Short Notes J Vect Borne Dis 43, March 2006, pp. 34–38 Susceptibility status of Anopheles dthali and An. fluviatilis to commonly used larvicides in an endemic focus of malaria, southern Iran A.A. Hanafi-Bojd, H. Vatandoost & R. Jafari Department of Medical Entomology & Vector Control, School of Public Health & Institute of Health Research, Tehran University of Medical Sciences, P.O. Box 6446, Tehran 14155, Iran Key words Anopheles dthali – An. fluviatilis – Iran – larvicides Malaria control is increasingly recognised as playing a key role in poverty reduction in high burdened countries. The programme for malaria eradication based on vector control using very large quantities of DDT started in 1949 in the country and resulted in a dramatic reduction in malaria incidence. Vector population recovery, mainly due to resistance to DDT in Anopheles populations as well as DDT’s lack of selectivity affecting non-target populations including mosquito competitors, predators and pathogens, soon reversed early success 1 . Therefore, other insecticides belonging to organochlorine, orga- nophosphate, carbamate and pyrethroid groups were produced and used in the following years. Extensive use of chemical insecticides against vector mosqui- toes for the control of malaria for about four de- cades, has resulted in development of resistance in vector mosquitoes to these insecticides and hazards to the environment. The main control measures in Iran are the use of lambdacyhalothrin WP 10% and deltamethrin WP 5% for indoor residual spraying as well as chlor- pyrifos-methyl and Bacillus thuringiensis as larvi- cides in breeding places. Gambusia affinis and Aphanius dispar as larvivorous fish have also been introduced into the breeding sites. Treated bednets using deltamethrin EC 25% is another attempt to control malaria in southern part of the country. In spite of all these vector control activities in Iran, malaria continues to be the most important parasitic and vector-borne disease in the country. Anopheles fluviatilis James and An. dthali Patton (Diptera : Culicidae) are both considered as the secondary ma- laria vectors in southern Iran, after An. stephensi. Studies in other countries showed that An. fluviatilis is resistant to DDT in Afghanistan, India, Nepal and Pakistan. Also in Pakistan and Saudi Arabia it is re- ported resistant to Dieldrin 2 . A study on insecticides resistance in India showed that An. fluviatilis has developed resistance to HCH and is susceptible to DDT 3 . Investigation carried out in Kazerun, south- ern Iran, showed that An. fluviatilis was susceptible to organochlorine and organophosphorus com- pounds, mortality rate with 2 and 4% DDT after one- hour exposure was 96–100 and 100%, respectively. The mortality rate with malathion 1.6 and 3.2% after one-hour exposure was 95.8 and 100%, res- pectively 4 . An. dthali is resistant to chlorpyrifos,