Killing mosquitoes with a genetic trick that makes digesting blood deadly

In trying to curb malaria, biologists and epidemiologists have pulled some dirty tricks on mosquitoes (some quite literally dirty; remember the dirty sock trap from last week?). But after all the genetic tinkering to make mosquitoes disease resistant and the laser and nano-attacks that kill the insects on the wing, this one might be the meanest of all: a genetic trick that blocks mosquitoes’ ability to digest blood.

Not that we’re taking the mosquitoes side or anything like that--we don’t like them either, especially the malaria- and yellow fever-bearing bugs--but just imagine: You’ve just come back from your local haunt with a belly full of your favorite comfort food, when suddenly you find your self doubled over, bloating, and dying. It’s no way to go.

Nonetheless, it could make for an effective means of thinning out mosquito populations, at least among the females that carry the malaria parasite (and also handle the more important part of the breeding process). Mosquitoes generally feed on nectar, but when it’s time to breed the females need protein. That means blood, which digests a bit differently than other stuff. To digest blood, mosquitoes need to produce a certain enzyme in their guts. Researchers simply switched off the genes that lead to the production of those enzymes, and let nature take its course.

The result for the mosquito is not good. After ingesting blood, the clock begins ticking. The body can’t handle what it’s ingested, and the lack of those key enzymes causes the cells lining the mosquito’s gut to begin to break down. Eventually, the ingested blood seeps into the mosquitoes body where it’s not supposed to be. Within 48 hours, 90 percent of the bugs tested were dead after what must have been a slow, agonizing ordeal.

Of course, you have to find a way to deliver this genetic bomb to mosquitos besides individually injecting them with RNAi. That’s the challenge going forward. If researchers can find a way to get their special recipe into a small molecule that could be sprayed on mosquito netting or packed into a pill, the next meals for many mosquitoes could be their last.


/Popular Science/