Flight path data shows how mosquitoes target humans

Transmitted infectious diseases By mosquitoes, e.g malariaDengue and Zika fever – kill more than 770,000 people worldwide every year. Understand how Mosquitoes Finding humans has long been a challenge in controlling the spread of these diseases. However, little is known about how mosquitoes integrate multiple signals, including visual information and carbon dioxide, to reach their targets.

In this context, a research team led by the Georgia Institute of Technology and the Massachusetts Institute of Technology has reached a conclusion He succeeded Automatically derive a dynamic model that governs mosquito flight by applying Bayesian inferential statistical methods to a vast amount of data recording mosquito movements.

Bayesian inference is a statistical technique that probabilistically determines the most plausible model parameters from observed data. Using this method, the researchers were able to build a mathematical model that can reproduce experimental results with high accuracy while compressing mosquito behavior to fewer than 30 parameters.

“The big question was: How do mosquitoes find a human target?” He explains Cheng Yifei is a postdoctoral researcher at MIT. “There have been previous experimental studies on what kind of signals might be important. But there have been no particularly quantitative studies.”

Mosquitoes have two ways of flying

The search team released two women Aedes aegypti Mosquitoes were housed in an enclosed experimental space and recorded their flight paths in 0.01-second increments using two infrared cameras. The data obtained from a total of 20 experiments exceeds 53 million points, with more than 400,000 flight paths recorded. This represents the largest data set ever collected for a study quantitatively measuring mosquito flight.

The experiment began by filming mosquitoes flying around humans who were wearing dark clothing. This observation revealed that Aedes aegypti The mosquitoes focused their approach on human heads. This was a fundamental finding that served as the starting point for the entire study.

Next, the researchers conducted experiments on people wearing black on one side and white on the other. They found that although carbon dioxide and body odor were emitted equally from both sides of the body, the mosquitoes’ flight paths were concentrated only on the black side. Although strange at first glance, this result clearly demonstrated that visual stimuli play an important role in searching for targets in a windless environment.

Furthermore, a detailed analysis of mosquitoes flying in a stimulant-free environment revealed that their flight patterns can be broadly classified into two types. One was the active state, where they actively explored space while maintaining a speed of about 0.7 meters per second. The other was an idle state, where they flew with almost no propulsion. The dormant state is thought to be a preparation phase for landing, and has been repeatedly observed near the ceiling of the experimental space.

Analysis of mosquitoes’ responses to visual stimuli revealed that mosquitoes are attracted to dark objects and slow down when they reach a distance of approximately 40 cm. However, without additional cues such as body odor, humidity, or heat, mosquitoes often fly away even after approaching their target. This suggests that visual stimuli alone are insufficient to induce landing and blood absorption.

The response to carbon dioxide sources was quite different. Mosquitoes that came within a radius of about 40 cm of the carbon dioxide source suddenly slowed to 0.2 m/s and began flying erratically, swaying without clear direction. Numerical simulations also showed that mosquitoes can detect carbon dioxide concentrations as low as 0.1 percent, and that their detection range extends to about 50 cm from the source.

Furthermore, the mosquitoes’ response changed more dramatically when visual stimuli and carbon dioxide were presented simultaneously. Mosquitoes began to circle around the target, and significantly more mosquitoes concentrated near the target than when either stimulus was used alone.