Research Contributing to Improvements in Controlling Florida’s Mosquitoes and Mosquito-Borne Diseases
- Walter J. Tabachnick
Field experiments with the mosquito adulticide fenthion (Baytex) compared the conventional flat-fan nozzle system (Tee Jet 8002SS) and a new high-pressure hollow-cone nozzle system (1/8 MISS). Ground deposition and aerial flux of the mosquito adulticide fenthion were measured up to 4.83 km downwind by using filter paper and yarn collectors, respectively. Biological efficacy was investigated by using caged salt-marsh mosquitoes (Ochlerotatus taeniorhynchus), and caged fiddler crabs (Uca pugilator) were exposed to quantify nontarget impact. Peak deposits to the ground were 1,729 microg/m2 and 240 microg/m2 for the flat-fan nozzles and high-pressure cones, respectively. Deposits from the flat-fan nozzles resulted in a cumulative fiddler crab mortality of 80%, whereas no deaths were recorded with the high-pressure system. The range of fenthion flux detected in the air when using the yarn collectors was similar for the 2 systems, with both showing drift through 4.83 km. For the flat-fan spray nozzle system, the aerosol flux ranged from 3.02 to 67.33 microg/yarn collector. The range of aerosol flux for the high-pressure nozzle spray system was 0.15-50.66 microg/yarn collector. Although the 2 systems produced comparable ranges of flux, the high-pressure system provided higher control efficacy against mosquitoes. Maximum mosquito control when using the flat-fan spray nozzle system against female salt-marsh mosquitoes was 26.6%, whereas maximum control with the high-pressure spray system was 92.9%.