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  • wheat  (539)
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  • Springer  (1,518)
  • American Meteorological Society
  • 1995-1999  (668)
  • 1990-1994  (850)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 185 (1999), S. 131-141 
    ISSN: 1432-1351
    Keywords: Key wordsHelicoverpa zea ; Noctuidae ; Lepidoptera ; Sex pheromone ; Antagonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The limits of a male moth's ability to resolve closely spaced odor filaments have been investigated. Male Helicoverpa zea normally respond to their conspecific sex pheromone blend by exhibiting an upwind flight, which culminates in source contact by at least 50% of the bioassayed individuals. When loaded onto the same filter paper source containing this hitherto attractive pheromone blend, or onto a separate filter paper and co-emitted from the same pipette source with pheromone, (Z)-11-hexadecenyl acetate severely reduced upwind flight and source contact by male H. zea. A similar level of upwind flight inhibition was recorded when the antagonist (Z)-11-hexadecenyl acetate was emitted from its own point source placed 1 mm upwind of the pheromone point source, both plumes being simultaneously emitted in a continuous mode to form a confluent strand. However, (Z)-11-hexadecenyl acetate was less effective in reducing upwind flight and source contact when it was isolated and pulsed from its own source, placed 1 mm either upwind, downwind or cross-wind of a pipette source from which pheromone was simultaneously being pulsed, such that both filaments were separated in time by 0.001–0. 003 s. These results suggest that male H. zea are able to distinguish between odor sources separated by as little as 1 mm in space and 0.001 s in time.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 184 (1999), S. 535-541 
    ISSN: 1432-1351
    Keywords: Key words Insects ; Lepidoptera ; Macroglossum stellatarum ; Colour vision ; Red receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Hymenopterans have long been shown to choose colours by means of the spectral distribution and independently of the intensity (true colour vision). The same ability has only very recently been proven for two butterfly species. We present evidence for the existence of true colour vision in the European hummingbird hawkmoth, Macroglossum stellatarum. Moths were trained in dual-choice situations to spectral lights of a rewarding and an unrewarding wavelength. After training, unrewarded tests were performed during which the intensities of the lights were changed. The results confirm that the species has three spectral receptor types and uses true colour vision when learning the colour of a food source. If colour vision is not possible since only one receptor type is receiving input from both stimuli, the moths learn to associate some achromatic cue correlated to the receptor quantum catch, with the reward. The moths learn spectral cues rapidly and choose correctly after one to several rewarded visits even when trained to different colours in sequence.
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  • 3
    ISSN: 1432-1351
    Keywords: Threshold ; Olfaction ; Insect ; Lepidoptera ; Noctuid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Responses of Trichoplusia ni HS(A) receptor neurons were measured to determine the minimum detectable concentration (absolute threshold) and the minimum detectable increment (difference threshold) for the major sex pheromone component (Z)-7-dodecen-1-ol acetate (Z7-12∶Ac). The absolute threshold was 1000-fold below the ∼10-11 M level of Z7-12∶Ac at a calling female. The Weber fraction, i.e., the ratio of the difference threshold to the stimulus concentration, declined from ∼0.8 to ∼0.06 as the concentration rose from threshold to high intensities. Relatively smaller fluctuations were detected as the stimulus increased. 2. The HS(A) responses were interpreted in relation to behavior by considering an ideal observer as approximating the central nervous system (CNS). The ideal thresholds were 3–9-fold lower than the HS(A) thresholds. 3. The ideal absolute threshold of the T. ni CNS is comparable to observed behavioral thresholds for wingflutter and taking flight. However, only a low percentage response occurs at threshold. Most males take flight at higher concentrations. Also, the ideal Weber fraction is lower than in most flight-tunnel bioassays. Yet, males respond to small fluctuations in orienting to pheromone plumes. These differences between moths and ideal observers may reflect inhibition at points in the CNS that control the flow of olfactory input.
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  • 4
    ISSN: 1432-203X
    Keywords: Triticum aestivum L. ; wheat ; transformation ; biolistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have developed a method for the accelerated production of fertile transgenic wheat (Triticum aestivum L.) that yields rooted plants ready for transfer to soil in 8–9 weeks (56–66 days) after the initiation of cultures. This was made possible by improvements in the procedures used for culture, bombardment, and selection. Cultured immature embryos were given a 4–6 h pre-and 16 h post-bombardment osmotic treatment. The most consistent and satisfactory results were obtained with 30 μg of gold particles/bombardment. No clear correlation was found between the frequencies of transient expression and stable transformation. The highest rates of regeneration and transformation were obtained when callus formation after bombardment was limited to two weeks in the dark, with or without selection, followed by selection during regeneration under light. Selection with bialaphos, and not phosphinothricin, yielded more vigorously growing transformed plantlets. The elongation of dark green plantlets in the presence of 4–5 mg/l bialaphos was found to be reliable for identifying transformed plants. Eighty independent transgenic wheat lines were produced in this study. Under optimum conditions, 32 transformed wheat plants were obtained from 2100 immature embryos in 56–66 days, making it possible to obtain R3 homozygous plants in less than a year.
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  • 5
    ISSN: 1432-203X
    Keywords: wheat ; rye ; embryogenesis ; growth ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The influence of the short arm of rye chromosome 1 (1RS) from Secale cereale var. Imperial on the growth and differentiation of callus cultures from wheat Triticum aestivum var. Chinese Spring immature embryos was analysed. This chromosome arm was found to stimulate both embryogenesis and the rate of growth of calli. Recombinant lines carrying segments of 1RS were used to delineate the regions of 1RS responsible for the tissue culture effects. The enhancement of embryogenesis and the stimulation of growth were shown to be associated with two distinct genetic regions of the chromosome arm; the former is located between the centromere and the Sec 1 locus, while the latter is situated in the immediate vicinity of the Sec 1 locus.
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  • 6
    ISSN: 1432-1939
    Keywords: Key words Insect-plant interactions ; Lepidoptera ; Polyphagy ; Specialization ; Host plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analyzed geographic differentiation in oviposition preference in the anise swallowtail butterfly, Papilio zelicaon Lucas, which is one of the most widely distributed and polyphagous butterflies in western North America. Among 13 populations that span 1200 km of the range of P. zelicaon in the Pacific Northwest of North America, the overall oviposition preference hierarchy has not diverged significantly, even though these populations differ in the plant species they use in the field. The results indicate that differences in host availability and use have not favored major reorganizations in the preference hierarchy of ovipositing females. Instead, this butterfly has a conserved preference hierarchy that varies within a narrow range among populations. All populations ranked the four test plant species in the same overall relative order, even though these populations differ in the plant species they use in the field.
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  • 7
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    Oecologia 119 (1999), S. 565-571 
    ISSN: 1432-1939
    Keywords: Key wordsVespula ; Lepidoptera ; Phenology ; Shared predator ; Ecological impact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Introduced social wasps (Vespula vulgaris) reach high densities in some New Zealand beech forests, because honeydew provides an abundant high-energy food source. We manipulated wasp density to estimate an “ecological damage threshold” for large, free-living Lepidoptera larvae. There will be a continuum of ecological damage thresholds for wasp density depending on the prey species or habitat. Experimentally placed small caterpillars had a significantly higher survival rate than large caterpillars, and the survival rate of both groups decreased with increasing wasp density. Spring-occurring caterpillars have a probability of surviving of 0.90–0.95, assuming wasps are the only source of mortality. However, at the peak of the wasp season we predict caterpillars would have virtually no chance (probability of 10−78 to 10−40) of surviving to adults. Wasp abundance must be reduced by at least 88% to conserve the more vulnerable species of free-living caterpillars at wasp densities similar to those observed in our study sites. This equates to a damage threshold of 2.7 wasps per Malaise trap per day. It was exceeded for about 5 months of the year in non-poisoned sites. There are currently no biological or chemical control techniques available in New Zealand that will reduce wasp abundance below this damage threshold throughout the year. Our models show that most Lepidoptera with spring caterpillars will be able to persist, but species with caterpillars occurring in the peak wasp season will be eliminated.
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  • 8
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    Oecologia 89 (1992), S. 229-235 
    ISSN: 1432-1939
    Keywords: Lepidoptera ; Digestion ; Larvae ; Mandible ; C4 grasses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cynodon dactylon (Poaceae) leaf pieces recovered from the frass of final-instar Paratrytone melane larvae (Lepidoptera: Hesperiidae) were composed of 14–22 percent crushed cells and 78–86 percent uncrushed cells, yet approximate digestibilities of soluble carbohydrates and protein averaged 78 and 88 percent, respectively. Therefore, nutrients from uncrushed cells were extracted by P. melane. The ability of P. melane and another leaf-snipping lepidopteran, Pseudaletia unipuncta (Noctuidae), to digest the contents of uncrushed bundle sheath and mesophyll cells in C. dactylon was examined with transmission electron microscopy. Organelles and plasma membranes were digested in the foreguts and midguts of both species. These findings suggest that nutrients in uncrushed leaf cells may be extracted through plasmodesmata and cell wall pores after membranes are digested. The generality of leaf-snipping, vis-a-vis leaf crushing, among larval Lepidoptera was assessed by surveying the mandible morphologies of 202 species. In 82 percent of the species surveyed only incisor regions were present. I conclude that leaf-snipping is a common mode of feeding among phytophagous Lepidoptera and that the digestion of cell contents is efficient despite the fact that few of the cells of ingested plant tissues are crushed.
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  • 9
    Electronic Resource
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    Springer
    Oecologia 96 (1993), S. 575-582 
    ISSN: 1432-1939
    Keywords: Diet specialization ; Host plant chemistry ; Lepidoptera ; Paraponera clavata ; Predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To evaluate the role of predation in the evolution of diet specialization and to determine the effectiveness of various larval defenses, we offered lepidopteran larvae to colonies of the tropical ant Paraponera clavata. We recorded behavioral and physical characteristics of prey items and used log-linear models to analyze their importance as deterrents to predation by P. clavata. The most important determinant of probability of prey rejection by P. clavata was a prey's diet breadth; specialists were rejected by the ants significantly more than generalists. Other less important, but significant, predictors of prey rejection included ontogeny, morphology and chemistry. Late instar caterpillars were rejected more frequently than early instars, hairy caterpillars were rejected more frequently than caterpillars with other morphologies, and one caterpillar species with an unpalatable extract was rejected more frequently than two species with palatable extracts.
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  • 10
    ISSN: 1432-1939
    Keywords: C3 and C4 grasses ; Lepidoptera ; Hesperiidae ; Paratrytone melane ; Nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We tested the hypothesis that C4 grasses are inferior to C3 grasses as host plants for herbivorous insects by measuring the relative performance of larvae of a graminivorous lepidopteran, Paratrytone melane (Hesperiidae), fed C3 and C4 grasses. Relative growth rates and final weights were higher in larvae fed a C3 grass in Experiment I. However, in two additional experiments, relative growth rates and final weights were not significantly different in larvae fed C3 and C4 grasses. We examined two factors which are believed to cause C4 grasses to be of lower nutritional value than C3 grasses: foliar nutrient levels and nutrient digestibility. In general, foliar nutrient levels were higher in C3 grasses. In Experiment I, protein and soluble carbohydrates were digested from a C3 and a C4 grass with equivalent efficiencies. Therefore, differences in larval performance are best explained by higher nutrient levels in the C3 grass in this experiment. In Experiment II, soluble carbohydrates were digested with similar efficiencies from C3 and C4 grasses but protein was digested with greater efficiency from the C3 grasses. We conclude (1) that the bundle sheath anatomy of C4 grasses is not a barrier to soluble carbohydrate digestion and does not have a nutritionally significant effect on protein digestion and (2) that P. melane may consume C4 grasses at compensatory rates.
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  • 11
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    Oecologia 108 (1996), S. 643-651 
    ISSN: 1432-1939
    Keywords: Migration rate ; Lepidoptera ; Mark-recapture study ; Population density ; Movement behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rapidly increasing fragmentation of natural landscapes decreases the ability of many species to reach the smaller and more isolated patches of habitat in a metapopulation. The densities of local populations of several moth species and the butterfly Hipparchia semele in a network of small islands, and the rates of inter-island movement and movement patterns, were investigated, to determine the factors affecting the rate and pattern of movements. The estimated population densities ranged from 0.001 to 0.2 individuals/m2. The observed emigration and immigration rates depended on island isolation and various traits of the species, with great variability in migration rates among species. Thin-bodied, slow-flying species did not move among the islands, whereas many robust, fast-flying species moved among the islands relatively frequently. Migration rate increased significantly with body size and was significantly higher in oligophagous than in polyphagous species, suggesting that these factors are important determinants of the migration rate of the species. Migration rate was low when the surface temperature of the sea was low, and a greater proportion of individuals emigrated from small than large patches of habitat. The migration distances of female noctuids were shorter than those of males and those of both sexes of the butterfly H. semele. The observed movement patterns are consistent with a metapopulation structure in most of the moth species.
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  • 12
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    Journal of comparative physiology 178 (1996), S. 55-61 
    ISSN: 1432-1351
    Keywords: Electrophysiology ; Lepidoptera ; Photoreceptor ; Spectral sensitivity ; Vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. The ommatidia of the butterfly Papilio have a fused and tiered rhabdom. The distal tier of the rhabdom is made up of four distal photoreceptors (R1–4), whereas the proximal tier is made up of four proximal (R5–8) and one basal photoreceptor cell (R9). 2. We first confirmed by light microscopy that the ommatidia of Papilio are not twisted, i.e. have the same spatial organization all about the longitudinal axis. The polarization method, previously applied to the distal tier, hence is applicable to identify the photoreceptor location from the peak angle of the polarization sensitivity. 3. We determined the polarization and spectral sensitivity of in total 109 proximal and basal photoreceptors in the lateral looking eye region. All of the photoreceptors were either green or red type, most of which fall into three classes as judged by the peak angles of the polarization sensitivity: around 40°, 150°, and 180° (= 0°) with respect to the dorso-ventral axis. The first two classes are formed by the proximal photoreceptors with straight microvilli oriented at the average angle of 39° (R6, 8) and 144° (R5, 7) respectively, and the third is formed by the basal photoreceptors R9 with straight microvilli oriented at 180° (= 0°). The mean polarization sensitivity (PS = maximal sensitivity/minimal sensitivity) was about 2. 4. 75% of the proximal and 48% of the basal photoreceptors were of the red type. 5. A single ommatidium of Papilio appears to contain two to four types of spectral receptors.
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  • 13
    ISSN: 1432-1351
    Keywords: Heliothis ; Noctuidae ; Lepidoptera ; Plume structure ; Behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1) Male Heliothis virescens moths flew upwind to pulsed pheromone plumes. Upon truncation of the pulsed plume males flew into clean air, turning their tracks crosswind (〉 60° relative to directly upwind direction at 0°) within an average of 0.27 s, and were casting, perpendicular to the wind-line (90°), within 0.43 s. 2) The characteristic casting flight in clean air consisted of left-right crosswind reversals, continuing for many seconds without further pheromonal stimulation. Males intercepting a single strand of pheromone during casting flight responded by surging upwind (track angles 〈 60°). The phasic surge lasted only 0.38 s before reverting to crosswind flight (〉 60°). 3) Average templates of responses in two and three dimensions were created. Males controlled their vertical deviations very tightly when in contact with pheromone but upon entering clean air, lateral and vertical excursions became much greater. 4) Males failed to sustain upwind flight to repetitively pulsed plumes generated at 〈 4 filaments/s. At the threshold frequency of 4 pulses/s we show that upwind flights were composed of reiterated surges followed by crosswind casting. As the pulse frequency increased, the tracks became straighter and the single filament cast-surge-cast template could be viewed only sporadically when, for example, a male apparently failed to intercept filaments.
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  • 14
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    Journal of comparative physiology 171 (1992), S. 289-297 
    ISSN: 1432-1351
    Keywords: Electrophysiology ; Lepidoptera ; Photoreceptor ; Spectral sensitivity ; Vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. A butterfly Papilio has 5 types of spectral receptors in the compound eye. The spectral sensitivity of each type peaks in the UV, violet, blue, green, and red wavelengths, respectively. The green type contains two subtypes with and without a UV secondary peak. Here we studied the localization of these spectral receptors within the ommatidium. 2. An ommatidium contains 9 photoreceptors (R1–9), each of which is one of the 5 spectral receptor types. The photoreceptors bear parallel microvilli to form a nontwisted rhabdom, and thereby the photoreceptors are polarization sensitive. 3. We first examined the microvillar orientation by electron microscopy. The microvilli of R1, 2, and 9 are oriented dorso-ventrally (0°), whereas those of R3 and 4 are parallel to the antero-posterior axis (90°). The R5–8 bear microvilli diagonally: 45° for R6 and R8, 135° for R5 and R7. 4. We then recorded spectral and polarization sensitivities from single photoreceptors. The peak angle of the polarization sensitivity (θmax) of the UV, violet, and blue receptors were around 0°, whereas that of the green receptors was around 90°. In the double-peaked green receptors, the θmax at UV was also around 90°. The red receptors showed a θmax at around 35°. The polarization sensitivity ratio (PSmax/PSmin) of the double-peaked green receptors measured at UV was around 4, whereas the ratio of other receptors was around 2. 5. We conclude that R1 and R2 are either UV, violet, or blue receptors whereas R3 and R4 are green receptors. Some R6 and R8 are red receptors. We also conclude that the UV secondary peak in the double-peaked green receptor is not simply attributable to the coupling with UV receptors.
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  • 15
    ISSN: 1432-1351
    Keywords: Carbon dioxide ; Chemoreception ; Lepidoptera ; Microclimate ; Sensory transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In recordings of single unit action potentials, the responses of CO2-receptors in the labial palp organ of the moth Heliothis armigera to modulation of CO2-density around a background of 350 ppm were investigated. Modulation of CO2-density by square wave changes in concentration at constant barometric pressure evokes modulation of the spike rate. Modulation of CO2-density by square wave changes in barometric pressure at constant CO2-concentration evokes responses similar to those evoked by concentration modulation. For modulation depths of less than 1.5%, the output modulation depth is linearly related to the input; at higher modulation depths the gain decreases progressively. Using sinusoidal pressure modulation, the frequency dependence of both gain and output noise was determined over a range of 0.05 to 12.8 Hz. With increasing frequency the gain progressively increases at a rate of 2.4 dB/octave up to a maximum of 63 at 3 Hz; at higher frequencies, it decreases rapidly. The threshold sensitivity of the receptors, using input noise amplitude density as a criterion, is broadly tuned, with a minimum of 1 % contrast Hz-0.5 between 0.3 and 3 Hz. Using these figures, it is concluded that the sensory organ is capable of detecting fluctuations in CO2-density of 0.14% or 0.5 ppm. The results are related to the fluctuations in CO2-density which occur in a natural environment.
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  • 16
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    Journal of comparative physiology 173 (1993), S. 783-799 
    ISSN: 1432-1351
    Keywords: Insect vision ; Lepidoptera ; Medulla neurons ; Optomotor stimulation ; Direction selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract InManduca sexta, large tangential cells connect the medulla via the lobula valley (LoV) tract to the midbrain and the contralateral medulla. Tract neurons have been stained and recorded to determine their responses to optomotor stimulation. Neurons in the LoV-tract comprise a physiologically and anatomically heterogeneous population: 1. Motion insensitive medulla tangential (Mt) neurons arise from cell bodies in the ventral rind. Heterolateral cells arborize massively in both medullae and one or both halves of the midbrain. Mt-neurons respond to changes in light intensity. Physiological and anatomical evidence argues for their monocularity and transmission from the medulla on the side of the soma to the central brain and the contralateral medulla. 2. Motion sensitive neurons with cell bodies behind the protocerebral bridge connect the midbrain to the ipsior contralateral medulla. Direction-selective responses are characterized by excitation to motion in the preferred and inhibition in the opposite direction with maxima either in a horizontal or vertical direction. Peak values appear at contrast frequencies of appr. 3/s. The results suggest that these neurons are binocular and relay information from the midbrain to the medulla. They have been labelled as centrifugal medulla tangential (cMt) neurons. The possible roles for tract neurons in visually guided behaviour are discussed.
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  • 17
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    Journal of comparative physiology 167 (1990), S. 309-320 
    ISSN: 1432-1351
    Keywords: Chemosensory integration ; Olfaction ; Brain ; Larva ; Caterpillar ; Manduca sexta ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The physiology and morphology of olfactory interneurons in the brain of larval Manduca sexta were studied using intracellular recording and staining techniques. Antennal olfactory receptors were stimulated with volatile substances from plants and with pure odorants. Neurons responding to the stimuli were investigated further to reveal their response specificities, dose-response characteristics, and morphology. 2. We found no evidence of specific ‘labeled-lines’ among the odor-responsive interneurons, as none responded exclusively to one plant odor or pure odorant; most olfactory interneurons were broadly tuned in their response spectra. This finding is consistent with an ‘across-fiber’ pattern of odor coding. 3. Mechanosensory and olfactory information are integrated at early stages of central processing, appearing in the responses of some local interneurons restricted to the primary olfactory nucleus in the brain, the larval antennal center (LAC). 4. The responses of LAC projection neurons and higher-order protocerebral interneurons to a given odor were more consistent than the responses of LAC local interneurons. 5. The LAC appears to be functionally subdivided, as both local and projection neurons had arborizations in specific parts of the LAC, but none had dendrites throughout the LAC. 6. The mushroom bodies and the lateral protocerebrum contain neurons that respond to olfactory stimulation.
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  • 18
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    Cellular and molecular life sciences 46 (1990), S. 1016-1017 
    ISSN: 1420-9071
    Keywords: In vitro absorption ; calcium ; wheat ; Bengal gram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The in vitro absorption of calcium from the duodenum was significantly less in a group of rats fed on a wheat diet than in a group fed a wheat and Bengal gram (70∶30) diet.
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  • 19
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    Cellular and molecular life sciences 49 (1993), S. 998-1001 
    ISSN: 1420-9071
    Keywords: Lepidoptera ; Tortricidae ; synomone ; pheromone ; behavior ; oviposition ; Lobesia botrana ; Cydia pomonella ; Cydia molesta ; Eupoecilia ambiguella ; fatty acids ; esters of fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Oviposition of four tortricid pests of vineyards (the European grapevine moth and the grape berry moth) and fruit orchards (the codling moth and the oriental fruit moth) is deterred by a blend of straight chain fatty acids and esters of fatty acids that have been identified in the eggs of one of them: the European grapevine moth (EGVM)Lobesia botrana. This is the first evidence of inter-specific recognition of an egg-like signal in moths. We demonstrate that oviposition site selection is influenced by population density, avoidance of deterrent being most important when females are isolated. Inter-specific egg recognition might be an important phenomenon, especially in species competing for a common food resource. We propose the term ‘oviposition regulating synomone’ for molecules and blends that affect the inter-specific spacing of eggs.
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  • 20
    ISSN: 1420-9071
    Keywords: Oviposition-deterring pheromone ; Lepidoptera ; Tortricidae ; Lobesia botrana ; eggs ; fatty acids ; esters of fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The oviposition of the European grapevine moth (EGVM)Lobesia botrana can be deterred by an extract of conspecific eggs corresponding to 20 egg equivalents. The reduction of the oviposition behavior is dose-dependent. Nine chemicals have been extracted from the eggs and identified as straight chain fatty acids and esters of fatty acids. A mixture of these rather simple molecules induces the same levels of deterrence as the total extract. It might be possible to use oviposition regulating pheromone in the future for the control of EGVM populations.
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  • 21
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    Cellular and molecular life sciences 49 (1993), S. 721-724 
    ISSN: 1420-9071
    Keywords: Lepidoptera ; Noctuidae ; Agrotis ipsilon ; black cutworm ; juvenile hormone ; allatectomy ; pheromone reception ; sexual behaviour ; tenoxycarb ; KK-42
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In Lepidoptera, reproduction is linked to chemical communication between conspecific partners. When exposed to the female sex pheromone, males respond by exhibiting typical sexual behaviour which leads to mating. Here we show that presence of the juvenile hormone producing gland (corpora allata) of the male black cutworm,Agrotis ipsilon, is necessary for pheromone responsiveness. Allatectomized males do not show any sexual behaviour, although their antennal olfactory system is functional. Allatectomized males implanted with active corpora allata recover full pheromone receptivity. It is suggested that reproductive processes are synchronized in males and females through endocrine control; timing of the mating activity could serve as an adaptive strategy linked to the migratory behaviour of this species.
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  • 22
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    Cellular and molecular life sciences 50 (1994), S. 176-181 
    ISSN: 1420-9071
    Keywords: Cardiac glycoside loss ; Danaus plexippus ; aging ; breakdown of chemical defense ; three trophic level interactions ; automimicry ; Lepidoptera ; Asclepias
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Monarch butterflies (Danaus plexippus) are unpalatable to various vertebrate predators because their larvae sequester bitter and emetic cardiac glycosides (CGs) from milkweed plants (Asclepias spp.). Here we show that the concentration of the defensive CGs decrease as individual butterflies age, regardless of the CGs' initial amounts or specific chemical structures. Consequently, individual monarch butterflies can change from being unpalatable models to palatable mimics during their lifetime. Since monarchs breed continuously over the spring and summer in North America, freshly emerged adult butterflies may serve as noxious models for older individuals which become automimics as they age.
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  • 23
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    Cellular and molecular life sciences 50 (1994), S. 571-575 
    ISSN: 1420-9071
    Keywords: Ancient DNA ; archaeobotany ; carbonized grain ; DNA sequences ; glutenin alleles ; seed proteins ; Triticum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used hybridization analysis to detect ancient DNA in wheat seeds collected from three archaeological sites in Europe and the Middle East. One of these samples, carbonizedT. spelta dated to the first millennium BC, has yielded PCR products after amplification with primers directed at the leader regions of the HMW (high molecular weight) glutenin alleles. Sequences obtained from these products suggest that the DNA present in the Danebury seeds is chemically damaged, as expected for ancient DNA, and also indicate that it should be possible to study the genetic variability of archaeological wheat by ancient DNA analysis. Finally, we describe a PCR-based system that enables tetraploid and hexaploid wheats to be distinguished.
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  • 24
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    Cellular and molecular life sciences 46 (1990), S. 269-273 
    ISSN: 1420-9071
    Keywords: Sex pheromone ; biosynthesis ; Lepidoptera ; Epiphyas postvittana ; deuterium-labelling ; (E)-11-tetradecenyl acetate ; (E,E)-9,11-tetradecadienyl acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fatty acyl moieties present in the female sex pheromone gland of the lightbrown apple moth,Epiphyas postvittana, include the analogues of the two sex pheromone components, (E)-11-tetradecenyl acetate and (E,E)-9,11-tetradecadienyl acetate. Application of deuterium-labelled fatty acids followed by analysis by gas chromatographymass spectrometry showed that biosynthesis of the two pheromone components involved initial Δ11-desaturation of myristic and palmitic acids respectively.
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  • 25
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    Cellular and molecular life sciences 47 (1991), S. 945-948 
    ISSN: 1420-9071
    Keywords: Juvenile hormone ; Manduca sexta ; Lepidoptera ; immunotaxonomy ; monoclonal antibodies ; hemolymph
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The hemolymph from various species of moths was analyzed for cross-reactivity with a panel of six monoclonal antibodies made against the hemolymph juvenile hormone binding protein ofManduca sexta. With the exception of one antibody, the immunoreactivity was limited to the sphingid family. One monoclonal antibody cross-reacted with a number of lepidopteran species; however, families such as Noctuidae and Pyralidae, known to have high affinity, low molecular weight juvenile hormone binding proteins, did not cross-react. Immunological cross-reactivity withManduca sexta juvenile hormone binding protein in several primitive moth families supports the current model of phylogenetic relationships in the order Lepidoptera.
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  • 26
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    Cellular and molecular life sciences 51 (1995), S. 1003-1027 
    ISSN: 1420-9071
    Keywords: Olfaction ; olfactory receptor neuron ; sensillum ; antenna ; antennal lobe ; glomerulus ; pheromone ; kairomone ; host odour ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Odours play a very important role in the life of insects belonging to the order Lepidoptera. In the present paper, a review is given of the current knowledge of morphology, development and function of the olfactory system in larval and adult moths and butterflies. Research regarding both the antennal and accessory olfactory pathways, as well as both the pheromone and the host odour detecting systems, is reviewed.
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  • 27
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    Cellular and molecular life sciences 48 (1992), S. 97-102 
    ISSN: 1420-9071
    Keywords: Lepidoptera ; Arctiidae ; pyrrolizidine alkaloids ; cannibalism ; acquired defense ; phagostimulation ; specific hunger
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The mothUtetheisa ornatrix derives protection against predation from systemic pyrrolizidine alkaloids (PAs) that it sequesters as a larva from its foodplants (Leguminosae,Crotalaria spp.). We here show, in laboratory tests, thatUtetheisa deficient in body PA can make up for the chemical shortfall by cannibalizing pupae. We present evidence indicating that cannibalism in larvae is elicited not by hunger, but possibly by PA deficiency itself, and that in making cannibalistic choices larvae prefer PA-containing over PA-free pupae. PAs themselves, either in crystalline form or as additives to food items, proved phagostimulatory to larvae. In natureUtetheisa tend to pupate away from their foodplant, essentially out of reach of larval attack. The threat of cannibalism may have contributed to the evolution of this pupation behavior.
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  • 28
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    Cellular and molecular life sciences 52 (1996), S. 259-263 
    ISSN: 1420-9071
    Keywords: Senecio cannabifolius ; Compositae ; foliar surface chemistry ; tobacco cutworm ; Spodoptera litura ; Lepidoptera ; Noctuidae growth inhibition ; ethyl (1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl) acetate ; methyl (1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl) acetate
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    Notes: Abstract Dewaxed leaf surface extracts of 12 plants from Hokkaido, prepared by dipping fresh leaves in chloroform for 3 min, were used in a choice leaf-disk bioassay against larvae of the tobacco cutwormSpodoptera litura. Activity was found only in the extract ofSenecio cannabifolius, a very successful weed in Hokkaido. Individual fractions of the extract, however, were not active. Incorporation of the individual fractions of the surface extracts as well as fractions of the methanolic extracts of the leaf residue into an artificial diet fed to neonateS. litura led to the isolation of ethyl (1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl) acetate, the major surface compound, as the active principle. This compound was also present in the methanolic extract of the leaf residue together with methyl (1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl) acetate, which had the same growth inhibitory effect on the larvae. The presence of these compounds in the foliar surface and tissue suggests a defensive role against herbivores.
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  • 29
    ISSN: 1420-9071
    Keywords: Mating ; pheromone ; epoxyheneicosadiene ; enantiomer ; Arctiidae ; Callimorpha ; Tyria ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract It has been suggested that a common sex pheromone composition may account for interspecific sexual interactions observed with certain moths in the Arctiidae. In this study, it is demonstrated that the sex pheromones released by females of the Scarlet Tiger Moth,Callimorpha dominula L., and the Cinnabar Moth,Tyria jacobaeae L., have similar activities and elute at the same retention time on analysis by coupled gas chromatography (GC)-electrophysiology with males from each species. Peak enhancement on GC, chiral GC and coupled GC-mass spectrometry using authentic compounds show that the sex pheromone for bothC. dominula andT. jacobaeae is (3Z,6Z,9S,10R)-9,10-epoxyheneicosa-3,6-diene.
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  • 30
    ISSN: 1423-0445
    Keywords: chemical defence ; comparative sequestration ; feeding guilds ; insect herbivory ; natural enemies ; cardenolides ; Lepidoptera ; Danainae ; Danaus plexippus (L.) ; Homoptera ; Aphidae ; Aphis nerii B. de F. ; Asclepiadaceae ; Asclepias curassavica L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cardenolide sequestration by a hemimetabolous aphid and a holometabolous butterfly from the neotropical milkweed,Asclepias curassavica L., is compared. The oleander aphid,Aphis nerii B. de F., sequestered a similarly narrow range of cardenolide concentrations to the monarch butterfly,Danaus plexippus (L.), from the wide range of concentrations available in leaves of A.curassavica. However, A.nerii sequestered significantly less cardenolide (269 µg/0.1 g) thanD. plexippus (528 µg/0.1 g). The honeydew excreted by A.nerii was comprised of 46% cardenolide. The complete polarity range of 25 cardenolides detected by thin layer chromatography in A.curassavica was represented in the 17 whole aphid cardenolides and the 20 aphid honeydew cardenolides detected. D.plexippus sequestered a narrower polarity range of 11 cardenolides, having eliminated low polarity cardenolide genins and glycosides. It is suggested that these chemical differences may be related to interactions among the broad feeding tactics of sucking or chewing milkweed leaves, life history constraints of holometabolyversus hemimetaboly, the distribution of milkweed food resources in space and time, and the dynamics of natural enemies.
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  • 31
    ISSN: 1423-0445
    Keywords: variation of secondary substances ; pharmacophagy ; pyrrolizidine alkaloids ; Lepidoptera ; Ithomiinae ; Aeria olena ; Tithorea harmonia ; Mechanitis polymnia ; Apocynaceae-Echitoideae ; Solanaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The primitive, Apocynaceae-feeding Ithomiine,Tithorea harmonia, incorporates dehydropyrrolizidine alkaloids (PAs) from its larval foodplant (Prestonia acutifolia), rarely visiting PA sources pharmacophagously in the adult; females show higher concentrations of PAs than males, with similar variance. The close relativeAeria olena (feeding onP. coalita, without PAs) shows similar PA concentrations in both sexes and greater variation in males, like more advanced Solanaceae-feeding Ithomiine such asMechanitis polymnia, which likeA. olena obtain PAs by pharmacophagy in the adult (mainly males). This difference is due to the dynamics of PA incorporation in these species. Little variation in PA content was found among allopatric populations of the same species, but variation in available PA sources in different months was correlated with different average storage levels in the butterflies.
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  • 32
    ISSN: 1423-0445
    Keywords: chemical defense ; mimicry ; evolutionary strategies ; hostplants ; cyanogenesis ; linamarin ; pyrrolizidine alkaloids ; Lepidoptera ; Acraeinae ; Asteraceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary American Acraeinae butterflies often ingest large amounts of dehydropyrrolizidine alkaloids (PAs) from their Asteraceae hostplants in both larval and adult stages, but do not normally store these compounds for defence, instead biosynthesizing large amounts of the cyanogenic glucoside linamarin in all stages. This defence syndrome (rejection of plant toxins andde novo synthesis of protective chemicals) is considered to be the most evolved among aposematic (unpalatable mimicry-model) butterflies, as are the Acraeinae and Heliconiini which also synthesize cyanogens. Storage or minimal processing of larval hostplant-derived defensive chemicals is widespread and characterizes the most primitive model groups; an intermediate series (Danainae/Ithomiinae) also obtains the principal defensive chemicals (PAs) from plants, but mostly in the adult stage. These syndromes are discussed and contrasted with the pattern seen in Chrysomelidae beetles, wherede novo synthesis is widespread and considered primitive.
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  • 33
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    Chemoecology 1 (1990), S. 81-85 
    ISSN: 1423-0445
    Keywords: phototoxicity ; harmane ; harmine ; harmalol ; alpha-terthienyl ; skimmianine ; Lepidoptera ; Oecophoridae ; Depressaria pastinacella ; parsnip webworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The parsnip webworm,Depressaria pastinacella (Lepidoptera: Oecophoridae), feeds exclusively on apiaceous hostplants containing furanocoumarins, compounds capable of oxygen-dependent and oxygen-independend photosensitization. Despite high titers of antioxidant enzymes relative to other herbivorous insects, webworms cannot tolerate nonhost photosensitizers such as alpha-terthienyl or beta-carboline alkaloids at dietary concentrations of 0.01% or less. Tolerance of skimmianine, a furano-quinoline alkaloid, may be due to its structural resemblance to furanocoumarins, which are metabolized by cytochrome P450 monooxygenases in this species.
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  • 34
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    Chemoecology 1 (1990), S. 69-76 
    ISSN: 1423-0445
    Keywords: green leaf volatile ; semiochemical ; synomone ; volatile attractant ; tritrophic ; host location ; parasitoid behavior ; Hymenoptera ; Braconidae ; Microplitis ; Ichneumonidae ; Netelia ; Lepidoptera ; Noctuidae ; Heliothis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.
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  • 35
    ISSN: 1423-0445
    Keywords: taste aversion ; toxicology ; chemical defense ; cardiac glycoside ; cardenolides ; digitoxin ; pyrrolizidine alkaloids ; monocrotaline ; Mammalia ; Muridae ; Peromyscus ; Reithrodontomys ; Lepidoptera ; Danainae ; Danaus plexippus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Of three common mouse species at the Mexican overwintering sites of the monarch butterfly, onlyPeromyscus melanotis eats monarchs. We hypothesized thatP. aztecus andReithrodontomys sumichrasti reject monarchs because they are more sensitive to the bitter taste and/or toxic effects of the cardiac glycosides (CGs) and pyrrolizidine alkaloids (PAs) in the butterflies. Two-choice preference tests revealed no difference in taste avoidance thresholds to free base and N-oxide forms of the PA, monocrotaline, but very different avoidance thresholds to the CG, digitoxin. Avoidance thresholds forR. sumichrasti andP. aztecus were, in respective order, 1020 and 34 times less than that forP. melanotis. We also tested the toxic sensitivity of juvenile mice by chronically feeding diets containing digitoxin or monocrotaline at concentrations similar to those used in the preference tests. No species developed CG toxicity, but bothP. melanotis andP. aztecus developed moderate PA toxicity (R. sumichrasti was not tested for PA toxicity).P. aztecus grew more slowly and manyP. melanotis had hepatic metabolic lesions. Thus, the three mouse species responded very differently to the taste and toxic properties of CGs and PAs at ecologically relevant concentrations: 1) CGs were taste rejected by all species exceptP. melanotis, while PAs were not; and 2) PAs were toxic, while CGs were not.
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  • 36
    ISSN: 1423-0445
    Keywords: taste aversion ; chemical defense ; predatory attack patterns ; insectivory ; cardiac glycosides ; cardenolides ; Mammalia ; Muridae ; Peromyscus ; Reithrodontomys ; Lepidoptera ; Danainae ; Danaus plexippus
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Peromyscus melanotis is the only one of three mouse species that eats monarch butterflies at their overwintering sites in Mexico. I tested two hypotheses: 1)P. aztecus avoids monarchs because of a bitter taste aversion to cardiac glycosides (CGs) and an inability to reject CG-rich body parts; 2)Reithrodontomys sumichrasti avoids monarchs principally because of a bitter taste aversion to the CGs. None of the species are sensitive to the toxic effects of ingested CGs. Feeding responses of laboratory-reared mice of each species to monarchs with low, medium and high CG concentrations were compared. BothP. aztecus andR. sumichrasti ate significantly fewer of all three types of monarchs thanP. melanotis. ForP. aztecus andR. sumichrasti, the number of monarchs eaten decreased with increasing CG concentration, whereas forP. melanotis, the number remained constant.Peromyscus melanotis andR. sumichrasti developed a feeding technique for rejecting the CG-laden cuticular material, which reduced the bitterness of ingested monarch material. However,R. sumichrasti displayed the technique significantly less often thanP. melanotis; andP. aztecus never developed it. I conclude that high taste sensitivity to CGs and less versatile food handling preventP. aztecus andR. sumichrasti from overcoming the monarch's chemical defenses.
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  • 37
    ISSN: 1423-0445
    Keywords: growth inhibition ; phytochemical prospecting ; Meliaceae ; Lepidoptera ; Noctuidae ; Peridroma saucia ; Orthoptera ; Acrididae ; Melanoplus sanguinipes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thirty-one species in twenty genera of the plant family Meliaceae were assayed for the production of growth-inhibiting phytochemicals, using the generalist herbivorePeridroma saucia. Most species were inhibitory when methanolic extracts were incorporated into artificial diets at concentrations at or below those occurring naturally. In general members of the subfamily Melioideae were more inhibitory than members of the Swietenioideae. Extracts of deciduous species with short leaf lifetimes were significantly more inhibitory than those of evergreen species with longer leaf lifetimes. In a smaller sample of species, evergreen species showed a trend towards having tougher leaves than deciduous species. These results support the resource availability hypothesis of Coleyet al. (1985), and suggest that life history attributes may be of some value in selecting plants for phytochemical prospecting.
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  • 38
    ISSN: 1423-0445
    Keywords: predation ; plant-insect interactions ; tritrophic level interactions ; iridoid glycosides ; catalpol ; Lepidoptera ; Nymphalidae ; Junonia coenia ; Hymenoptera ; Formicidae ; Camponotus floridanus
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary We investigated the role of the iridoid glycoside, catalpol, as a deterrent to the predator,Camponotus floridanus. Four laboratory colonies of this ant were offered buckeye caterpillars (Junonia coenia: Nymphalidae) raised on diets with and without catalpol. The same colonies were offered sugar-water solutions containing varying concentrations of catalpol, in both no-choice and choice tests. Regardless of diet, buckeye caterpillars appeared to be morphologically protected from predation by the ants, possibly because of their large spines or tough cuticle. However, buckeyes raised on diets with catalpol had high concentrations of catalpol in their hemolymph; extracts of this high-catalpol hemolymph proved to be an effective deterrent to the ants. When starved ants were not given the choice of food items, they were more likely to consume sucrose solutions that contained 5 mg catalpol/ml or 10 mg catalpol/ml than they were to consume solutions with 20 mg catalpol/ml. When they were given a choice of sugar solution or a sugar solution containing catalpol, the ants avoided solutions with catalpol at any of these concentrations. Ant colony responses to catalpol in sucrose solutions varied considerably over time and among colonies.
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  • 39
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    Chemoecology 5-6 (1994), S. 127-138 
    ISSN: 1423-0445
    Keywords: sequestration ; defence substances ; toxic substances ; pheromones ; host selection ; aristolochic acids ; pyrrolizidine alkaloids ; grayanotoxins ; cyanoglycosides ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A number of aposematic butterfly and moth species sequester toxic substances from their host plants. Some of these insects can detect the toxic compounds during food assessment. Some pipevine swallowtails use aristolochic acids among the host finding cues during oviposition and larval feeding and accumulate the toxins in the body tissues throughout all life stages. Likewise, a danaine butterfly,Idea leuconoe, which sequesters high concentrations of pyrrolizidine alkaloids in the body, lays eggs in response to the specific alkaloid components contained in the apocynad host. Insect species sharing the same poisonous host plants may differ in the degree of sequestration of toxins. Two closely ralated aposematic geometrid moth species,Arichanna gaschkevitchii andA. melanaria, sequester a series of highly toxic diterpenoids (grayanotoxins) in different degrees, while a cryptic geometrid species,Biston robstus, does not sequester the toxins, illustrating the diversity in adaptation mechanisms even within the same subfamily. By contrast, a number of lepidopteran species store the same compounds though feeding upon taxonomically diverse plant species. A bitter cyanoglycoside, sarmentosin, was characterised from several moth species in the Geometridae, Zygaenidae and Yponomeutidae, and from the apollo butterflies,Parnassius spp. (Papilionidae), although each species feeds on different groups of plants. Interspecific similarities and differences in life history and ecology are discussed in relation to variable characteristics of sequestration of plant compounds among these lepidopteran insects.
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  • 40
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    Chemoecology 5-6 (1994), S. 101-117 
    ISSN: 1423-0445
    Keywords: cardenolides ; cardiac glycosides ; chemical defence induction ; latex ; parasitism ; predation ; sequestration ; Insecta ; Diptera ; Tachinidae ; Lepidoptera ; Nymphalidae ; Danainae ; Danaus plexippus ; Asclepiadaceae
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary The contribution of Miriam Rothschild to the “monarch cardenolide story” is reviewed in the light of the 1914 challenge by the evolutionary biologist, E.B. Poulton for North American chemists to explain the chemical basis of unpalatability in monarch butterflies and their milkweed host plants. This challenge had lain unaccepted for nearly 50 years until Miriam Rothschild took up the gauntlet and showed with the help of many able colleagues that monarchs are aposematically coloured because they sequester toxic cardenolides from milkweed host plants for use as a defence against predators. By virtue of Dr Rothschild's inspiration and industry, and subsequently that of Lincoln Brower and his colleagues, this tritrophic interaction has become a familiar paradigm for the evolution of chemical defences and warning colouration. We now know that the cardenolide contents of different milkweeds vary quantitatively, qualitatively and spatially, both within and among species and we are starting to appreciate the implications of such variation. However, as Dr Rothschild has pointed out in her publications, cardenolides have sometimes blinded us to reality and it is curious how little evidence there is for a defensive function to cardenolides in plants — especially against adapted specialists such as the monarch. Thus the review will conclude with a discussion of the significance of temporal variation and induction of cardenolide production in plants, the “lethal plant defence paradox” and an emphasis on the dynamics of the cardenolide-mediated interaction between milkweeds and monarch larvae.
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  • 41
    ISSN: 1423-0445
    Keywords: speciation ; reinforcement ; character displacement ; biosynthesis ; phylogeny ; sex pheromones ; reproductive isolation (Z)-11-tetradecenyl acetate ; (E)-11-tetradecenyl acetate ; Lepidoptera ; Yponomeutidae ; Yponomeuta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sex pheromone communication in the nine European species of small ermine moths (Yponomeuta) is reviewed in regard to the potential role of pheromones in the speciation process. Six of the nine species studied (viz.,Y. evonymellus, Y. cagnagellus, Y. padellus, Y. irrorellus, Y. plumbellus, andY. vigintipunctatus) use a mixture of (E)-11-and (Z)-11-tetradecenyl acetate in different ratios as primary pheromone components, with combinations of tetradecyl acetate, (Z)-9-tetradecenyl acetate, (Z)-11-hexadecenyl acetate and the corresponding alcohols of the acetates as additional pheromone components. Analysis of (Z)- to (E)-11-tetradecenyl acetate ratios produced by individual females of these species demonstrated significant variation among females of all species. However, the ranges of ratios produced byY. cagnagellus, Y. irrorellus, andY. plumbellus, sharing the same host-plant species, spindle tree, did not overlap. Niche separation of all six species mentioned required consideration of at least one additional pheromone component or of temporal aspects. The remaining three species,i.e. Y. malinellus, Y. mahalebellus andY. rorellus, have pheromones that differ qualitatively. Biosynthetic routes to the pheromone components identified are proposed on the basis of fatty acid pheromone precursors found in the pheromone glands. A phylogenetic tree for the genus is constructed based on allozyme frequency data and changes in pheromone composition are superimposed on this tree. We suggest that the ancestral ermine moth pheromone is a mixture of (Z)-11- and (E)-11-tetradecenyl acetate and the corresponding alcohols, and a scenario of how present-day patterns evolved is outlined. The pheromone differences among the three species using spindle tree as their host-plant might have evolved throughreproductive character displacement upon secondary contact between populations that had already diverged genetically in allopatry. Pheromone differences within the so-calledpadellus-complex (includingY. cagnagellus, Y. mahalebellus, Y. malinellus, Y. padellus, andY. rorellus) in which species might have originated sympatrically, may have evolved byreinforcing selection as these species still hybridise and produce viable offspring when confined in cages. The role of pheromones in reproductive isolation amongYponomeuta species is emphasised by (1) the function of pheromone components of some of the species as behavioural antagonists to other species, (2) the cross-attraction under experimental conditions between allochronic species with similar pheromones, and (3) the formation of hybrids in the laboratory between species that are isolated in nature by pheromone differences.
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  • 42
    ISSN: 1423-0445
    Keywords: insect-plant interactions ; intraplant variation ; chemical variation ; oviposition ; iridoid glycoside ; catalpol ; aucubin ; Lepidoptera ; Junonia coenia ; Plantaginaceae ; Plantago lanceolata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chemical analysis of each individual leaf of fivePlantago lanceolata (Plantaginaceae) plants showed that iridoid glycoside content increased from undetectable in the oldest photosynthetic leaves to over 9% dry weight in the youngest leaves. The relative proportion of the two iridoid glycosides inP. lanceolata also changed with leaf age: older leaves had significantly more aucubin, whereas the youngest leaves had primarily or solely catalpol. Oviposition tests with femaleJunonia coenia (Nymphalidae) butterflies, showed that they laid most of their eggs on new leaves.
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  • 43
    ISSN: 1423-0445
    Keywords: pheromone synergists ; host-plant volatiles ; Lepidoptera ; Noctuidae ; Helicoverpa zea ; corn earworm ; Olethreutidae ; Cydia pomonella ; codling moth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The capture of adult male moths in female sex pheromone traps of two key agricultural pests, the corn earworm (Helicoverpa zea) and the codling moth (Cydia pomonella), is enhanced or synergized by a certain group of host-plant volatiles, the “green-leaf volatiles” (GLVs). Since female adults of both species call and release their sex pheromones while perched upon the leaves of their host-plants, the volatile constituents from the leaves of a number of host-plants were compared. Sex pheromone traps containing one of the prominent leaf volatiles of certainH. zea hosts, (Z)-3-hexenyl acetate, not only significantly increased the capture ofH. zea males but were preferred over traps baited only with sex pheromone. Similarly, traps baited with synthetic sex pheromome ofC. pomonella plus a blend of GLVs captured significantly more males than traps baited only with sex pheromone. Since male moths are not captured in traps baited only with these GLVs, it appears that these GLVs act as pheromone synergists which increase or enhance the attraction or arrestment of male moths in pheromone traps.
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  • 44
    ISSN: 1423-0445
    Keywords: green leaf volatiles ; cotton ; synergist ; behaviour ; sex attractant ; pheromone ; Lepidoptera ; Noctuidae ; Heliothis virescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Components of the green leaf volatile complex (Z-3-hexenyl acetate andE-2-hexenyl acetate) were shown to enhance responses of tobacco budworm,Heliothis virescens, males to the sex attractant pheromone of conspecific females in the field. The results are discussed with regard to green leaf volatiles which enhance the attractant pheromone of a cohabiting species, and serve as attractants of a parasitoid of conspecific larvae.
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  • 45
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    Chemoecology 5-6 (1994), S. 26-36 
    ISSN: 1423-0445
    Keywords: chemoreception ; olfaction ; plant volatiles ; electroantennogram ; combined GC-EAG ; evolutionary adaptation ; Lepidoptera ; Papilionidae ; Papilio polyxenes ; Papilio machaon hippocrates ; Papilio troilus ; Apiaceae ; Daucus carota ; Pastinaca sativa ; Asteraceae ; Artemisia dracunculus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Antennae of femalePapilio butterflies perceive many volatile plant constituents with widely differing, constituent-specific sensitivities. We compared the responses of threePapilio species to volatiles from host and non-host plants to assess species-specificity and the degree of evolutionary conservatism in olfactory responses. Since previous studies had demonstrated that the polar constituents in odor fromDaucus carota stimulate oviposition behavior inPapilio polyxenes, we collected headspace volatiles fromD. carota, Pastinaca sativa (both Apiaceae) andArtemisia dracunculus (Asteraceae) and separated the polar fraction of these volatiles by gas chromatography. GC-coupled electroantennograms (GC-EAG) were recorded from the speciesPapilio polyxenes, P. machaon hippocrates andP. troilus. In addition, the responses of the three species to five compounds known as generally occurring constituents of plant odor were recorded. The relative sensitivities for these compounds were nearly identical in all threePapilio species. The response spectra to the separated plant volatiles also showed considerable similarities among the species. From the limited set of GC peaks evoking a response in one of the species, 64% (D. carota), 44% (P. sativa) and 29% (A. dracunculus) also evoked a response in both of the other species. The responses of the two closely related Apiaceae feeders (P. polyxenes, P. m. hippocrates) to volatiles fromD. carota were more similar to each other than was either to the response ofP. troilus, which feeds on Lauraceae. However, this was not true for the responses to volatiles fromP. sativa. The least congruence among the three species was found in the responses to volatiles fromA. dracunculus, a non-host for all of them. The differences and similarities found in the response profiles of the threePapilio species are discussed with respect to evolutionary adaptation to host odor versus evolutionary conservatism in adaptation of olfactory receptors.
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  • 46
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    Chemoecology 5-6 (1994), S. 75-77 
    ISSN: 1423-0445
    Keywords: larval host plants ; distribution ; Lepidoptera ; Noctuidae ; Othreis fullonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The adult fruit piercing moth,Othreis fullonia, a native of the indo-Malaysian region, causes severe damage to fruits grown throughout the tropical and subtropical belt from Africa through Asia and Australia to the Pacific Islands. Plants of the family Menispermaceae and the genusErythrina (Fabaceae) serve as larval hosts but the adult moths prefer Menispermaceae plants for oviposition. In Africa, Asia and Australia, the moth does not lay eggs onErythrina since members of the Menispermaceae are abundant. However in the insular Pacific region, where most islands have few or no species of Menispermaceae, the introduced fruit piercing moth utilizesErythrina as an alternate larval host, and either depletes, endangers or causes the possible extinction of Menispermaceae.
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  • 47
    ISSN: 1423-0445
    Keywords: oviposition ; stimulants ; deterrents ; glucosinolates ; Lepidoptera ; Pieridae ; Pieris rapae ; Pieris napi oleracea ; Alliaria petiolata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Differential acceptance of garlic mustard,Alliaria petiolata byPieris rapae L. andP. napi oleracea is explained by their differential sensitivities to oviposition stimulants and deterrents in the plant. Fractions containing the stimulants and deterrents were isolated by solvent partitioning between water and n-butanol and by open-column chromatography followed by HPLC.P. napi oleracea showed no preference when offered a choice ofA. petiolata or cabbage, but was strongly stimulated to oviposit by post-butanol water extracts ofA. petiolata. The most abundant glucosinolate in this extract was identified as sinigrin, which could explain the high degree of stimulatory activity.P. rapae preferred cabbage plants overA. petiolata, and the relatively low stimulatory activity was also associated with the glucosinolate-containing aqueous extract. However, this species was strongly stimulated by a fraction that contained small amounts of glucotropaeolin along with unknown compounds. Deterrents to both species were found in the butanol extract fromA. petiolata, andP. napi oleracea was more sensitive thanP. rapae to these deterrents. Some HPLC fractions from the BuOH extract were strongly deterrent toP. napi oleracea, but were inactive toP. rapae. The ecological significance of these behavioral differences between the twoPieris species is discussed.
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  • 48
    ISSN: 1423-0445
    Keywords: sex pheromone ; synergist ; antagonist ; mate recognition ; reproductive isolation ; chemotaxonomoy ; phylogeny ; evolution ; Lepidoptera ; Tortricidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The geometric isomers (E,E)-, (E,Z)-, (Z,E)-, and (Z,Z)-8,10-dodecadien-1-yl acetate were identified as sex pheromone components or sex attractants in the tribes Eucosmini and Grapholitini of the tortricid subfamily Olethreutinae. Species belonging to the more ancestral Tortricinae were not attracted. Each one isomer was behaviourally active in males ofCydia andGrapholita (Grapholitini), either as main pheromone compound, attraction synergist or attraction inhibitor. Their reciprocal attractive/antagonistic activity in a number of species enables specific communication with these four compounds.Pammene, as well as otherGrapholita andCydia responded to the monoenic 8- or 10-dodecen-1-yl acetates. Of the tribes Olethreutini and Eucosmini,Hedya, Epiblema, Eucosma, andNotocelia trimaculana were also attracted to 8,10-dodecadien-1-yl acetates, but several otherNotocelia to 10,12-tetradecadien-1-yl acetates. The female sex pheromones ofC. fagiglandana, C. pyrivora, C. splendana, Epiblema foenella andNotocelia roborana were identified. (E,E)- and (E,Z)-8,10-dodecadien-1-yl acetate are producedvia a commonE9 desaturation pathway inC. splendana. CallingC. nigricana andC. fagiglandana females are attracted to wingfanning males.
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  • 49
    ISSN: 1423-0445
    Keywords: defensive chemistry ; alterable ; elicitation ; herbivory ; antioxidant ; Fabaceae ; Glycine max ; Lepidoptera ; Noctuidae ; Trichoplusia ni
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The water-soluble antioxidant, L-ascorbic acid (vitamin C), proved elicitory to alterable anti-herbivory inGlycine max againstTrichoplusia ni larvae. Elicitation by vitamin C was influenced especially by dose, time after elicitation and space in the plant. Results allow an analogy between antioxidant and herbivory elicitation. Elicitation apparently involves a sulfhydryl-protein-dependent redox mechanism which can be significantly affected by antioxidants. Findings would also support a proposed common redox-based mechanism, involving the plasma membrane, for communication between plant and animal cells and their environments.
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  • 50
    ISSN: 1432-0789
    Keywords: Key words Phosphorus dynamics ; Olsen ; phosphorus ; Soil phosphorus fractions ; Manure ; Soybean-wheat rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soil P availability and efficiency of applied P may be improved through an understanding of soil P dynamics in relation to management practices in a cropping system. Our objectives in this study were to evaluate changes in plant-available (Olsen) P and in different inorganic P (Pi) and organic P (P0) fractions in soil as related to repeated additions of manure and fertilizer P under a soybean-wheat rotation. A field experiment on a Typic Haplustert was conducted from 1992 to 1995 wherein the annual treatments included four rates of fertilizer P (0, 11, 22 and 44 kg ha–1 applied to both soybean and wheat) in the absence and presence of 16 t ha–1 of manure (applied to soybean only). With regular application of fertilizer P to each crop the level of Olsen P increased significantly and linearly through the years in both manured and unmanured plots. The mean P balance required to raise Olsen P by 1 mg kg–1 was 17.9 kg ha–1 of fertilizer P in unmanured plots and 5.6 kg ha–1 of manure plus fertilizer P in manured plots. The relative sizes of labile [NaHCO3-extractable Pi (NaHCO3-Pi) and NaHCO3-extractable P0 (NaHCO3-P0)], moderately labile [NaOH-extractable Pi (NaOH-Pi) and NaOH-extractable P0 (NaOH-P0)] and stable [HCl-extractable P (HCl-P) and H2SO4/H2O2-extractable P (resisual-P)] P pools were in a 1 : 2.9 : 7.6 ratio. Application of fertilizer P and manure significantly increased NaHCO3-Pi and -P0 and NaOH-Pi, and -P0 fractions and also total P. However, HCl-P and residual-P were not affected. The changes in NaHCO3-Pi, NaOH-Pi and NaOH-P0 fractions were significantly correlated with the apparent P balance and were thought to represent biologically dynamic soil P and act as major sources and sinks of plant-available P.
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  • 51
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    Journal of comparative physiology 182 (1998), S. 585-594 
    ISSN: 1432-1351
    Keywords: Key wordsHelicoverpa zea ; Noctuidae ; Lepidoptera ; Single-cell recordings ; Antennal neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Responses of single receptor neurons in the antennae of male Helicoverpa zea to sex pheromone components and to behavioral antagonists were recorded using a cut-sensillum extracellular recording technique. Three types of sensilla were identified from sampling 325 male-specific sensilla trichodea located at the lateral edge of antennomeres. The majority of these sensilla (71%) contained a receptor neuron tuned to the principal sex pheromone component (Z)-11-hexadecenal. A second sensillar type (10%) contained a receptor neuron that responded only to (Z)-9-tetradecenal. A third sensillar type (19%) contained a large-spiking neuron tuned to the secondary pheromone component (Z)-9-hexadecenal, but this neuron also could be stimulated to equivalent spike frequencies by the same emitted amounts of (Z)-9-tetradecenal. A smaller-spiking neuron in this sensillar type responded to two compounds known to act only as behavioral antagonists, (Z)-11-hexadecen-1-ol and (Z)-11-hexadecenyl acetate, and to (Z)-9-tetradecenal. Cross-adaptation studies confirmed the presence of one large- and one small-spiking neuron in the third sensillar type. Dose-response studies correlated to collected stimuli amounts showed that the large-spiking neuron in the third sensillar type was equally tuned to (Z)-9-hexadecenal and (Z)-9-tetradecenal, whereas the smaller-spiking neuron was far more sensitive to (Z)-11-hexadecen-1-ol and to (Z)-11-hexadecenyl acetate than to (Z)-9-tetradecenal.
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  • 52
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    Journal of comparative physiology 168 (1991), S. 697-707 
    ISSN: 1432-1351
    Keywords: Ecdysis ; Eclosion hormone ; Manduca sexta ; Neuropeptide ; Lepidoptera ; Pupal molt ; Verson's gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Ecdysis, a behavior by which insects shed the old cuticle at the culmination of each molt, is triggered by a unique peptide hormone, eclosion hormone (EH). In pupal Manduca sexta, EH is released into the hemolymph just prior to ecdysis, and circulating hormone is sufficient to elicit this behavior. 2. Removal of the proctodeal nerves in prepupal animals eliminated the appearance of blood-borne EH, but ecdysis behavior occurred on schedule. Therefore, circulating EH is not necessary for the triggering of ecdysis. 3. In contrast, a set of dermal glands failed to show their expected bout of secretion after proctodeal nerve removal. Injection of exogenous EH rescued this secretion. Thus, circulating EH appears necessary for action on peripheral but not central targets. 4. A major reduction in EH immunostaining is seen in the proctodeal nerves just preceding ecdysis; this coincides with a 〉90% reduction in extractable EH from this structure and the appearance of circulating EH. A similar, concomitant reduction was seen in central EH cell processes, suggesting release of peptide within the CNS. 5. Antidromic stimulation of the proctodeal nerve stumps following proctodeal nerve removal triggered precocious ecdysis. This result further supports the conclusion that centrally released EH is sufficient to trigger the motor program.
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  • 53
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    Environmental geology 30 (1997), S. 224-230 
    ISSN: 1432-0495
    Keywords: Key words Sediment ; Washington ; DC ; Pollution ; phosphorus ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Sediments in the rivers and basins around Washington, DC, have high concentrations of phosphorus, which, based on geographic distributions, is largely derived from urban runoff and municipal sewage. Dissolved-particulate phosphate exchange reactions and biological uptake of dissolved phosphorus from the water column may be an added source of phosphorus to the sediments. Concentrations of total sedimentary phosphorus ranged from 24 to 56 μm P/g-dw, and were highest in areas near combined sewer outfalls. As a part of this study, sedimentary phosphorus was fractionated into Fe-P, Ca-P, Al-P, and organic phases using a selective-sequential leaching procedure. The distribution of the phases in all sediments analyzed follow the order , Fe-P〉Ca-P〉Al-P. Spatial variations in the amounts of phosphorus in the different phases is related to the sources of phosphorus to the area. The proportions of occluded Al-P and organic P are 10–20% of the total P, respectively. This suggests that phosphorus from natural sources is small compared to anthropogenic inputs in this area. The high leachable Fe-P and Ca-P in these sediments might contribute a substantial amount of P to the water column under conditions of remobilization.
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  • 54
    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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  • 55
    ISSN: 1423-0445
    Keywords: aposematism ; cardenolide fingerprint ; chemical defense ; emesis ; plant-insect interaction ; migration ; Asclepiadaceae ; Apocynales ; Asclepias humistrata ; milkweed ; Lepidoptera ; Danainae ; Danaus plexippus ; monarch butterfly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper is the fourth in a series on cardenolide fingerprints of monarch butterflies (Danaus plexippus, Danainae) and their host-plant milkweeds (Asclepiadaceae) in the eastern United States. Cardenolide concentrations ofAsclepias humistrata plants from north central Florida ranged from 71 to 710 µg/0.1 g dry weight, with a mean of 417 µg/0.1 g. Monarchs reared individually on these plants contained cardenolide concentrations ranging from 243 to 575 µg/0.1 g dry weight, with a mean of 385 µg/0.1 g. Cardenolide uptake by butterflies was independent of plant concentration, suggesting that sequestration saturation occurs in monarchs fed cardenolide-rich host plants. Thinlayer chromatography resolved 19 cardenolides in the plants and 15 in the butterflies. In addition to humistratin,A. humistrata plants contained several relatively non-polar cardenolides of the calotropagenin series which are metabolized to more polar derivatives in the butterflies. These produced a butterfly cardenolide fingerprint clearly distinct from those previously established for monarchs reared on otherAsclepias species. In emetic assays with the blue jay,Cyanocitta cristata, the 50% emetic dose (ED50) per jay was 57.1 µg, and the average number of ED50 units per butterfly was 13.8, establishing that this important south eastern milkweed produces highly emetic, chemically defended monarchs. Our data provide further support for the use of cardenolide fingerprints of wild-caught monarchs to make ecological predictions concerning defence against natural enemies, seasonal movement and larval host-plant utilization by monarch butterflies during their annual cycle of migration, breeding and overwintering.
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  • 56
    ISSN: 1423-0445
    Keywords: oviposition ; 3-indolylmethyl glucosinolate ; sinigrin ; glucoiberin ; cabbage ; Cruciferae ; Brassica oleracea ; Lepidoptera ; Pieridae ; Pieris rapae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The chemical stimulation of oviposition byPieris rapae on cabbage was investigated by leaf washing and extraction. Isolation of the stimulant by various chromatographic techniques was monitored by a bioassay using Sieva bean as a surrogate host plant. Cold water, chloroform, or chloroform followed by cold water washes failed to release the stimulant from leaf surfaces. Boiling water or chloroform followed by methanol was required. The most active stimulatory compound was identified as 3-indolylmethyl glucosinolate (glucobrassicin). Other glucosinolates were identified as sinigrin, which was only slightly active, and glucoiberin, which was completely inactive as a stimulant. The significance of the selective response ofP. rapae andP. brassicae to different glucosinolates and the implications of the binding of polar allelochemicals to leaf surfaces is discussed with respect to host utilization and perception mechanisms of pierids.
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  • 57
    ISSN: 1423-0445
    Keywords: oviposition ; kairomone ; host plant selection ; indole glucosinolates ; Cruciferae ; Brassica oleracea ; cabbage ; Lepidoptera ; Pieridae ; Pieris brassicae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chemicals present on the surface of cabbage (Brassica oleracea L.) leaves were extracted by dipping these leaves for 3 s in dichloromethane followed by a 3 s dip in methanol. When offered in dual choice bioassays using green paper cards as a substrate, the methanol extract stimulated oviposition activity byPieris brassicae L. (Lepidoptera: Pieridae) females. The oviposition stimulant was isolated using medium pressure liquid chromatography, reversed-phase HPLC, ion-pair HPLC and ion exchange chromatography. Using1H-NMR spectroscopy, the stimulant could be identified as glucobrassicin (3-indolyl-methyl-glucosinolate). When pure glucobrassicin was offered at a dose identical to that in the crude methanol extract, butterflies did not discriminate between these two substrates in a dual choice test. It is argued that a high sensitivity for indole glucosinolates as host recognition factors may confer an adaptive value for these specialist crucifer feeders. The nutritional significance of their precursor tryptophan and the non-volatile nature of the aglycones formed upon enzymic hydrolysis in damaged tissues are proposed as properties of indole glucosinolates that contribute to this possible adaptive advantage.
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  • 58
    ISSN: 1423-0445
    Keywords: first instar survival ; latex ; cardiac glycosides ; cardenolides ; Lepidoptera ; Danainae ; Danaus plexippus ; Asclepiadaceae ; Asclepias humistrata ; milkweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Our paper addresses field survivorship of first instar monarch butterfly larvae (Danaus plexippus L., Lep.: Danainae) in relation to the dual cardenolide and latex chemical defenses of the sand hill milkweed plant,Asclepias humistrata (Asclepiadaceae) growing naturally in north central Florida. Survival of first instar larvae in the field was 11.5% in the first experiment (15–20 April 1990), and dropped to 3.4% in the second experiment (20–30 April). About 30% of the larvae were found glued to the leaf surface by the milkweed latex. Predator exclusion of non-flying inverte-brates by applying “tanglefoot” to the plant stems suggested that the balance of the mortality was due to volant inverte-brates, or to falling and/or moving off the plants. Regression analyses to isolate some of the other variables affecting survivorship indicated that first instar mortality was correlated with (1) increasing cardiac glycoside concentration of the leaves, (2) increasing age of the plants, and (3) the temporal increase in concentration of cardiac glycosides in the leaves. The study also provided confirmatory data of previous studies that wild monarch females tend to oviposit onA. humistrata plants containing intermediate concentrations of cardiac glycosides. Cardiac glycoside concentration in the leaves was not correlated with that in the latex. The concentration of cardenolide in the latex is extremely high, constituting an average of 1.2 and 9.5% of the mass of the wet and dry latex, respectively. The data suggest that an increase in water content of the latex is compensated for by an influx of cardenolide with the result that the cardenolide concentration remains constant in the latex systems of plants that are growing naturally. We also observed first instar larvae taking their first bite of milkweed leaves in the field. In addition to confirming other workers findings that monarch larvae possess elaborate “sabotaging” behaviour of the milkweed's latex system, we discovered that several larvae on their first bite involuntarily imbided a small globule of latex and instantly became cataleptic. This catalepsis, lasting up to 10 min, may have been in response to the high concentration of cardenolide present in the latex ofA. humistrata, more than 10 times that in the leaves. The results of the present study suggest that more attention should be directed to plant chemical defenses upon initial attack by first instar insect larvae, rather than attempting correlations of plant chemistry with older larvae that have already passed the early instar gauntlet. The first bite of neonate insects may be the most critical moment for coping with the chemical defenses of many plants and may play a much more important role in the evolution of insect herbivory than has previously been recognized.
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  • 59
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    Chemoecology 5-6 (1994), S. 139-146 
    ISSN: 1423-0445
    Keywords: biochemistry of plants ; sequestration by insects ; transformation by insects ; pyrrolizidine alkaloids ; alkaloidN-oxides ; Asteraceae ; Senecio ; Lepidoptera ; Arctiidae ; Tyria ; Creatonotos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Among alkaloids the pyrrolizidine alkaloids (PAs) play a unique role in the interactions between plants and adapted insects. InSenecio spp. (Asteraceae) PAs are synthesized in the roots as alkaloidN-oxides which are specifically translocated into shootsvia the phloem-path and channeled to the preferred sites of storage (e.g. inflorescences) where they are stored in the cell vacuoles. In differentSenecio spp. senecionineN-oxide is produced as the common product of biosynthesis, which subsequentlyvia a number of simple but specific reactions is transformed into typical speciesspecific PA-patterns. Insects from diverse taxa sequester PAs for their own defense. Lepidopterans (e.g. arctiids such asTyria jacobaeae andCreatonotos transiens) may hydrolyze plant acquired ester-PAs and convert the resulting necine base into insect-specific PAs by esterification with an acid of their own metabolism. Adapted arctiids and the grasshopperZonocerus take up PAs in the state of the tertiary amine.N-Oxides are reduced in the guts prior to uptake. In the bodies the tertiary PAs are rapidlyN-oxidized by a specific mixed-function oxigenase and are maintained in theN-oxide state. The importance of the reversible interconversion of the nontoxicN-oxide (pro-toxine) into the toxic tertiary alkaloid is discussed as the specific feature of PAs in plant-insect interactions.
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  • 60
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    Chemoecology 5-6 (1994), S. 167-171 
    ISSN: 1423-0445
    Keywords: inhibition ; indigestibility ; defence ; alkaloid ; glycosidases ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Glycosidase inhibitors are widespread in plants and can be sequestered by Lepidoptera, for which they can presumably serve as defences by making the insects indigestible to a range of potential predators. As a result of this study of eight British species of moth and butterfly it was found that glycosidase inhibitors in the insects could then be detected in the larval food plants which were not previously known to contain them; however, some were only detectable in the plants after concentration. In some cases the inhibition of specific glycosidases by Lepidoptera was detected even though the insects had not apparently acquired them from their food plants. Inhibition ofβ-N-acetylglucosaminidase was observed in most of the adult Lepidoptera analysed but further work is required to identify the inhibitors, though they are likely to be nitrogen-containing compounds. Weak anti-HIV activity was also observed in the glycosidase-inhibiting fractions ofAcherontia atropos and the plantUrtica dioica.
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  • 61
    ISSN: 1423-0445
    Keywords: protein solubility ; insect yolk protein ; buffering capacity ; phenolics ; Lepidoptera ; gypsy moth ; Lymantria dispar ; Malacosoma disstria ; Choristoneura rosaceana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A standard buffer (5 mM phosphate at pH 7) which is used to extract protein from insect eggs provided complete protein solubility for eggs from three of four tree-feeding lepidopteran species: obliquebanded leaf roller (Choristoneura rosaceana), forest tent caterpillar (Malacosoma disstria), and the eastern tent caterpillar (Malacosoma americanum). Under the same extraction protocol, egg proteins from the gypsy moth (Lymantria dispar), remained nearly insoluble. An array of methods typically used to solubilize insect egg proteins were tried and all but the most denaturing (2% SDS) were ineffective. Extraction buffers with typically high pH values were then evaluated. The results indicated that 1) solubility of gypsy moth egg proteins was pH dependent, and full solubility of most egg proteins required the extraction buffer to have a pH of 12 or more prior to the addition of eggs. We also determined that 2) the gypsy moth egg has a buffering capacity which must be surpassed for complete protein extraction, 3) low salt/high pH buffers gave slightly higher total protein values than did high salt/high pH buffers, 4) parental nutritional history (host species utilized) and egg developmental state (pre-embryonatedvs postembryonated/pre-hatch) were unrelated to the requirements for complete egg protein solubilization, and 5) the presence of soluble phenolics, compounds that have the potential to bind to protein and cause insolubility, was confirmed for the gypsy moth egg with 2-D paper chromatography and several other tests. Based on these results, we present a hypothesis about the cause of egg protein insolubility in the gypsy moth.
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  • 62
    ISSN: 1420-9055
    Keywords: Sediment ; interstitial water ; phosphorus ; iron ; persulfate digestion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    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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  • 63
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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
    Source: Springer Online Journal Archives 1860-2000
    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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    Aquatic sciences 52 (1990), S. 199-220 
    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; ecosystem ; chlorophyll-a ; mathematical modelling
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    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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    Topics: Biology
    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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    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. 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
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    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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    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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    Entomologia experimentalis et applicata 62 (1992), S. 29-36 
    ISSN: 1570-7458
    Keywords: Alkaloids ; cinnabar moth ; insect genetics ; larval performance ; Lepidoptera ; nutritional ecology ; nitrogen ; sugar ; Tyria jacobaeae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a laboratory experiment using full-sibs, 60% of the variation in pupal weight of the monophage Tyria jacobaeae L. (Lepidoptera, Arctiidae) could be explained by variation in the nitrogen concentration of the food plant, Senecio jacobaea L. and only 4% by variation in sugar concentration. Larval weight and growth rates of young and old larvae were also positively correlated with nitrogen and sugar concentration. Developmental time was negatively correlated with nitrogen concentration. In a second experiment full-sib families differed significantly in larval weight at day 7, mortality, growth rate and developmental time. Pupal weight did not differ significantly among families, but was positively correlated with nitrogen concentration of Senecio. Larval performance was not significantly influenced by concentrations of sugars or alkaloids. We conclude that larval performance of Tyria during most of the larval period is mainly determined by genetic factors, but pupal weights are primarily determined by nitrogen concentration of the food plant.
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    Entomologia experimentalis et applicata 65 (1992), S. 199-204 
    ISSN: 1570-7458
    Keywords: Sesamia nonagrioides ; Lepidoptera ; Noctuidae ; calling behaviour ; mating behaviour ; circadian rhythm
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    Topics: Biology
    Notes: Abstract The mating behaviour of the corn stalk borerSesamia nonagrioides (Lef.) [Lepidoptera:Noctuidae] was studied under laboratory conditions at 25 ± 1 °C, 65 ± 5% r.h. and 16:8 (L:D) regime. The females began calling during the first scotophase following emergence, the peak of calling occurred during the second scotophase and thereafter decreased. Maximum calling was observed between the fourth and sixth hour of the scotophase. The calling pattern varied with age. During the first and second scotophase most of the females were calling continuously, while during the third and fourth scotophase periodic calling was observed. The mean onset of calling was advanced and the mean length of calling per day was increased slightly as the female became older. Females held for 72 h in continuous darkness exhibited an endogenous circadian rhythm of calling. Matings began during the first scotophase following emergence and the peak of mating was observed during the second scotophase. Mated females did not remate. Few males mated more than once during the following scotophases.
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    Entomologia experimentalis et applicata 68 (1993), S. 219-229 
    ISSN: 1570-7458
    Keywords: Hymenoptera ; Aphidiidae ; Homoptera ; Aphididae ; Schizaphis graminum ; wheat ; tritrophic interactions ; learning ; host-habitat location
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    Topics: Biology
    Notes: Abstract The effect of experience on the responsiveness of the aphidiid parasitoidLysiphlebus testaceipes (Cresson) (Hymenoptera: Aphidiidae) to host-associated cues was investigated using a wind-tunnel bioassay. Naive females were able to discriminate between uninfested wheat (Triticum aestivum L.) and wheat infested withSchizaphis gramimum (Rondani) (Homoptera: Aphididae), but oviposition experience significantly increased the parasitoid's propensity to respond to aphid-infested plants with upwind, targeted flight. The behavioural change associated with such experience was acquired rapidly (within five minutes) and persisted for at least 24 h. The parasitoid could be successfully conditioned to associate a novel odour with the presence of hosts, suggesting that the increase in response to aphid-infested plants which occurs as a result of experience is probably due to associative learning of olfactory cues from the plant-aphid complex.
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    Entomologia experimentalis et applicata 62 (1992), S. 87-91 
    ISSN: 1570-7458
    Keywords: Molting ; Lepidoptera ; nutritional indices
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    Entomologia experimentalis et applicata 70 (1994), S. 295-298 
    ISSN: 1570-7458
    Keywords: forest tent caterpillar moth ; Malacosoma disstria ; fluctuating asymmetry ; survival ability ; pest management ; Lepidoptera
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    Notes: Abstract Fluctuating asymmetry of the first tarsal segment of the proleg of the forest tent caterpiller mothMalacosoma disstria Hbn. (Lepidoptera: Lasiocampidae) was significantly inversely related to survival ability in the lab. The monitoring of population levels of fluctuating asymmetry could have important implications in pest management of this and other species by providing an indication of the health of a population.
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    Entomologia experimentalis et applicata 71 (1994), S. 33-39 
    ISSN: 1570-7458
    Keywords: Helicoverpa zea ; Noctuidae ; Lepidoptera ; Eucelatoria bryani ; Tachinidae ; Diptera ; host-parasitoid relationship ; host regulation
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    Topics: Biology
    Notes: Abstract The parasitoidEucelatoria bryani Sabrosky regulates the larval behavior of its hostHelicoverpa zea (Boddie). Parasitized third, fourth and fifth instars burrow into the soil 0.7–3.4 days earlier than unparasitized larvae that normally enter the soil to pupate at the end of the fifth and final larval instar. Parasitized third instars molt once then burrow as fourth instars, one instar earlier than normal. WhenE. bryani pupariated on the soil surface in the field, none survived to the adult stage. However,E. bryani adults emerged from 49.2% of hosts that had burrowed into the soil. By accelerating the timing ofH. zea burrowing behavior and causing host larvae to enter the soil before death,E. bryani ensures its pupariation in an environment with improved protection against natural enemies and lethal temperatures.
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    Entomologia experimentalis et applicata 67 (1993), S. 47-56 
    ISSN: 1570-7458
    Keywords: Platynota flavedana ; variegated leafroller ; Platynota ideausalis ; tufted apple bud moth ; Argyrotaenia velutinana ; redbanded leafroller ; mating disruption ; pheromones ; apple ; Lepidoptera ; Tortricidae
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    Notes: Abstract Mating disruption for control of variegated leafroller (VLR),Platynota flavedana (Clemens), tufted apple bud moth (TBM),P. ideausalis Walker, and redbanded leafroller (RBL),Argyrotaenia velutinana (Walker), was studied in Virginia apple orchards in 1989 and 1990. In 1989, each dispenser (1000/ha) contained 190 mg of 67.2%E11–14:Ac, 28.8%Z11–14:Ac, 1.4%E11–14:OH, 0.6%Z11–14:OH, and 2%Z9–12:Ac (a putative generic leafroller disruption blend). Trap captures of VLR, TBM and RBL were reduced by 97%, 51% and 55%, respectively. Average leafroller injury in the interior and edge of the pheromone block was 3.8% and 2.7%, respectively. The conventional control and abandoned blocks had 0.05 and 27.5% injury, respectively. Dispensers containingE11–14:OH (70%) andZ11–14:OH (30%) (close to the natural blend of VLR), more effectively disrupted orientation to pheromone traps by bothPlatynota spp. than did the generic blend. In 1990, dispensers containing 150 mg ofE11–14:OH (70%) andZ11–14:OH (1000/ha) were placed in two 2-ha blocks and one 4-ha block. One pheromonetreated block was sprayed in August with phosmet for codling moth, not timed for leafrollers. Trap captures of VLR and TBM were reduced by almost 100% and 69%, respectively. RBL captures were not reduced by VLR pheromone permeation. Injury fromPlatynota spp. in pheromone block middles and edges ranged from 0.3–1.7% and 0.3–2.3%, respectively. Injury in conventional blocks ranged from 0–1.1%. RBL injury in pheromone block middles ranged from 0–6.1%, and in edges, 1.7–4.8%. Injury in control blocks ranged from 0–1.1%. Combined leafroller injury in an abandoned block was 18% (s.e. 0.3). Release rates averaged 30 and 32 mg/ha/h for the VLR and generic pheromone dispensers, respectively.
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    Entomologia experimentalis et applicata 67 (1993), S. 79-85 
    ISSN: 1570-7458
    Keywords: Insecta ; Lepidoptera ; Noctuidae ; host-finding ; behavior ; oviposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mated femaleTrichoplusia ni (Hubner) moths, when presented a choice of either undamaged cotton plants,Gossypium hirsutum L., or damaged plants (cut leaves or feedingT. ni larvae) in a flight tunnel, were most often attracted first to the damaged plants. However, these same moths oviposited primarily on the undamaged plants. In a similar test with cabbage plants,Brassica oleracea L., the presence of conspecific larvae decreased both attraction and oviposition. Cuts to cabbage leaves had no significant effect on attraction or oviposition. When presented one plant at a time, percentages of cabbage looper moths attracted were not affected by the presence of larvae on either cabbage or cotton plants, or by cuts to cabbage plant leaves. Percentages of moths attracted were, however, higher using cotton plants with cut leaves. The results suggest an important role for damage induced plant volatiles in host location as well as host acceptance byT. ni.
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  • 78
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    Keywords: Lepidoptera ; Papilionidae ; Zerynthia ; Aristolochia ; herbivory ; phenology ; nutritional indices
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    Notes: Abstract The main host plants of the butterflyZerynthia rumina L. (Lepidoptera: Papilionidae) in southern Spain occur in different habitats and in general do not grow sympatrically. Therefore, each single local butterfly population uses the particular host available within its range.Aristolochia longa L. is a tuberous perennial herb available only in the spring, whileA. baetica L. is an evergreen perennial vine with indeterminate growth. However, because of the toughness of older leaves, newly hatched larvae feed only on new leaves ofA. baetica, and most of these leaves are produced well before the larvae hatch. In laboratory experiments, caterpillars feeding on either new or matureA. longa leaves grew faster and converted food into biomass more efficiently than those feeding on newA. baetica leaves. These differences are related to variation in nutritional quality among the host plants. Estimates of butterfly abundance were lower in sites whereZ. rumina usesA. baetica, compared with those where the host isA. longa. The potential differential effect of these two food plants on the densities of local butterfly populations relying on them is discussed here.
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    Entomologia experimentalis et applicata 72 (1994), S. 25-31 
    ISSN: 1570-7458
    Keywords: diapause induction ; photoperiod ; temperature ; Phyllonorycter blancardella ; spotted tentiform leafminer ; Lepidoptera ; Gracillariidae
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    Topics: Biology
    Notes: Abstract The role of photoperiod and temperature in the induction of overwintering diapause inPhyllonorycter blancardella (F.) (Lepidoptera: Gracillariidae) was examined in the laboratory and field using leafminers from commercial apple orchards in Ontario, Canada.P. blancardella exhibited a long-day response to photoperiod: long daylengths resulted in uninterrupted development whereas short daylengths induced diapause. The estimated critical photoperiod for diapause induction was L14.25∶D9.75. The larvae of leafminers destined to enter diapause took ca. 3× longer to complete development than the larvae of non-diapausing leafminers. The development prolonging effect of photoperiod decreased with decreasing daylength. Temperature modified the diapause inducing effect of photoperiod. At L14.25∶D9.75, diapause incidence was similar at 15 and 20°C but was lower at 25°C. Photoperiod also altered the normal relationship between development rate and temperature. At L14.25∶D9.75, the duration of larval development of diapausing leafminers was similar at 15, 20 and 25°C. Temperature alone is unlikely to have a role in the induction of diapause because leafminers exposed to natural late summer and fall temperature regimes and L16∶D8 did not enter diapause.
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    Entomologia experimentalis et applicata 72 (1994), S. 173-180 
    ISSN: 1570-7458
    Keywords: feeding performance ; diapausing propensity ; genetic correlation ; heritability ; host-range ; insect-plant interactions ; Lepidoptera ; Tortricidae
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    Topics: Biology
    Notes: Abstract Evolutionary constraints on the ability of herbivores to efficiently use a set of phytochemically similar hosts, while maintaining a high performance on phytochemically different hosts, are central in explaining the predominance of host specialization in phytophagous insects. Such feeding trade-offs could be manifested within insect populations as negative genetic correlations in fitness on different host species. We tested the hypothesis that feeding trade-offs were present within a population of the obliquebanded leafroller,Choristoneura rosaceana (Harris). Components of fitness were measured in families originating from an apple orchard that were fed on four host-plant species in the laboratory. Under the conditions of this experiment, all across-host genetic correlations were strongly positive, suggesting that this population comprised true generalists. With the exception of diapausing propensity, the heritability of the fitness components tended to be lower in caterpillars fed on apple leaves than in insects fed other hosts. This suggests a constraint on the selective response of the fitness components in the orchard environment.
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    Entomologia experimentalis et applicata 77 (1995), S. 347-350 
    ISSN: 1570-7458
    Keywords: inhibition ; sex attractant ; Recurvaria nanella ; R. leucatella ; (3E)-3-tetradecenyl acetate ; (3E, 5Z)-3,5-tetradecadienyl acetate ; (5Z)-5-tetradecenyl acetate ; Lepidoptera ; Gelechiidae
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    Entomologia experimentalis et applicata 78 (1996), S. 1-8 
    ISSN: 1570-7458
    Keywords: induction ; imprinting ; learning ; caterpillar ; Lepidoptera ; experience ; diet breadth
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    Notes: Abstract This review discusses the ambiguity of results obtained from dual-choice feeding tests, especially in relation to the study of effects of experience. Induced preference experiments done this way can be caused by up to nine potential changes in caterpillar behavior. In addition different physiological mechanisms that could lead to the process of induced preference are discussed. These include habituation to deterrents, the increased ability to process xenobiotics, the acquisition of specific positive responses, sensitization, and associative learning. These different processes might relate to function in different ways so that distinguishing them is important to progress in understanding the phenomenon. Suggestions for experimental designs that provide details on processes involved are indicated.
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    Entomologia experimentalis et applicata 79 (1996), S. 227-234 
    ISSN: 1570-7458
    Keywords: Helicoverpa zea ; Lepidoptera ; Noctuidae ; Eucelatoria bryani ; Eucelatoria rubentis ; Diptera ; Tachinidae ; parasitoid competition ; host discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Multiple parasitism of Helicoverpa zea (Lepidoptera: Noctuidae) had differential effects on the gregarious endoparasitoids Eucelatoria bryani and E. rubentis (Diptera: Tachinidae). Both species were able to survive in multiparasitized hosts. However while the survival of E. bryani was not affected by the presence of E. rubentis, E. rubentis survival was reduced when competing with 24-h older E. bryani. The presence of E. rubentis did not result in a decrease in the size of E. bryani except when E. rubentis was 24-h older than E. bryani. The presence of E. bryani tended to result in smaller E. rubentis. The presence of similarly aged heterospecific competitors often resulted in prolonged development time for both species. Naïve females did not alter oviposition between unparasitized and heterospecifically parasitized fifth-instar larvae of H. zea, either by ovipositing less frequently in parasitized hosts than unparasitized ones, or by reducing clutch size in parasitized hosts. These results indicate that in H. zea, E. bryani is a superior competitor compared with E. rubentis. These factors should be considered in evaluating the potential of E. bryani and E. rubentis as biological control agents of H. zea.
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  • 84
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    Keywords: rice leaffolder ; Cnaphalocrocis medinalis ; Lepidoptera ; Pyralidae ; (Z)-11-hexadecenyl acetate ; (Z)-13-octadecenyl acetate ; (Z)-13-octadecen-1-ol ; octadecyl acetate ; sex pheromone ; attractant
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    Notes: Abstract Analysis of ovipositor washings from virgin femaleCnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) of Indian origin by linked gas chromatography and electroantennography indicated the presence of three electrophysiologically-active compounds. These were identified on the basis of their gas chromatographic retention times and mass spectra as (Z)-11-hexadecenyl acetate, (Z)-13-octadecenyl acetate and (Z)-13-octadecen-1-ol with (Z)-13-octadecenyl acetate present in amounts of between 0.25 and 1.5 ng per ovipositor and the other two components at less than 10% of this. Trace quantities of octadecyl acetate were identified by mass spectrometry but no electroantennographic responses were observed to this compound. Field trials conducted with a range of blends of the three electrophysiologically-active compounds showed that blends containing between 5% and 30% (Z)-11-hexadecenyl acetate in (Z)-13-octadecenyl acetate dispensed from either white rubber septa or polythene vials were more attractive to male moths than a virgin female moth. Addition of (Z)-13-octadecen-1-ol reduced attractiveness to male moths in the blends and concentrations tested.
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  • 85
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    Keywords: in vitro rearing ; Campoletis sonorensis ; Hymenoptera ; Ichneumonidae ; Heliothis virescens ; Lepidoptera ; Noctuidae ; artificial medium ; sugars ; amino acids ; proteins ; luminosity ; medium volume
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Campoletis sonorensis is a solitary larval endoparasitoid of several Heliothis spp. pests. This study was carried out to develop media devoid of insect sources for in vitro rearing the parasitoid. Trehalose, lysine, threonine, asparagine, glutamine, hydroxyproline, serine, bovine serum albumin, and lactalbumin were beneficial to C. sonorensis. Addition of fresh chicken egg yolk at a low level improved the artificial media. Addition of 20-hydroxyecdysone increased the molting rate, reduced the critical size at molt and decreased development time. Parasitoid development in vitro was dependent on eggs that had been in the host for at least 22 h. Luminosity was also critical for the development of C. sonorensis in vitro. Optimal development occurred in a L14:D10 photoperiod at 43 Lux light intensity. Utilizing the best media and conditions, 100% of the parasitoid larvae reached the second instar and over 37% molted to the third instar. However, no further development occurred.
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    Entomologia experimentalis et applicata 86 (1998), S. 313-318 
    ISSN: 1570-7458
    Keywords: Ostrinia palustralis ; sex pheromone ; identification ; (E)-11-tetradecenyl acetate ; (Z)-11-tetradecenyl acetate ; Lepidoptera ; Pyralidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By means of gas chromatography with electroantennographic detection, gas chromatography-mass spectrometry and a series of bioassays, (E)-11-tetradecenyl acetate (E11-14:OAc) and (Z)-11-tetradecenyl acetate (Z11-14:OAc) at a ratio of 99:1 were identified as female sex pheromone components of Ostrinia palustralis. The average amounts of E11- 14:OAc and Z11-14:OAc in a single sex pheromone gland were 37.2±24.4 ng and 0.3±0.2 ng, respectively. In a wind-tunnel bioassay, the binary blend of E11- and Z11-14:OAc elicited the same male behavioral responses as did virgin females.
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    Entomologia experimentalis et applicata 80 (1996), S. 120-123 
    ISSN: 1570-7458
    Keywords: electroantennography ; Lepidoptera ; plant odours ; Ostrinia nubilalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 88
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Gelechiidae ; Pectinophora gossypiella ; cotton ; pheromone ; wind tunnel ; attraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms by which the application of formulated pheromone interferes with mating in the pink bollworm moth (PBW), Pectinophora gossypiella were examined in 0.4 ha cotton fields using high-dose (78 mg A.I.) sealed polyethylene dispensers. Walk-in, field wind tunnels 6.2 m long were placed over two rows of cotton. Treatments consisted of a control, a tunnel in a field free of disruptant formulation; a 3-rope treatment, in which the field was free of pheromone but one of the cotton rows in the wind tunnel was treated with 3 PBW ropes; and a rope-grid treatment, in which the field was treated with PBW ropes at the standard density of 1000 ha−1 and one of the cotton rows inside the wind tunnel was treated with 3 PBW ropes. We released marked males into the tunnels near sunset or held them in field cages for 24 h prior to assay. Two pheromone traps at the tunnel's upwind end monitored the ability of males to locate point sources of pheromone. In the 3-rope tunnel, traps placed upwind of the cotton row treated with disruptant pheromone captured far fewer males than those placed upwind of the untreated cotton row. In the tunnel situated in the centre of the rope-gridded field, very few males were caught in traps in both rows, indicating a camouflage of the pheromone plumes from the traps by the background of airborne disruptant drawn into the tunnel from the field. Activity of moths near the synthetic pheromone sources was video-recorded. Males oriented to, landed on or near, and walked on or near, PBW ropes, indicating competition between pheromone sources as a mechanism of mating disruption. Most males visiting PBW ropes became quiescent or disappeared from the field of view after a few minutes, suggesting a habituation/adaptation of response. The rhythm of attraction of males held in the field for 24 h before release was comprised of a small peak of activity near 2000 h, with the majority of attraction between 2300 and 0300 h. Much of the attraction before 0100 appears to be an advancement of the male's normal diel rhythm, caused by the presence of disruptant. Together these findings indicate that mating disruption of pink bollworm using the PBW ropes is achieved by a combination of mechanisms: a camouflage of natural plumes, competition between pheromone sources, habituation, and some advancement of the male's rhythm of response.
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  • 89
    ISSN: 1570-7458
    Keywords: insect growth regulators ; diflubenzuron ; pyriproxyfen ; Podisus maculiventris ; Heteroptera ; predation ; Spodoptera exigua ; Lepidoptera ; side-effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transport and retention of the insect growth regulators (IGRs) diflubenzuron and pyriproxyfen in larvae of the beet armywormSpodoptera exigua (Hübner) and in nymphs of the predatory bugPodisus maculiventris (Say) were investigated. In a first experiment, the retention of orally administered [14C]radiolabeled isotopes of both compounds in fifth-instar larvae of the beet armyworm was studied. Rate of excretion of both IGRs inS. exigua caterpillars was high, with a 50% excretion time of approximately 6 h after intake. In a second experiment, the transport of the compounds from prey to predator and their retention inside the predator were studied. Fifthinstar nymphs ofP. maculiventris were allowed to feed on caterpillars that had been given contaminated food. For both diflubenzuron and pyriproxyfen, more than 80% of the amount of radiolabel applied was recovered in consumed prey. Low levels of radioactivity (c. 3% of the applied amount of radiolabel) were also found in the fluid regurgitated by the prey larvae when attacked by the predatory bugs. Relatively small amounts of radiolabel (c. 8 and 15% of the amount orally applied to the prey for diflubenzuron and pyriproxyfen, respectively) were ingested byP. maculiventris nymphs when feeding on beet armyworm caterpillars. The data suggest that the predators did not use gut content as food. The pattern of excretion in nymphs ofP. maculiventris differed between compounds. For diflubenzuron, there was a drastic decrease of radioactivity inside the predator body of around 40% within the first 6 h and then the level of retained radiolabel remained stable at 3–4% up to 72 h. For pyriproxyfen, a slow decrease of radioactivity inside the body was observed and at 72 h only 2% of the applied quantity was detected. Results of this study are discussed in relation to the findings from previous studies on the toxicity of both IGRs toP. maculiventris.
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  • 90
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    Entomologia experimentalis et applicata 77 (1995), S. 167-176 
    ISSN: 1570-7458
    Keywords: epipharyngeal sensilla ; contact chemoreception ; electrophysiology ; Lepidoptera ; Bombyx mori
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One pair of gustatory sensilla was found on the epipharynx ofBombyx mori larvae, and some morphological and electrophysiological characteristics of the epipharyngeal sensilla were investigated. They are sensilla coeloconica composed of a small papilla with a pore at the tip and a swelling of cuticle encircling the papilla. Three bipolar neurons innervate each sensillum. One neuron is an inositol receptor which responds to inositol only. Another cell responds with action potentials of relatively large amplitude to some feeding deterrent substances, such as strychnine nitrate. The thresholds of these cells for inositol and strychnine nitrate are approximately 10−4 M and 10−7 M, respectively. At least two kinds of spikes can be observed when these sensilla are stimulated with some salts and acids. Dose-response relationships and time courses of responses to inositol and strychnine nitrate were also examined in this study.
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  • 91
    ISSN: 1570-7458
    Keywords: Sesamia nonagrioides ; Lepidoptera ; Noctuidae ; sex pheromone ; pest monitoring ; electrophysiological behaviour ; EAG ; wind tunnel tests ; field tests ; (Z)-11-hexadecen-1-yl acetate ; (Z)-11-hexadecen-1-ol ; (Z)-11-hexadecenal ; dodecyl acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The electrophysiological and behavioural responses of male Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae) to several synthetic blends of its sex pheromone components were investigated. Electroantennogram (EAG) recordings showed the greatest response to a 77:8:10:5 blend of the four compounds found in the female glands: (Z)-11-hexadecen-1-yl acetate, (Z)-11-hexadecen-1-ol, (Z)-11-hexadecenal and dodecyl acetate. A logistic equation was fitted to the dose-response data and differences in relative EAG responses were analysed by deriving five parameters of this equation. Flight responses of males were also evaluated in a wind tunnel where the proposed blend (77:8:10:5) also elicited the best response. Field tests confirmed the laboratory findings as the 77:8:10:5 blend captured more S. nonagrioides males than other pheromone mixtures and showed more selectivity for male S. nonagrioides over other noctuid species, Discestra trifolii Rottenberg and Lacanobia oleracea L., but not for Mythimna unipuncta Haworth, a species with a sex pheromone composition almost identical to that of S. nonagrioides.
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  • 92
    ISSN: 1570-7458
    Keywords: insect ; parasitoid ; protein ; free amino acid ; cadmiun ; lead ; copper ; zinc ; Lepidoptera ; Hymenoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heavy metal contamination of the forest pest insect Lymantria dispar (L.) (Lepidoptera; Lymantriidae), the gypsy moth, can alter its haemolymph composition, as has already been shown for carbohydrates and lipids in recent studies. L. dispar larvae are frequently parasitized by Glyptapanteles liparidis (Bouché) (Hymenoptera; Braconidae) larvae, which can—to some extent—regulate the population size of the pest insect. The parasitoids feed on the haemolymph of L. dispar larvae; hence, a different haemolymph composition of the host alters the trophic situation of the parasitoids. The aim of the present study was to investigate whether metal contamination also affects the concentrations of free amino acids in L. dispar haemolymph, and protein concentrations in their haemolymph and tissue. L. dispar larvae were parasitized on the first day of the second instar and then reared on diets contaminated with Cd, Pb, Cu or Zn at two concentrations each. Haemolymph and total body tissue of the larvae (fourth instar/third day) were analyzed. The concentrations of the free amino acids were elevated in five out of the eight contamination groups (Cd6, Pb4, Cu6, Cu10, Zn60), whereas haemolymph protein concentrations were significantly reduced in all contaminated individuals. The haemolymph protein concentration was 18 mg/ml in the control group and decreased to less than 10 mg/ml due to cadmium and zinc contamination at both concentrations and in the low copper contamination group. In contrast, total body proteins (136 μg/mg dry weight in the control group) were elevated due to heavy metal stress. Analyses of haemolymph protein concentrations during the fourth instar demonstrated an increase of the proteins from day one to day four (followed by a decrease on the fifth day) in the control group and the cadmium contamination group. A steady increase of proteins from the first to the fifth day in the copper and zinc contaminated larvae indicated a retarded development in these groups. Thus, the present study along with other recent studies demonstrated, that heavy metal stress changes the concentrations of all main haemolymph compounds of L. dispar larvae.
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  • 93
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    Entomologia experimentalis et applicata 92 (1999), S. 53-62 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Tortricidae ; host selection ; correlation ; lightbrown apple moth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polyphagous leafroller moth, Epiphyas postvittana, is a pest of many fruit crops in New Zealand. Since the larva is highly mobile, host selection in this insect may involve both the adult female and the larva. In order to test the relative importance of the adult female and the neonate larva in the selection of host plants, the ovipositional preferences of females, and the preferences or acceptances of neonate larvae towards 26 plant species, consisting of 15 plants considered hosts and 11 not considered hosts, were investigated. In the ovipositional tests, the mean preferences of females for hosts and non-hosts were very similar. In contrast, larvae showed a significantly greater mean preference or acceptance towards hosts than to non-hosts, in both choice and no-choice bioassays, respectively. There were highly significant correlations between the preferences and acceptances of larvae for plants in the choice and no-choice tests. In the no-choice tests, there was a highly significant correlation between the acceptances of neonate larvae towards plants after one and three days (i.e., acceptances changed little over time). Moreover, in these no-choice tests, there was a significant negative correlation between larval acceptance at 1 day and larval mortality after 3 days; that is, the less acceptable a given plant at 1 day, the more likely larvae would fail to establish, feed, and survive on it by three days. Female and larval preferences towards the various plants were also negatively correlated. Together, these data suggest that the selection of a plant for the neonate larva to feed on is largely governed by the preferences of the larva, rather than by the preferences of the female. However, selection of a plant for oviposition by the female, may be important in host selection for reasons unrelated to larval preferences, for example, by encouraging dispersal, perhaps to other plant species, of the neonate larvae and thereby decreasing intersibling competition.
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  • 94
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    Entomologia experimentalis et applicata 92 (1999), S. 157-164 
    ISSN: 1570-7458
    Keywords: plant resistance ; antibiosis ; tolerance ; antixenosis ; Russian wheat aphid ; wheat ; Homoptera ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Russian wheat aphid, Diuraphis noxia (Mordvilko), is one of the most important aphid pests of wheat, Triticum aestivum L., worldwide. Among the various pest management options, plant resistance is an economical management tactic to control D. noxia in cereal crops such as wheat. Researchers have identified D. noxia resistant germplasm and it has been incorporated into wheat. This study compared D. noxia resistance between the ‘Betta’ wheat isolines Betta-Dn1, Betta-Dn2, and Betta-Dn5 and their corresponding donor gene plant introduction (PI) lines PI 137739 (Dn1), PI 262660 (Dn2), and PI 294994 (Dn5). Although the Betta isolines and PI lines showed D. noxia resistance when compared with Betta wheat, the degree of resistance in the isolines to D. noxia was different from their corresponding PI donors. Aphid number, aphid fecundity, and biomass per aphid were not different between Betta-Dn1 and PI 137739 or Betta-Dn2 and PI 262660; however, the same parameters were significantly lower on PI 294994 compared with Betta-Dn5. This indicated that aphid resistance in PI 137739 and PI 262660 was probably governed by a single dominant gene, while the resistance in PI 294994 was controlled by more than one gene. Additionally, plant biomass reduction was aphid density dependent, which suggested that use of appropriate aphid infestation level is important when using plant biomass reduction as an indicator of resistance. Plant resistance categorization showed that there was no detectable difference in antixenosis among the seven lines evaluated. However, the higher aphid fecundity observed on PI 262660 compared with PI 137739 and PI 294994, in addition to no significant differences among the three PIs in plant biomass reduction, suggested PI 262660 was a tolerant line, while PI 137739 and PI 294994 were antibiotic lines. Plant tolerance could not be elucidated among the three Betta isolines using aphid fecundity and plant biomass reduction as indicators.
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  • 95
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    Entomologia experimentalis et applicata 92 (1999), S. 321-330 
    ISSN: 1570-7458
    Keywords: rush moth ; Juncus squarrosus ; fluctuating food resources ; ‘bet-hedging’ ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adult emergence in Coleophora alticolella held at 15 °C was accelerated by exposure to L18:D6 in autumn and midwinter. The effect decreased during winter and exposure of individuals, held at low temperature over winter, to L18:D6 or L6:D18 at 15 °C at the end of March resulted in the same mean emergence date. Long daylength experienced at 5 °C did not promote emergence nor did exposure to low temperature during winter. The number of adults emerging increased with the length of time cultures were held on short day but was always below 50% of the larvae. When larvae were exposed to L18:D6 and L6:D18 at 15 °C at the end of March, on long day 61% adults emerged and 39% remained in diapause, whereas on short day, 25% became adult and 75% remained diapausing larvae. The possibility of cohort splitting, with some individuals undergoing prolonged diapause, is discussed.
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  • 96
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    Entomologia experimentalis et applicata 83 (1997), S. 347-360 
    ISSN: 1570-7458
    Keywords: dispersal ; Lepidoptera ; Mamestra brassicae ; mortality ; Noctuidae ; parasitism ; predation ; survival rate ; white cabbage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mortality of eggs, larvae and pupae and larval dispersal of the cabbage moth, Mamestra brassicae (L.) (Lepidoptera: Noctuidae) was investigated in a series of small-scale field experiments in white cabbage, Brassicae oleracea var. capitata (L.), and in the laboratory during 1990–1992 in south–eastern Norway. The highest mortality was found in young larvae and in hibernating pupae. In 1990, larval mortality in the first instar was 80% (range 9–97% for the individual cohorts). Most larvae died within the first 1–3 days after hatching. The dispersal activity during these days was high, and failure to establish feeding sites and predation were probably the main mortality causes. Pupal mortality during winter was 90% on average for 1990–1993 (range 81–100%). The main mortality factor was probably unfavourable weather conditions, and indications of cold stress were found. The impact from parasitoids and diseases was generally low. Trichogramma semblidis (Aurivillius) (Trichogrammatidae) was reared from M. brassicae eggs in very low numbers in 1991. Larval parasitism increased from 〈 1% in 1990 to almost 24% in 1992, and was almost totally caused by the braconids Microplitis mediator (Haliday) and Aleiodes (Aleiodes) sp. Predation of frozen larvae on the soil surface was 75% on average (range 63–96%) during 1990–1992 in first instar larvae and decreased gradually with larval age. The consumption rates of Philonthus atratus (Gravenhorst) (Staphylinidae) and the carabids Bembidion tetracolum (Say), Pterostichus melanarius (Illiger) and Harpalus rufipes (Degeer) on M. brassicae eggs and larvae were investigated in non-choice experiments in the laboratory. A preliminary survival model based on estimates of the mortality factors identified in this study is presented.
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  • 97
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    Entomologia experimentalis et applicata 81 (1996), S. 307-313 
    ISSN: 1570-7458
    Keywords: feeding deterrents ; desensitization ; habituation ; azadirachtin ; neem ; Spodoptera litura ; Lepidoptera ; Noctuidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The deterrence of azadirachtin, in its pure form and as a constituent of neem seed extract, to fifth instar Spodoptera litura (Fab.) larvae, was measured using cabbage, Brassica oleraceae (L.) var. capitata, leaf disc assays. Paired-choice assays, in which larvae could choose between feeding on a treated (1.3 ng azadirachtin per square cm leaf area) or an untreated leaf disc for 2 h, were conducted at 24 h intervals throughout the fifth instar. In addition, no-choice assays, in which larvae could feed on only one leaf disc (10 ng azadirachtin per square cm leaf area) for 1.5 h, were conducted consecutively over a six hour period at the beginning of the fifth instar. The effects of hunger and habituation on desensitization in our no-choice tests were partitioned. After repeated exposures, larvae became desensitized to pure azadirachtinal in both choice and no-choice tests, but did not desensitize to neem containing the same absolute amount of azadirachtin in choice tests. Hunger was responsible for approximately one third of the desensitization response in the no-choice tests. Sensitivity to azadirachtin was independent of age within the fifth instar.
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  • 98
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    Entomologia experimentalis et applicata 87 (1998), S. 209-209 
    ISSN: 1570-7458
    Keywords: Chrysodeixis chalcites ; EAG ; electroantennography ; electrophysiology ; greenhouse cultures ; Lepidoptera ; mating disruption ; Noctuidae ; paprika ; pheromone distribution ; sex pheromones ; sweet pepper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mating disruption using pheromone dispensers is an emerging insect control method in greenhouses in the Netherlands. For routine measurements of the pheromone level in greenhouses a portable and compact device based on electroantennography (EAG) was developed. The instrument was tested in different greenhouses under varying conditions using antennae of males of the noctuid moth Chrysodeixis chalcites. Relative differences in pheromone concentration between greenhouses loaded with pheromone dispensers and control greenhouses could be measured in a reliable way. Changes in pheromone concentration were clearly demonstrated by measurements during the growing season. The advantages of the instrument presented over previously described devices are its true portableness, ease of use and uncomplicated measuring principle. The device can be operated routinely by non-experts, and many measurements can be made in a short period of time. Preliminary outdoor measurements using antennae of male Cydia pomonella as sensor showed the potential of the instrument for use in the open field. The portable EAG sensor described here may provide a practical means for monitoring pheromone concentration and dispersal from dispensers applied for mating disruption.
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  • 99
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    Entomologia experimentalis et applicata 88 (1998), S. 101-107 
    ISSN: 1570-7458
    Keywords: sex pheromone ; pheromone-based mating disruption ; Spilonota ocellana ; Lepidoptera ; Tortricidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The potential for pheromone-based mating disruption of eye-spotted bud moth (ESBM), Spilonota ocellana (Denis & Schiffermüller) (Lepidoptera: Tortricidae), in apple orchards in the Okanagan Valley of British Columbia was examined in small-plot trials. In a preliminary experiment, treatment of the orchard atmosphere with a 99:1 blend of Z8-tetradecenyl acetate (Z8-14:OAc) and Z8-tetradecenyl alcohol (Z8-14:OH) completely inhibited captures of male ESBM in pheromone-baited traps, but treatment with Z8-14:OAc alone did not. Therefore, all subsequent trials used the two-component blend as a disruptant. Mean catches of male ESBM in traps baited with 0.1, 1, 10, or 20 mg of 99:1 Z8-14:OAc and Z8-14:OH were significantly reduced (81–97%) in pheromone-treated plots relative to similar traps placed in control plots. In both control and treated plots, there was a significant positive relationship between trap bait dose and trap catch. In pheromone-treated plots, this suggests that high doses of trap baits over-ride the camouflage effect of disruption or overcome the effect of sensory adaptation and habituation. The number of virgin-female baited traps capturing at least one male ESBM was reduced by 96%, and mating of virgin females on mating tables was reduced by 95% in plots treated with the two-component pheromone. The total amount of Z8-14:OAc released from pheromone disruption dispensers during the latter field trials was estimated to average 6.4 g ha-1 over 11 days or 26.4 mg ha-1 h-1. The low levels of Z8-14:OH released from disruption dispensers could not be estimated by GC analysis. Dispensers loaded with a 99:1 blend of Z8-14:OAc and Z8-14:OH were highly attractive to males in baited traps, indicating that they have the potential to induce false trail following.
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  • 100
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Pyralidae ; Plodia interpunctella ; Indian meal moth ; pheromone components ; GC-EAD ; stored-product pest ; behaviour ; flight tunnel ; trapping ; Ephestia kuehniella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pheromone gland extracts from calling female Plodia interpunctella contained at least seven compounds that consistently elicited electroantennographic responses from male antennae upon gas chromatographic analysis. Three of these compounds were found to be the previously identified gland constituents, i.e., (Z,E)-9,12-tetradecadienyl acetate (Z9,E12-14:OAc), (Z,E)-9,12-tetradecadienal (Z9,E12-14:Ald) and (Z,E)-9,12-tetradecadienol (Z9,E12-14:OH). A fourth EAD-active compound was identified as (Z)-9-tetradecenyl acetate (Z9-14:OAc). The homologue (Z)-11-hexadecenyl acetate (Z11-16:OAc) was also identified in the extracts, but showed no EAD activity. The identity of all five compounds was confirmed by comparison of GC retention times and mass spectra with those of synthetic standards. In flight tunnel tests there were no significant differences in response of male P. interpunctella to the bait containing all four EAD-active compounds and the responses to female gland extacts. A behavioural assay of different two-compound blends in the flight tunnel showed that only addition of the corresponding aldehyde to the major pheromone component Z9,E12-14:OAc raised the male response. A subtractive assay, however, revealed that the exclusion of any of the compounds from the complete four-compound blend reduced its activity significantly. We thus conclude that the female-produced sex pheromone of P. interpunctella consists of at least four components, i.e., Z9,E12-14:OAc, Z9,E12-14:Ald, Z9,E12-14:OH and Z9-14:OAc. In a field trapping test performed in a storage facility, the four-component blend attracted significantly more males of P. interpunctella than traps baited with Z9,E12-14:OAc alone. In contrast, the highest number of Ephestia kuehniella males was found in the traps baited with this major component, suggesting that the secondary pheromone components contribute to the species specificity of the blend.
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