Orientation of Tribolium castaneum (Coleoptera: Tenebrionidae) following pre-exposure to abamectin towards traps with 4,8-dimethyldecanal and commercial kairomone

Authors: SENEVIRATHNE, W.M.S.S. - Rajarata University Of Sri Lanka; PREMATHILAKA, P.A.P.I. - Rajarata University Of Sri Lanka; EGODAWATTA, W.C.P. - Rajarata University Of Sri Lanka; WIJAYARATNE, L.K.W. - Rajarata University Of Sri Lanka; Morrison Iii, William

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2025
Publication Date: 7/5/2025
Citation: Senevirathne, W., Premathilaka, P., Egodawatta, W., Wijayaratne, L., Morrison III, W.R. 2025. Orientation of Tribolium castaneum (Coleoptera: Tenebrionidae) following pre-exposure to abamectin towards traps with 4,8-dimethyldecanal and commercial kairomone. Journal of Stored Products Research. https://doi.org/10.1016/j.jspr.2025.102742.
DOI: https://doi.org/10.1016/j.jspr.2025.102742

Interpretive Summary: Red flour beetle is a serious and widespread pest infesting grain storage and food processing facilities. Often, insecticides are used without fully understanding their effect on the efficacy of long-term trapping programs and the behavioral responses to pheromones and food oils commonly used as lures. Previous studies have reported that prior exposure to certain insecticides increased trap catches, but the influence of the commonly used insecticide abamectin on trap catches is not known. This research aimed to determine the effect of exposure to abamectin by red flour beetle on trap catches and behavioral attraction to a combination of food and pheromone lures in lab assays. Under laboratory conditions, behavioral attraction to the lures was similar when insects were exposed to 0 and 7.5 ppm abamectin. However, attraction was reduced after exposure to 10-20 ppm. The highest attraction (53%) was actually observed in the 2.5 ppm abamectin treatment, which was greater than adults not exposed to abamectin. In a pilot-scale warehouse, the highest trapping (29%) occurred in insects with a prior exposure of 0 to 2.5 ppm abamectin, but trapping was reduced after exposure to 5-20 ppm abamectin. In both attraction and trapping studies, a low dose of abamectin improved trap captures and attraction with pheromone plus food lures, suggesting that a chemical control tactic can improve the sensitivity of pheromone and food lures in monitoring programs. Additionally, these findings suggest that food facilities need to schedule highly concentrated abamectin treatments so that it will not jeopardize the effectiveness of trapping programs.

Technical Abstract: 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 pre-exposure to certain chemicals enhanced their trapping but the influence of the insecti-cide abamectin is not known. This research aimed to determine the effect of pre-exposing T. castaneum to abamectin on subsequent orientation to traps containing its aggregation pheromone 4,8-dimethydecanal and a kairomone. Under laboratory condi-tions, 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 ob-served 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 pre-exposed to 1 ppm abamectin and was not significantly different from 0 ppm (no phero-mone) and 2.5 ppm. The lowest trapping (8%) occurred at 15 ppm which was not sig-nificantly different than 20 ppm. With pheromone + kairomone, the highest trapping (48.75%) obtained in adults pre-exposed to 0 ppm abamectin which was not significant-ly 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 phero-mone alone. But, pre-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.