Resistance to conventional insecticides still constitutes a major obstacle to control of malaria vectors. Xenobiotic pollutants encountered by aquatic stages of natural populations of malarial vector species in agricultural and domestic environment are often selected due to resistance to various insecticides. The Laboratory Matatuine (MAT) and Kayamba (KGB) strains of Anopheles arabiensis were subjected to controlled dosages of DDT for over twenty generations. WHO insecticide susceptibility protocols was used to monitor changes in mortality between generations. The selected lines of both strains developed resistance to DDT and cross resistance to permethrin. Polymerase Chain Reaction (PCR) detection of knock-down resistance (kdr) gene and sequencing revealed absence of L1014F mutations. Biochemical analysis of detoxification enzymes showed significant Glutathione S transferase (GST) activity in the selected lines [MAT: 0.236 (P>0.001) and KGB: 0.221 (P>0.014)], thus suggesting the presence of GST-based resistance mechanism. Key words: Dichloro-diphenyl-trichloroethane (DDT), Anopheles arabiensis.
