Bats gobble about 60 per cent of the earworms that typically
attack a corn field.
Josiah J. Maine, a graduate student at the Southern Illinois
University at Carbondale working under Justin Boyles, put a net around part of
a corn field hear Horseshoe Lake in Southern Illinois to keep bats out.
Then for two years he gathered data on corn ear damage and
fungus attacks to come up with his esimate that bats are worth about $1 billion
a year in insect control.
The findings have been published in the Proceedings of the
National Academy of Sciences.
of them and away from the corn.
“The main pest in my system was the corn earworm, a moth
whose larvae cause billions of dollars’ worth of damage to corn, cotton,
tomatoes, and many other crops,” Maine said.
“The larvae feed on corn ears, causing direct damage to
yield, but they also can introduce an avenue for infection of the corn ear by
fungi, which produce compounds that are toxic to humans and livestock.”
Bats are not the only predators of these agricultural pests,
so to ensure that only bats were excluded by the exclosures Maine moved the
structures twice daily so birds could forage normally.
After analyzing the results, Maine said he found nearly 60
percent more earworm larvae inside the exclosures – protected from the hungry
bats – than in the unprotected control areas.
He also found more than 50 percent more corn kernel damage
per ear in the corn inside the exclosures.
“By consuming crop pests, bats have tremendous ecological
impacts in crop fields.
Based on the difference in crop damage I observed, I
estimated that bats provide a service to corn farmers worth about $1 billion
globally” Maine said.
