Air Date: Week of January 3, 2003

Living on Earth’s Maggie Villiger reports on the chemical weapons a wasp uses to get into an ant nest to lay its eggs inside a caterpillar hiding inside.

Transcript

CURWOOD: Just ahead: Little oil drips add up in the ocean. First, this page from the Animal Notebook with Maggie Villiger.

VILLIGER: There’s more clandestine behavior inside the nest of Myrmica schencki red ants than at a spy convention. The first level of intrigue: Caterpillars of the Maculinea rubeli butterfly emit a pheromone that tricks ants into thinking they are ant larvae. The cuckolded ants cart the larvae home and adopt them as their own.

But the caterpillars aren’t home free. A particular parasitic wasp can only lay its eggs in the caterpillars’ bodies. And it knows how to make it past the ants’ line of defense. Its weapon of choice: chemical warfare.

Scientists have discovered that the wasp is covered in a kind of oily wax made up of six chemicals that cause ant behavior to go haywire. The chemical cocktail attracts ants to investigate the intruder, then repels them and makes them start fighting with each other. The nest starts to look like a barroom, with brawling ants biting each other and pulling on legs.

All this misdirected mayhem allows the wasp to move unnoticed through the nest ‘til she reaches her target, the caterpillar. The wasp lays her eggs, and then sneaks out again while the ants are still distracted.

The researchers suggest that these newly discovered wasp chemicals could eventually lead to a new kind of long-lasting pesticide. That’s this week’s Animal Note. I’m Maggie Villiger.

CURWOOD: And you're listening to Living on Earth.

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