Interactions among Myzus persicae, predators and parasitoids may hamper biological control in Mediterranean peach orchards

Abstract

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is a serious pests of peach trees. It has traditionally been managed with insecticides, but social concerns on insecticides use claim for alternative control strategies. Aphids are attacked by many natural enemies, so the use of conservation biological control could be feasible. However, the existence of a wide array of natural enemies increases the chances of intraguild predation and can also trigger behavioral changes in aphids. To evaluate interactions among predators and parasitoids of M. persicae, we conducted laboratory experiments to determine the contribution of three predators, Episyrphus balteatus DeGeer (Diptera: Syrphidae), Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), and Orius majusculus (Reuter) (Hemiptera: Anthocoridae), to the control of M. persicae. In addition, we examined changes in aphid behavior due to cornicle exudate and the interaction of the aforementioned predators with the parasitoid Aphidius matricariae (Haliday) (Hymenoptera: Braconidae). Our results showed that the most voracious predator was E. balteatus followed by A. aphidimyza. At 72 hours, the aphid population had tripled in the arenas where cornicle exudate was present compared to those where it was absent. In a confined environment, the presence of a single individual of A. aphidimyza and O. majusculus in conjunction with the parasitoid increased the aphid population instead of reducing it. However, the fact that all predators avoided feeding on mummified aphids and that A. aphidimyza and O. majusculus preferred to feed on unparasitized aphids highlight the possibility that parasitoids and predators can jointly contribute to aphid control.