Five decades ago, entomologists confronting the many kinds of suffering that mosquitoes inflict on humans began to consider a new idea: What if, instead of killing the mosquitoes (a losing proposition in most places), you could disarm them? Even if you couldn’t keep them from biting people, what if you could block them from passing on disease? What if, in fact, you could use one infectious microbe to stop another?
These scientists began to consider a parasitic bacteria called Wolbachia, which lives quietly in all kinds of insect species. A female mosquito with Wolbachia passes it on in her eggs to all of her offspring, who eventually pass it on to the next generation.
But Wolbachia isn’t naturally found in the mosquito species that cause humans the most problems — the Aedes aegypti, the virus carrier, and the Anopheles subspecies, which carry malaria. If it were, it might eventually render those species essentially harmless.
So how do you infect a mosquito with Wolbachia?
Researchers found, after painstaking trial and error, that they could insert the bacteria into mosquito eggs using minute needles. The mosquitoes that grew from those eggs were infected.
The Aedes aegypti mosquitoes that hatched and lived with Wolbachia did just fine. And as hoped, the Wolbachia mostly blocked the viruses: The mosquito who bit someone with dengue, and picked up the virus, didn’t pass it on to the next person it bit.
That got the researchers thinking: If they could infect all the mosquitoes in a village or city, they might stop the disease. Unlike truckloads of insecticides, sprayed down every street and running off into water systems, this method would not harm the ecosystem. [Continue reading…]