Laboratory selection for and characteristics of pyrethroid resistance in the malaria vector Anopheles funestus R. H. HUNT 1,3 , B. D. BROOKE 1,2 , C. PILLAY 1,3 , L. L. KOEKEMOER 1,2 and M. COETZEE 1,2 1 Vector Control Reference Unit, National Institute for Communicable Diseases, Sandringham, South Africa, 2 Division of Clinical Microbiology and Infectious Diseases, School of Pathology of the National Health Laboratory Service and the University of the Witwatersrand, Johannesburg, South Africa and 3 School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa Abstract. A laboratory colony of Anopheles funestus Giles (Diptera: Culicidae) was established in 2000 from material collected from southern Mozambique where pyrethroid resistance had been demonstrated in the wild population. A subsample of the colony was selected for pyrethroid resistance using 0.1% lambda-cyhalothrin. Bioassay susceptibility tests in subsequent generations F 2 to F 4 showed increased resistance with each successive generation. Survival of individual mosquitoes fed only on 10% sugar solution, increased with age up to 4 days, but by day 10 had decreased significantly. However, females that had been mated and given bloodmeals showed no such increase in mortality with age. Biochemical analysis of resistant and susceptible individuals showed increased monooxygenase and glutathione S-transferase activity but no significant correla- tion with age of the mosquitoes. Key words. Anopheles funestus, biochemical analysis, insecticides, pyrethroid resistance, southern Africa. Introduction Anopheles funestus Giles is one of the major malaria vector mosquitoes in Africa. It is the nominal member of a group of nine morphologically similar species that includes: An. aruni Sobti, An. rivulorum Leeson, An. vaneedeni Gillies and Coetzee, An. parensis Gillies, An. brucei Service, An. confusus Evans and Leeson, An. fuscivenosus Leeson and An. leesoni Evans (Gillies & De Meillon, 1968; Gillies & Coetzee, 1987). Anopheles rivulorum is the only other member of this group implicated as a minor vector in malaria transmission at a single locality in Tanzania (Wilkes et al., 1996). Resistance to pyrethroids and carbamate insecticides was recently recorded in An. funestus from South Africa (Hargreaves et al., 2000) and Mozambique (Brooke et al., 2001). South Africa had switched from DDT to deltame- thrin for indoor residual house spraying in 1996, unaware that the populations of An. funestus in southern Mozambique were resistant to pyrethroids (Hargreaves et al., 2003). The resultant malaria epidemic in 1999/2000 was the worst experienced in South Africa for 30 years with a 10-fold increase in case incidence over 5 years. It was brought under control by reverting to DDT spraying of traditional houses. Biochemical and synergist assays implicated monooxy- genase detoxification as the major resistance mechanism in An. funestus samples from South Africa and Mozambique (Brooke et al., 2001). Subsequent colonization of An. funestus from Matola Province, southern Mozambique, has enabled more detailed analysis of insec- ticide resistance in this species. The Vector Control Reference Unit is currently the only laboratory in the world to successfully colonize An. funestus and this has Correspondence: Maureen Coetzee, VCRU, National Institute for Communicable Diseases, Private Bag X4, Sandringham 2131, South Africa. Tel: þ27 11 386 6480; Fax: þ27 11 386 6481; E-mail: maureen.coetzee@nhls.ac.za Medical and Veterinary Entomology (2005) 19, 271–275 # 2005 The Royal Entomological Society 271