Daily News Archive
Promise For Mosquito Control
Since cholesterol is hydrophobic, organisms must have a way to shield it from water when transporting it in a liquid medium, such as blood or cell fluids. That shield is typically a carrier protein. Using the yellow fever mosquito, Dr. Lan and her research colleagues discovered that a sterol-carrying protein, AeSCP-2, is the vehicle that transports the cholesterol in mosquito cells.
Lan and her colleagues reasoned that if they could block the carrier protein, it would disrupt the uptake of cholesterol by the mosquito. Screening what she calls "a small chemical library of 16,000 compounds," Lan and her team found 57 compounds that inhibited the cholesterol-binding capacity of SCP-2. The top five most viable inhibitor compounds were then tested on mosquito larvae, producing promising results--the larvae died. The results were dose-dependent; that is, at higher concentrations, larger numbers of larvae died. Still, the concentrations were very small, Lan says, in the range of 10 parts per million.
"Control is urgent," Dr. Lan, who is from China, says. "Mosquito-borne illnesses are endemic in parts of China. Malaria is a big problem in south-central China. South of the Yangtze River the infant mortality rate is high, especially in homes without screens on the windows."
The common insecticides that are used to kill mosquitoes are broad-spectrum adulticides, which kill all adult flying insects they contact, including mosquito predators such as dragonflies, leaving populations with fewer natural controls. While traditional adulticide methods look like action, in actuality they accomplish very little. Dr. Lan believes that a more fine-tuned chemical approach is more practical: only one compound is selected, it works for a short period, and it targets a single insect. "People might ask, 'Why do we need more pesticides?'" Lan says. The answer is twofold: resistance and the effect on non-target species. "I believe you should develop smart pesticides to only kill the mosquitoes," Lan says. "We don't want to go down the same road as DDT."
To that end, her
team is testing the most promising handful of SCP inhibitor compounds
on a variety of insect and vertebrate species. So far three of the five
compounds tested were not toxic to mouse cells and the other two were
only slightly toxic. They will also test the compounds on other pest
species, including flies, roaches and termites. Environmental and degradation
tests have yet to be performed. "We want a specific target with
low residue time- two to three weeks and it should be degraded,"
Read more about Dr. Lan's research in Medical News Today
TAKE ACTION: Fight to prevent unnecessary adulticiding in your community and promote effective, intelligent mosquito management. For help see Beyond Pesticides Tools for Activists page. For more information on West Nile Virus and mosquito management see a new factsheet by Beyond Pesticides: The Truth About Mosquitoes, Pesticides, and West Nile Virus.