Intraguild predation of the parasitoid wasp, Aphelinus mali (Haldeman) by the syrphid predator Heringia calcarata (Loew)

Heringia calcarata (Loew) (Diptera: Syrphidae) and Aphelinus mali (Halderman) (Hymenoptera: Aphelinidae) are specialized natural enemies of Woolly Apple Aphid, Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae). The Research organization, Plant and Food Research New Zealand and the apple industry organization, PipfruitNZ are interested in importing H. calcarata into New Zealand to supplement biological control of Woolly Apple Aphid (WAA) in New Zealand. A. mali is the keystone natural enemy of WAA in New Zealand orchards; A. mali provides effective biological control most of the time. Therefore, disruption of A. mali populations as a result of IGP by an introduced predator is highly undesirable. Heringia calcarata will oviposit on WAA colonies parasitized by A. mali and will prey upon parasitized aphids. Understanding the impact of intraguild predation (IGP) of A. mali by H. calcarata is important for satisfying regulatory requirements for introducing H. calcarata into New Zealand. These data show that IGP does occur between H. calcarata and A. mali and highlights the need for quantification of the impact of IGP on A. mali populations within their native range.