Antiviral RNA interference activity in the predatory mosquito, Toxorhynchites amboinensis

The replication of arboviruses in arthropod vectors is controlled by their innate immune responses. One response which has been shown to be of particular importance for the control of virus infections is the RNA interference (RNAi) mechanism. Although much as been done to understand the role of RNAi in vector populations, little is known about it’s importance in non-vector species. Here, we investigated the presence of an RNAi response in Toxorhynchites amboinensis, an important species used as a biological control agent against pest mosquitoes. Using a derived cell line (TRA-171), we demonstrate that these mosquitoes possess a functional RNAi reponse which is active against a mosquito-borne alphavirus, Semliki Forest virus. As observed in vector species, RNAi is induced by sequence- specific dsRNA and produces small RNAs that target virus sequences. Taken together, this data suggests that Tx. amboinensis are not passively infected but are able to control an arbovirus infection in a similar way to natural vector species. Understanding their ability to manage viral infections will be advantageous when selecting particular species as biocontrol agents in the use against pest species.