The Impact of Sequential Ultra-Low Volume Ground Aerosol Applications of Malathion on the Population Dynamics of Aedes aegypti (L.)

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  • * Insects Affecting Man and Animals Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, P.O. Box 14565, Gainesville, Florida 32604
  • Florida Medical Entomology Laboratory, Institute of Food and Agricultural Sciences, University of Florida, 200 Ninth Street S.E., Vero Beach, Florida 32962
  • New Orleans Mosquito Control Board, 6601 Lakeshore Drive, New Orleans, Louisiana 70126

The efficacy of sequential, ultra-low volume ground aerosol applications of malathion at current U.S. label rates was evaluated as an emergency control measure for adult populations of Aedes aegypti (L.) in New Orleans, Louisiana. Replicates of 11 sequential aerosol treatments applied 12 hr apart during a 5.5-day period reduced mean adult captures and oviposition rates during the treatment period 73% and 75%, respectively. We hypothesize that oviposition was not completely suppressed because females with a developing egg burden remained sequestered during treatment periods or were more tolerant to the pesticide. We further concluded that adults could not be totally suppressed because of continued emergence. After treatment, adult densities recovered to pretreatment and control levels within approximately 1 week. A simulation study of the results suggested that, under the conditions of closely spaced housing and abundant vegetation that is typical of much of New Orleans, a single aerosol killed an average of 88% of the males and only 30% of the females present.