TOXICITY OF NEEM TO NATURAL ENEMIES OF APHIDS

Neem [Azadirachta indica (A. Juss.)] seed oil (NSO) applied in three c oncentrations, 0.5%, 1% and 2%, to petted plants infested with green p each aphid, Myzus persicae (Sulzer), totally prevented adult eclosion of larval coccinellids, Coccinella undecimpunctata L., and reduced adu lt eclosion of syrphids, Eupeodes fumipennis (Thompson), to 11%, 7% an d 0%, respectively, of the controls. Under the same conditions, NSO di d not reduce the rate of parasitism of M. persicae by Diaeretiella rap ae (McIntosh), but emergence of parasitoid adults from aphid mummies c ollected from treated plants was reduced to 35%, 24% and 0%, respectiv ely, of the controls. Although topical treatment of predator larvae wi th NSO at concentrations of up to 5% did not affect survival, emergenc e of parasitoids from mummies dipped in aqueous emulsions of NSO at si milar rates was reduced significantly. Under field conditions, sprays of NSO and neem seed extract to plants had no significant impact on th e number of aphids parasitized. Although total numbers of predators we re reduced, numbers of predators relative to aphid numbers were simila r to those in controls. Neem insecticides may be suitable for use in i ntegrated pest management programs, as under field use they appear to be relatively benign to aphid predators and parasitoids.