Influence of the Virus LbFV and of <em>Wolbachia</em> in a Host-Parasitoid Interaction

<div><p>Symbionts are widespread and might have a substantial effect on the outcome of interactions between species, such as in host-parasitoid systems. Here, we studied the effects of symbionts on the outcome of host-parasitoid interactions in a four-partner system, consisting of the parasitoid wasp <em>Leptopilina boulardi</em>, its two hosts <em>Drosophila melanogaster</em> and <em>D. simulans</em>, the wasp virus LbFV, and the endosymbiotic bacterium <em>Wolbachia</em>. The virus is known to manipulate the superparasitism behavior of the parasitoid whereas some <em>Wolbachia</em> strains can reproductively manipulate and/or confer pathogen protection to <em>Drosophila</em> hosts. We used two nuclear backgrounds for both <em>Drosophila</em> species, infected with or cured of their respective <em>Wolbachia</em> strains, and offered them to <em>L. boulardi</em> of one nuclear background, either infected or uninfected by the virus. The main defence mechanism against parasitoids, i.e. encapsulation, and other important traits of the interaction were measured. The results showed that virus-infected parasitoids are less frequently encapsulated than uninfected ones. Further experiments showed that this viral effect involved both a direct protective effect against encapsulation and an indirect effect of superparasitism. Additionally, the <em>Wolbachia</em> strain <em>w</em>Au affected the encapsulation ability of its <em>Drosophila</em> host but the direction of this effect was strongly dependent on the presence/absence of LbFV. Our results confirmed the importance of heritable symbionts in the outcome of antagonistic interactions.</p> </div>