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  • 1
    Electronic Resource
    Electronic Resource
    Variation in fruit size and susceptibility to seed predation among and within populations of the cocklebur, Xanthium strumarium L. (1980)
    Springer
    Oecologia 46 (1980), S. 217-222 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Burr size is the major factor affecting variation in the intensity of predation by two species of insect on the seeds of the cocklebur, Xanthium strumarium. Mean burr size varied among 10 adjacent local populations studied over three years, as did intensity of seed predation. Seed predation was more intense in populations with low mean burr length and declined linearly with increasing burr length under field and experimental conditions. Seed predation thus is a selective factor influencing the evolution of both burr size and correlated protective characteristics such as burr spine length and wall thickness. As in some other plants, morphological rather than chemical features appear to pose the major barrier to attack by host-specific seed predators. The advantage of more highly developed tissues protecting seeds may occur at the expense of total seed production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00540129
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  • 2
    Electronic Resource
    Electronic Resource
    Different effects of variation in Xanthium strumarium L. (Compositae) on two insect seed predators (1978)
    Springer
    Oecologia 37 (1978), S. 109-120 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To determine the relative importance of variation in several plant characters on susceptibility to herbivores, we examined patterns of seed predation by two monophagous insect species and patterns of variation in ten populations of the cocklebur, Xanthium strumarium. Multiple regression analysis disclosed that one seed predator was most influenced by plant chemical variation, the other was significantly influenced by both chemical and morphological variation, but variation in yet another character, general burr size, was most important in conferring resistance to both insects simultaneously. The plant populations differed most in this character. Although many of the plant characters were correlated with each other, those important in determining susceptibility to each insect species were uncorrelated and independent of those conferring resistance to both insects simultaneously. These results imply that ecological similar herbivores may be influenced by different aspects of plant variation, and that predictions of evolutionary responses of local plant populations to herbivory may require knowledge of the structure of local herbivore communities and the dynamics of their establishment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349997
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  • 3
    Electronic Resource
    Electronic Resource
    Foliar terpenoids in Tsuga species and the fecundity of scale insects (1984)
    Springer
    Oecologia 63 (1984), S. 185-193 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The relationship between the reproductive success of two Japanese scale insects, Fiorinia externa Ferris and Nuculaspis tsugae (Marlatt) (Homoptera: Diaspididae) and the concentrations of 15 terpenoids in needles of Tsuga sieboldii, the Japanese host, and T. canadensis, the North American host, was investigated during 1981 and 1982 in a field plot of 8-year-old trees in New Haven, CT, USA. Both scales produced significantly more eggs per female on T. sieboldii than on T. canadensis. Stepwise multiple regression analyses indicated that the variation in fecundity within both scales was strongly associated with variation in the terpenoid profile between tree species. General patterns of phytochemical variation between the two Tsuga species based on differences in the concentration of terpenoids having similar chemical structures were revealed by the multivariate statistical technique, principal components analysis. The volatile leaf oil profile of T. sieboldii was relatively richer in terpene alcohols, while that of T. canadensis was relatively richer in terpene hydrocarbons and terpene acetates. The individual terpenoids were then assigned to one of five groups based on chemical structure and regression analyses were repeated; fecundity of both scales increased with increasing concentration of terpenoid alcohols. Fecundity of F. externa was negatively associated with the relative concentration of acyclic terpenes but the opposite was true for N. tsugae. Analysis of foliar terpenoids may provide a basis for predicting the relative susceptibility of Tsuga species to attack by F. externa and N. tsugae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379876
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  • 4
    Electronic Resource
    Electronic Resource
    Volatile cues used by the parasitoid, Aphytis melinus, for host location: California red scale revisited (1998)
    Springer
    Entomologia experimentalis et applicata 88 (1998), S. 235-245 
    Details
    ISSN: 1570-7458
    Keywords: foraging behavior ; olfactometer ; host location ; Aonidiella aurantii ; Aphytis melinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aphytis melinus DeBach (Hymenoptera: Aphelinidae) is a biological control agent of diaspidid scale insects. The parasitoid has a narrow host range but its hosts are polyphagous. We determined the source of volatile cues the wasp uses to locate its few host species when those hosts occur on more than one host plant species. We addressed four questions in regard to the use of volatile cues in host location of California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae): (1) Does A. melinus use volatile cues to assist in host location? (2) Are these cues innately recognized or learned? (3) Are cues produced by female California red scale, or from other sources? (4) Are the cues specific to the host or host plant? These questions were tested through the use of a Y-tube olfactometer. Female A. melinus used volatile cues to orient toward both infested and uninfested host plant material. Wasps learned these cues by associating odors from the host plant with host presence. They had no innate preferences for scale insect or host plant volatile stimuli. Contrary to previous studies, we found no evidence of orientation toward the female-produced sex pheromone of California red scale, nor to volatile cues from the attacked host stage. Wasps given experience with scale insects growing on lemon fruit subsequently oriented toward lemon and orange fruit and leaves. The scale species with which the wasp was given experience did not affect this preference. Wasps given experience with California red scale growing on squash did not orient toward infested lemon fruit. The host ranges of the parasitoid and its hosts are used to explain the adaptive value for the evolution of learned rather than fixed responses to cues used in foraging behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003400215721
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  • 5
    Electronic Resource
    Electronic Resource
    Environmental variation in physical and chemical cues used by the parasitic wasp,Aphytis melinus, for host recognition (1994)
    Springer
    Entomologia experimentalis et applicata 72 (1994), S. 97-108 
    Details
    ISSN: 1570-7458
    Keywords: Aphytis melinus ; Aonidiella aurantii ; kairomone ; O-caffeyoyltyrosine ; host recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract O-caffeoyltyrosine is a host recognition kairomone forAphytis melinus DeBach (Aphelinidae) found in the covers of its host, California red scale,Aonidiella aurantii (Maskell) (Diaspidae). This study tests the hypothesis that the concentration ofO-caffeoyltyrosine and scale cover size are reliable indicators of scale body size, an important component of host quality forA. melinus, over a range of scale rearing conditions. Both scale cover area andO-caffeoyltyrosine concentrations were only qualitatively related to scale body size during the third instar, the scale life stage most suitable forA. melinus. Scale cover area andO-caffeoyltyrosine concentrations were reduced, relative to scale body size, when scale were reared on bark and leaves compared to fruits. Scale cover area andO-caffeoyltyrosine concentration were also relatively reduced when scales were reared in mid-summer compared to spring and fall, and when reared on orange cultivars compared to lemon cultivars in the field. Finally, scale cover area andO-caffeoyltyrosine concentration were reduced when scale were reared at 52% compared to 100% humidity in the laboratory. Scales appear to be chemically conspicuous toA. melinus for a short period of the time in which they are physiologically susceptible. Scales that minimize their cover size and maximize the incorporation rate ofO-caffeoyltyrosine into covers may minimize their conspicuousness toA. melinus. Minimizing scale cover size, but not necessarily incorporation rates, may make scales more vulnerable to predators, however.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02383544
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of genetic and environmental host plant variation on the susceptibility of two noctuids toBacillus thuringiensis (1994)
    Springer
    Entomologia experimentalis et applicata 70 (1994), S. 165-178 
    Details
    ISSN: 1570-7458
    Keywords: Bacillus thuringiensis ; host plant resistance ; seasonal variation ; Spodoptera exigua ; Trichoplusia ni
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TwoApium graveolens var.rapaceum (L.) cultivars that differ in their suitability for the survival and growth ofSpodoptera exigua (Hübner) andTrichoplusia ni (Hübner) were used to examine the effect of genetic and seasonal environmental variation in host plant suitability on the efficacy ofBacillus thuringiensis subsp.kurstaki (Berliner). The effects of host plant genotype andB. thuringiensis were generally independent, so thatB. thuringiensis efficacy was greatest on the resistant host plant cultivar. Host plant suitability varied within growing season for both insect species but, while host plant suitability decreased with increasing plant age forT. ni, the response ofS. exigua to plant age was not as clear. Within season variation in host plant suitability affectedB. thuringiensis efficacy and the interaction betweenB. thuringiensis and host plant cultivar forS. exigua but not forT. ni. Soluble protein and Folin-Denis phenolic concentrations of host plant tissue were not correlated with changes in host plant suitability to either insect species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02380524
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  • 7
    Electronic Resource
    Electronic Resource
    Increased parasitization of California red scale in the field after exposing its parasitoid, Aphytis melinus, to a synthetic kairomone (1997)
    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 73-81 
    Details
    ISSN: 1570-7458
    Keywords: O-caffeoyltyrosine ; host recognition ; learning ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The introduced parasitoid, Aphytis melinus DeBach (Hymenoptera: Aphelinidae), utilizes a kairomone, O-caffeoyltyrosine, to recognize California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae). Wasps used in augmentative release programs for California red scale on California citrus are reared on oleander scale, Aspidiotus nerii Bouché (Homoptera: Diaspididae), themselves reared on squash. Previous laboratory studies demonstrated that wasps reared on oleander scale but exposed to O-caffeoyltyrosine before bioassay more readily accepted California red scale covers for probing than wasps reared similarly but not exposed to O-caffeoyltyrosine. The goal of this study was to determine if wasps reared on oleander scale but exposed to O-caffeoyltyrosine actually parasitized a greater number of field-reared California red scale than unconditioned wasps. In order to distinguish between progeny of conditioned and unconditioned wasps in the field, we utilized two A.melinus strains that carried different electrophoretically distinguishable alleles. In half of the releases, Strain ‘A’ was conditioned to O-caffeoyltyrosine and Strain ‘B’ served as the control, while this pattern of conditioning was reversed for the remaining releases. Although there were differences in the rates of population growth of the two strains, whichever strain was the conditioned strain left a greater than expected number of progeny compared to the control strain in all comparisons. Exposure of A. melinus reared in commercial insectaries to O-caffeoyltyrosine prior to release may be a means to improve the effectiveness of such wasps in augmentative release programs to control California red scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002910400320
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  • 8
    Electronic Resource
    Electronic Resource
    Survival of the Colorado potato beetle on virus-infected tomato in relation to plant nitrogen and alkaloid content (1987)
    Springer
    Entomologia experimentalis et applicata 44 (1987), S. 31-35 
    Details
    ISSN: 1570-7458
    Keywords: host quality ; nitrogen ; survival ; Leptinotarsa decemlineata ; Lycopersicon esculentum ; plant virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Pour vérifier l'hypothèse selon laquelle une contamination par un virs végétal peut accroître la consommation de plantes délaissées ou partiellement résistantes, nous avons examiné les interactions entre Leptinotarsa decemlineata Say, Lycopersicon esculentum Mill., et le virus de la mosaïque du tabac (TMV). La survie des larves de L. decemlineata a augmenté avec la contamination par TMV; les teneurs en azote et en tomatine étaient toutes deux plus élevées dans les plantes contaminées par le virus. La survie a augmenté linéairement avec la teneur en azote, mais sans dépendre de la teneur en tomatine. L'influence positive pour L. decemlineata de la contamination par le virus peut être attribuée au moins en partie à la teneur en azote plus élevée. Nos résultats correspondent à l'hypothèse selon laquelle la consommation de plantes délaissées ou partiellement résistantes peut être augmentée par la contamination virale, et que cette contamination peut faciliter l'adaptation d'insectes phytophages sur des plantes marginalement consommables.
    Notes: Abstract Infection by tobacco mosaic virus improved the suitability of tomato, Lycopersicon esculentum Mill. for survival of Colorado potato beetle, Leptinotarsa decemlineata (Say), larvae. This improvement was due, at least in part, to the increase in total nitrogen content of virus-infected plants. The simultaneous increase in tomatine content had no discernable effect on L. decemlineata survival. Our results are consistent with the suggestions that virus infection may improve the suitability of partially resistant or non-preferred hosts, and that virus infection may facilitate the adaption of phytophagous insects to such ‘marginal’ host plant species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361306
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  • 9
    Electronic Resource
    Electronic Resource
    Egg production and survival of the citrus red mite on an artificial feeding system (1988)
    Springer
    Entomologia experimentalis et applicata 47 (1988), S. 137-143 
    Details
    ISSN: 1570-7458
    Keywords: Panonychus citri ; artificial diets ; egg production ; mite nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Une méthode d'alimentation sur diète artificielle a été mise au point pour l'acarien du citrus, Panonychus citri Mc Gregor (Acari: Tetranychidae) et a été utilisée pour déterminer l'influence de différentes solutions nutritives sur la fécondité et la survie des femelles adultes. La fécondité augmente avec la teneur en sucre jusqu'à une concentration maximale de 30%, et décline ensuite pour des concentrations supérieures. Du caséinate de sodium autoclavé s'est révélé être la meilleure source d'azote et la fécondité a été la plus forte sur des milieux contenant 8% de caséinate de sodium, concentration la plus élevée testée. La fécondité est plus grande lorsque l'azote alimentaire est fourni entièrement sous forme de protéine plutôt que sous forme d'acides aminés libres, en tout ou en partie. Les résultats sont qualitativement semblables à ceux obtenus précédemment chez Tetranychus urticae Koch, cependant les concentrations optimales des nutriments majeurs sont environ 4 à 10 fois plus élevées pour P. citri que pour T. urticae.
    Notes: Abstract An artificial feeding system was developed for the citrus red mite, Panonychus citri McGregor (Acari: Tetranychidae) to determine egg production and survival of adult female mites in response to various nutrient solutions. Egg production increased with increasing sugar concentration up to 20%, then declined. Autoclaved sodium caseinate was the most suitable nitrogen source examined, and egg production was highest on diet fractions containing 8% sodium caseinate, the highest concentration examined. Fecundity was higher when dietary nitrogen was provided entirely by protein than in whole or in part by free amino acids. Results are qualitatively similar to studies with Tetranychus urticae Koch, however optimal concentrations of major nutrients were ca. 4 to 10 times higher for P. citri than for T. urticae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367479
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  • 10
    Electronic Resource
    Electronic Resource
    Identification and synthesis of a kairomone inducing oviposition by parasitoidAphytis melinus from California red scale covers (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 1721-1736 
    Details
    ISSN: 1573-1561
    Keywords: Kairomone ; oviposition stimulant ; O-caffeoyltyrosine ; Aphytis melinus ; Hymenoptera ; Encyrtidae ; Aonidiella aurantii ; Homoptera ; Diaspididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The parasitoid waspAphytis melinus uses a kairomone from the cover of its scale host, California red scale (Aonidiella aurantii), as an oviposition stimulant. The kairomone was isolated from extracts of scale covers, and identified asO-caffeoyltyrosine by a combination of spectroscopic methods. The kairomone was synthesized, and the synthetic compound was determined to be as active as the chemical isolated from scale covers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00982303
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