Plastic lipid synthesis in the parasitic wasp Leptopilina heterotoma: Effects of the environment and maternal choice

Details

Supervisors

Hance, Thierry

Faculty

Faculté des sciences

Degree label

Master [120] en biologie des organismes et écologie, à finalité approfondie

Abstract

Leptopilina heterotoma is an endoparasitoid that parasitizes Drosophila larvae. The parasitism behavior of females varies according to seasonal conditions since the females superparasitize more often and in a greater proportion during autumn than during summer. Most insects accumulate fat in preparation for winter. Since the fat content of host can vary in the wild, and since in parasitoids, lipid ressources at emergence depend on the amount of lipid collected on their hosts, the present work aims to study the consequences of seasonal conditions on host choice by the parasitoid mothers. For this purpose, traps were placed in the field during the summer and autumn to capture the parasitoids used in our experiments. However, due to time constraints and problems in capturing parasitoids during the autumn session, this study focuses on the behavior of female parasitoids during the summer season. Our original hypothesis was that females would not show a preference in host choice during the summer in order to lay as many eggs as possible and maximize fitness. We also assumed that offspring fitness was a function of host quality. Our results showed that wasps exposed to summer conditions did not express preferences in host choice. Regarding offspring fitness, our results showed that parasitoid size was correlated with host size, that female fecundity was particularly important during the first few days and also depended on host size, and that longevity was only a function of the sex of the parasitoids and not of the quality of the host from which they came. Overall, our results are confirming our initial hypotheses, and will be of importance for the future experimentations of this research project.