Insecticide Susceptibility Status of Wild Population of Phlebotomus kandelakii and Phlebotomus perfiliewi transcaucasicus Collected from Visceral Leishmaniasis Endemic Foci in Northwestern Iran

BACKGROUND: Phlebotomus kandelakii and Phlebotomus perfiliewi transcaucasicus sand flies are the vectors of visceral leishmaniasis in Iran. The aim of this study was to evaluate the susceptibility of Ph. kandelakii and Ph. perfiliewi transcaucasicus, collected from an endemic focus of visceral leishmaniasis (VL) in the northwest of Iran, to different selected insecticides. METHODS: Sand flies were collected from the villages of Meshkinshahr and Germi Counties using light traps and aspirators from May to October 2019. The sand flies were identified as Ph. kandelakii and Ph. perfiliewi transcaucasicus using standard identification keys. Susceptibility test was carried out against DDT (4%), Malathion (5%), Propoxur (0.1%) and Lambda-cyhalothrin (0.05%) according to the WHO standard method. MedCalc statistical software was employed to calculate LT(50) and LT(90) and to compare the chances of sand flies surviving the exposure to the studied insecticides. RESULTS: A total of 1,278 female specimens were used for the susceptibility tests. Out of which 1,063 samples were used for the test and 215 for the control group. The estimated LT(50) values for DDT (4%), Malathion (5%), Propoxur (0.1%), and Lambda-cyhalothrin (0.05%) for Ph. kandelakii were 15.1, 13.4, 15.4 and 5.8 minutes respectively, and for Ph. perfiliewi transcaucasicus were 11.9, 15.6, 15.9 and 5.8 minutes respectively. CONCLUSION: This susceptibility studies revealed different LT(50) values for different insecticides efficient against Ph. kandelakii and Ph. perfiliewi transcaucasicus. The regular monitoring for the resistance of Ph. kandelakii and Ph. perfiliewi transcaucasicus sand flies seems necessary in diseases control programs in this area.