Affiliations :
      ^a National Institute of Health, Department of Medical Sciences, Ministry of Public Health 88/7 Tiwanon Rd., Nonthaburi 11000, Thailand
      ^b Department of Entomology, University of California, Riverside, California 92521, USA

Source:
      Journal of the American Mosquito Control Association: Vol. 20, No.2, pp. 176-182.

Language :
      English

Abstract :
       Field trials on the initial and long-term efficacy of a new formulation of temephos granules (1% on zeolite) applied at 1 ppm active ingredient (AI) were conducted in water-storage containers against Aedes aegypti  in 3 villages in the Kanchanaburi Province in Thailand. A total of 316 water -storage containers of various types and sizes were included in the study. In the initial survey, we found that some containers were positive for larval Ae. aegypti , whereas others were devoid of larvae before the initiation of treatments. The containers all were numbered with paint and divided into 4 groups: with larvae and treated, without larvae and treated, with larvae untreated, and without larvae and untreated. Assessment of larval abundance was made 48 h after treatment and monthly thereafter for 5 months. Containers with larvae and that were treated exhibited almost complete absence of larval Ae. aegypti  for 2 months, but a small proportion became positive after 3 months. Most of these positive containers were devoid of zeolite granules, which are visible in the containers. The number of positive containers increased in months 4 and 5, despite the fact that residues of temephos granules were present in some of the larvae-positive containers. The containers initially without larvae and treated with temephos essentially were devoid of larvae for 2 months. After 3,4, and 5 months, about 6-23% of the containers became positive despite the fact that some had visible amounts of temephos granules. In the 2 control groups initially with and without larvae, sustained and consistent production of larvae occurred. Even in the group initially without a larval population, the containers became positive for larvae 1 month after the start of the experiment and the positivity rate increased as the trial progressed. From these studies, the conclusion can be made that a single application of temephos zeolite granules at 1 ppm AI can provide highly satisfactory control of larval Ae. aegypti  in water-storage containers for at least 3 months in the field under normal water-use practices.

Keywords: Aedes aegypti , mosquito control, village trials, temephos, zeolite granules.