Study demonstrating the potential of a potent new tool; breakthrough technique harnessing two methods to target disease carrying mosquitoes was able to effectively eradicate buzzing biters. The mosquitoes targeting are a type that is particularly difficult to control called Aedes albopictus more popularly known as the Asian tiger mosquito which are a major vector for diseases including Zika and dengue.
Preventing the release of Wolbachia-infected female mosquitoesis difficult, with sex-sorting techniques usually resulting in a “female contamination rate” of about 0.3%. The study conducting a two-year trial at two sites on river islands in Guangzhou; where Asian tiger mosquitoes are to blame for the highest dengue transmission rate in China.
Technique eradicates mosquitoes
The results were “remarkable”; the number of hatched mosquitoes eggs plunging by 94%; with not a single viable egg recorded for up to 13 weeks in some cases. And the average number of female mosquitoes which transmit disease to humans; when they bite caught by traps fell by in between 83 and 94 %.
The results were also borne out by a decline of nearly 97% in bites suffered by locals which in turn shifted attitudes among residents; who were initially sceptical of the project’s plan to release more mosquitoes into the local area. SIT works by releasing radiation-sterilising male mosquitoes into an environment to mate with wild female mosquitoes; reducing the size of the population over time as females fail to reproduce.
But irradiation of male mosquitoes tends to reduce both their mating competitiveness and their survival rates, undermining the technique’s effectiveness. The IIT method involves a bacteria called Wolbachia. When males infecting with it mate with female mosquitoes that are not infecting, their eggs do not hatch.
To overcome that, researchers decided to subject their Wolbachia-infected lab-reared mosquitoes to low-level irradiation, which rendered the females sterile but left the males able to reproduce; technique still holds promise if natural barriers like highways are using to limit the arrivals of outside mosquitoes.