Aphid resistance traits influence competition between rival parasitoids
Kraft, Laura Joan
MetadataShow full item record
Inherited facultative symbionts commonly infect herbivorous insects and can mediate interactions with natural enemies. Hamiltonella defensa, infecting the pea aphid, Acyrthosiphon pisum, confers varying levels of protection against the common parasitoid Aphidius ervi. Following its introduction to North America to control A. pisum, A. ervi completely displaced all parasitoid species except the native wasp Praon pequodorum. Importantly, H. defensa does not protect against, P. pequodorum. We conducted population cage experiments to determine if varying proportions of H. defensa infected aphids influence competition between these two rival parasitoids. Indeed, we find that cages containing any amount of H. defensa resistance (20-100%) resulted in the persistence of P. pequodorum likely by providing a reservoir of aphids susceptible only to attack by this wasp. Resistance traits, however, did not mediate internal competition between these parasitoids. Thus, aphid resistance traits that target specific natural enemies have the potential to structure aphid food webs.