Mosquitoes also have their own preferences for blood sucking: they prefer certain species, even individuals. At the same time, depending on the environment, their tastes will change. For example, a mosquito in California likes to suck robin's blood in summer; but once the birds go south for the winter, they also turn to sucking mammal's blood.

　　But how do mosquitoes decide what they eat today, and when do they decide to try new products? This seems to depend on the nose and the behavior of the food eater. A study has shown that mosquitoes not only remember their preferred host odor, but also use these olfactory cues to avoid creatures that have tried to pat them. The findings have been published in Current Biology.

　　Researchers placed female Aedes aegypti mosquitoes into a Y-shaped maze, filled with the odor of a human volunteer on one side and a control group containing mineral oil solutions on the other. Not surprisingly, mosquitoes apparently prefer human odors.

　　Next, researchers tried to train mosquitoes to escape the "temptation" scent of humans. They put mosquitoes in the human scent, and at the same time imposed a mechanical vibration, similar to the violent shock of escaping from the slap of the host. Sure enough, after training, mosquitoes associate human odors with their potentially lethal defenses, and even when they encounter the previously attractive odor, they immediately lose their appetite and escape.

　　Researchers have found that dopamine, a neurotransmitter, is responsible for the acquisition of this avoidance behavior. Previous studies have found that dopamine plays a role in female mosquitoes'search for blood-sucking targets; it also affects learning and memory in other insects.

　　The researchers then used a series of molecular techniques to eliminate the ability of Aedes aegypti to sense and respond to dopamine. Once the neurotransmitter is lost, the learning ability of mosquitoes to avoid harm becomes much worse.

　　For this "smart" mosquito, scientists may find new ways to control diseases transmitted by Aedes aegypti, such as Zika, dengue and yellow fever. After all, mosquitoes with poor learning ability are more likely to be killed.