Aphid facultative symbiont affects induced plant defenses

Abstract

It has long been known that insects are colonised by a diverse community of mutualistic symbionts that provide their hosts with nutrients that are missing in the diet. In the last decade, it has become apparent that facultative symbionts (i.e. not required for host survival) in herbivore insects can also play an important role in insect-plant interactions. When attacked by insects, plants are able to defend themselves by triggering defensive mechanisms aimed at poisoning the herbivore or to attract herbivore natural enemies. Recent research demonstrates that facultative insect symbionts can play an important role in this context, for example by down-regulating the expression of plant defensive traits. We explore the role of pea aphid (Acyrthosiphon pisum) facultative endosymbionts in plant defences. Our results suggest that insect symbionts can have intricate effects on aphid natural enemies, some of them mediated by changes in plant quality.