Science Briefs: Mosquitoes have limits for finding hot lunch

A thermal image from a sunlit patch of grass in Central Park in New York: Mosquitos seek out heat to help them find blood. Researchers are examining the molecular mechanisms behind this behavior.
A thermal image from a sunlit patch of grass in Central Park in New York: Mosquitos seek out heat to help them find blood. Researchers are examining the molecular mechanisms behind this behavior. Laboratory of Neurogenetics and Behavior at The Rockefeller University

Mosquitoes have heat-seeking limits

Researchers at Rockefeller University, in New York, have demonstrated that mosquitoes are exquisitely tuned to find heat sources that match the temperature of warm-blooded hosts, including humans. What’s more, they uncovered part of the molecular mechanism the insects use to fine-tune their behavior: When a specific gene was blocked, mosquitoes lost the ability to distinguish between different temperatures.

In one experiment, described this month in the journal eLife, researchers placed Aedes aegypti mosquitoes – carriers of yellow fever, dengue virus and other diseases – in a box lined with metal plates that could be heated up to specific temperatures. Opposite the plates, the researchers placed a tiny camera that captured how many mosquitoes were present on each plate at any given time. The results were obvious, grad student Roman Corfas noted: “The hotter a plate became, the more mosquitoes were attracted to it. But it got to the point when the plate became so hot, most mosquitoes began to avoid it."

The upper limit? Approximately 104 degrees Fahrenheit, close to the maximum temperature of birds – one of the hottest food sources for mosquitoes.

“The animals could even distinguish between temperature differences as small as 2.5 degrees,” Corfas said. Next, Corfas and Vosshall wanted to learn more about how mosquitoes fine-tune their temperature sensitivity. They blocked a gene called TRPA1, which is known to help other species seek out appropriate temperatures. The mosquitoes were unable to fine-tune their ability to seek out the ideal temperature.

Chitchat could be evolutionary need

We think of chitchat and small talk as the things people say to pass the time or kill an awkward silence. New research suggests, however, that these idle conversations could be a social-bonding tool passed down from primates.

Princeton University researchers report in the journal Animal Behaviour that social primates use vocalizations far more selectively than scientists previously thought. They found that ringtailed lemurs living in groups primarily call and respond to the individuals with which they have close relationships. While grooming is a common social-bonding experience for lemurs and other primates, the researchers found that lemurs reserved vocal exchanges for the animals that they groomed most frequently.

Venus, Saturn to pass in morning skies

Astronomers at the Pisgah Astronomical Research Institute, in Rosman, southwest of Brevard, have been watching the beautiful ringed planet Saturn gradually rise out of the morning twilight following its Nov. 30 passage behind the sun. In the meantime, the beautiful planet Venus, the “Morning Star” since August, is gradually sinking towards the sun in the same area of the sky.

An advisory from PARI said, “Since all the planets appear to move along almost the same elliptical path in the sky, these two must pass each other soon. ... This beautiful conjunction of the planets will be apparent on the morning of Jan. 9.

“Also visible in the morning skies from now until well into the new year are Mars and Jupiter. Just before dawn the bright planet Jupiter lies well up in the southwest on the border between Leo and Virgo. The red planet Mars, much dimmer than either Venus or Jupiter, lies about halfway between these two just to the left of Spica, the brightest star in Virgo. The moon, of course, is the brightest object in the nighttime sky. Venus is the brightest planet and Jupiter the second brightest. Both of these are brighter than any star at night.