Too Hot or Too Cold: Scientists Discover Insect Sensor that Detects Temperature

Is it too hot or too cold? Apparently insects can tell---in more ways than one. Scientists have discovered that a previously unknown molecular temperature sensor in fruit flies belongs to a protein family responsible for sensing tastes and smells. The findings could allow researchers to understand why blood-seeking pests, such as mosquitoes, seek out warm-blooded prey.

Scientists have known for years that insects possess very sensitive temperature sensors. These detect a relatively narrow margin in which they can survive, but researchers knew very little about how they operated. These sensors, though, allow mosquitoes to detect the warmest areas of a body--usually where the most blood is. This allows them to feed more efficiently.

"If you can find a mosquito's temperature receptor, you can potentially produce a more effective repellent or trap," said Paul Garrity, one of the researchers, in a news release.

In order to examine these receptors a bit more closely, the researchers examined the fruit fly. They were able to find a sensor in the insect that belongs to a family of proteins, called gustatory receptors. These receptors have been studied for over a decade, but have never been linked to thermosensation before. Yet in this latest study, the scientists found that one kind of gustatory receptor senses heat rather than smell or taste.

The newly discovered receptor is known as Gr28b. It's responsible for sensing external temperatures and also triggering a quick response if these temperatures exceed the "Goldilocks zone" that the fly can survive in.

The findings reconcile previously conflicting views as to how a fruit fly senses warmth. In addition, it could have implications for other insects that spread disease, such as mosquitoes. The more scientists understand about how insects respond to and sense heat, the better they can understand the spread of disease through insect bites.

"The research reveals a new way in which animals detect temperature," said Garrity. "It's important because heat detection is critical for the behavior of insects that spread disease, kill crops and impact the environment."

The findings are published in the journal Nature.