By Paloma Almoguera
Singapore, Oct 8 (EFE).- In Singapore, encountering a swarm of millions mosquitoes may paradoxically offer protection against dengue fever. But how?
The island has undertaken the “Wolbachia Project,” which involves releasing thousands of mosquitoes inoculated with the Wolbachia bacteria to control their reproduction and reduce the spread of dengue.
Nurashikin Binte Abdul Halim begins her day early in a leafy neighborhood in western Singapore, close to a nature reserve.
She carries a basket filled with cylindrical containers, each containing 2,400 non-biting male Aedes aegypti mosquitoes, a species that can potentially transmit dengue and other diseases.
As a researcher for the “Wolbachia Project,” Nurashikin has a seemingly simple task, made possible through a complex process.
She carefully opens each container and releases the mosquitoes at designated locations within the neighborhood, a task she repeats up to twice a week, for an unspecified duration.
“The releases basically have to be done in the morning because that is when it is cooler for them. A mosquito is more active during that time. So, that’s why we normally do releases between 6:30 and 11 am,” she tells EFE after releasing the dipteran insects.
The objective is for these mosquitoes, bred in a local laboratory, to seek out wild female Aedes aegypti mosquitoes (the carriers of dengue) and mate with them.
However, thanks to the inoculated Wolbachia bacteria, they do not produce viable offspring.
This microorganism, naturally present in 60 percent of the world’s insects but typically in Aedes aegypti, triggers a biological phenomenon known as cytoplasmic incompatibility, rendering the eggs non-viable.
The project was launched in Singapore in 2016 and is estimated to have covered 30 percent of the subsidized housing blocks on the island this year, where around 80 percent of the local population resides.
Caleb Lee, a scientist on the project launched in Singapore in 2016, explains the process as a kind of “competition” between the laboratory-bred and wild male mosquitoes.
According to Lee, they they release around 20 times more male mosquitoes than those naturally present in the area to compete with them.
The goal is for female mosquitoes (with an outdoor lifespan of about two weeks) to encounter as many laboratory-bred Aedes aegypti insects as possible, reducing or preventing offspring.
According to program data, supported by the National Environment Agency of Singapore, the strategy has succeeded in reducing the Aedes aegypti population, leading to a decrease in dengue cases.
In areas where mosquitoes have been released for at least a year, the total population of these insects has dropped by up to 98 percent, and dengue cases have decreased by 88 percent.
Deng Lu, who works in the island’s industrial zone laboratory, says it is is basically a suppression technique.
Over 300 million “Wolbachia” mosquitoes have been bred since the project’s inception, with around 7 million produced per week.
However, the most challenging aspect of expanding the project lies in the complex and costly technology required for tasks such as egg collection, larva counting, gender identification, and inoculating the bacteria.