Ovicidal activity of an insect growth disruptor (methoxyfenozide) against Culex pipiens L. and delayed effect on development

Abstract

Current researches for mosquito control have focused on insect specific insecticides without environmental concerns. The present study was conducted to evaluate the Ovicidal activity of an ecdysone agonist (methoxyfenozide) on Culex pipiens L. (Culicidae: Diptera) under laboratory conditions using standard WHO protocol. Lethal concentrations (LC50= 24.54 µg/L and LC90= 70.79 µg/L) previously determined were tested against freshly laid eggs. The egg viability was examined and the deferred effects of treatment were also investigated on the development duration and the sex ratio. Data obtained show that egg hatching inhibition was dose dependent, with a reduction of 13.44% and 46.99% with LC50 and LC90, respectively. In treated groups, the total development duration was significantly longer as compared to controls. The adult sex - ratio was significantly skewed in favor of males emerged from treated eggs with LC50 and LC90 of methoxyfenozide. Moreover, changes in the egg shell morphology and abnormal egg hatching pattern were observed. Morphologic abnormalities in larva were also recorded. Data from the current investigation clearly demonstrated that methoxyfenozide possess remarkable larvicidal and ovicidal activities against a medically important vector as ideal eco-friendly approach for mosquito’s control.