Insecticide Resistance Development in Culex pipiens Population under Selection Pressures with Temephos

A collection of Culex pipiens from Boussalem, Northwestern Tunisia, with a low level of temephos resistance (14.90 at LD95) was selected to higher resistance with temephos in the laboratory. After 6 generations of pressure, the temephos resistance ratio increased to 103.95 at LD95. Synergism tests showed that temephos resistance was not associated with monooxygenase and esterases or (GST); however, evidence of insensitive acetylcholinesterase was found. It is evident that this important vector species, Culex pipiens, has the potential to develop resistance to temephos.