A small scale field trial with Temephos (Abate) for the control of four species of Mansonia (Mansonioides) (Diptera: Culicidae) in Thailand.

A 60-week control experiment with Temephos (Abate) against a largely isolated population of Mansonia annulata, Ma. annulifera, Ma. indiana and Ma. uniformis was carried out in a pool of 1.2 ha area and average depth of over 2 m in southern Thailand. Floating paper tea bags containing 24 g of 1% Abate sand granules were applied in two rounds at a density of 1 bag 4 m-2. Each round consisted of five applications at intervals of 13 days. During the application rounds mosquito larvae disappeared completely from the pool. This apparent effect of Abate was confirmed by bioassays made with pool water and larvae of Culex quinquefasciatus. Inactivation of Abate was linear during one week, with a slope of 5.8% per day. Adult densities dropped during the application rounds and, over a period of 48 weeks, were 78-85% less than during the corresponding time of the preceding reference year. The annual pattern of adult abundance that normally shows distinct seasonal peaks was strongly altered, although meterological data were comparable to the reference year.