In what could give a boost to malaria control efforts, researchers have discovered that pregnant malaria-transmitting mosquitoes are drawn to the odour released by a naturally occurring chemical cedrol.
The discovery published in the Malaria Journal could lead to new "attract and kill" strategies to control malaria.
"Our study for the first time has carefully demonstrated that egg-bearing Anopheles gambiae mosquitoes can detect the chemical cedrol and are drawn to it in real world circumstances," said project leader Ulrike Fillinger from the London School of Hygiene & Tropical Medicine.
The researchers followed the Anopheles gambiae mosquito's journey: after a blood meal from a human, the female mosquito heads off to lays her eggs in a pool of still water. They noticed that some pools would be full of larvae, while others remained empty.
The team set up a number of pools of water with different infusions, such as grasses, different soils, even rabbit food pellets, and judged which pools the mosquitoes preferred to lay in by counting the number of mosquito larvae in each.
After various studies to confirm that it was an odour released from the soil infusion, rather than the look of the turbid water, that was attracting mosquitoes, the challenge was to isolate the precise chemical that drew them in.
The team determined that the mosquitoes were two times more likely to lay eggs in water with cedrol in the laboratory and a controlled field environment.
During their field test, the team showed that wild mosquitoes were three times more likely to be caught in traps baited with cedrol than in traps with lake water alone.
