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Benrey, Betty
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Benrey, Betty
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Betty.Benrey@unine.ch
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- PublicationAccès libreExperimental Growth Conditions affect Direct and Indirect Defences in two Cotton Species(2023)
; ; ; ; ; Cotton has been used as a model plant to study direct and indirect plant defence against herbivorous insects. However, the plant growing conditions could have an important effect on the outcome of such plant defence studies. We examined how common experimental growth conditions influence constitutive and inducible defences in two species of cotton, Gossypium hirsutum and G. herbaceum. We induced plants by applying caterpillar regurgitant to mechanical wounds to compare the induction levels between plants of both species grown in greenhouse or phytotron conditions. For this we measured defence metabolites (gossypol and heliocides) and performance of Spodoptera frugiperda caterpillars on different leaves, the emission of plant volatiles, and their attractiveness to parasitic wasps. Induction increased the levels of defence metabolites, which in turn decreased the performance of S. frugiperda larvae. Constitutive and induced defence levels were the highest in plants grown in the phytotron (compared to greenhouse plants), G. hirsutum and young leaves. Defence induction was more pronounced in plants grown in the phytotron and in young leaves. Also, the differences between growing conditions were more evident for metabolites in the youngest leaves, indicating an interaction with plant ontogeny. The composition of emitted volatiles was different between plants from the two growth conditions, with greenhouse-grown plants showing more variation than phytotron-grown plants. Also, G. hirsutum released higher amounts of volatiles and attracted more parasitic wasps than G. herbaceum. Overall, these results highlight the importance of experimental abiotic factors in plant defence induction and ontogeny of defences. We therefore suggest careful consideration in selecting the appropriate experimental growing conditions for studies on plant defences. - PublicationAccès librePopulation genetic structure of two primary parasitoids of Spodoptera frugiperda (Lepidoptera), Chelonus insularis and Campoletis sonorensis (Hymenoptera): to what extent is the host plant important?(2010)
; ; Franck, PierrePlant chemistry can strongly influence interactions between herbivores and their natural enemies, either by providing volatile compounds that serve as foraging cues for parasitoids or predators, or by affecting the quality of herbivores as hosts or prey. Through these effects plants may influence parasitoid population genetic structure. We tested for a possible specialization on specific crop plants in Chelonus insularis and Campoletis sonorensis, two primary parasitoids of the fall armyworm, Spodoptera frugiperda. Throughout Mexico, S. frugiperda larvae were collected from their main host plants, maize and sorghum and parasitoids that emerged from the larvae were used for subsequent comparison by molecular analysis. Genetic variation at eight and 11 microsatellites were respectively assayed for C. insularis and C. sonorensis to examine isolation by distance, host plant and regional effects. Kinship analyses were also performed to assess female migration among host-plants. The analyses showed considerable within population variation and revealed a significant regional effect. No effect of host plant on population structure of either of the two parasitoid species was found. Isolation by distance was observed at the individual level, but not at the population level. Kinship analyses revealed significantly more genetically related—or kin—individuals on the same plant species than on different plant species, suggesting that locally, mothers preferentially stay on the same plant species. Although the standard population genetics parameters showed no effect of plant species on population structure, the kinship analyses revealed that mothers exhibit plant species fidelity, which may speed up divergence if adaptation were to occur. - PublicationMétadonnées seulementEfectos de los metabolitos secundarios vegetales en el comportamiento y desarrollo de avispas parasitoides(México: Instituto de EcologÃa, 2001)
; ; - PublicationMétadonnées seulementEffects of plant metabolites on the behavior and development of parasitic wasps(1998)
; Parasitoids are insects that spend their immature stages feeding from the tissues of other arthropods, eventually killing them. Many insects that serve as hosts for parasitoids are herbivorous, and metabolites from plants on which they feed can influence both the location of hosts by adult parasitoids and the development of the immature stages. For example, adult female parasitoids, which have the formidable task of locating often scarce and well-hidden hosts, may make effective use of chemical signals that plants emit in response to herbivory. The signals are used to guide them to herbivores that are damaging the plants. Also, plant-produced toxins along with digestibility reducers may slow down herbivore development, prolonging the time that they are vulnerable to parasitoids. The influence of plant chemicals continues after a parasitoid egg has been deposited in or on a host. An immature parasitoid uses the host as its sole source of nutrients. As the diet of hosts, plants can affect their development and physiological condition and thus, the overall suitability and quality of hosts as resources for parasitoid larvae. Here we give an overview of what is known about these interactions between plants and parasitoids and speculate on the possibility that parasitoids and other natural enemies of herbivorous arthropods may have, to some extent, contributed to the evolutionary pressures from which plant chemical traits have evolved.