Temephos Resistance in Three Populations of Culex pipiensCollected from Three Districts of Southern Tunisia and its Significance for the Resistance Mechanism

Objectives: The aim of this study was to investigate the resistance to temephos (OP) in three populations of Culex pipiens collected from three districts of Southern Tunisia and its significance for the resistance mechanism.

Methods: Resistance to temephos insecticide was studied on Culex pipiens mosquitoes collected in three localities of Southern Tunisia. Larvae were used for different bioassays and adults were stored in -80°C for esterases identification.

Results: Bioassays revealed the susceptibility of sample # 3. The weakest resistance was recorded in sample # 3 (RR50 = 0.68) and the strongest resistance for the sample # 2 (RR50 = 3.6). At LC95, two samples (# 1, and 3) were susceptible. The use of synergists showed the non-involvement of resistance mechanisms inhibited by DEF and Pb. Our investigation reported that temephos resistance could be explained by the two most common mechanisms of resistance to OP (overproduced esterases and AChE 1 mutation).

Conclusion: Both detoxification mechanisms and target site alteration were involved in the resistance to temephos as reported in our study. These results are very important for the implementation and development of vector control strategies