In the present study, both male and females of Culex quinquefasciatus were sampled from five different localities of Lahore District of Punjab, Pakistan. (that is, Jaman, Mohlanwal, Noorpur Bhatta A1, Yohanaabad–2 and GCU Lahore). Bioassays against 5% deltamethrin were performed to evaluate the level of resistance in Culex quinquefasciatus against deltamethrin. For the adult bioassays standard protocol of WHO was adopted. Results of the bioassays showed that individuals of all populations were susceptible to 5% of deltamethrin. Male specimens from all populations showed significantly higher mortality as compared to females. Biochemical tests were performed to measure the esterase activity, both in males and females of C. quinquefasciatus. Significant variation was observed in the level of esterases in C. quinquefasciatus populations, collected from five different localities. Alpha naphthyl acetate was hydrolyzed faster than beta naphthyl acetate by mosquito homogenates of Yohanabad-2, GC University Lahore and Noorpur Bhatta A1 while mosquito homogenates of Mohlanwal and Jaman population hydrolyzed the beta naphthyl acetate faster than alpha naphthyl acetate. Only one band was observed in all populations for esterases A. For esterases B band pattern was similar in Yohanabad-2 and GC University. In these two populations there were three bands (B1, B2 & B3). In the population of Noorpur Bhatta A1, Mohlanwal and Jaman band B2 was absent. There was no resistance detected in C. quinquefasciatus from Jaman, Mohlanwal populations after 1 h exposure to 5% deltamethrin while population of GC University, Yohanabad and Noorpur Bhatta A1 showed a high level of tolerance to deltamethrin.
Key words: Esterases, Culex quinquefasciatus, resistance, pyrethroids.
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