Laboratory evaluation of two organophosphate and one pyrethroid insecticide against the Culex quinquefasciatus (Say) (Diptera: Culicidae) mosquito larvae

Abstract

Two organophosphate (OP) insecticides (Chlorpyrifos and Fenitrothion) and one synthetic pyrethroid insecticide (Deltamethrin) were evaluated against 4th instar larvae of Culex quinquefasciatus (Diptera: Culicidae) under laboratory condition. The larvae were collected from nearby area of Bangladesh Agricultural University, Mymensingh 2202 campus and reared at the Insect Biotechnology and Biopesticide Laboratory of Department of Entomology. For bioassay, five concentrations (viz. 10, 30, 50, 70 and 90ppm) of each of the insecticide were prepared. Ten actively swimming 4th instar larvae of C. quinquefasciatus were added into respective concentration. Mortality was recorded and the LC50 and LC90 values were determined by probit analysis. The LC50 values for Fenitrothion, Deltramethrin Chlorpyrifos, and were found to be 8.88, 26.73 and 71.14ppm, respectively. Thus, the Fenitrothion exhibited comparatively higher toxicity about 3 and 8 times more toxic compared to deltamthrin and chlorpyrifos. The order of the tested insecticides was found to be Fenitrothion > Deltamethrin > Chlorpyrifos. The LC90 values were also followed similar trend. Hence, the Fenitrothion and Deltamethrin could be suggested for Culex mosquito larvae management.