CONTROL OF APPLE MAGGOT FLIES (DIPTERA, TEPHRITIDAE) WITH PESTICIDE-TREATED RED SPHERES

The effectiveness of baited pesticide-treated red spheres in controlling Rhagoletis pomonella (Walsh) flies was studied under both field-cage and field (orchard) conditions. Spheres (8-cm diameter) were treated with a mixture containing dimethoate, feeding stimulant, and residue-extending agent. Under field-cage conditions, where potted apple trees containing 'Gravenstein' apples were placed singly inside field cages, a baited fresh pesticide-treated sphere was as effective as a baited fresh sticky sphere in killing released flies as well as reducing oviposition. A pesticide-treated sphere hung in a fruiting tree was as attractive to wild R. pomonella flies as a sticky sphere. Field studies conducted in four commercial orchards showed variation in the efficacy of baited pesticide-treated spheres in controlling R. pomonella. In one orchard with 'Gravenstein' apple trees, a commercial level of control (<0.5% fruit damage) was not achieved using either baited dimethoate-treated spheres (2.5% fruit damage) or baited sticky spheres (4.0% fruit damage). In three other orchards with `Liberty' (and some 'McIntosh') trees, nearly acceptable commercial-level control was achieved using either baited pesticide-treated spheres (1.0% fruit damage) or two foliar applications of azinphosmethyl (0.8% fruit damage).