Leptopilina boulardi Filamentous Virus

Insect parasitoids lay their eggs inside the body of other arthropods, usually within immature stages (eggs, larvae). Adults parasitoids are thus free-living whereas their larval stages live as parasites within the host. Because the parasitoid larvae progressively consume all the tissues of their hosts they finally kill them and play a major role for regulating the population densities of insect pests.

When parasitoid females encounter a host that have already been parasitized, they usually refrain from laying a supernumerary eggs, preferring to search for unparasitized hosts: they refrain to super-parasitize.

However, in the parasitoid Leptopilina boulardi (Hymenoptera), some females often superparasitize their host (larvae of Drosophila species, Diptera). This is puzzling because in this system only one parasitoid can develop inside a host. Thus, a female laying an egg in such parasitized host condemns her offspring to face harsh competition.

It has been recently discovered that this superparasitism behaviour is in fact caused by an inherited virus (LbFV for Leptopilina boulardi Filamentous Virus) that manipulates the behaviour of females. The virus benefits from superparasitism since it is infectiously transmitted within a superparasitized Drosophila host.

The aim of the project is to sequence the genome of the virus, and to identify the mechanisms by which the virus is able to manipulate the behaviour of the parasitoid. In particular we will investigate how the virus modifies the expression of parasitoid’ genes.