Field experiment on susceptibility of macrobenthos in streams to temephos

Abstract

Emulsifiable temephos was applied to two small streams from 1ppm to 20ppm stepwise and drifting macrobenthos were trapped with a net 10m below the application point. Number of species of drifting macrobenthos increased with the sequential application of gradually increasing concentration of temephos, whereas number of drifting individuals of each species showed respective peak at certain concentration of temephos. Simulium larvae were among susceptible species together with four other species, Baetis sp., Isoperla sp., Dolophilodes sp. and Anisogammarus sp. Other approximately 20 species began to drift with 5ppm but 10ppm was necessary to flush out most individuals.