Economic analysis for commingling effects of insect activity in the elevator boot area

Authors: Tilley, Dennis; Casada, Mark; LANGEMEIER, MICHAEL - Purdue University; SUBRAMANYAM, BHADRIRAJU - Kansas State University; Arthur, Franklin

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2015
Publication Date: 12/15/2015
Publication URL: http://handle.nal.usda.gov/10113/62728
Citation: Tilley, D.R., Casada, M.E., Langemeier, M.R., Subramanyam, B., Arthur, F.H. 2015. Economic analysis for commingling effects of insect activity in the elevator boot area. Journal of Economic Entomology. 108(6): 2800-2807. doi: 10.1093/jee/tov222.

Interpretive Summary: The boot and pit areas of commercial grain elevators and feed mills contribute to mixing and movement of insects with grain that moves through the elevator leg, reducing grain quality and causing higher costs and risks to facilities. We developed an economic model to improve pest management decision-making and risk analysis assessment from commingling of insects with grain in the boot area. Modified pilot-scale bucket elevator legs were used to facilitate residual grain removal and preservation in the boot in experiments. These experiments quantified the amount of commingling as a function of insect density, with grain discounts applied to grain samples obtained from clean grain transfers over boots that were insect-free, untreated infested, and chemical-treated infested boots. Economic modeling indicated that boot sanitation (cleanout) about every 30 days would avoid costly grain discounts from insect commingling and is the preferred operator choice. Chemical spray treatments of the empty boot also reduced insect populations in some tests. However, in our results boot cleanout always had lower insect pest populations than the chemical treatments and usually zero insect pest populations in the boot residual grain. Thus, the regular boot cleanout was preferred because it provided higher facility operational net income, reducing costs by avoiding grain discounts without the use of chemicals.

Technical Abstract: Boot areas in commercial grain elevators and feed mills contribute to commingling of insects with grain that moves through the elevator leg. A partial budget and stochastic dominance model was developed to improve pest management decision-making and risk analysis assessment from commingling effects of insect activity in the boot area. Modified pilot-scale bucket elevator legs, containing residual wheat or corn, were infested with varying insect pest densities prior to clean grain transfers. Appropriate grain discounts were applied to grain samples obtained from clean grain transfers over either: (1) insect-free and untreated boots, (2) infested and untreated boots, or (3) infested and chemical-treated ('-cyfluthrin) boots. The insect-free boots simulated performing clean-out of the boot area. Partial budget analysis and stochastic dominance modeling indicated that boot sanitation (cleanout) about every 30 days, avoiding costly grain discounts from insect commingling, is the preferred choice. Although chemical spray treatments of the empty boot may reduce insect populations of some boot residual grains, boot cleanout always had lower and usually zero insect pest populations in the boot residual grain, providing higher facility operational net income without the use of chemicals.