Improving mosquito (Aedes aegypti) sex-sorting methods for sterile insect technique using RNAi gene knockdowns
Doublesex (dsx) is an alternatively spliced mosquito (Aedes aegypti) gene that controls sex development by producing male (DSXM) or female (DSXF) transcription factors that regulate gene expression in a sex-specific manner. As both DSXF and DSXM bind the same DNA sequence, their ability to regulate differential gene expression is predicted to be modulated by other proteins that interact with DSX. A previously conducted protein-protein interaction study identified several proteins that bind to DSXF and their role in altering female development was explored in this study by knocking down their corresponding transcripts using RNA interference during the larval stages of development. Knockdowns of the genes nop-14, wdr-48, and rnmt was achieved by feeding mosquito larvae HT115 strain E. coli transformed with a pl4440 plasmid containing a dsRNA template specific to each of three target genes. The knockdowns were carried out at their normal rearing temperature, 28oC, and at 22oC to slow mosquito development. Knockdown of one of the genes, wdr-48, at either temperature, significantly increased the time to pupation of females compared to males. This delayed development of females could prove useful in the sex sorting of males and females during the pupal stage by providing a method to select only males for a sterile male insect (SIT) population control program for Ae aegypti. Of note, the 22oC growth conditions provided a larger difference in the pupation times between the sexes than the 28oC conditions did, and thus may provide even better sex-sorting for mosquito SIT.
Mosquito, Aedes aegypti, RNAi, Gene knockdown, sex sorting