Birds Save Coffee Crop from Borer Beetles

STANFORD, Calif.Borer beetleswho are a threat to coffee bean growers around the worldare known for destroying coffee plants.  Researchers suggest that birds are the beetles  number one enemy, according to a recent study published in the journal Ecology-Letters.

Being the most economically profitable crop, coffee and its harvest supports the livelihoods of some 100 million people globally. Unfortunately, the beetle "is the most damaging insect pest by far, causing some $500 million in damage per year," Daniel Karp, lead author of the study said.

To quantify the benefit birds provide to plantations, the researchers calculated coffee bean yieldthe amount of healthy, beetle-free beans that could be harvestedof infected plants that were housed in bird-proof cages versus yield from infected plants in the open where birds were eating the beetles.

"We had the not-so-glamorous task of collecting the birds' poop, and then taking it back to Stanford and looking through the DNA within it to learn which birds were the pest preventers," Karp said.

Five different species of birds contribute to cutting beetle rates in half. The farms featuring more forests had a larger number of these birds.

"Depending on the season, the birds provide $75 to $310 increases in yield per hectare of farmland," Karp said. The birds' activity could become even more valuable if the beetle infestation worsens.

The conclusion the scientists came up with was that the closer the forests were to the farm the greater benefit the birds provided. Specifically, smaller stands of treesroughly the size of a few football fieldssituated throughout crop fields provided better levels of beetle protection than the much larger forest preserves set on the outskirts of farms.

"This works suggests that it might be economically advantageous to not farm in certain areas of a plantation," Karp said. "We're going to start trying to generalize these results so that farmers, conservationists, land managers and governments can use them anywhere to make simple estimates of what they might gain in pest protection by protecting certain patches of the landscape."