Mite flaring impact of pesticides on European red mites in apple trees

European Red Mite, Panonychus ulmi (Acari: Tetranychidae), is the principal phytophagous mite pest in Michigan apples. A preliminary survey of mite populations in pesticide-treated orchards was carried out at the Michigan State University Trevor Nichols Research Complex, in Fennville, Michigan. We examined the impact of pesticides applied to tree canopies on the population dynamics of P. ulmi and its phytoseiidae and stigmaeidae predators, Amblyseius fallacis (Garman) (Acari: Phytoseiidae) and Zetzellia mali (Ewing) (Acari: Stigmaeidae). The response of European Red mite egg and motile populations was measured throughout the growing season after two post-petal fall applications of pesticides treatments. Insecticides tested were from the pyrethroid, neonicotinoid, carbamate, spinosyn, diamide and insect growth regulator classes while the fungicide was from ethylene bis-dithiocarbamate (EDBC). In field trials, 50 randomly selected leaves were picked from two-three plots for a total of 200 leaves per treatment. Mites and eggs were removed with mite brushing machine and counted under a stereo microscope Nikon SMZ1000. The number of predator mite motiles were also recorded using the method described for European red mite.