Aerosol dispersal patterns and resulting effects on Tribolium confusum (Coleoptera: Tenebrionidae) adults

Authors: Scheff, Deanna; Campbell, James - Jim; Arthur, Franklin

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2018
Publication Date: 9/26/2018
Citation: Scheff, D.S., Campbell, J.F., Arthur, F.H. 2018. Aerosol dispersal patterns and resulting effects on Tribolium confusum (Coleoptera: Tenebrionidae) adults. Journal of Economic Entomology. 111(5):2435-2442. doi: 10.1093/jee/toy166.
DOI: https://doi.org/10.1093/jee/toy166

Interpretive Summary: Aerosol applications of insecticides as part of integrated pest management programs is becoming more widely adopted in food facilities such as flour mills. However, the method of application and the complex structural features within a facility can impact how insecticide particles travel and settle on surfaces and therefore impact the variation in efficacy obtained. By releasing aerosol insecticide from different locations within a flour mill or by splitting the release among all the locations, we demonstrated that application method significantly impacted the pattern of insect mortality obtained. Using confused flour beetle, as a model stored-product insect pest in bioassay dishes placed throughout the mill, we found that the percent of insects affected by the insecticide at locations ranged from 0 to 100% regardless of application type. Applying the aerosol split among three different locations, provided more consistent coverage compared to applying all the aerosol from one of the three positions. However, regardless of the treatment location there were still areas of a mill where little efficacy was observed, so further improvement in application methods is needed. The effectiveness of an aerosol application is a culmination of the how the aerosol was applied, distance the aerosol particles traveled, and the complexity of the environment inside the milling facility which impacts how particles move. A better understanding of the impact of these factors will improve the effectiveness of aerosols in integrated pest management programs.

Technical Abstract: Aerosol application of insecticides as part of an integrated pest management programs is becoming more widely adopted in food facilities such as flour mills. However, the method of application and the complex structural features within a facility can impact how insecticide particles travel and settle on surfaces and therefore impact the consistency in efficacy obtained. Here we investigated how the location from which an aerosol insecticide is released impacts the spatial pattern of aerosol deposition, using efficacy against Tribolium confusum Jacquelin du Val, the confused flour beetle, as model insects. Concrete bioassay arenas containing T. confusum adults and flour were exposed to two commercial aerosol formulations, pyrethrin + pyriproxyfen and pyrethrin + methoprene, and observed for initial adult knockdown and subsequent mortality. Aerosols were applied from one of three static locations or a fourth application comprised of multiple aerosol release points. Aerosol release position had a significant effect on T. confusum adult knockdown and mortality; both ranged from 0-100% depending on bioassay arena location. The multiple aerosol release positions tended to have more bioassay arenas with higher knockdown and mortality, and had a more consistent impact across all arena locations yet there were still areas on the mill floor where little adult beetle efficacy was observed. The effect of each aerosol on T. confusum adults is a culmination of the how the aerosol was applied, distance the aerosol particles traveled, and the complexity of a milling facilities.