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Bitter moths can't be bothered by hungry bats

By Brooks Hays
Some moths do not engage in evasive maneuvers to avoid predators such as bats because they know they're less appetizing. Pictured is one of the so-called lazier moths that helped researchers make the finding, Carales arizonensis. Photo by <a href="https://en.wikipedia.org/wiki/Carales_arizonensis#/media/File:Carales_arizonensis.jpg">Benoit Vincent</a>/BOLD Systems/Wikimedia<br>
Some moths do not engage in evasive maneuvers to avoid predators such as bats because they know they're less appetizing. Pictured is one of the so-called lazier moths that helped researchers make the finding, Carales arizonensis. Photo by Benoit Vincent/BOLD Systems/Wikimedia

Dec. 16 (UPI) -- Prey rely on all sorts of defense mechanisms to evade hungry predators. For at least a few moth species, the defense comes with a side of indifference.

While studying predator-prey interactions, scientists noticed some tiger moth species appeared unfazed by attacking bats. While most moths use aerial maneuvers, swoops and dives, to avoid getting eaten, a few lazily fluttered as if danger was faraway.

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Nicolas Dowdy, of the Milwaukee Public Museum and Wake Forest University, hypothesized that the lazier moths had evolved chemical defenses that make them taste bad.

Still, Dowdy wondered why bitter moths wouldn't try to avoid aerial attacks anyways. He surmised such maneuvers weren't worth the risks.

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Midair ducks and dives increase the odds of a collision with a spider web. An erratic aerial maneuver might also take a moth off the track of a potential mate or food source.

Dowdy hypothesized that some moths decide to play it safe and avoid the risks.

To test the hypothesis, he and his research partners released several tiger moth species into the night sky in a place frequented by hungry bats. Infrared cameras helped the researchers capture the predator-prey interactions.

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In addition to tracking the flight patterns of each moth, the cameras also helped scientists observe whether bats consumed a moth or spit it out after catching the insect.

"Strikingly, we observed that moths with weak or no chemical defenses often dive away to escape bat attacks," said Dowdy. "However, moths with more potent chemical defenses are more 'nonchalant,' performing evasive maneuvers less often."

Dowdy and his partners published their observations on Monday in the journal Frontiers in Ecology and Evolution.

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The authors of the new studied measured the chemical makeup of different tiger moth species and estimated how palatable each were. Using their predator-prey interaction data, researchers were then able to estimate which moths would prove to be lazy fliers and which would swerve and dive to avoid bats.

Scientists estimate that they could use their research -- and the newfound relationship between bitterness and lazy flying -- to determine the flying styles of extinct insects.

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