Toxicity of pesticides to predatory mites and insects in apple-tree site under field conditions.

Abstract

Various applications of active ingredients of six fungicides and three insecticides and acaricides at normally recommended dosages were tested on two predatory mite species (Amblyseius andersoni Chant and Anthoseius bakeri Garman) from the family Phytoseiidae and on two predatory insect species (Coccinella septempunctata L. Chrysopa perla L.) dominantly present on apple trees. Small differences were found between fungicide treatments. On the trees treated with six fungicide applications the predatory mites and insects survived and increased to a high level, often 20-40 phytoseiids per 100 leaves and 4-8 predatory insects per sample unit. Only the active ingredients tolylfluanid and myclobutanil resulted in lower densities of predatory mites (10-20 phytoseiids per 100 leaves). One application of insecticides-acaricides (active ingredients: clofentezine, phosalone) showed no toxic effect on predatory mites and insects. Two applications of phosalone and one of alpha-cypermethrine were slightly or moderately toxic. Two applications of alpha-cypermethrine and eight routine sprays of various insecticides-acaricides and fungicides were very toxic and resulted in the lowest maximum number of predatory mites and insects, approximately 0-10 phytoseiids per 100 leaves and 1-4 predatory insects per sample unit. The toxicity of pesticides to predatory mites and insects is based on the toxicity of the pesticide' active ingredient and the spray frequency. The active ingredients of fungicides and only one or two applications of insecticides and acaricides were not or slightly toxic and could be used in integrated pest management.