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| Earth | Human World on Sep 11, 2013

Wild birds help Costa Rica’s coffee farmers

When wild birds have undisturbed tropical forests near Costa Rica coffee plantations, they help control the coffee berry borer beetle.

In Costa Rica, coffee plantations with patches of undisturbed tropical forests have better coffee yields. That’s because the forests are habitat for wild birds that, in turn, prey on the main scourge of coffee plantations: Hypothenemus hampeii, the coffee berry borer beetle. Recently, researchers have put a monetary value on the benefits these birds bring to coffee plantations. They’ve found increases in the yield per hectare amounting to between $75 and $310, depending on the season. A paper about their findings was recently published in Ecology Letters.

The coffee berry borer beetle is the most serious pest in coffee plantations across the world. In Costa Rica, they're also a source of food for native birds. Image credit: Daniel Karp, et al.

The coffee berry borer beetle is the most serious pest in coffee plantations across the world. In Costa Rica, they’re also a source of food for native birds. Image credit: Daniel Karp, et al.

The paper’s principal author, Daniel Karp, a graduate student in biology at Stanford University, commented in a press release:

The benefits that we might get are huge. There’s lots of unrealized value in these small patches of rainforest. This looks like a sustainable, win-win opportunity for pest management.

Coffee is one of the world’s most lucrative crops. But everywhere it is cultivated, a major pest has been introduced, the coffee berry borer beetle. The destruction begins when a female beetle burrows into the coffee berry where she lays about 35 to 50 eggs. Upon hatching, the maggots proceed to eat the coffee berry from the inside. This tiny and prolific insect, native to Africa, has become a serious pest in coffee plantations across the world, causing about $500 million in damage each year.

A hole drilled by the coffee berry borer beetle. Image credit: L. Shyamal, via Wikimedia Commons.

A hole drilled by the coffee berry borer beetle. Image credit: L. Shyamal, via Wikimedia Commons.

To figure out how much the birds were contributing to the coffee economy of Costa Rica, Karp and his colleagues first calculated how much yield to expect if borer beetles were absent from the plantations. Then, they compared yields from infested plants under normal growing conditions with those from yields of infested plants grown in bird-proof enclosures. Commenting on the results of their calculations, Karp said:

Depending on the season, the birds provide $75 to $310 increases in yield per hectare of farmland.

To quantify the benefit birds brought to coffee plantations, Karp and his colleagues calculated the difference in yield between infested plants housed in bird-proof cages and infested plants open to beetle-eating birds. Image credit: Daniel Karp, et al.

To quantify the benefit birds brought to coffee plantations, Karp and his colleagues calculated the difference in yield between infested plants housed in bird-proof cages and infested plants open to beetle-eating birds. Image credit: Daniel Karp, et al.

The next major focus of study was to determine which birds were preying on the beetles. Karp described the experiment,

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.

The DNA results showed that there were five bird species responsible for picking off 50% of the borer beetles. Not surprisingly, there were greater numbers of these birds in coffee farms that had more rainforest habitat.

The yellow warbler can be found in Costa Rica plantations eating the coffee borer beetle.

The yellow warbler can be found in Costa Rica plantations eating the coffee borer beetle. Image credit: Daniel Karp, et al.

Plantations that contained small rainforest preserves, each about several football fields in area, scattered throughout the plantations, had the highest efficiency pest control by the birds compared to those plantations that had large forest preserves in the outskirts. Karp said:

This work suggests that it might be economically advantageous to not farm in certain areas of a plantation. 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.

Bottom line: In Costa Rica, coffee farmers that provide habitat for wild birds, as undisturbed patches of tropical forest in plantations, have better coffee yields. That’s because the birds feed on a major coffee plantation pest, the coffee berry borer beetle. In a paper published in the journal Ecology Letters, researchers report that their analysis shows these birds saving farmers between $75 to $310 per hectare, depending on the season.