Friday Cat-erpillar Blogging: Hair

Pieris rapae caterpillar

Cabbage Worms, Pieris rapae, have glandular hairs with defensive secretions

The cabbage white butterfly is the most common butterfly in Indiana. An invasive species, it is a pest of cabbages and is is not controlled adequately by diseases, predators and parasitoids. Cabbage worm caterpillars are defended by tiny glandular hairs that secrete droplets of a liquid, deterrent to insect predators. The chemical secretions, identified by Smedley and colleagues*, belong to a new group of lipids, the mayolines.

Smedley and colleagues collected the caterpillar secretions and tested them against predatory ants. Ants that contact the secretions reject the caterpillars and engage in “cleaning” behaviors to remove the chemicals. The droplets can be rinsed from the caterpillars by solvent. Droplet removal eliminates much of the deterrent properties of the caterpillar. Ants will eat mealworms, but transferring the mayolines to the mealworms will deter the ants.

Ants can be important biological control agents, keeping pest populations in check. Caterpillars that can deter ants, can minimize mortality due to predation and develop large populations. This is another reason why Cabbage White Butterflies are so numerous.

*Scott R. Smedley, Frank C. Schroeder, Douglas B. Weibel, Jerrold Meinwald, Katie A. Lafleur, J. Alan Renwick, Ronald Rutowski, and Thomas Eisner. Mayolenes: Labile defensive lipids from the glandular hairs of a caterpillar (Pieris rapae). PNAS May 14, 2002 vol. 99 no. 10 6822-6827
doi: 10.1073/pnas.102165699

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in behavior, Biomaterials, by jjneal, Caterpillar Blogging, Environment. Bookmark the permalink.

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