What’s the News: Biochemists at the University of Arizona have found a promising new way to fight disease-carrying mosquitoes. In their research project, published in the journal PNAS
, the scientists blocked mosquitoes' ability to digest blood, making blood-sucking deadly to the winged pests. This technique could someday be used alongside other strategies to battle mosquitoes, like repellents and traps. How the Heck:
Mosquitoes, like many other insects, draw most of their nutrients from nectar. But when it comes time to produce eggs, female mosquitoes require large amounts of protein, which they get from blood. So, Roger Miesfeld and his research team decided to see what would happen if they blocked a mosquito’s ability to digest blood.
The researchers focused on a protein complex called coatomer protein 1, or COPI, which is made up of several subunits that cells use to secrete gut enzymes that break down blood proteins. When a mosquito draws blood, cells lining its gut package enzymes in small droplets called vesicles, and release the packages into the gut.
Using a technique called RNAi, the researchers shutdown individual COPI subunits in about 5,000 mosquitoes. Surprisingly, more than 90 percent of the yellow fever mosquitoes died within 48 hours of blood feeding. “When she does [feed], all hell starts breaking loose, biochemically and anatomically speaking,” Miesfeld said in a prepared statement.
The researchers think that the removal of a COPI subunit makes the whole secretion process defective—It causes the cells lining a mosquito’s gut to fall apart, allowing blood to seep into its body.
What’s the Context:
There are many techniques scientists have used to kill mosquitoes. Recently, a study in the American Journal of Tropical Medicine and Hygiene showed that a cheap deworming pill used against river blindness is temporarily effective for battling the spread of malaria, too. Mosquitoes that bite people who have taken the drug ultimately die.
Researchers are also looking at ways to prevent mosquitoes from biting people. Earlier this year, scientists found a possible new mosquito repellent: a molecule that overloads a mosquito’s sense of smell.
Other scientists want to use mosquitoes’ sense of smell to draw them into traps. The lure? Smelly socks.
The Future Holds: Miesfeld says that the research could be used in conjunction with other mosquito-fighting techniques, if they can develop a small molecule that works in place of the injected RNAi. Scientists could douse mosquito nets with the molecule to create an effective mosquito-specific insecticide, or place it in a pill for people to swallow (as with the deworming pill above). Though, Miesfeld notes that genetic changes would eventually make mosquitoes immune to the molecule. Reference: J. Isoe, J. Collins, H. Badgandi, W. A. Day, R. L. Miesfeld. PNAS Plus: Defects in coatomer protein I (COPI) transport cause blood feeding-induced mortality in Yellow Fever mosquitoes. Proceedings of the National Academy of Sciences, 2011; 108 (24): E211 DOI: 10.1073/pnas.1102637108
Image: USDA
