Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 22, 2006
Publication Date: April 1, 2007
Citation: Tilley, D.R., Langemeier, M.R., Casada, M., Arthur, F.H. 2007. Cost and risk analysis of heat and chemical treatments. Journal of Economic Entomology. Vol. 100(2):604-612. Interpretive Summary: Our previous research has shown that heat treatments are effective as a non-chemical method for disinfestation of empty grain storage bins. We developed an empirical economic risk model to compare variable costs for five tested heating systems for disinfestation of empty, 5000 bu grain storage bins with fitted drying floors. The high-output, 29 kW, propane heating system had the lowest cost and risk level of all heating systems and achieved the target temperature of 50 C within 2 hours at all test locations. Lower power systems requiring complex heat distribution or recirculation were not cost effective and exhibited higher risk levels of insect survival. These results indicate that properly-sized portable propane heat treatment systems are equal to chemical applications for low-cost, low-risk disinfestation of empty bins, but without the concerns that arise with using chemicals.
Technical Abstract: An economic evaluation of newly developed methods for disinfesting empty grain storage bins by heat treatment will be a useful tool for decision-making by grain storage managers. The economic empirical model of heat treatment and chemical applications that was developed to evaluate these heat treatments minimized costs at a target risk level associated with the grain-damaging insects Tribolium castaneum (Herbst), Sitophilus oryzae (L.), and Rhyzopertha dominica (F.). Risk was measured as a deviation below a target mortality goal. Insect mortality and air temperature during heat treatment were evaluated for empty storage bins with a full drying floor, along with a similar evaluation of insect mortality for chemical application of cyfluthrin 20% WP. A high-output propane heater (29 kW) had the lowest cost and risk level of all heating systems and produced 100% mortality in 2 h for the three insect species at all test locations. An electric duct-heater system (18 kW) also produced 100% mortality at all test locations after 40 h, but had significantly higher costs. Other heating system configurations had significantly higher risk levels of insect mortality and the electric systems were not cost effective. Both chemical rates had low costs and risk levels, with high mortality results.