'Blinding' an insect's sense of smell may be the best repellent | Science Blog:
The researchers studied four very different insect species: a benign insect favored by researchers, the fruit fly, which is attracted to rotting fruit, and three pest insects: the medfly, which is a citrus pest; the corn earworm moth, which damages corn, cotton and tomato crops; and the malaria mosquito, which targets humans. They found that one gene, shown to be responsible for the sense of smell in fruit flies, has the same function in these pest insects, which are separated by over 250 million years evolution
“While all these insects have sensitive olfactory systems, they all have very different smell preferences,” says Vosshall, head of the Laboratory of Neurogenetics and Behavior. “Yet this odorant receptor is highly conserved across all of these different species.”
Hmm. Evolutionary hypothesis leads to an experiment. The results show common descent, and reveals a means of preventing mosquitoes from noticing people, agricultural pests from noticing fruit, etc.