Aerosol applications as a Methyl Bromide Alternative for Milling, Processing, and Food Storage

Non-Technical Summary: The Methyl Bromide Technical Options Committee (MBTOC) has identified aerosols as a methyl bromide alternative for the milling, processing, and food storage industries. However, there are few published reports on aerosol treatments regarding field efficacy, distribution patterns of aerosols, level of residual persistence, impact on resident insect populations, or economic value of these treatments in commercial establishments. This project is to use a multi-disciplinary approach to evaluate aerosols as an alternative to methyl bromide in commercial flour mills, processing plants, and food storage facilities. We will conduct a series of tests in commercial sites to evaluate the spatial distribution and efficacy of different aerosol formulations and application methods. In addition, we will determine impact of food barriers on egg hatch and larval development of eggs exposed to aerosols. We will estimate residual efficacy and quantify residue degradation on different structural surfaces, on packaging materials and finished products. We will assess the prevalence of insects in commercial sites and determine impact of aerosol applications on pest populations. Finally, an extensive economic analysis will be conducted to evaluate the potential of aerosols as methyl bromide alternatives, identify points for control, and model the effects of control strategies. During our study, and at the conclusion, we will share our results and transfer the technology to commercial flour millers and food processors, through written and oral communication. <P> Approach: 1) Aerosol dispersion, insecticidal efficacy, and impact of sanitation on efficacy of different aerosol formulations of synergized pyrethrins and methoprene on the red flour beetle, confused flour beetle, and Indianmeal moth will be assessed in the community food bank and a flour mill in Kansas. After Petri dishes containing eggs, pupae, and larvae of each pest species are exposed to the aerosol of each insecticide, they will be collected the day after treatment for various assessments. 2) The impact of food barriers on egg hatch and larval development of eggs exposed to aerosols will be determined using different amounts of a food barrier. Red flour beetle and Indianmeal moth eggs will be placed at the center of the bottom of a dish, and covered with a "dusting" of various amounts of flour. Mortality will be assessed by contour mapping, with open versus hidden areas and the amount of food barrier as our treatment variables. 3) Residual efficacy of pyrethrin and methoprene aerosols and residue degradation on different surfaces and on exposed packaging and finished packaged products will be assessed. Both pyrethrin and methoprene residues will be extracted form concrete surfaces, bagged commodity surfaces, and in the flour samples following the application of the aerosols. Pyrethrin residues will be analyzed using gas chromatography (GC) whereas methoprene residues will be analyzed using high performance liquid chromatograph (HPLC). 4) The prevalence of insects in commercial sites will be assessed and impact of aerosol applications on pest populations will be monitored in six different commercial facilities. Insects inside structures will be monitored using Dome and Pherocon II pheromone traps. Trap captures before and after treatment will be compared as well as the longer term trends in the different sites. Population trends inside and outside the facility will also be compared to evaluate effectiveness of aerosol applications. 5) A modified Target MOTAD model will be used to analyze net economic returns of aerosols as alternatives. The tradeoff between costs of aerosol treatments relative to the cost of methyl bromide fumigation, and total deviations below a target mortality rate of 95% will be examined. A separate cost model will be developed for each aerosol and compared to the cost of methyl bromide fumigation. The optimal mix of treatments, cost, and total deviations below the target mortality rate will also be compared across control strategies. The investment cost associated with installing the application system will be annualized using a long-term interest rate. 6) Technology to commercial flour millers and food processors will be transferred through presentations and dissemination of results. Oral and written presentations will be given at various meetings (e.g., methyl bromide alternatives and emission reductions, the harvesters food bank). Short summaries of our findings will be published in industry trade journals in addition to publications in peer-reviewed scientific journals. Research presentations will also be given at industry training sessions and at the national workshop on stored product insect control in 2007.