Effects of aggregation pheromone concentration and distance on the trapping of Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults

Authors: DISSANAYAKA, D.M.S. - Rajarata University Of Sri Lanka; SAMMANI, A.M. - Rajarata University Of Sri Lanka; WIJAYARATNE, WOLLY L. - Rajarata University Of Sri Lanka; RAJAPAKSE, R.H. - University Of Ruhuna; HETTIARACHACHI, S. - Rajarata University Of Sri Lanka; Morrison, William - Rob

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2020
Publication Date: 7/14/2020
Citation: Dissanayaka, D.K., Sammani, A.P., Wijayaratne, W.K., Rajapakse, R.S., Hettiarachachi, S., Morrison III, W.R. 2020. Effects of aggregation pheromone concentration and distance on the trapping of Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults. Journal of Stored Products Research. 88:101657. https://doi.org/10.1016/j.jspr.2020.101657.
DOI: https://doi.org/10.1016/j.jspr.2020.101657

Interpretive Summary: For many stored product species, it has been unknown from what distance they are attracted to pheromonal and food cues in and around food facilities. This is of primary concern to stakeholders because there has been some reluctance to deploy attractive compounds in the vicinities of food facilities if the result will be attraction of more insects to an area where they could potentially infest commodities. In this study, we found that the lesser grain borer, a key damaging and cosmopolitan pest of whole grain, are attracted within a 70 cm radius around a commercial pitfall trap with pheromone and/or food cues. We also investigated the optimal concentration of pheromone for attraction of lesser grain borer in traps and found that 100 microliters of pheromone per square meter provided the strongest response. Some important caveats to the conclusions of this study include the fact that beetles typically respond at greater range to volatiles under moving air conditions, while only still air conditions were tested here, and that pitfall traps generally are not used to assess lesser grain borer abundance. Nevertheless, for lesser grain borer walking in and around food facilities, beetles may be diverted to a pitfall trap in the immediate area of activity when baited with pheromones and kairomones.

Technical Abstract: Rhyzopertha dominica male adults produce an aggregation pheromone that attracts both sexes. While many studies have tested the behavioral response of R. dominica to its pheromone, an understanding of the distance of attraction, and effective pheromone concentration by R. dominica adults to baited traps has been lacking. Therefore, the objectives of this study were to determine the recapture rate of R. dominica adults released at different distances from a pheromone-baited and pheromone + kairomone-baited trap, as well as the most effective pheromone concentration for R. dominica. Experiments were arranged as complete randomized design with four replicates. A commercial pitfall trap containing R. dominica pheromone alone or pheromone + kairomone was placed inside an experimental arena. Adult R. dominica were released at different distances from a trap and the adults captured were counted. A separate experiment was conducted using pitfall traps containing different concentrations of the aggregation pheromone in an experimental arena. Adult R. dominica were released 60 cm away from the pitfall trap and the recaptured adults were recorded. The trapping efficiency was higher when the trap contained both the pheromone and kairomone than the pheromone alone. Trap capture was highest when the beetles were released at distances up to 70 cm and at a concentration of 100 µL/ m2. Our findings suggest that food facility managers should take into account the effective pheromone concentration and distance of attraction, while also strongly consider including food kairomones in traps when developing monitoring programs for R. dominica.