Synergism and antagonism of Baygon with some additives against Baygon-resistant strains of Culex pipens larvae

Larvae of the mosquito Culex pipiens were subjected to continuous laboratory selection with Baygon for 15 successive generations. This resistant strain was tested with some additives, piperonyl–butoxide, sesame oil and clove oil, to investigate their synergistic or antagonistic effect. The use of sesame oil and piperonyl-butoxide considerably enhanced the toxicity of Baygon. Clove oil also potentiated Baygon but to a lower extent than sesame oil and piperonyl-butoxide. The activity of each synergist was found to be concentration dependent. Results showed the possibility of using the piperonyl-butoxide and sesame oil as a synergist against a Baygon–resistant strain of C. pipiens. KEY WORDS: mosquitoes, insecticide, clove oil, sesame oil, resistant Egyptian Journal of Biology Vol.4 2002: 127-13