Resistance Status of Anopheles maculipennis and Anopheles superpictus to the Conventional Insecticides in Northeastern Caspian Littoral, Iran

BACKGROUND: Malaria resurgence has occurred in the northern half parts of Iran. The resurgence of malaria in the prone area could arise from various factors, e.g. wide use of pesticides in the agriculture sector and factors such as habitual patterns of movement of local people from problematic southeastern foci in Iran toward the Caspian Littoral. There are no new data on the resistance status of main malaria vectors in the Caspian Littoral, and this study was aimed at renewal data on conventional insecticides. METHODS: The field strain of adult Anopheles superpictus and Anopheles maculipennis were collected using the hand catch method and transferred to the laboratory. The susceptibility tests were carried out against DDT 4%, Malathion 5%, Permethrin 0.75%, Deltamethrin 0.05%, and Lambda-cyhalothrin 0.05%, followed by the WHO’s procedure. RESULTS: The primary malaria vector in Caspian Littoral is An. maculipennis, revealed to be still resistant to DDT and mortality rate, LT(50) and LT(90) of female mosquitoes were 75.0%, 54.2, minutes and 111.3 minutes. The under ‘verification required’ status of An. maculipennis was also revealed to Lambda-cyhalothrin based on recent WHO’s criteria. The malaria vector An. superpictus is also considered the second malaria vectors in the west parts of the studied area, which showed to be susceptible to all insecticides tested. CONCLUSION: DDT resistance is persisted in An. maculipennis despite stopping residual spraying with DDT since 1978 in the Caspian Littoral, but the occurrence of pyrethroid under ‘verification required’ status is a progressive threat to the possible development of cross-resistance in the future.