Effects of Wind Speed on Aerosol Spray Penetration in Adult Mosquito Bioassay Cages
NAVY ENTOMOLOGY CENTER OF EXCELLENCE JACKSONVILLE FL
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Bioassay cages are commonly used to assess efficacy of insecticides against adult mosquitoes in the field. To correlate adult mortality readings to insecticidal efficacy andor spray application parameters properly, it is important to know how the cage used in the bioassay interacts with the spray cloud containing the applied insecticide. This study compared the size of droplets, wind speed, and amount of spray material penetrating cages and outside of cages in a wind tunnel at different wind speeds. Two bioassay cages, Center for Medical, Agricultural and Veterinary Entomology CMAVE and Circle, were evaluated. The screen materials used on these cages reduced the size of droplets, wind speed, and amount of spray material inside the cages as compared to the spray cloud and wind velocity outside of the cages. When the wind speed in the dispersion tunnel was set at 0.6 msec 1.3 mph, the mean wind speed inside of the CMAVE Bioassay Cage and Circle Cage was 0.045 msec 0.10 mph and 0.075 msec 0.17 mph, respectively. At air velocities of 2.2 msec 4.9 mph in the dispersion tunnel, the mean wind speed inside of the CMAVE Bioassay Cage and Circle Cage was 0.83 msec 1.86 mph and 0.71 msec 1.59 mph, respectively. Consequently, there was a consistent 50-70 reduction of spray material penetrating the cages compared to the spray cloud that approached the cages. These results provide a better understanding of the impact of wind speed, cage design, and construction on ultra-low-volume spray droplets.