Caterpillars With Varied Plant Diet Are More Likely To Be Eaten By A Bird

Caterpillars that have a well-rounded diet are more susceptible to hungry birds, according to a recent study.

Researchers from the University of California, Irvine and Wesleyan University found that caterpillars that feed on one or two plant species are better able to hide from predatory birds than caterpillars that consume a wide variety of plants.

Researchers said this may be because the color patterns and hiding behaviors of the caterpillar "specialists" have evolved to allow them to blend into the background flora more effectively than caterpillars that eat many different plant species. Moving among these diverse plant types, the nonspecialists are not as camouflaged, making them easier for hungry birds to spot.

"It's a classic example of risk vs. reward," Kailen Mooney, leader of the study and associate professor of ecology & evolutionary biology at UC Irvine, said in a news release. "Evolutionarily speaking, a caterpillar must choose between having a broad array of plants to feed upon but facing increased risk of being nabbed by a bird."

Or Caterpillars could settle with a very limited menu and be less exposed to predators.

Researchers also found that all of this matters a lot to the plants. A species consumed by caterpillars more vulnerable to birds (those with varied diets) benefits from birds removing those caterpillars. In contrast, a plant species fed upon by caterpillars better able to hide from birds (those with highly restricted diets) doesn't benefit as much from birds and must instead defend itself.

Mooney noted that this insight into the secret lives of caterpillars reveals not only the processes driving the evolution of insect diets but also the broad significance of caterpillar feeding for associated plants and birds.

The findings were recently published in the early online edition of Proceedings of the National Academy of Sciences.