A SURVEY OF PREDATORY MITES IN ONTARIO APPLE ORCHARDS WITH DIVERSE PESTICIDE PROGRAMS

Leaves were collected between 28 July and 10 September from 36 (1986) and 85 (1987) apple orchards, and examined for mites. Twelve species of Phytoseiidae were found: Amblyseius fallacis (Garman), Typhlodromus longipilus Nesbitt, A. andersoni (Chant), T. caudiglans Schuster, T. pyri Scheuten, T. pomi (Parrott), Phytoseius macropilis (Banks), T. herbertae Chant, A. driggeri Specht, A. finlandicus (Oudemans), T. conspicuus (Garman), and A. pusillus (Kennett), in order of frequency. The stigmaeid mites Zetzellia mali (Ewing) and Agistemus fleschneri Summers, a complex erythraeid mites of Balaustium spp. and Hauptmannia spp., and tydeid mites, primarily Tydeus spp., were other common predatory species. Species of Tetranychidae, Bdellidae, Eriophyidae, Winterschmidtiidae, and Tarsonemidae, also were collected. Predatory mites were present each season in all abandoned orchards and in 43-74% of the commercial orchards. Their abundance in commercial orchards was compared with the use of insecticides applied only for control of the spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.). Fewer (P < 0.05) phytoseiids occurred where pyrethroids were employed than in sites without pyrethroids, but differences were not found for similar use of the carbamoyl oxime, methomyl. Fewer (P < 0.05) stigmaeids occurred in sites treated with methomyl than in sites without methomyl, whereas such differences were not found for pyrethroid use.