Good Riddance To Mosquitoes
Aug. 30, 2010, 1:56 p.m.
Lasers, parasites and other methods could help prevent a disease that afflicts hundreds of millions of people
By Elizabeth Svoboda
BLOOD LUST leads mosquitoes to bite--and spread diseases.
Editor's note: This story is part of a series of online exclusives about natural phenomena and human endeavors we'd like to see come to an end. They are connected with the September 2010 special issue of Scientific American called "The End".
Mosquitoes that carry the Plasmodium parasite cause some 300 million cases of malaria every year, claiming one million lives. That's a lot of carnage generated by an insect smaller than a pinky fingernail—but if enterprising researchers have their way, their blood-thirsty assault won't continue much longer. Here are some of the most promising strategies for wiping out malaria-carrying mosquitoes:
- Zap 'em. This February, inventor Nathan Myhrvold of the investment firm Intellectual Ventures unveiled a Star Wars-inspired mosquito killer: a laser death ray. Myhrvold mounts LED lamps on a fence post and uses a sensor called a charge-coupled device to monitor the field of light they create. When a disturbance in the field indicates the presence of an insect, a nonlethal laser beam is fired to determine how quickly the insect's wings beat—a trait that reliably distinguishes one species from another. Only female, malaria-bearing mosquitoes get zapped with the powerful kill laser (their wings beat at a low frequency); other insects are allowed to escape unharmed. "This is the first example of a smart insecticide," Myhrvold says. "If you sprayed, you'd kill all kinds of bugs."
- Fight parasite with parasite. Scientists at Imperial College London have experimented with using microsporidian parasites to keep malaria-bearing mosquito populations in check. When adult mosquitoes are infected with these fungi, they live shorter lives and their larval offspring are less likely to survive, devastating populations over time. Because the parasites evolve in tandem with the mosquitoes, subtly changing their attack strategies in response to the mosquitoes' attempts to develop resistance over time, this method would continue to be effective even as mosquito populations evolve new defenses.
- Practice good breeding. Johns Hopkins University researchers have devised genetically modified mosquitoes that express a protein known as SM1, making them immune to the Plasmodium parasite. If these GM skeeters can outcompete their wild counterparts, malaria-bearing mosquitoes could find themselves a casualty of human-directed evolution.
- Attack on two fronts. When mosquitoes evolve resistance to commonly used chemical pesticides, pest-eradication gurus have to look elsewhere for solutions. One effective alternative is the fungus Beauveria bassiana. A 2009 study in Proceedings of the National Academy of Sciences indicates that although B. bassiana spores can kill malarial mosquitoes in their own right, the spores also make mosquito hosts more susceptible to death by pesticide application—a devastating one-two punc