THE IMPORTANCE OF USING SELECTIVE INSECTICIDES AGAINST KEY PESTS IN APPLE ORCHARDS TO PRESERVE THE PARASITOID FAUNA OF LEAFMINERS

The preservation of beneficial arthropods is possible by applying sele ctive pesticides. From 1992 to 1994 the impact of different control st rategies against key tortricid pests on the population dynamics of lea fminers and their parasitoids was investigated. Comparisons were made between the use of insect growth regulators (IGR) (diflubenzuron, trif lumuron, fenoxycarb) and two granulosis virus (GV) products (Cydia pom onella-GV, Adoxophyes orana-GV). The degree of parasitism was always l ower in the IGR plots than in the GV- and control plots. Most parasito ids, mainly reared from mines of the GV- and control plots, were chalc ids, dominant species being Achrysocharoides atys (Walk.) (Chalcidoide a, Entedontinae) and Cirrospilus lyncus Walk. (Chalcidoidea, Elacherti nae). Furthermore, two braconid species, Pholetesor bicolor (Nees) and Pit. ci, circumscriptus (Nees), and three ichneumonids were found.