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Interaction between the parasitoid Cotesia typhae and its host Sesamia nonagrioides : insights into virulence and resistance traits. Interaction between the parasitoid Cotesia typhae and its host Sesamia nonagrioides : insights into virulence and resistance traits: PhD works, supervised by Florence Mougel-Imbert and Laure Kaiser-ArnauldIn collaboration with Claire Capdevielle-Dulac, Pascaline Venon and Florian Lasfont

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Gornard, Samuel | Mougel, Florence | Kaiser-Arnauld, Laure, Marie-Paule

Edité par CCSD -

International audience. Cotesia typhae is a parasitoid Hymenoptera specialized on Sesamia nonagrioides, a lepidopteran stem borer. Both species originate from east Africa, but S. nonagrioides colonized the Mediterranean Basin during the last interglacial, more than hundred thousand years ago. There, S. nonagrioides has become a crop pest of maize. It is then considered to introduce C. typhae in France to regulate S. nonagrioides populations through biocontrol. In Kenya, two strains of C. typhae, named Kobodo and Makindu (after Kenyan locations sampled), differ in their parasitism success on the French S. nonagrioides population (SNF). While both strains score a good parasitism success on the Kenyan host population (SNK), that of Makindu is lower on SNF while that of Kobodo remains high. A QTL approach to investigate this difference of virulence between C. typhae strains had yielded 3 locus carrying hundreds of candidate genes, among which genes coding for venom proteins. To confirm their implication, we lead a comparative analysis on female proteomic venom content and abdomen transcriptomes, in order to identify candidate proteins and their related genes. In parallel, we investigated the difference of resistance between the S. nonagrioides populations with a comparative transcriptomic analysis of parasitized host larvae hemolymph RNA content, depending on their population origin, on C. typhae strain and on the time elapsed after oviposition. Temporal sampling of parasitized larvae was based on a histological study of capsule formation. Together, these analyzes will allow us to refine candidate genes involved in this virulence/resistance interaction between the parasitoid and its host.

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