Disorientation of male Agriotes click beetles in the presence of granulate pheromones - a case for mating disruption

Abstract

1. Larvae of multiple click beetle species, i.e. wireworms, are important pests of agriculture worldwide, and are generally managed with insecticides. Conceivably, semiochemical-based management tactics that target male beetles and reduce the mating success of females, would reduce the formation of new larvae in the field. 2. Using two of the best studied species, Agriotes obscurus (AO) and A. lineatus (AL), we evaluated the ability of male beetles to find traps that simulate calling female beetles in field plots treated with various formulations and densities of pheromone-treated substrates. Four disorientation studies were conducted, and the response of wild and marked-released beetles inferred from frequent trap collections. 3. Beetle responses differed between male AO, female AO, and male AL. The presence of AO pheromone increased male AO movements, reduced captures in baited traps, and attracted wild AO beetles into the plots. By the final experiment, the pheromone-treated substrate effectively disoriented male AO for > 17 d. However, treatment with AL pheromone reduced male AO movements and/or repelled them from the plots. Female AO were slightly attracted to their own pheromone early in the season, but not thereafter. Treatment with AL pheromone attracted male AL into plots but did not increase their activity. Both AO and AL pheromone disrupted male AL behaviour, but less significantly than observed for male AO. 4. These results suggest pheromone-based click beetle mating disruption for wireworm management is feasible. However, further work is required to determine application rates and methods, and if this can be developed for other species.