The effectiveness of ultra-low-volume applications of malathion at a rate of 3 US fluid ounces per acre in controlling Aedes aegypti in Thailand.

Ultra-low-volume (ULV) aerial applications of malathion at a rate of 3 US fl oz per acre (219 ml/ha) for the control of Aedes aegypti and Culex pipiens fatigans were evaluated in 2 areas near Bangkok, Thailand. A housing project of the Royal Thai Air Force received 2 applications a week apart while the village of Bang Khen received 1 application. Bioassays, oil-sensitive red dye cards, landing-rate counts, ovitraps, and light-traps were used to evaluate the effects of the treatment. A comparison of pre- and post-treatment indices indicated good control of A. aegypti following all treatments. The results of these tests when compared with those of an earlier study using 6 US fl oz/acre (438 ml/ha) showed that the higher rate of application rate was more effective. Only fair control of C. p. fatigans was obtained. A comparison of light-trap collections before and after treatment demonstrated fairly good over-all control of other species of mosquitos for 3-4 days following each of the 2 treatments on the Air Force housing area.