A control trial of the vector of onchocerciasis, Simulium ochraceum (Diptera : Simuliidae) in the Lavaderos River Valley, Guatemala

Abstract

The field trial of larviciding Simulium ochraceum was carried out during the period from March to May 1979,in the Lavaderos River Valley, Municipality of San Vicente Pacaya, Department of Escuintla, Guatemala. A 10% temephos solid formulation was applied at a rate of 1 ppm for 60 in with a 14 day cycle. In the 57 sites for application, a total of 245g of solid larvicide had been applied. The larval density of the blackfly decreased rapidly in many larvicided tributaries of the River. After a few times of application the density of adult females captured with a human bait for 3 hr trended to decrease until the minimum of 6 flies in comparison with the ranging from 20 to 500 at the pre-application. The result of the present trial reveals the feasibility of the solid formulation of temephos against S. ochraceum in the field if the preapplication survey on the breeding streams of the target species are thoroughly made.