Sniff Gene

Mosquitoes that spread deadly human diseases like malaria, dengue and chikungunya generally distinguish humans from other animals using body odour. Thus altering a gene that helps mosquitoes sniff out humans can help keep the pesky insect off. Experiments on a genetically modified mosquito have shown that a specific gene called orco makes the insects prefer humans over other mammals. While a mutant mosquito with orco gene shut off might land on a human it flies off without biting just as it would do with a guinea pig. Given the ubiquity of orca gene in the insect world, it can be of significant help in development of life-saving repellants. 

Source

Down To Earth, July, 2013