Tiger moths use signals to warn bats: Toxic not tasty

May 9, 2016, Wake Forest University
One of two tiger moths studied is pictured. Credit: Joseph Scheer

Acoustic warning signals emitted by tiger moths to deter bats - a behavior previously proven only in the laboratory - actually occur in nature and are used as a defense mechanism, according to new research from Wake Forest University.

Field research of free-flying bats conducted in their natural habitats by biology graduate student Nick Dowdy and colleagues shows that tiger moths produce to warn bats they don't taste good. This behavior - called acoustic aposematism - was previously proven in the laboratory by biology professor Bill Conner and Jesse Barber, who earned his doctorate at Wake Forest in 2007.

Birds and other mammals use visual aposematic signals like bright or highly contrasting patterns to advertise their toxicity. But, bats - the main predators for moths - don't rely on vision at night; they rely on sound. So, the moths developed an acoustic signal to deter the bats.

"The signals are, in essence, a warning to the bats that the moth is unpalatable and potentially harmful if ingested by the bats," Dowdy said.

The research, published in PLOS ONE, furthers the understanding of the evolution of animal behavior in the bat vs. moth arms race. Dowdy, who works in Conner's lab, said this is the first time the researchers have been able to show that this phenomenon, acoustic aposematism, actually occurs in nature. Dowdy specifically studied two types of tiger moths, the Pygarctia roseicapitis and the Cisthene martini.

Dowdy said he was also able to show evidence for what he calls a "nonchalance continuum" seen in multiple species. This means they don't always dive out of the way when bats approach. He said most moths enact evasive dives and spiraling flight when a bat is about to capture them, "presumably at a cost to the moth as it can be energetically costly to do these maneuvers. "We've found that this is only sometimes true in tiger moths and different species appear to use these behaviors at different rates."

The implication is that certain species may have evolved to rely on their warning sounds instead of the evasive maneuvers common to most eared moths. Dowdy said the results suggest that acoustic aposematism is likely to be the ancestral function of sound production in tiger moths.

"This means that in evolutionary history these moths first evolved these sounds for use in warning of their toxicity and then sometime later, these sounds grew in complexity in certain species to perform a sonar jamming function," he said.

Explore further: Toxic tiger moth: Researchers study evolutionary arms race in Arizona desert

More information: Nicolas J. Dowdy et al, Acoustic Aposematism and Evasive Action in Select Chemically Defended Arctiine (Lepidoptera: Erebidae) Species: Nonchalant or Not?, PLOS ONE (2016). DOI: 10.1371/journal.pone.0152981

Related Stories

Tiger moths: Mother Nature's fortune tellers

June 3, 2013

When it comes to saving its own hide, the tiger moth can predict the future. A new study by researchers at Wake Forest University shows Bertholdia trigona, a species of tiger moth found in the Arizona desert, can tell if ...

Large moths need to hear better

August 19, 2013

Bats orient themselves through echolocation, and they find their prey by emitting calls and then process the echoes reflected back to them from the prey. Small insects reflect small echo signals, and large insects reflect ...

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

EPA adviser is promoting harmful ideas, scientists say

March 22, 2019

The Trump administration's reliance on industry-funded environmental specialists is again coming under fire, this time by researchers who say that Louis Anthony "Tony" Cox Jr., who leads a key Environmental Protection Agency ...

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.