Mosquitoes despite being tiny can wreak havoc in human life with just one bite. Epidemics of diseases transmitted by mosquitoes were not uncommon throughout history. Even now, in places where environment favors the reproduction and growth of mosquitoes, break outs of malaria, dengue fever, sindbis fever, West Nile fever and other such diseases occur.
Scientists have long tried to come up with something that repels mosquito but for that a complete understanding of how sensory receptors have evolved to help mosquito locate the victim is essential. Scientists have known that CO2 derives mosquitoes to humans but other factors have been unknown.
Researchers from Leslie Vosshall’s lab of Neurogenetics and behavior, the Rockefeller University have carried some experiments to show some factors that mosquito depends on for biting. They used genome editing to introduce a mutant version of the mosquito that spreads the yellow fever, Aedes aegypti. The mutant was missing a gene Gr3 that codes for CO2 receptor, without which the mosquito cannot detect the gas.
The behavior of both normal and mutant mosquitoes was observed inside a chamber that held a plate heated to the temperature of human skin. Normal mosquitoes were not attracted to warmth unless CO2 was also emanating from the plate whereas mutants were not attracted to the plate at all. When their ability to detect the human host was tested in the real world, in humid greenhouse type enclosure in Australia, it was found that mutants were only 15% impaired in their ability of detection of host because they were clued in by other factors, the combination of heat and odor of the human subjects. When same experiment was carried out with mice as subjects, the mosquitoes were less likely to bite, proving that without CO2 as clue, the effects of odor and heat were diminished.
These findings can help scientists manipulate the sensory receptors of mosquitoes thus preventing the infections in humans. However, as for female mosquitoes blood feeding is necessary for development of the eggs, they have evolved several mechanisms to increase their chances of getting a fruitful bite, so for scientists there is still a lot to understand before inventing something that can keep mosquitoes away from humans .
Though many such researches are going on and scientists are hopeful they will discover something soon to bring an end to misery mosquitoes have put humans through for thousands of years.
[Source: The Rockefeller University | Image Credit: National Geographic]