Distorting the sex ratio of malaria mosquito populations, using a genetic modification strategy, can rapidly erode their breeding capabilities and suppress their growth. The study, reported this week in Nature Communications, indicates that an artificial increase in the production of male progeny may provide an effective means of controlling the spread of malaria.
In many pest species, the fitness of the female population is responsible for maintaining the overall population size. As such, the introduction of extreme, male-biased, reproductive sex ratios has been suggested in the past as an effective method for controlling pest populations.
Nikolai Windbichler and colleagues developed a system capable of distorting the naturally occurring male to female sex ratio in malaria mosquitos, Anopheles gambiae, using a modified enzyme to target and destroy a specific region of the A. gambiae X-chromosome. The modification restricts the enzyme activity to meiosis-the cell division phase of reproduction-and therefore does not affect fertility but prevents the X chromosome from being passed on to the next generation.
When introduced to caged wild-type mosquitos, the system was able to produce fertile mosquitos that produce more than 95% male offspring and effectively suppresses their population size. The authors suggest that this may provide a platform for the use of genetic manipulation to control the spread of pests and diseases.