Can a cup of sugar water at home repel mosquitoes? Is there a scientific basis for folk mosquito repellent law?

There is a folk mosquito repellent method called syrup mosquito repellent method. You need to prepare a cup, pour cold water, then add sugar and put it in the room. Beverage bottles with leftover drinks also have this effect. Sweetness will attract mosquitoes, thus attracting their attention to the human body. Although this folk prescription sounds unreliable, scientists have confirmed the scientific nature of liquid medicine mosquito repellent method. A study published in PLoS Biology found that sugar is a natural alternative food source for mosquitoes, and feeding sugar is probably a low-risk alternative strategy for female mosquitoes to bite humans before pregnancy.

Based on previous studies, researchers in university of pavia hypothesized that the behavior of looking for a host might be related to the female mosquito's own nutritional reserves. When the energy level became limited, they began to look for the blood of other creatures as a source of nutrition. Some observed natural phenomena can illustrate this point. For example, some female mosquitoes have good nutritional reserves, so they don't need to suck the blood of other organisms before laying the first batch of eggs, while those female mosquitoes with insufficient nutrition need to eat a lot? Blood meal? . In addition, female mosquitoes often feed on plant nectar rich in carbohydrates, and convert the ingested sugar into high carbohydrate and lipid reserves, which is also a way for them to supplement their own nutrition and energy.

In order to test this hypothesis, the researchers take Aedes albopictus (a mosquito that can spread diseases such as dengue fever, yellow fever and Zika) as the research object, hoping to test whether the nutritional level of mosquitoes is related to the behavior of finding a host by studying the effect of feeding sugar on mosquitoes. The researchers prepared some transparent plastic cups covered with nets and put mosquitoes into these cups respectively. Hang a cotton ball in each cup, and soak the cotton ball in sucrose water with different concentrations of 5%, 20% and 50% respectively. The researchers put a hand above the cup 1 minute every day to observe the attraction of the human body to these mosquitoes. The results showed that compared with the cup with pure water, the aggression of mosquitoes in the cup with sugar water was much weaker, and the higher the concentration of sugar water, the more obvious the aggression to people was.

Further molecular biology experiments found that the researchers' initial assumptions were wrong. Can Aedes albopictus eat? Blood meal? It has nothing to do with its own nutritional reserves, but with the expression of vitellin gene Vg-2 in vivo. When mosquitoes eat sugar water, the higher the expression of Vg-2, the smaller the impulse of mosquitoes to suck blood. When mosquitoes bite humans to suck blood, it will also lead to an increase in Vg-2 expression and inhibit the impulse to continue sucking blood. In other words, feeding female mosquitoes with sugar water can really replace biting. ? Sugar-mediated yolk protein gene expression reduces the activity of mosquitoes to find hosts. ? The researchers wrote in the article that sugar feeding can be used as an alternative strategy for biting human behavior, and this discovery will reduce the spread of diseases caused by mosquitoes.