Aerosol Dispersal Patterns and Resulting Effects on Tribolium confusum (Coleoptera: Tenebrionidae) Adults

Aerosol application of insecticides as part of an integrated pest management program 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 (Coleoptera:Tenebrionidae), the confused flour beetle, as a 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.The aerosol release position had a significant effect on T. confusum adult knockdown and mortality; both ranged from 0 to 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 how the aerosol was applied, the distance the aerosol particles traveled, and the complexity of a milling facility.