The USDA Forest Service pesticide spray behavior and application development program--an overview

The USDA Forest Service, even though a minor user of pesticides, has maintained an active program for understanding the performance, atomization, evaporation, efficacy, environmental fate, atmospheric dispersion, and environmental impact of chemical and biological insecticides. Since its self-imposed ban on use of dichloro diphenyl trichloroethane (DDT) in 1964, the USDA Forest Service has pursued insecticides that are less persistent and have reduced potential for impact on nontarget organisms, application technology that supports their efficient and efficacious use, and computer models that predict insecticide fate in the environment. This program has been active over the last 3 decades, beginning with research for chemical insecticide substitutes for DDT, progressing in time to biological insecticides and other biorational control agents. In our effort to make the less persistent insecticides work under forestry conditions, it was necessary to investigate insecticide monitoring, detection, and sampling methods; application systems; atmospheric influences; tank mixes and adjuvants; nozzles and atomization; evaporation; spray deposition and canopy penetration; biological response; and environmental fate. This paper reviews some of this work that might be applicable to mosquito control.