First report of N1575Y mutation in Anopheles gambiae in Sierra Leone

The resistance of mosquito vectors to insecticides is one of the biological obstacles in the fight against malaria. Understanding of the status and mechanisms underlying the insecticide resistance in Anopheles gambiae species is necessary for success of vector control efforts. The study aimed to determine the molecular forms of An. gambiae from four districts in Sierra Leone during May and June 2018, and the level of N1575Y mutation. The molecular form identification of adult female An. gambiae mosquitoes reared from larvae were carried out using polymerase chain reaction and sequencing. And the N1575Y mutations were detected using SNaPshot and sequencing. As a result, significant differences were found in the distribution of An. gambiae molecular forms among regions (P < 0.001). And a total of 638 An. gambiae sensu stricto, 106 An. coluzzi, and 4 hybrid individuals were identified. Moreover, the overall N1575Y mutation frequency was 10.2% with no statistical difference among regions (χ² = 3.009, P = 0.390). In addition, no significant differences in N1575Y mutation frequency were found among different An. gambiae molecular forms (P = 0.383). In conclusion, the N1575Y mutation in An. gambiae populations in Sierra Leone was reported for the first time in the present study. It provides key evidence for the necessity of monitoring vector susceptibility levels to insecticides used in this country.