Silencing ABCG4 transporter gene to increase insecticide efficacy against mosquito larvae

According to WHO, more than half of the world population lives under the risk of contracting illnesses carried by mosquitoes, and 3.2 billion people are at risk of getting malaria. Vector control is one of the main components in vector-borne diseases control programs, but resistance insurgence is nowadays an emerging problem threatening global efforts. A novel strategy for pest management implies the use of RNA interference against various gene targets in different arthropod species. Here, I performed the gene silencing of an ATP-binding cassette (ABC) transporter, ATP-dependent efflux pumps located in the cellular membranes both in prokaryotes and eukaryotes. These proteins are associated with trans-membrane transport of several substrates, including toxic compounds. In previous studies we have demonstrated the involvement of ABCs in larvae of Anopheles stephensi in the defence against permethrin. In particular, three families of ABC transporters (ABC-B, ABC-C and ABC-G) are implied through up and down-regulation at different time points, with maximum up-regulation of the ABCG4 gene. In my study, I treated three instar larvae of An. stephensi with permethrin alone or in combination with siRNAs at different concentrations and I evaluated larval mortality and the relative expression ABCG4 gene at different time points. My preliminary results demonstrate that RNAi on ABCG4 is effective and dose-dependent and significantly decrease the relative expression of the gene after 48h. Mortality results higher at 48h at higher siRNA concentration. This data show that silencing of ABC transporters through RNAi could be an effective and reliable method for increase chemicals efficacy against mosquitoes, allowing reduction of insecticide dosage and environmental pollution.