Influence of selective insecticides on populations dynamics of European red mite (Acari: Tetranychidae), apple rust mite (Acari: Eriophyidae), and their predator Amblyseius fallacis (Acari: Phytoseiidae) in apple

The predaceous phytoseiid mite, Amblyseius fallacis (Garman), is important to the biological control of spider mites in deciduous fruit orchards. Insecticides applied for control of insect pests may be toxic to A. fallacis, thereby causing spider mite outbreaks. Pyrethroids are highly toxic to A. fallacis and are not recommended for use after petal fall. Applications of permethrin at pink and petal fall resulted in outbreaks of European red mites, Panonychus ulmi (Koch) because of the elimination of A. fallacis. Permethrin-treated trees had European red mite populations averaging 5 times higher than in untreated trees. Materials which conserved A. fallacis populations maintained European red mite below economic thresholds throughout the season. The apple rust mite, Aculus schlechtendali (Nalepa), served as an alternate food source for A. fallacis, particularly in trees which had low European red mite populations