Evaluation of pesticide pollution in rivers using the susceptibility to fenitrothion in Cheumatopsyche species (Trichoptera: Hydropsychidae)
Research Bulletin of the Aichi ken Agricultural Research Center 33: 219-227
An experiment was conducted in Aichi Prefecture, Japan to determine the susceptibility of Cheumatopsyche brevilineata and C. infascia to fenitrothion. Pesticide concentrations, water temperatures, EC values and benthic insects were also studied. LC50s of fenitrothion for C. brevilineata were 1.32, 0.556 and 0.275 mg/litre for heavily polluted, less polluted and unpolluted river, respectively. LC50s of fenitrothion for C. infascia were 1.56 and 0.15 mg/litre for heavily contaminated and less contaminated rivers, respectively. The concentrations of organophosphorus insecticides were proportional to the concentrations and frequencies of the other pesticides detected in the river. There was no evidence that water temperatures and EC values directly limited the distributions of C. brevilineata and C. infascia. Both benthic abundance and diversity were low in rivers where C. brevilineata was dominant, and rivers where C. infascia was dominant had low EC values and probably riverbeds of rocks with pebbles and gravels. The results suggest that susceptibility to fenitrothion in Cheumatopsyche species is not affected by habitat related physiological or chemical factors but is closely correlated to ambient pesticide concentrations.