Abstract

Raspberry beetle (Byturus tomentosus) is one of the most important pests of cultivated raspberries in Europe, necessitating the application of prophylactic insecticide sprays to prevent larval contamination of the fruit. White sticky traps, first shown to trap adult raspberry beetles in Switzerland, were tested in Scotland, Switzerland and Finland in 1998-99 as part of the EU project 'Reduced Application of Chemicals in European Raspberry Production (RACER). The main objective of this study was to develop control thresholds based on relationships between numbers of trapped raspberry beetles and amounts of fruit damage. The traps were placed in insecticide-free plots in raspberry plantations at 'first flower bud' stage and changed at weekly intervals for 6-10 weeks. The percentage of damaged raspberries, estimated by examining harvested fruit and husks for raspberry beetle larvae and feeding damage, or by inspecting freshly exposed fruit husks in situ, could not be accurately predicted from the total number of raspberry beetles caught before and during flowering. In Finland, raspberry beetles were not often trapped once flowers opened, and there was usually no correlation between trap catches and fruit damage. Provisional damage threshold levels were set for Scotland and Switzerland, where traps usually caught raspberry beetles before and during flowering.