SENSITIVITY OF ODONATE NYMPHS TO DIFFERENT CLASSES OF AGRICULTURAL INSECTICIDES, FREQUENTLY APPLIED IN SWAT VALLEY PAKISTAN

The sensitivity of blue-tailed damselfly (Ischnura elegans) and crimson marsh glider dragonfly (Trithemis aurora)nymphs to six different insecticides were studied during 48-hour exposure in the laboratory conditions. Lambda cyhalthrin was found to be the most toxic. Chlorpyrifos was found least toxic. The highest concentrations of deltamethrin, cypermethrin, lambdacyhalothrin, chlorpyrifos, dichlorvos and acetamiprid that caused no mortality of I. elegans were 0.0078, 0.0039, 0.00048, 0.0078, 0.0039 and 0.00195 ppm, respectively. The highest concentrations of deltamethrin, cypermethrin, lambdacyhalothrin, chlorpyrifos, dichlorvos and acetamiprid that caused no mortality of T. aurora were 0.0039, 0.00195, 0.00048, 0.0156, 0.0078 and 0.000975 ppm, respectively. The lowest concentrations of deltamethrin, cypermethrin, lambdacyhalothrin, chlorpyrifos, dichlorvos and acetamiprid that caused 100% mortality of. elegans were 0.5, 0.5, 0.0156, 1.0, 0.5 and 0.25 ppm, respectively. The lowest concentrations of deltamethrin, cypermethrin, lambdacyhalothrin, chlorpyrifos, dichlorvos and acetamiprid that caused 100% mortality of T aurorawere 0.25, 0.25, 0.0312, 2, 1 and 0.125 ppm, respectively. Significantly (P<0.05) lowest LC90 values were observed for lambda cyhalothrin (LC90 against I elegans=0.01 ppm, LC90 against T aurora=0.018 ppm). Next to the lambda cyhalothrin, significantly (P<0.05) lowest LC90 values were observed for acetamiprid (LC90 against I. elegans=0.122 ppm, LC90 against T aurora=0.093 ppm). From the findings of the present study, it was concluded that I. elegans and T auroranymphs are highly sensitive to lambda cyhalothrin and acetamiprid.