For the US, weaponised mosquitoes to control destabilise Aedes mosquito populations, and thus help checkmate Zika and yellow fever, had been an anathema. To be sure, it wasn’t that regulators/administrators or policymakers didn’t want them. It was the people. Over 150,000 Florida Keys residents had signed a petition to bar UK-based biotech firm Oxitec from conducting field tests of its bio-engineered Aedes strains that could cause the local, wild population to crash. Protesters proffered a host of unsubstantiated reasons, from “this will cause more aggressive species to move in” and fill the void to “no local cases of dengue in Florida Keys” and even “bringing down Aedes population could destabilise the environment”. The US has come a long way from there. The US Environmental Protection Agency has just approved the release of similar bio-engineered strains by a Kentucky-based firm, MosquitoMate.
The bio-engineered specimen of Aedes albopictus (Asian tiger mosquito) that has received the EPA nod carries Wolbachia pipientis, a bacterium that is found in many mosquitoes but not in Aedes. Lab-reared males, when released into the wild, will mate with wild females; though fertilised, the eggs from such mating won’t hatch as the paternal chromosomes won’t form properly. Bio-engineered mosquitoes have been the talk of the town—from cytoplasmic incompatibility (that results in the unviable eggs) to feminisation/sterilisation in male mosquitoes, Wolbachia has been demonstrated as a potent tool against mosquitoes.
In Anopheles gambiae, the most commons Anopheles species in Africa, the bacteria compete with Plasmodium, the malaria pathogen, for nutrients and choke it off. A particular strain of the bacteria can even bring vector (in this case, mosquitoes) life down. While China has given the nod to Wolbachia-infected mosquitoes, in Brazil, where their potential was demonstrated for the first time, the health regulator killed off the proposal for a nationwide release. The US getting convinced of their bio-safety should perhaps spur others, like India, Brazil and South Asian nations where the burden of mosquito-borne diseases is the highest, to open their doors as well.