Assessment of the range of attraction of pheromone traps to Agriotes lineatus and Agriotes obscurus

1 The range of attraction of YATLOR pheromone traps was studied to gain information on the number of traps needed for mass trapping of males of two Agriotes species. 2 Male click beetles of the species Agriotes lineatus (L.) and Agriotes obscurus (L.) (25-30 individuals per release point) were marked and released at a distance of 2, 5, 10, 15, 20 and 60 m from a pheromone trap both along and opposite to the known prevailing wind direction. Traps were regularly inspected over approximately 1 month. The percentage of recaptured beetles was calculated and analyzed using analysis of variance. Maximum sampling ranges and effective sampling areas were calculated. 3 Averaged over all five trials and distances, approximately 40% of the released beetles (A. lineatus and A. obscurus) were recaptured. The percentage recapture of male adults was significantly affected by release distance, whereas no differences were found for species and release direction. 4 Males were recaptured from all release points and the percentage recapture decreased (in part significantly) with increasing distance from 76% (2 m) to 35% (15 m) and 9% (60 m), respectively. Most of the beetles were recaptured within the first 3 days after release, independent of the distance, except 60 m. The effective sampling area for A. lineatus was 1089 m(2) after 12 days and increased to 1735 m(2) after 30 days. Corresponding values for A. obscurus were considerably higher: 1518 m2 for 12 days and 2633 m(2) for 30 days. 5 We conclude that the range of attraction of the pheromone traps for A. lineatus and A. obscurus is comparatively low, providing high percentage recapture only for release distances up to 10 m. Accordingly, any approach targeted on preventing mating by male mass trapping would require a dense network of pheromone traps.