How do insects feel the heat?

March 6, 2019 by Lawrence Goodman, Brandeis University
Anopheles gambiae mosquito, feeding on blood. Credit: James Gathany, Centers for Disease Control and Prevention

Every year, nearly 700 million people contract mosquito-borne illnesses such as malaria, dengue, West Nile virus or yellow fever.

Mosquitoes are so good at spreading disease in large part because of their ability to seek out humans and feed on them. Both of these abilities depend on the acute sensitivity of a mosquito to its environment's .

When a gets a whiff of carbon dioxide, alerting them to a potential victim in the vicinity, it becomes drawn to heat and humidity. These cues help the mosquito find us and then begin to probe the warmest spots on our skin, which happen to be where the blood vessels reside.

To gain clues into how the ' sensory systems might operate, scientists often study how these processes work in , whose physiology is similar, but easier to study.

In a new paper in the journal Neuron, professor of biology Paul Garrity and his lab upend the traditional understanding of how flies sense and respond to temperature. The work may one day lead to more effective methods of keeping mosquitoes away from humans.

Fruit flies, a.k.a. Drosophila melanogaster, sense temperatures using at the tips of their antenna. However, researchers had long thought that these neurons acted like thermometers, reporting on whether the temperature was hot or cold. This is reflected in the names given to these neurons: the Hot and Cold Cells.

Credit: Brandeis University

As fruit flies are drawn to mild temperatures, it was assumed that Hot and Cold Cells signaled to the insects' brains that it was either too warm or cold, allowing the flies to steer themselves to their Goldilocks zone, where the temperature was just right.

Using a new method devised by post-doctoral fellow Gonzalo Budelli, Garrity and his colleagues found that Hot and Cold Cells don't detect hot and cold after all. Rather, they respond to changes in temperature.

For this reason, they propose renaming these neurons Heating and Cooling Cells. Together these don't tell the animals whether the environment is hot or cold, but only that the temperature is rising or falling. "They simply let the animal know that the temperature is changing," Garrity said.

Drosophila have six Heating and six Cooling Cells, with three of each type in each antenna. They are exquisitely sensitive to fluctuations in temperature. Garrity's lab found they can detect a few hundredths of a degree change per second—"incredibly subtle changes in thermal energy," Garrity said. As a result of this sensitivity, fruit flies are guided with the most precision and efficiency toward their Goldilocks zone. These findings suggest that mosquitoes may use a similar system to help drive precise and efficient movement of mosquitoes to their warm-blooded targets.

Garrity suspects that flies may also have Hot and Cold Cells, they are just not the ones scientists had thought they were.

Explore further: The temperature tastes just right: Scientists discover new insect temperature sensor

More information: Gonzalo Budelli et al. Ionotropic Receptors Specify the Morphogenesis of Phasic Sensors Controlling Rapid Thermal Preference in Drosophila, Neuron (2019). DOI: 10.1016/j.neuron.2018.12.022

Related Stories

Taking the temperature of the no-fly zone

June 11, 2008

Flies, unlike humans, can't manipulate the temperature of their surroundings so they need to pick the best spot for flourishing. New Brandeis University research in this week's Nature reveals that they have internal thermosensors ...

Recommended for you

Fish-inspired material changes color using nanocolumns

March 20, 2019

Inspired by the flashing colors of the neon tetra fish, researchers have developed a technique for changing the color of a material by manipulating the orientation of nanostructured columns in the material.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.