Study of Pesticide Residue

Aerial application of insecticide is one of the most commonly used methods of mosquito control in Florida. During application, insecticide can drift into estuarine habitats and cause mortality of nontarget organisms. Florida A&M University is testing a new nozzle for aerial application of pesticide to kill mosquitos. The new nozzle sprays a finer mist that eliminates most ground deposition. A study has been initiated to determine the resulting pesticide residue that accumulates in water, on vegetation and in the aerial spray zone with both conventional and the experimental nozzles.

This technology is currently being tested to ensure the efficiency of reducing mosquito populations with minimal nontarget mortality. Fiddler crabs are used as a bio-indicator of the toxicology of the pesticide.


Experimental Spray Nozzle Systems

Studies undertaken in cooperation with Collier County Mosquito Control utilize both the conventional and experimental spray nozzle systems. Fiddler crabs are exposed to varying concentrations of the pesticide while placed in different target areas, and are monitored for mortality at different time intervals. Deposition amounts are estimated using filter paper to intercept pesticide droplets.

Findings to date:

The experimental nozzle eliminates the high concentration of pesticide which resulted in 100% mortality of exposed fiddler crabs using conventional methods. The spray now remains airborne longer, killing more mosquitoes. The finer spray also diminishes the amount of pesticide that eventually reaches the ground. The small amount of pesticide that settles on the ground is not lethal to fiddler crabs. Results are still being analyzed and spray tests will continue to be run. This study will address public concerns regarding pesticide drift and analyze its ecological impact. Mosquito control districts across the state will be able to incorporate results into their spray methods and policies to effectively reduce impact on wildlife.