Data from: Wolbachia increases the susceptibility of a parasitoid wasp to hyperparasitism

The success of maternally transmitted endosymbiotic bacteria, such as Wolbachia, is directly linked to their host reproduction but in direct conflict with other parasites that kill the host before it reaches reproductive maturity. We therefore expect symbionts to evolve strategies that increase the ability of their host to evade lethal parasites. In a natural population of the parasitoid wasp Hyposoter horticola in the Åland Islands FI, the Wolbachia strain wHho persists at a low prevalence (~50%). Additionally, there is a negative correlation in the landscape between the prevalence of the Wolbachia and hyperparasitoid wasp, Mesochorus c.f. stigmaticus. Using a manipulative field experiment we address the low but persistent Wolbachia prevalence, and test whether the observed correlation is due to Wolbachia inducing susceptibility or resistance to parasitism. We show that Wolbachia-infection does not influence the ability of the wasp to parasitize their butterfly host, but that hyperparasitism of H. horticola increases in presence of wHho. Consequently the symbiont is detrimental, and in order to persist in the host population, must have a positive effect on fitness that outweighs the costly burden of susceptibility to widespread parasitism.