A relatively recent discovery is that many animals harbour microbial endosymbionts that help protect them against natural enemies, and that these play crucial and hitherto underappreciated roles in the ecology and evolution of host-parasite interactions. Many of these defensive symbioses are found in insects, where they are commonly transmitted from mothers to their offspring. Virtually nothing is known about the molecular mechanisms of symbiont-mediated defence, or whether there is specificity in defence across diverse natural enemies or against different parasite genotypes within a species. Nor do we understand how defensive symbionts persist in their hosts when natural enemies are rare or absent – do they impose significant costs on their hosts, and how might these costs be mitigated?
This collaborative projects bring together three very different research groups studying diverse but related study systems, in order to obtain a comprehensive understanding of the mechanism, specificity, and regulation of defensive symbiosis, using a wide range of tools and perspectives. We aim to integrate molecular biology and genetics with ecology and evolution to answer major unresolved questions in insect defensive symbiosis. We hope to unravel the mechanism of protection against parasites and pathogens across disparate symbiont strains and insect hosts, and we will harness the power of comparative genomics to address the fascinating question of how diverse symbiont strains have evolved the ability to protect against different parasites.