Scientists have developed a tool to study the biting behavior of mosquitoes, which are common carriers of pathogens. This is evident from new research published in eLife this week.
Using an artificial blood meal and a surface that mimics human skin, the tool provides a detailed understanding of blood nutrition without using human subjects as bait. It also fits comfortably in a backpack and allows mosquito testing in laboratory and natural settings.
Blood feeding is essential for mosquitoes to reproduce, but while feeding blood to human hosts they pass on pathogens such as malaria.
Although the first step in obtaining a blood meal – flying towards a host – is relatively well characterized, the steps that unfold after a mosquito lands on a host are less well understood. There is a dearth of tools for measuring mosquito bite behavior, and those that exist rely on the use of human hosts, limiting the number and types of experiments you can conduct. This way, you cannot examine mosquitoes carrying pathogens. “
Felix Hol, first author, researcher at the Pasteur Institute and the Center for Research and Interdisciplinarity, Paris, France
This is important because it is believed that factors such as infection can affect a mosquito’s feeding behavior, including the number of attempts at feeding and the size of the meal they ingest. These aspects, in turn, can change the transmission dynamics of pathogens. To remedy this, Hol and colleagues from Stanford University, California, USA, the Pasteur Institute, and the CRI (Universite de Paris / INSERM), Paris, France, developed the BiteOscope – a tool that can be used to examine how Mosquitoes research and examine host skin surfaces before eating.
It consists of a bite substrate – a transparent, temperature-controlled surface that mimics body temperature to attract mosquitoes. An artificial meal is placed on top and covered with a commonly used membrane that mosquitoes can penetrate. The meal is similar to blood and allows mosquitoes to multiply and add two to three times their weight. This bite substrate is then placed in a transparent cage and an external camera records the behavior of the mosquitoes.
The team tested BiteOscope with four medically important mosquito species and created a computer model to analyze behavior based on images taken of the mosquitoes as they landed on the “skin”. “We have found that the time a mosquito spends researching skin that does not lead to a successful diet is rarely longer than the duration of a successful diet,” says author Louis Lambrechts, director of research at the Institute for Virology Pasteur Institute. “This suggests that if no blood is found within a certain time, the mosquitoes will give up and move on.”
Next, they showed how the tool can track parts of the body to understand how the mosquitoes “pick up” the surface they are exploring. When they coated the skin mock-up with DEET insect repellent, they found that mosquitoes had a tendency to land and take off immediately, only making contact with their legs, suggesting that the repulsion is mediated through leg contact.
“We used the BiteOscope to describe the behavioral patterns of four major mosquito species. This provides a useful knowledge base for future studies of blood-feeding behavior,” concludes author Manu Prakash, assistant professor of bioengineering at Stanford University. ‘In a broader sense, we hope that the tools presented here offer a new perspective on mosquito behavior relevant to pathogen transmission, and allow researchers to gain a detailed understanding of blood nutrition without sacrificing their own skin have to.”
Hol, F. et al. (2020) BiteOscope, an open platform for studying mosquito bite behavior. eLife. doi.org/10.7554/eLife.56829.