New portable lures could help defeat mosquitoes and their diseases
A new avenue for defeating the triple menace of dengue, yellow-sickness and malaria, all diseases borne by blood-sucking mosquitoes, has been opened up by research published in tomorrow's Nature. A team from the University of California, Riverside, describes how blends of odor-stimulating compounds can fool female mosquito's from homing in on our CO2-laden breath.
Every breath exhaled leaves a carbon dioxide trail, one which disease-carrying mosquitoes use to home in on their next meal. And once latched onto their sleeping victim, female mosquitoes can be responsible for passing on such nasties as dengue, malaria and yellow fever. These diseases kill millions of people each year. But scientists from the University of California Riverside (UCR) think they have found a way to turn the CO2-sniffing abilities of mosquitoes against them - and so hopefully help to slash to that annual toll.
The results of their research, into the mosquito's odor-molecule detection apparatus, is published in the current issue of Nature, which comes out tomorrow. Anandasankar Ray, and his coworkers at the University, trialled their new approach to fooling disease-carrying mosquitoes in both wind tunnels in the US, and in controlled field trials in Kenya.
Current methods of mosquito-trapping relies on pumping out CO2 to try and lure mosquitoes away from their human prey. Whilst reasonably effective, the equipment is heavy, costly and difficult to maintain. Instead, the team from UCR looked at various other molecules, more easily deployed, which directly affect the CO2 detectors used by the insects.
They tried out combinations of three different sorts of odor molecules on mosquito CO2 receptors - blinders, imitators and inhibitors. Blinders such as butanedione, stimulate the receptors, causing them to go into overkill, so that they can no longer effectively work. Imitators mimic the action of CO2 molecules, and work well in traps. The inhibitors act to block the receptors from detecting CO2 at all, and include molecules such as hexanol and butanal.
"These chemicals offer powerful advantages as potential tools for reducing mosquito-human contact, and can lead to the development of new generations of insect repellents and lures," said Ray. In order to see how effective these molecules were in practice, two traditional huts were constructed in a test greenhouse, at the International Center of Insect Physiology and Ecology (ICIPE) in Kenya. The compounds were tested using both a control hut, and one equipped with the odor-altering chemicals. Rather than human volunteers, traditional CO2 traps were used to entice the mosquitoes.
The results showed that the blinder compounds were particularly effective, preventing the mosquitoes from finding the traps for several minutes after exposure to an 'ultra-prolonged' blend of butanedione, hexanol, butanal and pentanal. The team hopes that their research will lead to more widely deployed tools for combating the mosquito pest - and the diseases they carry.
"The identification of such odor molecules - which can work even at low concentrations, and are therefore economical - could be enormously effective in compromising the ability of mosquitoes to seek humans, thus helping control the spread of mosquito-borne diseases," said Ray.