Wake Forest study finds that moths mimic sounds to survive

[Mike Quinn]

Wake Forest University - Press Release

WFU study finds that moths mimic sounds to survive

May 29, 2007

In a night sky filled with hungry bats, good-tasting moths increase
their chances of survival by mimicking the sounds of their bad-tasting
cousins, according to a new Wake Forest University study.

To be published in the May 29 issue of the Proceedings of the National
Academy of Sciences, the study is the first to definitively show how
an animal species uses acoustic mimicry as a defensive strategy.

The research was conducted by Jesse Barber, a doctoral student in
biology at Wake Forest.  William E. Conner, professor of biology at
Wake Forest, co-authored the study.

In response to the sonar that bats use to locate prey, the tiger moths
make ultrasonic clicks of their own.  They broadcast the clicks from a
paired set of structures called "tymbals."  Many species of tiger moth
use the tymbals to make specific sounds that warn the bat of their bad
taste.  Other species make sounds that closely mimic those
high-frequency sounds.

"We found that the bats do not eat the good-tasting moths that make
the similar sounds," said Barber, who has worked on this research for
four years.

In the study, other types of moths that were similar in size to the
sound-emitting moths, but did not make sounds, were gobbled up by the
bats.

The researcher trained free-flying bats to hunt moths in view of two
high-speed infrared video cameras to record predator-prey interactions
that occur in fractions of a second.  He also recorded the sounds
emitted from each moth, as well as the sounds made by the bats.

All the bats quickly learned to avoid the noxious moths first offered
to them, associating the warning sounds with bad taste.  They then
avoided a second sound-producing species even though it was not
chemically protected. This is similar to the way birds avoid
butterflies that look like the bad-tasting Monarch.

The two species of bats used were big brown bats and red bats. Barber
raised the bats in the lab so behavior learned in the wild would not
influence the results of the experiment.

Barber said anecdotal observations have suggested that animals such as
snakes, owls and bees use acoustic mimicry.  This study takes the next
step and provides the definitive experimental evidence for how
mimicking sounds helps an animal survive.

http://www.wfu.edu/news/release/2007.05.29.a.php


Mike Quinn, Austin

 
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