animal production of 10–34%. The differing P excess balance of 55 to 88 kg P2O5 ha−1 a−1 is influenced by the level of the P application. The N and P efficacy of total agriculture hence is determined almost completely by that of animal production, since 83–95% (N basis) and 76–94% (P basis) of the total plant production (on top of the nationally varying levels of N and P use via imported feeds) are fed to animals — with the low N and P utilization cited above. Agriculture's share of the N and P emissions into surface water of several countries/regions in Western Europe (FRG, Netherlands, Italy, Denmark, Switzerland, Norway) ranges from 37 to 82% resp. 27 to 38%. Its share in the flus into the North Sea catchment basin will be about 60% for N and 25% for P related only to the anthropogenic material carried by the rivers. Agriculture's share in the atmospheric N emissions into the North and Baltic Seas can be estimated at about 65% or 55%, resp. while the remaining approx. 35% or 45%, resp. are traceable primarily to anthropogenic burning processes. For agriculture the priority lies in limiting N emissions into surface water caused by leaching, erosion and NH3 emissions, and reducing P emissions mainly through soil conservation (protection against erosion) and water protection. As regards N this means a demand for comprehensive protection of groundwater and atmosphere differentiated according to the potential for losses or the risk of losses on a site, also outside the protection zones. As regards P only those areas can be included in the demand for reduction of emissions that are actually threatened by erosion or surface runoff. Plenty of short-term and long-term measures are available to agriculture to reduce N and P emissions. Especially the long-range measures (such as creating nutrient balances on farms and fields, the integration of animal and plant production, maintaining maximum livestock densities according to the ability of areas to absorb nutrients, altered feeding programs in animal nutrition, changes in livestock keeping (slurry→deep litter), increasing the internal and external recycling of N and P) are capable of bringing about a satisfactory degree of success within the next 20 to 30 years.
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    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    ISSN: 1573-0867
    Keywords: Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
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    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
    ISSN: 1573-0867
    Keywords: Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
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    Nutrient cycling in agroecosystems 1 (1980), S. 137-155 
    ISSN: 1573-0867
    Keywords: energy consumption ; energy production ; photosynthesis ; mineral fertilization ; biomass and live energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract 1. The world consumption of energy is roughly 250 EJ. It increases with the level of technology and gross national product of a country. More than 83% of world energy consumption is used by the industrialized countries with one third of the world population; not quite 17% is used by the developing countries with two thirds of the world population. The world's resources of fossil fuels are estimated at 364,560 EJ; about 5–13% of this, and 31% in the case of natural gas, are considered reserves that are economically recoverable and utilizable with current technologies. 2. Agriculture's share of the economy's energy consumption in the Federal Republic of Germany is about 3.4%. It was five times higher per hectare of agricultural land in 1975 than in 1880, but the productivity of the energy was only half as high because of the enormous increase in productivity per unit of labor and area. In absolute terms, however, energy production per unit area increased tremendously, with gross agricultural production two and a half times its earlier size. 3. As a producer of plant material, agriculture qualifies as an energy producer, while as a producer of livestock it also is an energy consumer. In fact, through plant production agriculture becomes the only branch of our economic system that produces more energy than it consumes as fossil energy. Agriculture uses about 40% of its energy requirement for fuel, about 20% for machinery repair and replacement, 30% for mineral fertilizers, about 10% for electricity, and 1–2% for chemical crop protection. Forestry can be evaluated as particularly favorable from the energy viewpoint, while hothouse crops are very unfavorable. Agricultural chemicals support the energy output of green plants; agriculture as a whole is on balance energetically. 4. Solar energy and photosynthesis are the primary sources of energy to our plant. About 3 million EJ solar energy are radiated to the earth annually; 3000 EJ are fixed photosynthetically (2 ⋅ 1011 tons vegetable matter); the food requirement of 4 billion people is 15EJ. Another item of interest on the periphery of the energy balance is the enrichment of our atmosphere with oxygen, which has been accomplished for millions of years solely by the photosynthesis of green plants. 5. Through their additional yield effect, mineral fertilizers increase the energy output of plants more strongly than just the equivalent of the energy input. They cause the plant to produce more foliage and thereby promote more intensive assimilation, which means that mineral fertilizers enable the plant to utilize free solar energy better. A calculation of the energy involved in long-term field trials in cereals disclosed energy input: energy output ratios of 1:5.8 and 1:6.1. 6. Chemical crop protection has a similar effect since it protects against loss of plantproduced energy. Based on an average energy expenditure of 263 MJ ha−1 per kg ha−1 ‘typical’ active ingredient for a crop protection product, additional yields of only 4–4.5% — or considerably less in the case of high-energy crops such as cereals or sugar beets — would be sufficient to cover the energy expenditure; as a rule, however, the productivity of the chemical crop protectants is higher. The biological potential of our crops to utilize solar energy also has been improved considerably compared to earlier times — with cereals, for example, from 0.25% per unit area during the Middle Ages to 1.5% today; theoretically 4% is possible. The thesis that agrochemical aids in agriculture and horticulture are a waste of energy is unjustified. 7. Biomass also creates energy. Experts estimate the utilizable annual production of biomass in the Federal Republic of Germany to be 30 million tons mineral coal units (1 coal unit = 29.3 MJ), whereby undersized and refuse wood, straw and biogas are of special significance. Especially “fuel forests' of, for example, willows, poplars and alders could produce the equivalent of 486,000 MJ by way of 30 tha−1 biomass, contributing sizably to the fuel supply of the nation; at the moment, the conventional form of forestry produces only 30,240 MJ. It is considered feasible in Sweden to supply the entire energy requirement of the country from 93,000 km2 of ‘fuel forest’, and it must be remembered that mineral fertilization could be used to increase the productivity of land used for this purpose relatively quickly if the need were to become acute. The extraction of alcohol from crops offers other interesting aspects; the currently highest yield fuel crops (sugar beet, sugarcane and cassava) produce between 4,900 and 10,700 l ha−1 alcohol. 8. The energy problem of modern economies will not find its complete answer in the green plant. Prudent and well contemplated use of the green plant, however, may eventually do much to take the edge off today's energy dilemma.
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    Nutrient cycling in agroecosystems 35 (1993), S. 217-226 
    ISSN: 1573-0867
    Keywords: calcium ; dry matter distribution ; fertilizer ; harvest index ; magnesium ; manure ; millet ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; Senegal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a fertilizer and manure experiment, millet was grown under four treatments (no fertilizer or manure, farmyard manure, chemical fertilizer, and both). Grain yield and total aboveground biomass production of the unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutrient availability, as amount of rainfall and its distribution were favourable. Results show only small differences in distribution of dry matter among the various plant organs between the best and the non-fertilized treatments. Nutrient supply from natural sources, defined as crop content of N, P, and K at maturity without fertilizer application, amounted to 104, 16 and 103 kg ha−1, respectively, which are very high values. Total uptake of calcium and magnesium is related to that of potassium, as the combined content of these three elements is linearly related to total aboveground biomass production. Minimum removal of nitrogen and phosphorus per ton grain dry matter amounts to 29 and 4kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural biomass and for maintenance of electro-neutrality is discussed.
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    Nutrient cycling in agroecosystems 36 (1993), S. 95-103 
    ISSN: 1573-0867
    Keywords: eutrophication ; phosphorus ; fertilizer ; Peel-Harvey estuary ; algal blooms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An excess of plant nutrients has caused serious eutrophication in aquatic ecosystems of southwestern Australia manifested by excessive growth and accumulation of green and bluegreen algae. Phosphorus is generally the limiting nutrient for algal growth and phosphatic fertilizers applied to nutrient-deficient, leaching, sandy soils are the main source of P, supplemented by rural industry point sources. Nitrogen is the limiting nutrient in marine embayments with little drainage from the land. Measures to reduce the load of P delivered to drainage include basing fertilizer application rates on soil testing for P and the use of less soluble P fertilizers. Catchment management plans are being implemented with community involvement to reduce P loads and maintain agricultural production. This introductory paper reviews the history of eutrophication in southwestern Australia and of studies into its causes, principally in the large Peel-Harvey estuary. It briefly summarises other papers in this special issue concerned with different aspects of the problem: how to fertilize the land without causing eutrophication.
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    Nutrient cycling in agroecosystems 36 (1993), S. 115-122 
    ISSN: 1573-0867
    Keywords: phosphorus ; retention ; release ; sandy soils
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to manage phosphorus (P) losses from soils to waterbodies, knowledge of the mechanisms through which P is retained or released from the soil is essential. Sandy soils of the Peel-Harvey catchment (Western Australia) were subjected to a range of environmental and management factors in the laboratory and field in order to gain an understanding of the mechanisms that affect the magnitude of P losses. Sandy soils accumulated P, despite having little sorption capacity, and this accumulation could be monitored by measuring an acid-extractable fraction. The potential, short-term P loss could be estimated by determination of water-soluble soil solution P prior to winter rains. An annual cycle of the change in arbitrarily defined soil-P pools is discussed in relation to environmental and management factors. Laboratory experiments indicated that P rundown and potential annual P loss in the absence of P fertilizers could be estimated using bicarbonate extractable P. Phosphorus losses were decreased by the application of fertilizers with a low content of water-soluble P. The low ability of sandy soils of the Peel-Harvey coastal catchment to retain P, when compared to other Western Australian soils, is because of low contents of clay minerals and iron and aluminium hydrous oxides.
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    Nutrient cycling in agroecosystems 26 (1990), S. 229-235 
    ISSN: 1573-0867
    Keywords: Grass ; wheat ; nitrogen nutrition ; dilution curve ; mineral content ; mineral removal ; phosphorus ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The important effect of nitrogen in changing the patterns of mineral content and mineral removal is analysed for grass swards and wheat. Different models are proposed; accumulated dry matter developed throughout a growing period is shown to be an excellent reference for assessing the evolution of the plant mineral content and the mineral removal the growing crop. Applications in diagnosing mineral nutrition status and optimising fertilizer use are proposed and discussed.
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    Nutrient cycling in agroecosystems 3 (1982), S. 13-16 
    ISSN: 1573-0867
    Keywords: cocoa ; nitrogen ; phosphorus ; soil analysis ; Nigeria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract No extensive investigation on the effect of fertilizers on Amazon cocoa variety (Theobroma cacao L.) has been performed in Nigeria. Therefore eight fertilizer treatments involving nitrogen and phosphorus, replicated six times at four locations across southern Nigeria, were established in 1973. The four N levels (N0, N1, N2, N3) involved were 0, 80, 160 and 240 kg ha−1 y−1, and the two P levels (P0, P1) were 0 and 67 kg ha−1 y−1. Results of the first 5 years of fertilizer application are reported. Response to P was observed at all locations, and the response was statistically significant at 2 of the locations. There was no response to the application of nitrogen. The data suggest, however, that there is only a response to phosphorus when nitrogen is applied.
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  • 59
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    Nutrient cycling in agroecosystems 32 (1992), S. 223-227 
    ISSN: 1573-0867
    Keywords: Soil testing ; phosphorus ; relative yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment, with Okra (Abelmoschus esculentus L.) as the test crop, was conducted on twenty-one soils ranging in Olsen's extractable phosphorus from 1.8 to 15.5µg Pg−1 soil. The experiment was conducted at Punjab Agricultural University, Ludhiana, India. The soils were nonsaline with pH ranging from 7.7 to 8.6. A critical level of 2.55µg Pg−1 soil was predicted by Cate and Nelson's (1971) statistical procedure. Because of a wide range in relative yields, this value did not accurately predict response to applied P. An approach to compute minimum response to applied fertilizer, which is likely to be obtained at a particular Olsen P level, has been presented. It involves calculation of lower 60 percent confidence limits for relative yield and fitting loge-linear regression to the transformed data. The regression was tested on a published data set and was found to hold well.
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  • 60
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    Nutrient cycling in agroecosystems 32 (1992), S. 259-267 
    ISSN: 1573-0867
    Keywords: Nitrogen ; phosphorus ; timber increment ; fertilization ; Pinus radiata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two trials inPinus radiata growing on different sites in N.S.W. allowed consideration of fertilizer applications after 2nd or 3rd thinning. The trials included factorial applications of N and P at a single thinning intensity plus a further treatment which allowed assessment of different thinning intensities. The most significant growth responses were obtained by application of N and P in combination. The largest response (additional productivity compared with the unfertilized control) occurred 4 years after application and after 7 years there was no additional absolute response for either of the two sites. The largest fertilizer response was 70 m3 ha−1 over 7 years on one site and 36 m3 ha−1 on the other, indicating differences in absolute responses between sites. It was concluded that in planning treatments the most responsive sites near the end of the rotation should be selected to maximise economic returns. Foliage analyses indicated differences between sites at the commencement of the study. It was concluded that either a single year of foliage analyses at study commencement is of value, or sampling every year of the study should be used to analyse responses, but a single year of analysis during or at the end of the study would not be of value.
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  • 61
    ISSN: 1573-0867
    Keywords: interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
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  • 62
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    Nutrient cycling in agroecosystems 5 (1984), S. 371-382 
    ISSN: 1573-0867
    Keywords: nitrogen ; phosphorus ; dry areas ; apparent recovery fraction ; fertilizer management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agronomic efficiency (AE) is defined as the increase in economic yield of a crop per unit fertilizer applied. Components of AE are physiological efficiency and apparent recovery fraction. The latter can be further separated into uptake efficiency and availability index. Ways to increase the nitrogen fertilizer use efficiency in rainfed agriculture through fertilizer management are discussed.
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  • 63
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    Biodegradation 14 (1991), S. 167-191 
    ISSN: 1572-9729
    Keywords: leaf longevity ; nitrogen ; nutrient use efficiency ; phosphorus ; requirement ; retranslocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Aboveground nitrogen (N) and phosphorus (P) requirement, retranslocation and use efficiency were determined for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller), white pine (Pinus strobes L.), red pine (Pinus resinosa Ait.) and Norway spruce (Picea abies (L) Karst.) plantations on a similar soil in southwestern Wisconsin. Annual aboveground N and P requirements (kg/ha/yr) totaled 126 and 13 for red oak, 86 and 9 for European larch, 80 and 9 for white pine, 38 and 6 for red pine, and 81 and 13 for Norway spruce, respectively. Nitrogen and P retranslocation from current foliage ranged from 81 and 72%, respectively, for European larch, whereas red pine retranslocated the smallest amount of N (13%) and Norway spruce retranslocated the smallest amount of P (18%). In three evergreen species, uptake accounted for 72 to 74% of annual N requirement whereas for two deciduous species retranslocation accounted for 76 to 77% of the annual N requirement. Nitrogen and P use (ANPP/uptake) was more efficient in deciduous species than evergreen species. The results from this common garden experiment demonstrate that differences in N and P cycling among species may result from intrinsic characteristics (e.g. leaf longevity) rather than environmental conditions.
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  • 64
    ISSN: 1423-0445
    Keywords: toxin sequestration ; predation ; human dietary hazard ; cantharidin ; Coleoptera ; Meloidae ; Epicauta vittata ; Rana ; Hirudo ; Nerodia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Frogs(Rana pipiens) fed on blister beetles (Meloidae) or cantharidin, retain cantharidin systemically. After cessation of feeding, they void the compound relatively quickly. Systemic cantharidin does not protect frogs against ectoparasitic feeding by leeches(Hirudo medicinalis) or predation by snakes(Nerodia sipedon). As suggested by our data, and from reports in the early literature, ingestion of cantharidin-containing frogs can pose a health threat to humans.
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  • 65
    ISSN: 1423-0445
    Keywords: pheromone ; attractant ; triene ; tetraene ; hydrocarbon ; Insecta ; Coleoptera ; Nitidulidae ; Carpophilus freemani
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Males ofCarpophilus freemani Dobson (Coleoptera: Nitidulidae) produce an aggregation pheromone to which both sexes fly in a wind-tunnel bioassay. The major pheromone component (ca. 30 ng per male per day in volatile collections) was identified as (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene. A minor component, (2E,4E,6E,8E)-7-ethyl-3,5-dimethyl-2,4,6,8-undecatetraene, was 3–10% as abundant as the major triene and was 5–20% as active when compared at relative doses ranging from natural proportions to 1:1. These compounds act synergistically: a mixture of major and minor components in natural proportions attracted more than twice as many beetles as the major component alone, and the mixture fully accounted for the activity of male-derived volatile collections. Six other male-derived conjugated hydrocarbons, ranging from 2% down to 0.04% as abundant as the major component, were also identified. These are (in order of decreasing bioassay activity when compared on an equal-weight basis): (3E,5E,7E)-6-ethyl-4-methyl-3,5,7-decatriene, (2E,4E,6E)-5-ethyl-3-me-thyl-2,4,6-octatriene, (3E,5E,7E,9E)-8-ethyl-4,6-dimethyl-3, 5,7,9-dodecatetraene, (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6, 8-undecatetraene, (3E,5E,7E)-5-ethyl-7-methyl-3,5,7-undecatriene, and (2E,4E,6E)-3,5-dimethyl-2,4,6-nonatriene. All structure identifications were confirmed by synthesis. In the wind tunnel, the pheromone acted synergistically with “host”-type volatiles such as propyl acetate, valeric acid, and ethanol. This concept was verified by fields tests in California, in which there was dramatic synergism between the pheromone and fermenting host materials. Pheromone biosynthesis is discussed.
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  • 66
    ISSN: 1423-0445
    Keywords: secretion-grooming ; pygidial glands ; chemical defence against microorganisms ; respiration ; aquatic beetles ; Coleoptera ; Hydradephaga ; Gyrinidae ; Haliplidae ; Noteridae ; Hygrobiidae ; Dytiscidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All Hydradephaga investigated so far crawl onto land when exposed to an increase in water temperature and light intensity and spread the secretion from their pygidial glands over the body surface (“secretion-grooming”). The secretions have antimicrobial properties and are mainly applied to hydrofuge body regions important for aquatic respiration. Experimental prevention of secretion-grooming leads to the loss of the respiratory air bubble and a significant increase in mortality. These findings support the view that the secretion-grooming of adephagous aquatic beetles, like in some aquatic Heteroptera, inhibits the growth of microor-ganisms, thus preventing the contamination and wetting of the cuticular respiratory structures. Thus it keeps functional the air-retaining hydrophobous body regions essential for aquatic respiration. A model is presented on how secretion-grooming may have evolved in the Hydradephaga. Other possible functions of the pygidial gland secretions are discussed.
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  • 67
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; coccinelline ; Coleoptera ; Coccinellidae ; Coccinella septempunctata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 7-spot ladybirds secrete alkaloid (coccinelline)-rich fluid (reflex blood) from leg joints as a defence mechanism against predators. A technique is described that enables the collection and accurate quantification of reflex blood produced, and the amount of coccinelline therein. Coccinelline was found distributed throughout the body, although concentrated in the reflex blood. Reflex blood was collected from a large set of beetles at several time points. Significant variation was found among beetles in the amount of reflex blood produced (for males and for females corrected for body weight) and the coccinelline concentration of the reflex blood. The results are discussed in relation to automimicry and the maintenance of variation through energy trade-offs. The relationships between tendency to aggregate, ability to reflex bleed and the possession of aposematic coloration are also considered.
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  • 68
    ISSN: 1423-0445
    Keywords: specificity ; predation ; long-range orientation ; windtunnel ; Coleoptera ; Rhizophagidae ; Scolytidae ; Rhizophagus grandis ; Dendroctonus micans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The predator,Rhizophagus grandis, is linked to its specific prey,Dendroctonus micans, by semiochemical signals regulating oviposition and long range orientation. A mixture of simple oxygenated monoterpenes [(−)—fenchone, (−)—pinocamphone, rac. camphor, terpinene-4-ol, borneol, fenchol and verbenone], identified from the frass ofD. micans has been found to be extremely active in a flight windtunnel as a long—range attractant for the predator. The mixture elicited 84 % of the response to larval frass of the prey. Excluding pinocamphone from the mixture did not influence its activity. Also, changing the absolute configurations of some of the components (fenchol, terpinene-4-ol and borneol) did not influence the predators' response. However, the addition of (−)—α-terpineol increased the attractivity of the synthetic blend to almost that of larval frass of the prey. Ecological implications of the identified semiochemicals and their use in pest management are discussed.
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  • 69
    ISSN: 1423-0445
    Keywords: sequestration ; pharmacophagy ; defense ; allomone ; kairomone ; cucurbitacin ; Cucurbitaceae ; Coleoptera ; Chrysomelidae ; Luperini ; Diabrotica ; Aulacophora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.
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  • 70
    ISSN: 1423-0445
    Keywords: chemical defence ; tri-trophic interactions ; alkaloids ; Homoptera ; Aphis craccivora ; Icerya spp. ; Lepidosaphes ulmi ; Planococcus citri ; Coleoptera ; Coccinellidae ; Cryptolaemus montrouzieri ; Rodolia cardinalis ; Chilocorus bipustulatus ; Neuroptera ; Chrysopidae ; Chrysoperla carnea ; Hymenoptera ; Encyrtidae ; Encyrtus infelix ; Leguminosae ; Erythrina corallodendrum ; Spartium junceum ; Citrus sinensis ; Euphorbia tirucalli ; Pittosporum tobira
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.
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  • 71
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    Chemoecology 4 (1993), S. 29-32 
    ISSN: 1423-0445
    Keywords: chemical defence ; alkaloids ; predation ; Coleoptera ; Coccinellidae ; Adalia bipunctata ; Coccinella septempunctata ; Hymenoptera ; Formicidae ; Lasius niger
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Garden black ants,Lasius niger L., in a laboratory colony, attacked three species of live ladybirds found near their nest, killing the smaller two species. A second colony was offered artificial diets containing crushed ladybirds of two species, and the ants' choice of feeding site noted. Both the diets were aversive compared to control, but that containing 7spot,Coccinella septempunctata L., was more aversive than the diet containing 2spot,Adalia bipunctata L. The implications of this lesser protection for 2spots in terms of the chemical defence of the species are discussed.
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  • 72
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    Cellular and molecular life sciences 46 (1990), S. 1209-1211 
    ISSN: 1420-9071
    Keywords: Pheromone ; E-myrcenol ; ipsdienol ; Ips duplicatus ; Coleoptera ; Scolytidae ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Males of the Eurasian bark beetleIps duplicatus, when feeding in host Norway spruce (Picea abies (L.) Karst.), produced and released ipsdienol andE-myrcenol, which we show to be aggregation pheromone components. Bioassays using walking beetles indicated thatE-myrcenol in synergistic combination with ipsdienol is essential for attraction. Synergism ofE-myrcenol and ipsdienol released at natural rates in the forest was also demonstrated with a new technique using mechanical slow-rotation of sticky traps.
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  • 73
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    Cellular and molecular life sciences 48 (1992), S. 1023-1027 
    ISSN: 1420-9071
    Keywords: Chrysolina fuliginosa ; Coleoptera ; Chrysomelidae ; beetles ; cardenolides ; eggs ; glands ; chemical defence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Besides the known sarmentogenin 3-O-β-D-allopyranoside (1) and digitoxigenin-3-O-[β-D-xylopyranosyl-(1→4)-2′, 3′-di-O-acetyl-β-D-allopyranoside] (4), four new cardiac glycosides (2, 3, 5 and6) have been isolated from the defensive glands of adults ofChrysolina fuliginosa. The structures of the new compounds were determined by1H NMR at 600 MHz and FABMS. Compounds1–6, present in the adults ofC. fuliginosa, have also been identified in the eggs.
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  • 74
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    Aquatic sciences 54 (1992), S. 58-76 
    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; nitrogen ; chlorophyll-a ; slope estimator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We estimate the response of chl-a (mg · m−3) to changes in concentrations of total phosphorus (TP) by calculating the slopeS = Δchl-a/ΔTP in chl-a =f(TP) graphs. Results show that in years where algae are P-limited oligotrophic lakes respond less (median slope 0.21) to changes in nutrient concentrations than eutrophic lakes, (median slope 0.31) and these again less than hypereutrophic lakes, (median slope 1.02). We find no saturation value for the slope within the TP range considered (6–480 mg · m−3). Chl-a in eutrophic lakes responds more frequently to non-nutrient factors than oligotrophic and hypereutrophic lakes. Results obtained by replacing TP with a new nutrient parameter, TP′ = 0.056 · TP · IN0.226, in which inorganic nitrogen, IN, is factored in, suggest that nitrogen has an influence on chl-a in oligotrophic lakes. Blue-green algae respond less to changes in TP than other algal species, e.g., diatoms.
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    Aquatic sciences 54 (1992), S. 321-330 
    ISSN: 1420-9055
    Keywords: Algal pigments ; algal communities ; photosynthesis ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A one-year study of phytoplankton, primary production and related physical and chemical factors was made in a Swiss basin of Lake Lugano (Lago di Lugano). The chlorophylls and 12 carotenoids were analyzed with a TLC technique. The carotenoid monitoring was considered to be particularly interesting, because the role of these pigments in freshwater algae is still very poorly documented by field studies. The dependence of photosynthesis on several factors was statistically evaluated. Evidence was found of light-adaptation phenomena. The variations of photosynthetic activity and efficiency largely depended on the light regime in the few days before the field observations and on the cellular content of chlorophylls and single carotenoids, whose concentrations in their turn were closely linked with light, temperature, average cell size, and with the actual species assemblage.
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    Aquatic sciences 54 (1992), S. 381-390 
    ISSN: 1420-9055
    Keywords: Eutrophication ; phosphorus ; lake restoration ; internal restoration measures for lakes ; Swiss lakes ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In most lakes eutrophication is linked to an excessive input of phosphorus. Lake restoration by reduction of P-input (external measure) has led to a considerable drop of the P-concentration in all major Swiss lakes as well as in many other lakes. Internal restoration measures such as artificial mixing, drainage of hypolimnetic water, flushing, aeration, biomanipulation and others serve to improve and accelerate the response of a lake to external measures. For the case of Lago di Lugano, a simple two-box model is employed to demonstrate that a reduction of the P-input to about 25% of the present values is necessary to reach the “P-criterion” (P-concentration below 30 µg/l). Internal measures could possibly accelerate the extremely slow response of the northern basin.
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    Aquatic sciences 55 (1993), S. 132-142 
    ISSN: 1420-9055
    Keywords: nitrogen ; phosphorus ; uptake ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved inorganic nutrient pools are small relative to particulate pools, and dissolved pools turnover rapidly. It has been observed that pools change little from day to day on the sampling scales usually employed. A simple model is presented where uptake and regeneration rates balance to cause a local steady state concentration for dissolved inorganic nutrients. Enrichment and dilution perturbation experiments with lake water support the idea of steady state nutrient concentrations. Although inorganic nutrient concentrations are often controlled by biota, the absolute concentrations present tell little about the activity of that biota.
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  • 78
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    Aquatic sciences 56 (1994), S. 16-28 
    ISSN: 1420-9055
    Keywords: Chlorophyll-a ; phosphorus ; nitrogen ; lake ecosystem ; nutrient limitation ; regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regression results based on data from 46 northern temperate lakes show that total phosphorus (TP) is the best predictor for phytoplankton (as chl-a) at lower trophic levels, TP 〈 200 mg · m−3. A regression including both TP and TN as regressors is the best predictor for lakes with TP 〉 200 mg · m−3. However, the good correlation is probably due to a high correlation between lake average chl-a (all years observed) and lake average TP and TN. Within single hypereutrophic lakes, TN alone is the best predictor. It was not possible to identify a medium trophic domain where TN and TP in combination was the best predictor for chl-a. The ratio TN:TP in the water decreases from about 40 to about 5 with increasing trophic level. Optimum TN:TP ratio for algal species with high abundance during late summer and autumn reflects this decreasing ratio, but within a lesser range, i.e., 20 to 5. In contrast, TN:TP ratios for species abundant during the early vernal period showed no, or an inverse, relation to the TN:TP ratio of the water.
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  • 79
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
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  • 80
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; adaline ; Coleoptera ; Coccinellidae ; Adalia bipunctata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 2-spot ladybirds secrete alkaloid (adaline)-rich defence fluid (reflex blood) in response to predator attack. Reflex fluid was collected from individual ladybirds and weighed and the alkaloid content measured by GC. The amount of fluid produced built up rapidly following winter hibernation in animals feeding on aphids. The concentration of adaline in the fluid was highest in the first bleeding after winter hibernation. A large sample of beetles was reflex bled several times. Significant among beetle variation was found in the amount of fluid produced and the concentration of the reflex blood. The results are discussed in relation to the possibility that 2-spot ladybirds are Batesian mimics of 7-spot ladybirds and to the possible functions of adaline.
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  • 81
    ISSN: 1423-0445
    Keywords: defensive secretion ; hot secretion ; elytral flanges ; evolution ; benzoquinones ; hydrocarbons ; bombardier beetle ; Coleoptera ; Carabidae ; Paussinae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Australian bombardier beetle,Mystropomus regularis, sprays a mixture of quinones (1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone) and hydrocarbons (principallyn-pentadecane). The defensive fluid ist generated explosively in two-chambered glands, and is ejected audibly and hot (maximal recorded temperature = 59°C).Mystropomus is a member of the paussoid lineage of bombardiers. In common with other members of the group, it has a pair of elytral flanges (flanges of Coanda), associated with the gland openings, that serve as launching guides for anteriorly-aimed ejections of spray. It is argued thatMystropomus may be the least derived of flanged paussoids, and the closest living relative of the most primitive of extant bombardiers (Metriini).
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  • 82
    ISSN: 1423-0445
    Keywords: chemical defense ; predator-prey interaction ; synergism ; Coleoptera ; Staphylinidae ; Oxytelinae ; Bledius ; Carabidae ; Dyschirius ; Pogonus ; Dichirotrichus ; Formicinae ; Cataglyphis ; Dermaptera ; Labidura
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in eitherγ-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.
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  • 83
    ISSN: 1423-0445
    Keywords: adult mortality ; oviposition inhibition ; larval mortality ; aromatic hydrodistillated and non hydrodistillated plants ; Coleoptera ; Bruchidae ; Acanthoscelides obtectus ; Lamiaceae ; Origanum ; Thymus ; Satureia ; Rosmarinus ; Mentha ; Myrtaceae ; Eucalyptus ; Lauraceae ; Laurus ; Poaceae ; Cymbopogon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Acanthoscelides obtectus (Say) is one of the most damaging pests of kidney beans,Phaseolus vulgaris L. worldwide. However, aromatic plants from the families Lamiaceae, Lauraceae, Myrtaceae and Poaceae can protect kidney beans by direct or delayed insecticidal effect, through increased adult mortality and inhibition of beetle reproduction (both oviposition and adult emergence). The efficiency of hydrodistillated and intact plants fromThymus vulgaris andT. serpyllum, Mentha piperata, Rosmarinus officinalis, Satureia hortensis, Eucalyptus globulus, Laurus nobilis, Origanum vulgare, andCymbopogon nardus was compared. For both extracts,Origanum vulgare had the best effect. The insecticidal effect was induced by more than the essential oils because no significant difference was noticed between distilled and intact plants extract. Inhibition of reproduction was particularly important. These results suggest that lipidic as well as non lipidic, allelochemicals, such as phenolics, or non-protein amino-acids, or flavonoids may be involved in the toxicity of aromatic plants to this beetle.
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  • 84
    ISSN: 1423-0445
    Keywords: chemical defence ; sequestration ; reflex bleeding ; alkaloids ; chemotaxonomy ; biosynthesis ; repellency ; toxicity ; Coleoptera ; Coccinellidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The defensive mechanisms which protect ladybird beetles (Coccinellidae) against predators are reviewed. Besides behavioural mechanisms, such as thanatosis and reflex bleeding, chemical defence mechanisms are playing a prevalent role. Indeed, ladybirds are protected not only by their smell, but also by repulsive alkaloids, most of which are considered to be of autogenous origin. In a few cases, dietarily-acquired substances are also involved. Particular emphasis is laid on the repellent alkaloids which are contained in the haemolymph of many species. The structures of 34 nitrogen-containing compounds isolated so far are presented, and their distribution within the family is discussed in the light of the most widely accepted classification of these beetles. To conclude, the mode of release of the alkaloids, their variation through the life cycle and their repellent and toxic properties are discussed, as well as the few biosynthetic data yet available.
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  • 85
    ISSN: 1423-0445
    Keywords: oviposition ; repellents ; larval secretion ; Coleoptera ; Chrysomelidae ; Phaedon cochleariae ; Chrysomela lapponica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The exocrine glandular secretions of larvae of the subfamily Chrysomelinae are known to repel conspecific adults, other competitive phytophagous insects and natural enemies. InPhaedon cochleariae, the intraspecific activity of tlc fractions of the larval secretion was tested in order to examine the ecological significance of two fractions containing minor components and a fraction containing the major compound, the cyclopentanoid monoterpene (epi)chrysomelidial. InChrysomela lapponica, the defensive activity of the larval secretion against ants is known from specimens feeding upon willow or birch. The feeding preferences of larvae and adults ofC. lapponica from a Finnish and a Czech population were tested. The Finnish individuals significantly preferred feeding uponSalix borealis, whereas they hardly fed upon birch. The Czech specimens clearly preferred birch (Betula pubescens) to willow species. Application of salicin onto leaves of a willow species free of this phenolglycoside revealed that the Finnish individuals preferred feeding upon leaves with salicin. On the other hand, the Czech individuals avoided feeding upon leaves ofB. pubescens treated with salicin. The chemical composition of the glandular secretion of the Finnish larvae differed from the one of the Czech larvae. GC-MS-analyses of the secretions revealed that salicylaldehyde was the only major component of the secretion of Finnish larvae feeding upon the salicin-containing willowS. borealis. The glandular secretion of the Czech larvae feeding upon birch contained numerous esters of isobutyric acid and 2-methylbutyric acid. When Czech larvae had fed upon a salicin-containing willow (S. fragilis), the major compounds of their secretion were benzoic acid, salicylalcohol and benzoic acid esters; salicylaldehyde was only detected in traces. Thus,C. lapponica individuals from the Finland population adapted so closely to a salicincontaining willow that they clearly prefer this plant for food and that they obviously derive their main larval defensive compound (salicylaldehyde) from their host-plant.
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  • 86
    ISSN: 1423-0445
    Keywords: pyrrolizidine alkaloid N-oxides ; alkaloid sequestration ; defensive secretion ; host plant ; Coleoptera ; Chrysomelidae ; Oreina ; Asteraceae ; Adenostyles alliariae ; Senecio fuchsii ; Petasites paradoxus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima.
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  • 87
    ISSN: 1423-0445
    Keywords: larval frass ; predator ; prey ; biological control ; kairomones ; Rhizophagus grandis ; Dendroctonus micans ; Coleoptera ; Rhizophagidae ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Adults of the predatory beetleRhizophagus grandis are strongly attracted to both adult and larval frass of its specific prey,Dendroctonus micans, in walking bioassays. Spruce bark and resin are relatively unattractive. Solvent extracts of larval frass that were attractive toR. grandis adults in a flight wind tunnel contained a mixture of monoterpenes of host plant origin. A synthetic mixture of these monoterpenes, (+)—α-pinene, (−)—β-pinene, β-phellandrene,dl limonene and 3-carene, was responsible for 70–80% of the activity of the most attractive extract. We suggest that a blend of monoterpenes in frass acts as a kairomone forR. grandis but that attraction to monoterpenes is only the first of a sequence of behavioural responses that ensures successful host location and identification.
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  • 88
    ISSN: 1423-0445
    Keywords: competition ; inhibition ; sex-ratio ; mass-at-tack model ; ipsdienol ; E-myrcenol ; cis-verbenol ; 2-methyl-3-buten-2-ol ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ips duplicatus withI. typographus co-inhabiting Norway spruce (Picea abies (L.) Karst.) would benefit from a pheromone blend distinct from that of the larger competitorI. typographus. GC-MS analysis showed thatI. duplicatus males feeding in the host produced ipsdienol (Id),cis-verbenol (cV),trans-verbenol (tV), myrtenol (Mt), andE-myrcenol (EM) and traces of 2-methyl-3-buten-2-ol (MB).I. duplicatus produced Id in approximately racemic form (48.9-54.5% (+)-(S)-isomer). The amounts of Id and EM released over a 9 day period had a maximum of 250 and 5 ng/h/male, respectively, on day 2. Exposure ofI. duplicatus males to myrcene and α-pinene resulted in the production of small amounts of Id, cV, tV, Mt, andtrans-pinocarveol, but not of EM. In laboratory bioassays with walking beetles, the pheromone component Id alone was weakly attractive while EM was inactive, but in binary combination with Id strongly synergized attraction. A combination of EM and Id at a release rate equivalent to 100–200 males was more attractive in the field than 70 unmated males in a spruce log. The addition of myrcene ( a suggested pheromone precursor of Id) to Id did not enhance trap caches, while addition of EM increased catches 〉 10-fold. Subtracting EM from a blend of Id, EM, cV and MB drastically reduced trap catches while subtraction of cV or MB or both had no significant effect. Addition of EM over a wide concentration range to the synthetic pheromone ofI. typographus did not reduce the attraction of females of this species in the laboratory. A two-species pheromone interaction field test releasingI. typographus pheromone components (MB + cV) at 10–1000 male equivalents (ME) andI. duplicatus pheromone (Id + EM) at 0, 10–1000 ME in all possible combinations showed both positive intraspecific dose-response effects and an interspecific inhibition. Higher release rates of EM appeared to inhibitI. typographus, especially males. In a tree colonization model, the response of the two competing species to their respective pheromones show a good separation during the mass-attack with a small initial cross-attraction. It remains to be shown whether either of the two pheromone systems have in fact evolved in the present sympatry, or if they are an incidental effect of ancestry of these phylogenetically distantIps.
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  • 89
    ISSN: 1420-9071
    Keywords: Gastrophysa viridula ; Chrysomelidae ; Coleoptera ; chemical defence ; acetates ; hydrocarbons ; gas-liquid chromatography ; gas chromatography-mass spectrometry ; sexual dimorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The lipid fraction of the defensive secretion of adultGastrophysa viridula was analyzed by gas-liquid chromatography and gas chromatography-mass spectrometry. Three long chain acetates and two methyl-branched hydrocarbons were identified and their amounts in the secretion of single field-collected and laboratory-reared beetles determined. The composition of the secretion was affected by the sex, reproductive status, and age of the beetle. The ratio of (Z)-11-eicosenyl acetate to (Z)-13-docosenyl acetate ranged from 0.30 to 0.78 in male beetles and from 1.05 to 2.06 in female beetles. The biological significance of this sexual dimorphism is discussed.
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  • 90
    ISSN: 1420-9071
    Keywords: Migdolus fryanus ; Coleoptera ; Cerambycidae ; N-2′-methylbutanoyl 2-methylbutylamine ; N-formyll-isoleucine methyl ester ; sex pheromone ; chiral resolution ; dose-response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The first known long-range female-released sex pheromone for the family Cerambycidae is reported fromMigdolus fryanus, a sugarcane pest in South America. Although two female-specific compounds, namely, N-(2′S)-methylbutanoyl 2-methylbutylamine and N-formyll-isoleucine methyl esters were identified, field tests with synthetic chemicals revealed that only the amide was active and that the amino acid derivative neither increased or decreased trap catches by the amide. This is the first identification of amide as a sex pheromone.
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  • 91
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    Oecologia 65 (1984), S. 30-34 
    ISSN: 1432-1939
    Keywords: Stomatal conductance ; photosynthesis ; C4 grasses ; CO2xlight interaction ; light saturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The growth and photosynethetic responses to atmospheric CO2 enrichment of 4 species of C4 grasses grown at two levels of irradiance were studied. We sought to determine whether CO2 enrichment would yield proportionally greater growth enhancement in the C4 grasses when they were grown at low irradiance than when grown at high irradiance. The species studied were Echinochloa crusgalli, Digitaria sanguinalis, Eleusine indica, and Setaria faberi. Plants were grown in controlled environment chambers at 350, 675 and 1,000 μl 1-1 CO2 and 1,000 or 150 μmol m-2 s-1 photosynthetic photon flux density (PPFD). An increase in CO2 concentration and PPFD significantly affected net photosynthesis and total biomass production of all plants. Plants grown at low PPFD had significantly lower rates of photosynthesis, produced less biomass, and had reduced responses to increases in CO2. Plants grown in CO2-enriched atmosphere had lower photosynthetic capacity relative to the low CO2 grown plants when exposed to lower CO2 concentration at the time of measurement, but had greater rate of photosynthesis when exposed to increasing PPFD. The light level under which the plants were growing did not influence the CO2 compensation point for photosynthesis.
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  • 92
    ISSN: 1432-1939
    Keywords: Coleoptera ; Herbivory ; Host selection ; Maternal effect ; Paternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The natural host of Ophraella notulata is Iva frutescens (Asteraceae); its close relative feeds on a related plant, Ambrosia artemisiifolia. We reared beetles on both plants, obtained progeny from the four possible crosses (two sexes X two parental hosts), and reared the progeny on both plant species. Survival to the imaginal stage of progeny reared on Iva varied with both maternal and paternal host. Hatchling feeding response to both plants showed a maternal host X paternal host interaction. Consumption of Ambrosia by adult beetles was, counter to expectation, higher for progeny of Iva-reared males than Ambrosia-reared males. Oviposition response, although based on too few data to be definitive, was peculiar: parental host did not affect oviposition on Ambrosia; on Iva daughters of Iva-reared males laid significantly more eggs than did daughters of Ambrosia-reared males, but only if they had been reared on Iva; those reared on Ambrosia displayed the reverse pattern. We discuss the possibility that nongenetic paternal transmission of host plant effects may explain these results, but offer a somewhat uncomfortable hypothesis of selection as a preferable explanation. An important outcome of the experiment is that it provided no evidence of maternal effects of host plant on offspring feeding or oviposition.
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  • 93
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    Oecologia 90 (1992), S. 417-421 
    ISSN: 1432-1939
    Keywords: Coleoptera ; Predator-prey ratios ; Trophic structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In common with samples from less taxonomically constrained studies, significant correlations exist between the numbers of predatory and non-predatory species in assemblages of terrestrial beetles. Under logarithmic transformation the relationship can be described reasonably well by a straight line. Explanations for predator: non-predator relationships based on the dynamics of trophic interactions (e.g. competition for prey types or enemy-free space) seem insufficient to explain this pattern, because within beetle assemblages the necessary interactions are so few. Of other proposed determinants, those based on the relationship of local and regional species pools, on energetics, or on non-trophic factors seem the most plausible candidates for explaining proportionality amongst beetles. Much of the deviation from the overall pattern can be accounted for by sampling method and latitude. Temperate samples have a higher proportion of predatory species than tropical, whilst litter and pitfall trap samples have higher proportions of predatory species than Malaise trap and fogging samples.
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  • 94
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    Oecologia 92 (1992), S. 556-562 
    ISSN: 1432-1939
    Keywords: Herbivory ; Chemical defense ; Sequestration ; Coleoptera ; Chrysomelidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chrysomela confluens produces a salicylaldehyde-based defensive secretion which is very effective against generalist predators and apparently produced at no cost. If no cost defenses are common, then one of the basic assumptions in the plant-herbivore literature, i.e. tradeoffs among defense, reproduction, and growth, must be reconsidered. We examined the effectiveness of this defense by exposing defended larvae and larvae whose secretion had been removed to a generalist predator. Larvae which had their secretions intact were attacked by only 7% of the ants which encountered them, and none of these larvae suffered serious damage. In contrast, those which had been “milked” of their secretions immediately prior to exposure were attacked in 48% of such encounters, and two-thirds of the larvae were killed. Larvae which had been milked 24 or 72 h before exposure, then allowed to regenerate their defenses, were attacked at rates indistinguishable from larvae that had not been milked. Thus regenerated defenses are just as effective as original defenses. We also tested the hypothesis that the cost of defense production and maintainence would be reflected in reductions in developmental rates and final adult mass and increases in leaf consumption rate. We found that larvae which were milked daily of their secretions manifested no measurable cost of recharging reservoirs. Milked larvae grew and fed at the same rates as their control sibs, and became adults of equal or slightly larger size. The liberation of glucose from salicin, a precursor present in leaves of salicaceous hosts, during the production of salicylaldehyde apparently provides enough of an energetic benefit to offset the cost of maintaining an effective defense. Consistent with this hypothesis, we did not find that milked larvae compensated for increased nutritional or salicin demands by increasing their feeding rates. Although this patterns is familiar to chemical ecologists it is generally unappreciated in the plant-herbivore literature. It is likely that many arthropod herbivore defensive systems come at little or no cost, given the intimacy of association between herbivores and their food plants. Sequestration of host plant defensive chemicals which eliminates the cost of synthesis is common in arthropods. The de novo synthesis of chemical defenses may be less costly than expected if it is integrated into other parts of an insects metabolism. Calculations based on the bond energies or molecular constitution of the compounds will not yield a complete perception of cost. Tests over the life of the herbivore, coupled with an understanding of the herbivore's metabolism, are necessary.
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  • 95
    ISSN: 1440-1703
    Keywords: Clethra barbinervis ; interspecific difference ; intraspecific variation ; photosynthesis ; SO2 resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of SO2 on the photosynthesis ofClethra barbinervis collected from a smoke-polluted area near the Ashio copper smelter in Tochigi Prefecture was compared withC. barbinervis collected from a nonpolluted district in Tsukuba, Ibaraki Prefecture andQuercus mongolica var.grosseserrata grown in a nonpolluted field in Nagano Prefecture. The plants were exposed to 0.5–1.5 p.p.m. SO2 for 90 min (short-term) and to 0.3 p.p.m. SO2 for 31–39 days (long-term). TheClethra plants from both sites had a lower intrinsic stomatal conductance and photosynthetic rate thanQuercus plants. Short-and long-term fumigation caused stomatal closure inQuercus plants, but had little effect on the stomatal conductance ofClethra plants. Under short-term fumigation, nonstomatal photosynthetic inhibition per unit of absorbed SO2 was smallest inClethra plants from Ashio. Long-term fumigation caused photosynthetic decline and visible foliar injury toQuercus plants, but had no effect onClethra plants from Ashio. Consequently,Clethra plants from Ashio had a higher photosynthetic rate thanQuercus plants after long-term fumigation. These results suggest thatC. barbinervis populations in the smoke-polluted area of Ashio had evolved high SO2 resistance connected with SO2 detoxification ability in mesophyll cells.
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  • 96
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    Ecological research 8 (1993), S. 81-83 
    ISSN: 1440-1703
    Keywords: bract ; Carpinus laxiflora ; mast year ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light saturated net photosynthesis was measured in bracts and leaves ofCarpinus laxiflora, the major species in secondary forests in cool and intermediate temperate zones in Japan. The maximum net photosynthesis of leaves and bracts was essentially constant from May to early August and decreased gradually thereafter. For bracts, it was 3.2 μmol m−2s−1, approximately half that for the leaves. The photosynthesis of bracts would thus appear to contribute significantly to seed maturity. The estimated production of bract based on the photosynthesis would make seeds (3 mg dry weight) mature for 37 days, assuming all photosynthate of the bracts to have been distributed in the seeds only. This was quite consistent with the growth curve for the seeds. A mast year phenomenon is discussed in relation to bract photosynthesis and leaf number.
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  • 97
    ISSN: 1440-1703
    Keywords: Aucuba japonica ; photosynthesis ; Sea of Japan ; shading ; snow cover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aucuba japonica varieties are common evergreen understory shrubs in Japan.Aucuba japonica var.borealis is distributed on the Sea of Japan side of Honshu and Hokkaido where heavy snow cover lasts for more than 3 months in winter.Aucuba japonica var.japonica is distributed in areas with shallow or no snow on the Pacific Ocean side of Honshu and Shikoku. The ecophysiological characteristics of var.borealis were compared with those of var.japonica to examine the effects of heavy and long-term snow cover on the life cycle of var.borealis. Shoots of both varieties were shaded in crushed ice for 110 days, but their photosynthetic activities, chlorophyll contents and the chlorophylla/b ratio was not affected. The leaves of var.borealis were no less frost tolerant than those of var.japonica. In spite of the difference in environmental factors, both varieties had similar characteristics in seasonal changes of photosynthesis, respiration and chlorophylla/b ratio. These results suggest that var.japonica could survive in areas with heavy snow where it does not normally occur. Leaf net production (LNP) was estimated based on the microclimatic data and seasonal photosynthetic and respiration rates. The difference in the annual LNP between the two varieties was equivalent to the difference in the LNP during the snow season. One of the major effects of snow cover is to interrupt and reduce the production period of var.borealis.
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  • 98
    ISSN: 1440-1703
    Keywords: balloon system ; Coleoptera ; pollinators ; tree canopy ; wood borers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A system of suspending traps from a movable balloon was developed and tested on pollinating and wood boring Coleoptera in a tropical rainforest canopy in Pasoh Forest Reserve, Peninsular Malaysia. The balloons, 2.5 m in diameter, were filled with helium gas for levitation and moored in different directions by three pieces of thin rope. Traps in which benzyl acetate and ethanol were used as attractants for the pollinators and wood borers, respectively, were suspended from the balloon at different heights. The trapping results show that the balloon system can be used for studying canopy insects and their vertical distribution on a spatial and temporal scale.
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  • 99
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    Journal of chemical ecology 10 (1984), S. 1787-1798 
    ISSN: 1573-1561
    Keywords: Coleoptera ; Curculionidae ; Otiorhynchus sulcatus (F.) ; black vine weevil ; Ericaceae ; Rhododendron ; trichomes ; glandular scales ; essential oils ; volatiles ; plant resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Glandular scales on selected lepidote rhododendron species varied in density from 109 ± 13 to 4180 ± 60/cm2 of leaf surface. Globules contained within the scales stained with Sudan IV, a lipophilic dye. Essential oil contents of the scales varied with species from 24 ± 8 to 151 ± 35 ng/scale. Black vine weevil [(Otiorhynchus sulcatus (F.)] feeding on leaves from a sample of rhododendron species was inversely related to leaf essential oil content, and weevil feeding on membrane filters was inhibited by application of essential oil extracts from leaves of most lepidote rhododendrons tested. Results suggest that the glandular scales of the lepidote rhododendrons function, at least in part, in plant defense against insects.
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  • 100
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    Journal of chemical ecology 10 (1984), S. 723-752 
    ISSN: 1573-1561
    Keywords: Ips typographus ; pheromone ; release ; recapture ; diffusion ; model ; Coleoptera ; Scolytidae ; trap ; marking ; dispersal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The movement of bark beetles near an attractive pheromone source is described in terms of mathematical models of the diffusion type. To test the models, two release experiments involving 47,000 marked spruce bark beetles [Ips typographus (L.)] were performed. The attractive source was a pheromone trap, surrounded by eight concentric rings with eight passive trap stations on each ring. Captures were recorded every 2–10 minutes for the pheromone trap and once for the passive traps. The models were fitted to the distribution in time of the central pheromone trap catch and to the spatial distribution of catch among the passive traps. The first model that gives a reasonable fit consists of two phases: Phase one—After release the beetles move according to a diffusion process with drift towards the pheromone trap. The strength of the drift is inversely proportional to the distance from the traps. Phase two—those beetles attracted to, but not caught by, the pheromone trap are no longer influenced by the pheromone, and their movement is described by a diffusion process without drift. In phase two we work with a loss of beetles, whereas the experiment seems to indicate that the loss of beetles in phase one is negligible. As a second model, the following modification of phase one is considered: After release the beetles move according to a diffusion process without drift, until they start responding to the pheromone (with constant probability per unit time), whereafter they start moving according to a diffusion process with drift. This study, like other release experiments, shows that the efficiency of the pheromone trap is rather low. What is specific for the present investigation is that we try to explain this low efficiency in terms of dynamic models for insect movement. Two factors seem to contribute: Some beetles do not respond to pheromone at all, and some beetles disappear again after having been close to the pheromone trap. It also seems that the motility of the beetles decreased after they ceased responding to the pheromone. Furthermore, the data lend some support to the hypothesis that flight exercise increases the response of the beetles to pheromone.
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