SUSCEPTIBILITY OF THE WOOLLY APPLE APHID PARASITOID, APHELINUS-MALI (HYM, APHELINIDAE), TO COMMON PESTICIDES USED IN APPLE ORCHARDS IN ISRAEL

The effects of one acaricide (cyhexatin), two fungicides (penconazole and sulfur), and six insecticides (azinphos-methyl, chlorpyrifos, imid acloprid, pirimicarb, triazamate and vamidothion) on the adult stage o f the parasitoid Aphelinus mali (Haldeman), a parasite of the woolly a pple aphid Eriosoma lanigerum (Hausmann), were investigated under labo ratory conditions. Chlorpyrifos (an organophosphorus insecticide-OF) w as found to be highly toxic to the adult wasps. Vamidothion (OF) was m ore toxic to the parasitoid than azinphos-methyl (OF). On the other ha nd, both chlorpyrifos and azinphos-methyl were found to be harmless to the immature stages of the parasitoid in a test conducted under semi- field conditions. Of the other insecticides, imidacloprid was more tox ic to the adult parasitoid than pirimicarb and triazamate. Neither cyh exatin nor penconazole had a considerable toxic effect upon the parasi toid. In contrast, sulfur was found to be moderately toxic to the para sitoid under laboratory conditions, as well as in a field survey in wh ich we followed populations of E. lanigerum and A. mali parasitization in sulfur-treated plots, and in a plot heated with Ampelomyces quisqu alis Ces., a fungus antagonist to powdery mildew. The implications of these results to LPM programs of apple orchards in Israel are discusse d.