Bio-toxicity of Different Insecticides in Culex quinquefasciatus Larvae in Lahore Punjab, Pakistan

Purpose: Mosquitoes are medically important vector and transmit several viral diseases which cause devastating effect on human. New classes of insecticides, such as neo-necotinoids (imidacloprid) and phenylepyrazoles (fipronil) which were registered. Although these group of insecticides are used but comparative study of insecticides has not yet been taken in Pakistan. Therefore, this study was done to determine bio toxicity of different insecticides in culex quinquefasciatus larvae in Lahore, Punjab, Pakistan.

Methods: In the present study, bio toxicity of four insecticides from four major groups: neo-nicotenoids (imidacloprid 5% SC) phenyl-pyrazoles (fipronil 2.5% EC), pyrethroids (deltamethrin 2.5% SC) and organophosphates (DDVP 50% EC) were tested against Culex quinquefasciatus (Cx. quinquefasciatus) Samples were collected from different localities to determine the susceptibility of species against tested insecticides.

Results: The findings of the study displayed Larval toxicity results were different for Kot Lakhpat and Lahore College for Women University Lahore for each insecticide. Kot Lakhpat samples were considered as reference samples because these were exposed to insecticides at a very low extent as compared to LCW samples. Regression analysis of variance showed significant positive trend in mortality. Fipronil was proved to be most toxic against Cx. Quinquefasciatus having LC50 = 0.003 µl/ml and 0.006 µl/ml n KotLakhpat and L samples respectively.

Conclusion: Deltamethrin showed least efficacy against both localities representing its high tolerance and resistance against pyrethroids. Lahore College for Women University samples were more resistant than Kot Lakhpat as resistant ratio varies from 1.8-2.30 for insecticides to insecticides in Cx. Quinquefasciatus respectively.