Evaluation of mosquitocidal efficacy of Scorpion Toxin Tf2 from Tityus fasciolatus against Anopheles stephensi mosquitoes

Abstract

Vector control is crucial for mitigation of mosquito-borne diseases such as malaria. The emergence of insecticide resistance has begun to hamper vector control in recent years. Novel vector control strategies that do not depend on chemical insecticides are needed. We evaluated the potential of venoms, the poisonous secretion of the animals, as sources of novel mosquitocidal molecules. We screened for mosquitocidal effects of seven venoms, using Melittin (Mel) as a positive control by microinjection using the malaria vector Anopheles stephensi mosquitoes. Tf2, Hm3a (Hm3), Chlorotoxin (Ctx) and Mel caused significantly high mortality among these mosquitoes. To identify the most effective venom, we assayed for the lowest effective dose of Tf2, Hm3, Ctx, and Mel. Tf2 displayed the highest mosquitocidal potency. We next determined the LD₅₀ of Tf2 against An. stephensi mosquitoes. The LD₅₀ of Tf2 against An. stephensi was 5.9×10⁻¹³ mol/mosquito. Our results indicated that Tf2 was the most effective candidate venom molecule for a novel vector control agent. Further research regarding Tf2 is expected to contribute to the control of mosquito-borne diseases such as malaria.