Monitoring of Tribolium castaneum (Coleoptera: Tenebrionidae) adults following exposure to abamectin by traps with 4,8-dimethyldecanal and commercial kairomone

The aggregation pheromone 4,8-dimethyldecanal (4,8-DMD) and commercially-available kairomones are used for trapping Tribolium castaneum, a serious stored-product pest insect but low trapping is often reported. Previous studies reported that exposure to certain chemicals enhanced their trapping but the influence of the insecticide abamectin is not known. This research aimed to determine the effect of exposing T. castaneum to abamectin on subsequent orientation to traps containing its aggregation pheromone 4,8-dimethydecanal and a kairomone. Under laboratory conditions, trapping with pheromone was similar up to 7.5 ppm, then trapping was reduced at 10, 15 and 20 ppm. The highest attraction (53%) to pheromone + kairomone vial observed at 2.5 ppm which was greater than adults not exposed to abamectin. Overall, trapping decreased with increasing concentrations of abamectin beyond 2.5 ppm. Under simulated warehouse conditions, the highest trapping (29%) occurred in insects exposed to 1 ppm abamectin and was not significantly different from 0 ppm (no pheromone) and 2.5 ppm. The lowest trapping (8%) occurred at 15 ppm which was not significantly different than 20 ppm. With pheromone + kairomone, the highest trapping (48.75%) obtained in adults exposed to 0 ppm abamectin which was not significantly different than 2.5 ppm exposure while the lowest recapture was 11% at 20 ppm. The combination of pheromone and kairomone in traps captured more insects than pheromone alone. But, exposure to high concentrations of abamectin reduced trapping at 14 d following exposure. Therefore, future research needs to schedule the pre-treatment with abamectin so that it will not jeopardize monitoring efforts through pheromone and/or kairomone traps to ensure protection of stored food from insect damage.