Research undertaken at Virgina Tech has demonstrated how the alteration of a single gene can convert female Aedes aegypti mosquitoes into fertile male mosquitoes. The location of this gene and its subsequent modification may be all that is needed for mosquito control. The gene is the on necessary for male mosquito flight.
Aedes aegypti is otherwise known as the yellow fever mosquito. This mosquito can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses. The mosquito is not associated with the transmission of malaria.
An important differentiator between male and female mosquitoes is that male mosquitoes do not bite and therefore they are unable to transmit pathogens to humans. In contrast, female mosquitoes are able to bite. Limiting the proportion of females is one of the strategies considered for the control of tropical diseases. The evolutionary reason that female Aedes aegypti mosquitoes need blood is to produce eggs.
The means to control female numbers lies with the male-determining locus (M locus), formed of 30 genes. The researchers have identified a second gene, termed myo-sex, which is needed for male flight. Understanding this has revealed more about the M locus. The locus establishes the male sex in the mosquito. The gene is only inherited by the male offspring, in a way that parallels the human Y chromosome.
The researchers showed that by manipulating this one gene this was sufficient to breed mosquitoes with male-specific sexually dimorphic features and hence male-like gene expression. The significance of this is the generation of mosquitoes that will not bite and hence will not spread disease.
This represents an alternative to other measures to control disease-spreading mosquito populations, such as the Sterile Insect Technique (a subject covered on Digital Journal by Karen Graham). With the new method, further research will be needed – not least to consider the ecological impact – before new transgenic lines of predominantly male mosquitoes are produced within targeted niches.
The research has been published in Proceedings of the National Academy of Sciences, and the paper is titled “Nix alone is sufficient to convert female Aedes aegypti into fertile males and myo-sex is needed for male flight.”
