BEIJING: Scientists have wiped out the entire population of mosquitoes on two islands in southern China using radical techniques to render the males infertile, according to a new study that could transform the fight against a range of deadly diseases.
Over nearly two years, scientists released more than 200 million specially bred male Asian tiger mosquitoes on Shazai and Dadaosha islands in the delta to the south of Guangzhou city, the area with the highest number of dengue fever cases in China.
The study, published in the latest edition of the journal Nature, said the mosquitoes, also known as Aedes albopictus, had been exposed to short bursts of gamma radiation and received three artificially induced infections from three different species of Wolbachia, a parasitic microorganism, to make them infertile.
The males were also fed with sugar in the hope of making them bigger and stronger – and therefore more attractive to female mosquitoes during the mating season.
This, combined with the sheer weight of numbers of the infertile mosquitoes, was intended to tip the evolutionary balance by ensuring that the females’ eggs – if any were laid at all – would not hatch.
By the end of the two-year experiment, the native mosquito populations on the islands had vanished completely.
The scientists did find a few individual mosquitoes still living on the islands in Guangdong province, but genetic analysis suggested their origins lay elsewhere and they had probably been carried there by cars or by ships.
Although Asian tiger mosquitoes – so named because of their distinctive white stripes – can transmit a range of diseases, including the Zika and West Nile viruses as well as dengue fever, a lot of locals were initially sceptical about the project.
The research was led by Professor Xi Zhiyong from the Sun Yat-sen University-Michigan State University Joint Centre of Vector Control for Tropical Diseases, with official support from the Guangzhou Centre for Disease Control and Prevention.
The study said that in the beginning, only 13 percent of the people on Shazai island had supported the work.