Germline transformation of the West Nile virus and avian malaria vector Culex quinquefasciatus Say using the piggyBac transposon system

Culex quinquefasciatus Say is a mosquito which acts as a vector for numerous diseases including West Nile virus, lymphatic filariasis and avian malaria, over a broad geographical range. As the effectiveness of insecticidal mosquito control methods declines, the need has grown to develop genetic control methods to curb the spread of disease. The piggyBac transposon system - the most widely used genetic transformation tool in insects, including mosquitoes - generates quasi-random insertions of donor DNA into the host genome. However, despite the broad reported species range of piggyBac, previous attempts to use this tool to transform Culex quinquefasciatus mosquitoes have failed. Here we report the first successful transformation of Culex quinquefasciatus with the piggyBac transposon system. Using commercially synthesised piggyBac mRNA as a transposase source, we were able to generate three independent insertions of a ZsGreen fluorescent marker gene, with transformation efficiencies of up to 5 %. Through this work, we have expanded the genetic toolkit available for the genetic manipulation of Culex mosquitoes and thus removed a barrier to developing novel genetic control methods in this important disease vector.