Hungry Bats Prompt Firefly Flashes

We've all heard the phrase "blind as a bat," but fireflies make sure bats see them - and don't eat them. An article by Jennifer Viegas in Discovery News discusses a study about this that was published in Animal Behavior. The study explains that fireflies are toxic to bats, and fireflies advertise this by flashing a "don't eat me" signal at night. The bats see this flashing and know that eating these bugs is a bad idea.

This finding is the first evidence that fireflies flash to deter predators, not just for courtship. In fact, the researchers believe bioluminescence evolved in fireflies as a warning signal, and that bats helped maintain the signal, which later became used for courtship. Paul Moosman, Jr., the lead author of the study, explains that bat echolocation is not as perfect for hunting as it is for finding your way around without bumping into things; therefore, bats may try to eat fireflies if not for the flash.

The researchers examined the fecal pellets of insect-eating bats and found that 80% of the insects consumed were beetles, but very few were fireflies. Then the researchers fed the bats mealworms, with some of the mealworms coated with homogenized fireflies. When the bat's mouths came in contact with the mealworms coated with fireflies, they would cough or shake their heads and rub their snouts.

According to Moosman, one genus of firefly - Photinus - produces toxic compounds called lucibufagins. Another genus of firefly - Photuris sometime try to eat their smaller cousin, Photinus for their lucibufagins, which they could incorporate into their eggs.

The fireflies emit a series of flashes when they sense a predator. This signal is extremely beneficial to both fireflies and bats, and it would be interesting to learn more about its evolution.

http://news.discovery.com/animals/bats-fireflies-flash-poison.html

-Posted by Sarah Benjamin (week 7)