A 10-YEAR STUDY ON THE APPLICABILITY OF PHEROMONE-BAITED TRAPS FOR MONITORING THE EUROPEAN CORN-BORER (OSTRINIA-NUBILALIS HBN) IN THE FEDERAL-REPUBLIC-OF-GERMANY .2. INVESTIGATIONS ON THE APPLICABILITY OF PHEROMONE-BAITED TRAPS FOR CALCULATING THE DATE OF RELEASE OF TRICHOGRAMMA-WASPS

Since 1981, the suitability of pheromone-baited traps for monitoring the European corn borer (Z-strain) has been investigated in South Hesse. The 'Pherocon IC-trap' (Zoecon, USA) with an 'ECBI'-bait as well as the 'Biotrap' (Hoechst AG, FRG) with 20 or 60 mug of 97 Z- : 3 E-11-tetradecenyl acetate per dispenser proved to be useful in monitoring the beginning of the flight-period and, thus, to appoint the most suitable time for releasing Trichogramma-wasps for efficient pest control. A detailed proposal for placing the traps and a preliminary proposal for calculating the date of release are enclosed. Only in few cases, the number of trapped males was correlated with the population density. Even flight peaks of the moth could not be determined with certainty by pheromone traps.