Plant growth aided by insect-feeding animals

Summarizing the results of more than 100 experiments conducted on four continents, UC Irvine ecologist Kailen A. Mooney and colleagues found that these insect-gobbling animals increase plant growth by reducing the abundance of plant-feeding insects and the damage they do to the plant life that helps mitigate global warming.

Our efforts solidify the importance of birds, bats, lizards and other similar animals to ecosystem health, and underscores the importance of conserving these species in the face of global change," said Mooney, an assistant professor in ecology and evolutionary biology.

The results come at a time when the importance of birds and other insectivores as plant protectors has come into doubt, Mooney added. Studies on bird, bat and lizard diets show they devour both plant-feeding insects and the spiders and other insect predators that eat plant feeders.

Recognizing these complex feeding relationships, Mooney said it had become unclear whether animals like birds reduce plant-feeding insect populations, or whether they might in fact be protecting them from spiders and the like.

"It has long been hypothesized that birds and other insect-feeding animals may protect plants by keeping plant-feeding insects in check in accordance with the adage, 'The enemy of my enemy is my friend,' " Mooney said. "Our study provides the most comprehensive support of this hypothesis to date. It shows that despite feeding on predatory insects, birds, bats and lizards still act as plant protectors by having net negative effects on plant-feeding insects."

Study results appear in early online edition of the Proceedings of the National Academy of Sciences the week of April 5.

Daniel S. Gruner of the University of Maryland; Nicholas A Barber of the University of Missouri, St. Louis; Sunshine A. Van Bael of the Smithsonian Tropical Research Institute in Panama; Stacy M. Philpott of the University of Toledo; and Russell Greenberg of the Smithsonian Migratory Bird Center in Washington, D.C., contributed to this study.