Apiwat Tawatsin
Usavadee Thavara
Prakong Phan-Urai

Affiliations :
      National Institute of Health. Department of Medical Sciences Ministy of Public Health

Abstract
      Mosquito control strategies in the former time was focused on chemical insecticides which caused not only acute or chronic toxicity to human beings but also polluted the environment. On account of the attempt by several scientists, many other strategies were introduced to replace chemical use and one of these strategies was physical control. Laboratory study of insecticide effect of the Oil Surfactant, the water insoluble surfactant that has physical mechanism, was carried out in both larvae and pupae of the three mosquito species. Aedes aegypti, Culex quinquefasciatus   and Anopheles dirus.   The results revealed that mosquito pupae are more affected by the Oil Surfactant than larvae and An. dirus   was most affected, Ae.aegypti  next and Cx. quinquefasciatus  the least. Moreover, the appropriate amount of the Oil Surfactant for the control of An. dirus  was two ul. per 50 cm² of the surface area (this was equivalent to four litres per hectare) , while the appropriate amount for Ae. aegypi   and Cx. quinquefasciatus  was five ul per 50 cm² of the surface area (this was equivalent to ten litres per hectare). However the results of the Oil Surfactant from this study are preliminary data to be considered as an alternative insecticide instead of chemical insecticides, further studies of effectiveness in field mosquito-control and environmental impact are necessary.