Human blood is cappuccino for mosquitoes — stimulating and hot, but not too hot

Though a mosquito’s body temperature is a cool 28 degrees Celsius (82.4 Fahrenheit), its highly evolved thermosensory system prefers to drink the blood of organisms with a temperature of 37 degrees Celsius … Fahrenheit 98.6.

The millennia-old waltz between mosquitoes and the creatures possessing their optimal blood — humans — is one with tragic consequences for half of our planet today, each year yielding 200 million malaria cases and 400,000 human deaths.

Virginia Tech School of Neuroscience Assistant Professor Lina Ni hopes to cut in on this dance by researching one of a mosquito’s more lab-friendly and less dangerous colleagues, the fruit fly. Her research has recently been awarded a five-year $1.05 million grant from the National Institute of General Medical Sciences, part of the National Institutes of Health.

“If we limit mosquitoes’ ability to detect temperature change, we hope that we can better control them,” Ni said. “Hopefully then they will not be able to find us so the disease will not be spread.”

Like all animals, mosquitoes rely on ambient temperatures to set their body temperatures and “guide the blood-feeding behaviors through which they transmit human diseases,” Ni wrote in her grant proposal. “Thus, it is important to identify the temperature-sensing molecules and neurons to help control disease vectors.”

Igor Sharakhov, a professor in the Department of Entomology and an affiliated member of the Fralin Life Sciences Institute who is not part of the study, added “To study how mosquitoes sense temperature is important for understanding not only their blood-feeding behaviors but also other aspects of the mosquito’s biology. The temperature of the environment affects the mosquitoes’ geographic distribution, physiological adaptations, reproductive and development rates, migration patterns, and population dynamics. Ultimately, how mosquitoes sense temperature may impact the development and transmission of some of the most-deadly pathogens, including malaria parasites and dengue viruses.”

Fruit flies, or Drosophilia, share some mosquito traits without the ability to transmit disease to humans. They also have “very powerful genetics,” allowing them to be genetically manipulated to see if the neurons involved in the temperature-sensing systems can be tweaked, Ni said.

Preliminary studies from Ni’s lab, part of the Virginia Tech College of Science, have discovered a set of previously unidentified warm-activated neurons in fly larvae that detect warm temperatures. These neurons may have an additional function to modulate their neighboring cool-activated neurons. 

“This study might provide novel targets to control blood-feeding behaviors of mosquitoes and other disease vectors,” Ni wrote in her grant proposal.

For Alisa Omelchenko, manager of Ni’s laboratory, the experience of identifying thermosensory molecular targets has been exceptional.

“Temperature sensation is vital for animals to survive, mate, and reproduce but the molecular and cellular mechanisms are still widely unknown,” Omelchenko said. “Thermosensory research within [fruit flies] allows the development of simplified, though still complex, models and helps determine molecular targets that can be adapted to modify heat-seeing behaviors in disease vectors, such as mosquitos. This fundamental research creates an opportunity to develop methods of modifying mosquito feeding behavior and ultimately prevent their spread of diseases.”

Ever the neuroscientist, Ni insists that her research isn’t really about mosquitoes, despite the fact that the results of her research may abate a scourge that afflicts half the world. “I focus on temperature-sensing receptors and neurons,” Ni said. “When I saw that animals responded to temperatures behaviorally or neurons are activated by temperature changes, I always felt it was amazing.”

— Written by Michael Hemphill