Case study: A practical application of an aerosol treatment in commercial mill

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

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2019
Publication Date: 5/25/2019
Citation: Scheff, D.S., Brabec, D.L., Campbell, J.F., Arthur, F.H. 2019. Case study: A practical application of an aerosol treatment in commercial mill. Insects. 10(5):E150. https://doi.org/10.3390/insects10050150.
DOI: https://doi.org/10.3390/insects10050150

Interpretive Summary: Across the pest management industry there are various ways to treat large commercial facilities to control for stored product insects. One method that has seen increasing use is aerosol insecticides. Aerosol insecticides are insecticides are applied throughout a voluminous space at particle sizes under 50 µm, and can be effective across multiple insect species at life stages. The current study looked at an aerosol application in a commercial rice mill using insect bioassays to determine initial and residuals effects, and used aerodynamic particle sizer (APS) instruments to measure particle sizes and calculate particle deposition. Adult confused flour beetles, Tribolium confusum Jaquelin du Val, exposed during the actual application had high percentages of affected adults (>60%) nearest to the application point. APS data also showed higher particle deposition at locations closest to the aerosol application point. The aerosol also had vertical movement when released at the top of a three-story open room; instantaneous concentrations was recorded on the ground floor. The aerosol insecticide was also effective up to 6 weeks post-treatment, whereby 80% of bioassays, out of 20 different locations throughout the mill, did not have any adult emergence when larvae were exposed to treated surfaces. This research is the first of its kind to illustrate an aerosol application inside a commercial rice mill and demonstrates the effectiveness of this pest management strategy.

Technical Abstract: In recent years, there is an increasing interest and need for alternatives to structural fumigations, and one alternative that has been used across the industry is aerosol insecticides. Previous tests inside a pilot-scale mill demonstrated that aerosol particle size, delivery method, and spatial configuration of the mill, all influenced the effectiveness. However, there is no research conducted inside large commercial facilities. The objective of this research was to evaluate a pyrethrin-plus-methoprene aerosol application inside a commercial mill on adult Tribolium confusum Jacquelin duVal, confused flour beetle, directly exposed to the aerosol and residual effects on larvae. Additionally, five Aerodynamic Particle Sizers were placed in the facility and recorded instantaneous spray concentration and estimated aerosol deposition. Adult T. confusum exposed nearest to the aerosol application points had the high percentages of affected adults (>60%). The aerosol also had vertical movement when released at the top of a three-story open room; instantaneous concentrations was recorded on the ground floor. The aerosol residual was highly effective after 6-weeks post aerosol exposure, whereby 80% of the bioassays did not have any adult emergence. This research demonstrates a practical use of aerosol insecticides and their potential to be an effective alternative to structural fumigations.