The latest research has found a protein called yolk proteinogen in disease-carrying mosquitoes, which controls the attractiveness of human blood to mosquitoes. According to the latest study, feeding mosquitoes sugar is enough to have an effect on the protein, so that they don't bite humans for a while.
The findings have been published in the journal Public Science Library - Biology. Paolo Gabrieli, a zoologist at the University of Milan in Italy, said: "If you can avoid mosquitoes being attracted to human hosts, then you can reduce the chances of humans being infected by mosquito arboviruses. ”
The researchers studied the behavior of the Asian tabby mosquito, also known as Aedes albopictus. The mosquitoes are native to parts of Southeast Asia, but they have become invasive species that have spread to many tropical countries around the world. Humans are particularly attractive to mosquitoes, especially those living in urban areas, which can transmit a variety of nasty diseases such as dengue, chikungunya and yellow fever, and they may also transmit Zika virus.
Female tabby mosquitoes must suck blood to get the energy needed to lay their eggs, but they also sometimes feed on plant nectar or sugar in tree sap. The researchers wondered whether a full meal of sugar would reduce their desire to suck blood. They fed young female mosquitoes a sugar solution, then put 10 to 12 mosquitoes into a clear plastic cup and put the side of the opening in their hands to understand how much the mosquitoes were interested in human blood. They can observe how many mosquitoes try to bite their hands through a special barrier, but this barrier will block them.
They found that when these young female mosquitoes collectively ate sweets, they were no longer interested in human blood. Zoologist Gabrieli said the effect lasted five or six days at the time of the study. Jeff Riffell, a biologist at the University of Washington, was not involved in the study, but his lab is conducting a similar study. "We don't know much about how blood sucking affects mosquito feeding behavior, but we don't know much about how sugar changes the attraction of blood to them," he claims. This research can be said to fill an important academic gap. ”
The researchers also performed RNA sequencing on mosquitoes that had eaten sugar. They found an association between changes in the expression of some genes and their reduced interest in human blood. One of these, the pro-yolk protein gene called Vg-2, also plays a role in ovarian development in female mosquitoes. When mosquitoes eat sugar, there are more changes in this gene. Gabrieli said: "During the development of mosquito eggs, this protein (yolk proteinogen) is used to promote the development of the embryo. ”
When the researchers then conducted another experiment, they interfered with the mosquito's RNA and reduced the expression of Vg-2. As a result, they noticed that although the female mosquitoes had eaten sugar, they still felt hungry and thirsty for human blood. Riffell claimed: "This is a truly great interdisciplinary study. The combination of behavioral and molecular studies shows how mosquitoes make feeding decisions. In fact, we are very interested in how these hormones and chemicals regulate the attractiveness of blood to mosquitoes. ”
Riffell said this information could be used to develop a non-lethal way to suppress mosquito bites. Animals are already producing these chemicals naturally. If we really start synthesizing analogues or chemicals and somehow passing them on to mosquitoes. Then it has the potential to be a way to curb mosquito bite behavior.
Gabrieli said that while the technique may be effective in the short term, it will not be able to permanently drive away tabby stripes, especially tiger mosquitoes can survive for about 60 days (their lifespan in the laboratory), while sugar-induced inhibition of bite behavior lasts less than a week. Feeding sugar also appears to have an effect only on young female mosquitoes, as they may be more dependent on sugar after they leave the larval stage than older mosquitoes.
But Riffell said any measure to reduce the overall number of bites in humans should be able to reduce the rate of transmission of mosquito-borne diseases, which in turn could have a huge impact on the number of deaths worldwide. According to the World Health Organization (WHO), malaria, transmitted through another mosquito, killed 429,000 people in 2015 alone, while in some Latin American and Asian countries, dengue fever is the leading cause of child mortality. "If you can reduce their bites, then you can really reduce the chances of these diseases spreading," Riffell said. ”