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Theses

Bases comportementales, physiologiques et génétiques du succès reproducteur d'un hyménoptère parasitoïde

Abstract : Studying the ability of insect parasitoids to reproduce in novel hosts is important to understand adaptive mechanisms at play when they are used for biological control. Cotesia typhae is an African parasitoid specialized on the Lepidoptera Sesamia nonagrioides and it is a potential biological control agent against this maize pest. C. typhae belongs to a group of species harboring a symbiotic virus which is injected in the host during oviposition and which contributes to the parasitoid virulence. I have found out that two strains of C. typhae differed in their offspring number and in their virulence against a French population of S. nonagrioides, which represents a new host. A QTL analysis (Quantitative Trait Loci) has been done to identify genes involved in these variations. We have built a genetic map of C. typhae, identified four QTL and listed candidate genes. To explain the difference of virulence and offspring number, numbers of eggs and viral particles injected during successive ovipositions have been estimated. These experiments have shown that 1/ the two strains have different patterns of egg allocation among the successive hosts parasitized, 2/ the quantity of injected viral particles is not correlated to virulence. To understand to evolutionary origin of the virulence variation, this trait has been estimated for the natural host populations. The results suggest that local adaptation could explain the better pre-adaptation of one C. typhae strain to the French host population. This work also allowed an in-depth characterization of the parasitoid reproductive success, essential for its use in biological control.
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https://hal.archives-ouvertes.fr/tel-03006621
Contributor : Paul-Andre Calatayud Connect in order to contact the contributor
Submitted on : Monday, November 16, 2020 - 8:39:53 AM
Last modification on : Friday, December 3, 2021 - 11:42:36 AM
Long-term archiving on: : Wednesday, February 17, 2021 - 6:19:16 PM

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Romain Benoist. Bases comportementales, physiologiques et génétiques du succès reproducteur d'un hyménoptère parasitoïde. Sciences du Vivant [q-bio]. Sorbonne University UPMC; Sciences de la Nature et de l'Homme : Évolution et Écologie, 2019. Français. ⟨tel-03006621v1⟩

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