Model development for predicting the movement and concentrations of ultra-low-volume insecticides used for adult mosquito management

One of the more effective ways of managing insect vectors of human pathogens is the use of ultra-low-volume (ULV) insecticides. Little is known about the fate of insecticides applied by ULV techniques, and no model currently exists that can accurately estimate environmental concentrations. Current models are either over- or under-estimating environmental concentrations of ULV insecticides, which lead to uncertain exposures and thus risk. Therefore, I developed a predictive statistical model based on field experiments in Montana, California, North Dakota, and Louisiana for ULV insecticides used for adult mosquito management. For model development and validation, I measured environmental and physicochemical variables of various insecticide formulations. My results demonstrate that air temperature, wind speed, distance from the spray source, atmospheric stability, density of the formulation, and formulation type (water- or oil-based) influence the movement and deposition of ULV insecticides. Water-based formulation had greater deposition 100 m from the spray source, but oil-based formulations had greater disposition beyond 100 m. Density of the formulation had the largest impact on the model output because of its effect on the settling velocity of the droplets. Results also show that the human-health risks calculated by past studies seem to be sufficiently conservation.