Exploring multitrophic interactions of defensive insect symbionts at the community level

ongoing

Many animals acquire new abilities after establishing a symbiotic interaction with a microorganism, and the last decades have revealed the prevalence of defensive symbioses between animals and microorganisms. One of the best-studied cases are aphids that engage in a symbiotic relationship with a facultative bacteria that protect them against parasitic wasps (parasitoids). Parasitoids are small wasps that reproduce by injecting an egg as well as toxic venom compounds into their hosts, ultimately killing the host upon parasitoid development to adulthood. Defensive symbionts, however, can challenge this process and reduce parasitism success, a process that can alter the efficiency of biological control programs against aphids. While aphid defensive symbionts have been well studied in the past two decades, there is still no direct evidence of the defensive mechanisms against parasitism. Particularly, the interaction between aphid symbionts and parasitoid venom remains unexplored. In addition, studies have focused on the direct effects of symbionts on parasitoid populations, but complex indirect effects on the entire community of aphid natural enemies have been largely overlooked. In this multidisciplinary project, I propose to fill these gaps in knowledge by 1) unravelling the interaction between parasitoid venom and aphid symbiont protection, 2) investigating the indirect effects of aphid symbionts on the insect community of natural enemies and 3) regrouping these themes in a meta-analysis of the scientific literature to empirically assess the effects of insect microbial warfare. This proposal will advance our fundamental understanding of the effects of aphid symbionts, and it will be of applied interest to improve aphid biocontrol.