Summer Science: Firefly Babies Advertise Their Bitter Taste, UD Researchers Say

June 30, 1997

JULY 2, 1997--As children chase twinkling insects and the setting sun throws long shadows across the backyard, consider this: Light cues keep predators from snacking on baby fireflies, University of Delaware scientists report in the new Journal of Insect Behavior.

"A flashing neon sign may lure hungry humans to an all-night diner," says Douglas W. Tallamy, professor of entomology and applied ecology, "but the bioluminescence of firefly larvae sends a very different message to would-be predators."

The UD study is believed to offer the first laboratory-based evidence of an insect using bioluminescence--rather than coloration--as an "aposematic display," which warns predators of an unappetizing or hazardous meal. Bright colors, such as the orange and black patterns on a monarch butterfly or the yellow stripes on a wasp, are far more typical examples of aposematic display, Tallamy notes. Baby fireflies (Coleoptera: Lampyridae) clearly use light signals to ward off predators, UD researchers found.

This new insight into firefly behavior may serve as an educational tool for both adults and children this summer, Tallamy says. "The more people understand about their natural world, the more they are likely to appreciate why it must be preserved for future generations," he explains. "And, children who understand why fireflies are flashing may get hooked on science."

Decoding light signals

Since at least 1952, researchers have known that adult fireflies use light patterns as part of a mating ritual, Tallamy says. Because baby fireflies are not mature enough to reproduce, researchers have speculated that younger specimens might use light cues for survival, rather than reproduction. Without laboratory evidence to support the theory, however, the messages sent by firefly larvae have remained a mystery--until now.

With graduate student Todd J. Underwood and John D. Pesek, an associate scientist in UD's Department of Food and Resource Economics, Tallamy tested the aposematic display theory on ordinary house mice raised in a laboratory. But first, the UD researchers needed to find out whether mice think firefly larvae taste bad.

In previous laboratory studies, vertebrate predators have consistently turned up their noses at lucibufagins, compounds present in adult fireflies. But, Tallamy notes, "only anecdotal evidence suggested that larvae are also distasteful." So, mice were offered a choice of either a firefly or a mealworm--a delicacy for rodents. As expected, all mice rejected the bitter fireflies, Tallamy says, even when they were still hungry enough to eat more mealworms.

Next, the UD researchers tested the ability of mice to associate light with a bitter taste. At one end of a Y-shaped maze, they placed a single piece of crispy rice cereal. A second piece of cereal was soaked in a stomach-turning concoction of quinine sulphate and mustard powder before being placed on the other side of the maze, which was rigged with a light-emitting diode. Though mice initially entered the maze "with a bias toward the glowing branch," they quickly learned to steer clear of the bitter-tasting tidbit, UD researchers say. Within eight to 47 runs, all mice had selected the darkened side of the maze at least seven times in a row.

"Our study answers a fundamental question that entomologists have been pondering for some time," Tallamy says. It also suggests an interesting topic for discussion between parents and children, he adds.

###




University of Delaware

Related Predators Articles from Brightsurf:

Boo! How do mexican cavefish escape predators?
When startled, do all fish respond the same way? A few fish, like Mexican cavefish, have evolved in unique environments without any predators.

Herbivores, not predators, most at risk of extinction
One million years ago, the extinction of large-bodied plant-eaters changed the trajectory of life on Earth.

Bugs resort to several colours to protect themselves from predators
New research has revealed for the first time that shield bugs use a variety of colours throughout their lives to avoid predators.

Jellyfish contain no calories, so why do they still attract predators?
New study shows that jellyfish are an important food source for many animals.

'Matador' guppies trick predators
Trinidadian guppies behave like matadors, focusing a predator's point of attack before dodging away at the last moment, new research shows.

The European viper uses cloak-and-dazzle to escape predators
Research of the University of Jyväskylä demonstrates that the characteristic zig-zag pattern on a viper's back performs opposing functions during a predation event.

Predators help prey adapt to an uncertain future
What effect does extinction of species have on the evolution of surviving species?

To warn or to hide from predators?: New computer simulation provides answers
Some toxic animals are bright to warn predators from attacking them, and some hide the warning colors, showing them only at the very last moment when they are about to be attacked.

Dragonflies are efficient predators
A study led by the University of Turku, Finland, has found that small, fiercely predatory damselflies catch and eat hundreds of thousands of insects during a single summer -- in an area surrounding just a single pond.

Predators to spare
In 2014, a disease of epidemic proportions gripped the West Coast of the US.

Read More: Predators News and Predators Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.