Mosquitoes are the deadliest animal on earth. These little flying insects are the carriers of dengue fever, yellow fever, Zika, malaria, and several other diseases that kill and infect millions of people worldwide.
Since they transmit illness via human bites, it is critical to recognize their feeding habits in order to reduce the damage they bring. But without actually feeding mosquitoes, how can researchers observe their eating habits?
Rice University and Tulane University in the US worked together to make a biomaterial that could make it possible to study mosquito bites without using people or animals as test subjects.
“Several groups are dedicated to finding ways to stop mosquitoes from biting, but bringing new repellents to market is challenging,” remarks corresponding author Prof Omid Veiseh, Rice University. “This study attempts to increase testing throughput and decrease dependence on human volunteers and animal subjects.”
The team made a platform that used 3D-printed hydrogels made to look like human skin, along with video monitoring and computer vision techniques to analyze the data. The process of feeding on blood-perfused hydrogels was captured on film for mosquitoes, and this footage was utilized to train a machine learning model that could distinguish between mosquitoes that had fed from the hydrogels and those that had not. This made it simpler to swiftly and efficiently examine data on many feeding mosquitoes with an average accuracy of 92.5%.
It is possible to study various mosquito species that feed on various types of prey thanks to the hydrogels’ ability to be perfused with various types of blood and other liquids. The hydrogels also allowed scientists to validate their model by demonstrating that the mosquitoes were attracted to blood by perfusing it with various fluids.
The biomaterial was evaluated by comparing mosquito reactions to sets of plain hydrogels, hydrogels covered with DEET, and hydrogels coated in a plant-based repellant. Blood heated to 37 degrees Celsius was perfused into all of the hydrogels. The mosquitos given repellent-coated hydrogels did not feed on blood, but 13.8% of the mosquitos in the control cage did.
Despite the fact that this is a relatively low percent, the authors hypothesized that it may be because of the hydrogel’s limited surface area, which might be fixed by scaling up. The hydrogels’ ability to be made in huge quantities at a cheap cost and stored in the refrigerator until required is one of its benefits.
Although the platform is designed for use in the laboratory, the authors speculated that it may be modified for use in the field, more closely simulating real-world disease transmission settings. However, the authors noted that this would need more investigation.
“All of the experiments used lab strains of mosquitoes, and the majority involved one particular species: Aedes aegypti, the vector of the yellow fever virus, dengue virus, Zika virus, and others,” adds co-corresponding author Prof. Dawn Wesson. “It may take time to optimize our experimental platform and machine learning model to study other species. Also, since the behavior of laboratory strains sometimes differs from that of mosquitoes found in the wild, it would be important to validate our results on wild mosquito populations.”
“Overall, our results suggest that our experimental platform could be scaled up and adapted to screen different compounds for their effects on mosquitoes,” adds Veiseh, looking forward to future research.
“Also, the machine learning model we developed can automate experimental analysis and provide results far more quickly and consistently than a human could,” remarks Dr. Kevin Janson, first author of the study. “We hope that this platform could rapidly identify promising candidates for more effective repellents to decrease the spread of disease in the future.”
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