Killer Bugs Made Welcome on Green Farms

Brian Handwerk
for National Geographic News
August 12, 2009

Hungry pests cost farmers millions in crops losses each year, resulting in the widespread use of chemical pesticides, to which many bugs eventually become immune.

But one effective deterrent is clean, green, and sustainable—the wasps, flies, ladybugs, and other predators that happily feast on crop pests.

Scientists and farmers are learning to make better use of this powerful weapon by reshaping the landscape to create abundant habitat for pest predators, encouraging them to make farms their homes.

Rebecca Chaplin-Kramer, a doctoral candidate at the University of California, Berkeley, released the results of her multiyear "biological control" study last week at the Ecological Society of America's annual meeting in Albuquerque, New Mexico.

Promoting predator habitat doesn't have the instant impact of pesticides, but it could be highly sustainable, as established predator populations can thrive indefinitely, Chaplin-Kramer noted. (Learn more about sustainable agriculture.)

Inviting pest predators might also save money. The U.S. Environmental Protection Agency estimates that farmers spend more than U.S. $30 billion a year on pest control—and the cost continues to climb. (Related: "Pesticides Float From Distant Farms to Protected Forests, Study Says.")

Yet pests still wipe out more than a third of potential crops. In addition, more than 500 pest species have developed resistance to chemicals that once kept them in check.

Happily Harboring Killers

Previous studies had shown that diverse landscapes promote bigger populations of pest predators. But it's tough to evaluate the effect that farmers really care about: how much pest control such predators actually provide.

Chaplin-Kramer is hoping to find out.

She's been working in the fields of California's Salinas Valley since 2006, examining how predator habitat can provide pest control on both the local level—that is, within a farm's fields—and in the surrounding landscape.

Chaplin-Kramer specifically studies the cabbage aphid, the plague of many broccoli crops and favored prey of the syrphid fly. (Related: "Bugs Cuddle Up to Dead Comrades for Protection.")

Continued on Next Page >>




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