Population Dynamics of Amblyseius fallacies (Acari: Phytoseiidae) and European Red Mite (Acari: Tetranychidae) in Apple Trees Treated with Selected Acaricides

Experiments were conducted to evaluate the effects of early-scason ovicides, selective acaricides, horticultural oil, and potassium salts of fatty acids on the population dynamics of the phytoseiid predator Amblyseius fallacis (Garman) and its prey, the European red mite, Panonychus ulmi (Koch). Both ovicides prevented early-season European red mite outbreaks but only clofentezine-treated trees, with the help of A. fallacis, had low densities of European red mites throughout the entire season. However, treatment with clofentezine kcpt mites at subeconomic levels only if insecticide sprays did not disrupt predator mite populations. Two applications of permethrin drastically reduced natural enemies, and allowed European red mite outbreaks to occur. Selective acaricides varied in their effects on A. fallacies and European red mites. Although not significantly different from each other, all selective acaricides resulted in significantly fewer A. fallacis and European red mites than the untreated trees. Repeated applications of horticultural oils and M-Pede were required to reduce the European red mite populations and were no more effective in conserving predator mites than some of the selective acaricides.