Culture of an aphid heritable symbiont demonstrates its direct role in defence against parasitoids

Heritable symbionts are common in insects with many contributing to host defence. Hamiltonella defensa is a facultative, bacterial symbiont of the pea aphid, Acyrthosiphon pisum that provides protection against the endoparasitoid wasp Aphidius ervi Protection levels vary among strains of H. defensa that are differentially infected by bacteriophages named APSEs. By contrast, little is known about mechanism(s) of resistance owing to the...