Researchers at the Smithsonian Tropical Research Institute report that bats significantly reduce insect abundance and damage on plants. In a lowland tropical rainforest in Panama, bats can consume roughly twice as many plant-eating insects as do birds. This landmark study in the journal Science is the first to compare the ability of bats and birds to protect plants via insect predation in a natural forest ecosystem.
A previous study by the authors suggested that bats were underestimated predators of plant eating insects, based on video recordings of feeding events.
In the current study, Smithsonian short-term fellow Margareta Kalka, and co-authors Elisabeth Kalko, institute staff scientist and professor at the Institute of Experimental Ecology at the University of Ulm, and Smithsonian postdoctoral fellow Adam Smith, separated the insect-control effects of bats and birds by placing netting enclosures over five common tropical plant species only at night or only by day. Uncovered control plants accessed by both bats and birds lost merely 4.3 percent of their leaf area to insect herbivores. When only birds were excluded, plants lost 7.2 percent of their leaf area. When only bats were excluded, plants lost a striking 13.3 percent of their leaf area, demonstrating that in the tropical forest understory bats can be more effective pest control agents than birds.
Caterpillars, katydids, beetles and other insects devour tropical plant leaves. Plants directly defend themselves by producing tough leaves and toxic chemicals. Phyllis Coley, STRI research associate and University of Utah professor, who has documented tropical plant defenses for many years, considers this study to be a major contribution: The role of insect predators, such as birds and bats, is key to plant survival. However, the magnitude of this top-down pest control is still not well understood.
Previously, researchers estimating the top-down effects of birds on herbiv
|Contact: Beth King|
Smithsonian Tropical Research Institute