A review of ultralow-volume aerial sprays of insecticide for mosquito control.

This review of research on ultralow-volume (ULV) aerial sprays for mosquito control is a component of an Aerial SPray EXpert system (ASPEX). Topics include application volume, adulticiding, larviciding, droplet size, and meteorology. The review discusses the efficacy of ULV aerial sprays against many important pest and vector species of mosquitoes in a wide range of locations and habitats in the USA and in some countries of Asia, Africa, and the Americas. Nine conclusions were drawn from this review. 1) ULV applications are as effective for mosquito control as highly-diluted, water-based sprays. 2) More acres can be sprayed per aircraft load with the ULV method than with dilute sprays. 3) High-altitude ULV sprays using wide or stacked swaths could be used in emergencies if wind speed and direction data at appropriate altitudes are available to accurately place the spray. 4) Successful adult mosquito control can be achieved in dense foliage or open housing with ULV aerial sprays, but doses of insecticide must be increased. 5) ULV aerial application of mosquito larvicides can be used successfully in large areas. 6) The optimum droplet size for adult mosquito control is 5-25 microns volume median diameter (VMD). 7) For mosquito adulticiding, near optimum atomization of ULV sprays is achieved with flat-fan nozzles oriented straight down or slightly forward for high-speed aircraft (> or = 150 mph) or rotary atomizers on slow-speed aircraft (< 150 mph). 8) Optimum atomization minimizes paint spotting. 9) Maximum adult mosquito control is achieved just after sunrise and just before sunset with 2-10-mph crosswinds.