Integrated control of apple pests in new zealand 17. Relationships of amblyseius fallacis to phytophagous mites in an apple orchard

Abstract

The organophosphorus insecticide-resistant predatory phytoseiid mite Amblyseius fallacis (Garman) (Acarina: Phytoseiidae) was released into the Lincoln College apple orchard for control of European red mite, Panonychus ulmi (Koch), in the 1976-77 and 1977-78 seasons. Releases into trees in mid December resulted in predator establishment and control of P. ulmi. There were no differences in establishment between trees with white clover-dominant ground cover and trees with bare ground beneath them. In the season following release, A. fallacis appeared in the trees too late to effectively control P. ulmi. Bare ground beneath the trees resulted in predators appearing earlier and reaching greater numbers compared to the white clover-dominant ground cover treatment. A. fallacis was found to colonise the centre of the tree first, moving late in the season to the outer fruiting clusters. The twospotted spider mite, Tetranychus urticae Koch, was found to be an important alternative food source, particularly in the ground cover. Releases of T. urticae in early December into the ground cover resulted in significantly greater populations of A. fallacis in the ground cover and earlier movement of the predators into the apple trees. A possible association is suggested between A. fallacis and T. urticae populations within the apple tree. © 1980 Taylor & Francis Group, LLC.