Air Date: Week of August 30, 2002

Living on Earth’s Maggie Villiger reports on a novel survival technique for a caterpillar -- producing its own insecticide.

Transcript

CURWOOD: Coming up, the journey of the pink dolphins comes to our website. First, this page from the animal notebook with Maggie Villiger.

[THEME]

VILLIGER: The European cabbage butterfly is considered a pest here in North America where it likes to feast on vegetables like cauliflower, Brussels sprouts, and of course, cabbage. Scientists wondered what allows this species to gain such a strong foothold wherever it goes. The bug’s secret turns out to be a chemical defense system it produces in its larval stage. Rows of hairs run along the length of these caterpillars’ bodies. The tips of these hairs secrete a clear, oily fluid that collects in drops. In laboratory experiments, researchers watched as ants interacted with the cabbage butterfly caterpillars. As soon as an ant touched the caterpillar’s glistening hairs, it would back off and start frantically cleaning whichever body part had even brushed against the larva.

For good measure, the ant would also clean the body part it had used to clean the initial point of contact. When the scientists isolated the irritating secretion they found a new group of chemicals they named mayolenes. These chemicals derive from a family of compounds that plants use to repel insect attacks. It looks like the European cabbage butterfly is such a successful invader thanks to its own shield of insect repellant. That’s this week’s Animal Note. I’m Maggie Villiger.

[ANIMAL NOTE THEME]

CURWOOD: And you’re listening to Living on Earth

[GUITAR]

 

Links

Abstract of the article in Proceedings of the National Academy of Science