EFFICACY OF AN ESSENTIAL-OIL ADULTICIDE FORMULATION, BIGSHOT MAXIM CONCENTRATE, AGAINST RESISTANT AND SUSCEPTIBLE STRAINS OF AEDES AEGYPTI IN A WIND TUNNEL

An essential-oil adulticide formulation. BigShot Maxim Concentrate (14% cedarwood oil, 0.53% thyme oil, and 0.25% cinnamon oil), was evaluated using a wind tunnel against pyrethroid resistant (Puerto Rico, PR) and pyrethroid susceptible (Orlando, ORL) colony-reared strains of Aedes aegypti to determine whether the product could be used in operational mosquito control to supplement dwindling efficacy of pyrethroid formulations. The product was sprayed at 0.5x (146 mL/ha), 1.0x (291 mL/ha), and 2.5x (731 mL/ha) the maximum application rate through a ULV nozzle. After application, mortality was checked at 1 and 24 h. The 24 h mortality for the ORL strain was 85.9% ±5.0, 98.7% ±1.3, and 99.2% ±0.8 at the three application rates, respectively. In contrast, mortality at 24 h post exposure for the PR resistant strain was significantly lower, 26.4% ±6.5, 35.2% ±8.0, and 45.1% ±8.0, at the three application rates, respectively. Results suggest that the essential-oil formulation could be moderately effective against a resistant strain of Ae. aegypti if applied at very high rates and would likely need to be reapplied frequently, and target populations monitored for evolution of resistance to cedarwood and other essential oils.