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1.
Low rates of iridoid glycoside hydrolysis in two Longitarsus leaf beetles with different feeding specialization confer tolerance to iridoid glycoside containing host plants 下载免费PDF全文
Susanne Dobler 《Physiological Entomology》2015,40(1):18-29
Iridoid glycosides are plant defence compounds that are deterrent and/or toxic for unadapted herbivores but are readily sequestered by dietary specialists of different insect orders. Hydrolysis of iridoid glycosides by β‐glucosidase leads to protein denaturation. Insect digestive β‐glucosidases thus have the potential to mediate plant–insect interactions. In the present study, mechanisms associated with iridoid glycoside tolerance are investigated in two closely‐related leaf beetle species (Coleoptera: Chrysomelidae) that feed on iridoid glycoside containing host plants. The polyphagous Longitarsus luridus Scopoli does not sequester iridoid glycosides, whereas the specialist Longitarsus tabidus Fabricius sequesters these compounds from its host plants. To study whether the biochemical properties of their β‐glucosidases correspond to the differences in feeding specialization, the number of β‐glucosidase isoforms and their kinetic properties are compared between the two beetle species. To examine the impact of iridoid glycosides on the β‐glucosidase activity of the generalist, L. luridus beetles are kept on host plants with or without iridoid glycosides. Furthermore, β‐glucosidase activities of both species are examined using an artificial β‐glucosidase substrate and the iridoid glycoside aucubin present in their host plants. Both species have one or two β‐glucosidases with different substrate affinities. Interestingly, host plant use does not influence the specific β‐glucosidase activities of the generalist. Both species hydrolyse aucubin with a much lower affinity than the standard substrate. The neutral pH reduces the β‐glucosidase activity of the specialist beetles by approximately 60% relative to its pH optimum. These low rates of aucubin hydrolysis suggest that the ability to sequester iridoid glycosides has evolved as a key to potentially preventing iridoid glycoside hydrolysis by plant‐derived β‐glucosidases. 相似文献
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3.
Predator exclusion and habitat complexity factors that may affect juvenile red snapper Lutjanus campechanus habitat selection were examined in field and laboratory experiments. A significant predator exclusion effect was detected. Uncaged shell habitats showed significantly lower numbers of age 0 year red snapper, and both uncaged shell and block-shell habitats showed significantly lower numbers of age 1 year red snapper compared with caged habitats ( P < 0·001). Habitat complexity also affected age 0 year red snapper, as mean abundance significantly decreased with decreased habitat complexity ( P < 0·001). In the laboratory, age 0 year red snapper association with complex habitats significantly increased with exposure to a predator Gulf flounder Paralichthys albigutta ( P < 0·001). This study showed that predator exclusion and habitat complexity were significant factors that affected the abundance of juvenile red snapper in nursery areas of the northern Gulf of Mexico. Predation may affect juvenile red snapper abundance directly through mortality and indirectly by influencing habitat selection. 相似文献
4.
Abstract. 1. Pollen is considered to be an important dietary component for many species of flower-feeding herbivores. Its influence on oviposition site selection by the pollen beetle Meligethes aeneus , and on the development of its larvae was investigated.
2. The effects of pollen presence and absence on adult, egg, and larval incidence in the field, and on larval development in the laboratory were compared through the use of Synergy, a composite hybrid oilseed rape Brassica napus variety comprising male-fertile (with pollen) and male-sterile (without pollen) plants.
3. In the field, adult females were more abundant on male-fertile plants during flowering, and a greater proportion of male-fertile than male-sterile buds were accepted for oviposition. These data indicate a possible role of pollen in oviposition site selection by female pollen beetles.
4. The numbers of first instar larvae on the two plant lines did not differ; however, more second instars were found on male-fertile than on male-sterile flowers. This suggests a greater larval survival on male-fertile plants, possibly due to the more readily available food resources and better nutrition afforded by the presence of pollen.
5. Laboratory experiments confirmed that a diet which included pollen improved survival to adulthood and resulted in heavier pupae and adults; however, pollen was not obligatory for larval survival and development.
6. The pollen beetle, previously thought to be an obligate pollen feeder, is therefore more generalist in its requirements for development. These findings may relate to the nutritional and behavioural ecology of other flower-feeding herbivores. 相似文献
2. The effects of pollen presence and absence on adult, egg, and larval incidence in the field, and on larval development in the laboratory were compared through the use of Synergy, a composite hybrid oilseed rape Brassica napus variety comprising male-fertile (with pollen) and male-sterile (without pollen) plants.
3. In the field, adult females were more abundant on male-fertile plants during flowering, and a greater proportion of male-fertile than male-sterile buds were accepted for oviposition. These data indicate a possible role of pollen in oviposition site selection by female pollen beetles.
4. The numbers of first instar larvae on the two plant lines did not differ; however, more second instars were found on male-fertile than on male-sterile flowers. This suggests a greater larval survival on male-fertile plants, possibly due to the more readily available food resources and better nutrition afforded by the presence of pollen.
5. Laboratory experiments confirmed that a diet which included pollen improved survival to adulthood and resulted in heavier pupae and adults; however, pollen was not obligatory for larval survival and development.
6. The pollen beetle, previously thought to be an obligate pollen feeder, is therefore more generalist in its requirements for development. These findings may relate to the nutritional and behavioural ecology of other flower-feeding herbivores. 相似文献
5.
Jens Kvist Nielsen 《Entomologia Experimentalis et Applicata》1989,51(3):249-259
All recorded host plants of Phyllotreta nemorum L. (Coleoptera: Chrysomelidae) contain glucosinolates and belong to the plant families Brassicaceae (Cruciferae), Resedaceae and Capparaceae. The acceptability of 56 plant species from 28 other plant families (non-hosts) for young larvae has been studied in the laboratory. None of these species were fully acceptable for initiations of leaf mines when intact untreated leaves were presented, and only one species, Malva silvestris L. (Malvaceae), was partially acceptable. The acceptability of some species increased when leaf discs were presented instead of intact leaves; but the highest percentages of mine initiations occurred in leaf discs treated with the glucosinolate, sinigrin. A stimulatory effect of sinigrin could be demonstrated in experiments with 7 plant species: Papaver dubium L., Papaver rhoeas L., Fumaria officinalis L., Malva silvestris L., Pisum sativum L., Campanula latifolia L. and Lactuca sativa L. The majority of species remained unacceptable even after treatment with glucosinolates.The main causes for these differences between plant species are supposed to be differences in contents of deterrents and/or other stimulants for mine initiation. These possibilities are discussed in relation to the content of allelochemicals in acceptable plants and the position of these plants in botanical classifications.
Zusammenfassung Phyllotreta nemorum L. ist ein oligophager Erdfloh, der an Cruciferen und anderen Glukosinolat-haltigen Pflanzenarten gebunden ist. Die Imagines fressen Löcher in die Blätter und die Weibchen legen ihre Eier in den Boden. Die Larven sind Blattminierer. Nach dem Schlüpfen im Boden klettern sie an die Pflanzen hoch, und die Einbohrung und der Anfang der Minierung erfolgt in eines der unteren Blätter der Wirtspflanze.Die Wirkung von Glukosinolaten auf die Einbohrung von Junglarven in Pflanzenarten, die keine natürliche Inhalt von Glukosinolaten haben, ist in Laborexperimenten untersucht worden. 56 Pflanzenarten aus 28 Familien wurden präsentiert teils als unbehandelte Blätter und teils als Glukosinolatbehandelte Blattscheiben. Unbehandelte Blätter von nicht-Glukosinolathaltigen Arten waren immer unbefriedigend für die Larven. Nur in eine Art, Malva silvestris L. war die Frequenz der Einbohrung ein bisschen höher als 10%. Eine signifikante Erhöherung der Anzahl eingebohrten Larven nach der Sinigrin-behandlung erfolgte in 7 Pflanzenarten: Papaver dubium L., P. rhoeas L., Fumaria officinalis L., Malva silvestris L., Pisum sativum L., Campanula latifolia L. und Lactuca sativa L. Doch blieben die meisten Pflanzenarten (84%) auch nach der Sinigrin-Behandlung unbesiedelt.Pflanzenarten, die nach der Sinigrin-Behandlung nicht besiedelt werden enthalten vielleicht frasshemmende Stoffe, oder ihnen fehlen noch weitere Frass-stimulierende Stoffe. Diese Möglichkeiten werden diskutiert in Zusammenhang mit den Inhalt von Allelochemikalien in besiedelten Pflanzenarten und mit ihrer taxonomischer Position.相似文献
6.
The life history ofNephus reunioni, introduced from the Reunioni island has been studied. Optimum temperature for the development of the entomophagous insect
is 24–25°C. In this case the population has the highest survival at preimaginal stages, life duration of adults and reproductive
capacity. The rate of population growth was calculated by the formula:
相似文献
7.
Abstract.
8.
Predation by third instar larvae of Chrysoperla (=Chrysopa) carnea (Stephens) (Chrysopidae) did not alter the ratio of unparasitized Heliothis virescens (F.) (Noctuidae) larvae to H. virescens larvae parasitized by Microplitis croceipes (Cresson) (Braconidae) when these second instar larvae were exposed together to the predator on cotton (Gossypium hirsutum L., Malvaceae) in field cages. This indicates that C. carnea larvae did not prefer either parasitized or unparasitized larvae.
Prédation par Chrysopa carnea des chenilles d'Heliothis virescens parasitées par Microplitis croceipes Résumé Les prédations de chenilles d'Heliothis virescens, parasitées ou saines, élevées sur coton (Gossypium hirsutum L.), de la variété Stoneville 213, ont été comparées, dans des cages de 10 m2 chacune placées dans la nature. Des chenilles du second stade ont été placées sur des pieds de coton dans 10 cages, à raison de 160 chenilles préalablement exposées à M. croceipes pendant leur premier stade et 40 chenilles saines par cage. Des larves du troisième stade de Chrysopa carnea ont été ajoutées dans 6 cages, à raison de 500/cage, et 4 cages ont servi de témoins pour évaluer les autres causes de mortalité. L'expérience a été répétée 2 fois. Les chenilles d'H. virescens ont été retirées au bout d'un jour dans une expérience et au bout de 2 jours dans l'autre. C. carnea n'a fait aucun choix entre chenilles parasitées ou non; la fréquence moyenne de chenilles parasitées n'a pas présenté de différence significative entre les cages avec ou sans C. carnea. Qui qu'il en soit, C. carnea a réduit significativement la survie des chenilles d'H. virescens parasitées ou non.相似文献 9.
Luc De Meester 《Evolution; international journal of organic evolution》1996,50(3):1293-1298
The frequent use of neutral markers to quantify genetic variation in natural populations emphasizes the role of stochastic events in explaining genetic differentiation between populations. Complementary studies on ecologically relevant traits are needed to assess the role of natural selection acting on adaptive variation in the development of local genetic differentiation. To test the hypothesis of local adaptation in the cyclical parthenogenetic species Daphnia magna, the phototactic behavior in the absence and presence of fish kairomone was assayed for 30 clones derived from resting eggs isolated from three habitats characterized by a different predation pressure by fish. Clones derived from populations in which fish are present were, on average, more negatively phototactic in and more responsive to the presence of fish kairomone than clones derived from a fishless habitat. In addition, the results show a high genetic diversity for the traits studied in all three gene pools investigated, indicating a high potential for microevolutionary changes in behavior of these Daphnia populations in the face of changes in predation pressure. The results of the present study indicate that working with large samples at the expense of having less precise estimates of genotypic values for specific genotypes may result in a loss of information with regard to the evolutionary potential of local populations. 相似文献
10.
If generalist insect predators are a selective force contributing to patterns of feeding specialization by insect herbivores, then predators should be deterred from eating allelochemical-fed prey. The attack and feeding behaviors of naive predators (Podisus maculiventris stinkbugs) reared on control caterpillars (Manduca sexta) fed plain diet were compared to experienced predators reared on caterpillars fed tomato allelochemicals. Tomatine-fed prey were found more quickly by both naive and tomatine-experienced predators, and chlorogenic acid-experienced predators were more stimulated to begin searching for prey. However, experienced predators were less likely to attack both chlorogenic acidfed and tomatine-fed caterpillars than were naive predators. These results indicate that allelochemical-fed prey were easier for predators to locate, but allelochemical-containing prey often deterred predation by experienced predtors. 相似文献
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