26 Aug 2010: Report

Spurred by Warming Climate,
Beetles Threaten Coffee Crops

Coffee production has long been vulnerable to drought or excess rains. But recently, a tiny insect that thrives in warmer temperatures — the coffee berry borer — has been spreading steadily, devastating coffee plants in Africa, Latin America, and around the world.

by erica westly

The highlands of southwestern Ethiopia should be ideal for growing coffee. After all, this is the region where coffee first originated hundreds of years ago. But although coffee remains Ethiopia’s number one export, the nation’s coffee farmers have been struggling.

The Arabica coffee grown in Ethiopia and Latin America is an especially climate-sensitive crop. It requires just the right amount of rain and an average annual temperature between 64 degrees Fahrenheit and 70 degrees Fahrenheit to prosper. As temperatures rise — Ethiopia’s average low temperature has increased by about .66 degrees F every decade since 1951, according to the country’s National Meteorological Agency — and rains become more variable, Ethiopian coffee farmers have suffered increasingly poor yields. Last year was especially bad, with exports dropping by 33 percent. Some have moved their coffee trees to higher elevations, while others have been forced to switch to livestock and more heat-tolerant crops, such as enset, a starchy root vegetable similar to the plantain.

Now, there is evidence that a warming climate may be linked to one of the major threats facing the coffee industry in Ethiopia and elsewhere: A tiny insect known as the coffee berry borer beetle has been devastating coffee plants around the world, and new research suggests even slight temperature increases promote the spread of the pest.

The beetle is a relatively recent problem in Ethiopia and Latin America, where most Arabica coffee is grown. A field survey of Ethiopia’s coffee-growing regions conducted in the late 1960s found no trace of the beetle, but in 2003 researchers reported that the pest was widespread. Drought and heavy rains during harvest time may be the prevailing problems for coffee growers in Ethiopia and other countries; but the lack of an effective treatment for the coffee berry borer is cause for concern, especially given new research findings tying the spread of the beetle to rising temperatures.

Coffee may not be a basic food crop, such as wheat, but it is arguably one of the most important agricultural products. Valued as high as $90 billion a year, coffee, which is grown in more than 70 countries, is one of the most heavily traded commodities in terms of monetary value. Seventy percent of the world’s coffee comes from small, family-owned farms and more than 100 million people are dependent on the crop for their livelihood. Researchers estimate that the coffee berry borer causes more than $500 million in damages each year, making it the most costly pest affecting coffee today. Coffee growers have tried various tactics to stop the beetle, but to little avail. Pesticides don’t help, and even if they did, they are an unfavorable option, given their negative effects on coffee quality.

Until recently, the coffee berry borer was confined to just a few regions in Central Africa. But since the 1980s, the beetle has gradually spread to every
Since the 1980s, the beetle has spread to every coffee-growing region except Hawaii, Nepal, and Papua New Guinea.
coffee-growing region except Hawaii, Nepal, and Papua New Guinea. Juliana Jaramillo, a biologist at Kenya’s International Center of Insect Physiology and Ecology, suspects temperature increases are to blame. She and her collaborators recently identified the temperature range in which the beetle can survive. They found that the average minimum temperature the borer requires to reproduce is about 68 degrees F, and the mountainous regions of Ethiopia did not reach that temperature until 1984.

The borer did not appear in Colombia, Jaramillo’s native country, until 1988, but it has since become a persistent problem. Twenty years ago, Colombia was the second-largest coffee exporter in the world, and regularly sent abroad more than 12 million bags of Arabica coffee each year. But production has not reached that level since 1994, and 2009 was the country’s worst year ever. At an International Coffee Organization meeting in February, a Colombian coffee representative revealed that the country’s coffee exports had dipped to 7.9 million bags last year and that infestation by the borer — along with excessive rainfall and reduced application of fertilizer — was partly to blame.

Eliminating the coffee berry borer has become Jaramillo’s mission. She grew up in the picturesque Caldas region — the heart of Colombia’s coffee country — and her family still maintains a small coffee farm there. “It’s really a personal problem for me,” she said.

After establishing the temperature limits of the borer, Jaramillo and her colleagues used climate data to estimate the number of reproductive cycles the beetle could complete annually in four coffee-growing regions. While Ethiopia was on the low end, with only one to two generations per year,
For every 1.8 degree F increase, Colombian coffee growers will have to move up 550 feet in altitude.
Colombia was one of the highest, supporting up to 4.7 generations of the borer in one year. Jaramillo believes the discrepancy is largely due to Colombia’s year-long growing season. Coffee plants are most susceptible to pests when they’re flowering, so regions that receive rain all year, such as Colombia, are more vulnerable to the borer than those with distinct dry and rainy periods, such as Ethiopia and Kenya. Female borers kill coffee plants by burrowing into coffee berries to lay their eggs. (Each female can lay up to 200.) The resulting damage attracts herbivores and pathogens. In Latin America, the pest is known simply as la broca, which means “the drill.”

In their research, Jaramillo and her collaborators found that for every 1.8 degrees F increase in temperature, the coffee berry borer became 8.5 percent more infectious on average. Not only did the female beetles lay more eggs at higher temperatures, but they also drilled deeper into coffee berries, causing more physical damage. A follow up study, published this year in the Journal of Economic Entomology, found that higher temperatures also caused the female beetles to travel from berry to berry earlier.

Even more troubling, Jaramillo’s data indicate that the beetle can survive in a dormant state in sub-tropical conditions. That means farmers will not be able to escape the pest by moving to higher altitudes. Indeed, researchers in Uganda and Indonesia have already started finding the borer as high as 6,115 feet above sea level; the beetle is typically only found at 4,000 to 5,000 feet above sea level.

“Coffee is migrating,” said Dean Cycon, owner of Dean’s Beans, a Massachusetts-based specialty coffee company that works with farmers around the world. “As it’s getting hotter at the lower altitudes, the lower plants are dying off, so it marches the coffee forest up the slopes.” Jaramillo’s research indicates that the borers are migrating with the coffee plants.

Jaramillo’s father, Alvaro Jaramillo — a climatologist at the National Coffee Research Center in Manizales, Colombia — has calculated that for every 1.8 degrees F increase in temperature, Colombian coffee growers will have to move their plants up about 550 feet in altitude to maintain current levels of quality and quantity.

The coffee berry borer could also be more difficult to control at higher altitudes since moving a pest into a new ecosystem makes its behavior
Coffee growers need new strategies to combat threats such as the borer, and that requires research.
harder to predict. For example, insects that could serve as natural enemies to the coffee berry borer may not interact with the beetle in the same way at higher elevations. “Natural enemies can be very useful in pest control, but their cycle has to be in sync with the pest’s,” said Curtis Petzoldt, a researcher at Cornell University’s Integrated Pest Management Program.

Traditionally, the cooling effects of shade trees have provided some of the best protection from coffee pests, including the coffee berry borer. Studies have shown shade trees can reduce the temperature around coffee leaves by 3 degrees F to 7 degrees F, depending on the environment. There is also evidence that shade-grown coffee plants produce higher-quality coffee. But many coffee growers have cut down the trees around their coffee plants in order to increase sun access.

“There is a dogma that sun-grown coffee produces higher yields than shade-grown coffee,” explained Fernando Vega, a coffee researcher at the U.S. Department of Agriculture and Jaramillo’s main collaborator. And consistently dwindling supplies can make farmers desperate. “If you’re getting a lesser crop — and in many of the countries they are — there’s more fear that you have to grab every percentage you can,” said Cycon.


What’s Killing the Great
Forests of the American West?

What’s Killing the Great Forests of the American West?
Across western North America, huge tracts of forest are dying off at an extraordinary rate, mostly because of outbreaks of insects. Scientists are now seeing such forest die-offs around the world and are linking them to changes in climate, science journalist Jim Robbins reports.
But shade trees can take years to grow, and while some coffee retailers, including Starbucks, have started promoting shade-grown coffee, it’s still the exception rather than the rule. The notion of sustainable growing practices has also become popular with coffee importers, but these forward-looking efforts, which focus largely on conserving water and reducing carbon emissions, do little to address the climate-related problems that coffee growers are now facing.

Coffee farmers need new strategies to combat threats such as the coffee berry borer, Jaramillo said, and that requires research. “I think the coffee industry has two options,” she said. “Either they start investing in climate research, or they educate the consumers to drink something else.”

POSTED ON 26 Aug 2010 IN Climate Policy & Politics Science & Technology Africa Central & South America Central & South America 


A very important story, and beautifully written. You
might like to see some of the issues also arising of
late at the intersection of energy and agriculture.
see www.gregor.us

Your story suggests certain thresholds have been
crossed. The notion of temperate bands, or other
delicate zones or ledges suffering dislocation is
becoming more common and not just from
temperature change.

Posted by Gregor Macdonald on 05 Sep 2010

Had my attention until it turned into an infomercial for AGW fund raising. I see the new eco-fascist mantra is "Grab them by the lattes and their hearts and minds will follow".

Posted by Shoshin on 30 Sep 2010

Just for the record. The coffee berry borer is now in Hawaii. Kona in particular.

Posted by Barry on 04 Nov 2010

The coffee berry borer is simmerly related to the pine beetle and other similar tree borers and it has been found that when the trees are properly sprayed with environmentally friendly products and fed with local products raising the "Brix" level in the trees, the beetles will not endanger the trees and the trees will prosper. Also other products can be used on the trees which will convince the borers that the trees are healthy and also some available products will disable the beetles.

Posted by James F. Holland on 08 Nov 2010

Comments have been closed on this feature.
erica westlyABOUT THE AUTHOR
Erica Westly is a freelance science writer based in Brooklyn, New York. Her work has appeared in numerous publications, including Scientific American, Slate, and the New York Times.



African Lights: Solar Microgrids
Bring Power to Kenyan Villages

Small-scale microgrids are increasingly seen as the most promising way to bring electricity to the 1.3 billion people worldwide who currently lack it. In Kenya, an innovative solar company is using microgrids to deliver power to villages deep in the African bush.

For U.S. Tribes, a Movement to
Revive Native Foods and Lands

On ancestral lands, the Fond du Lac band in Minnesota is planting wild rice and restoring wetlands damaged by dams, industry, and logging. Their efforts are part of a growing trend by Native Americans to bring back traditional food sources and heal scarred landscapes.

Alien Islands: Why Killing Rats
Is Essential to Save Key Wildlife

Alien rats introduced by ships are decimating populations of birds and other wildlife on islands from the sub-Antarctic to California. Effective programs to eradicate the rats are underway but are encountering opposition from animal activists and some green groups.

In South Korea, An Innovative
Push to Cut Back on Food Waste


The Big Waste: Why Do We
Throw Away So Much Food?

An e360 video looks at the staggering amount of food wasted in the U.S. Filmmaker Karim Chrobog focuses on efforts in Washington, D.C., to see that food ends up with those who need it rather than dumped in landfills. First in a series.
Watch the video.


MORE IN Reports

For Storing Electricity, Utilities
Are Turning to Pumped Hydro

by john roach
High-tech batteries may be garnering the headlines. But utilities from Spain to China are increasingly relying on pumped storage hydroelectricity – first used in the 1890s – to overcome the intermittent nature of wind and solar power.

On Thin Ice: Big Northern Lakes
Are Being Rapidly Transformed

by cheryl katz
As temperatures rise, the world’s iconic northern lakes are undergoing major changes that include swiftly warming waters, diminished ice cover, and outbreaks of harmful algae. Now, a global consortium of scientists is trying to assess the toll.

The Haunting Legacy of
South Africa’s Gold Mines

by mark olalde
Thousands of abandoned gold mines are scattered across South Africa, polluting the water with toxics and filling the air with noxious dust. For the millions of people who live around these derelict sites, the health impacts can be severe.

The Sushi Project: Farming Fish
And Rice in California's Fields

by jacques leslie
Innovative projects in California are using flooded rice fields to rear threatened species of Pacific salmon, mimicking the rich floodplains where juvenile salmon once thrived. This technique also shows promise for growing forage fish, which are increasingly threatened in the wild.

A Delicate Balance: Protecting
Northwest’s Glass Sponge Reefs

by nicola jones
Rare and extensive reefs of glass sponges are found only one place on earth – a stretch of the Pacific Northwest coast. Now, efforts are underway to identify and protect these fragile formations before they are obliterated by fishing vessels that trawl the bottom.

As the Fracking Boom Spreads,
One Watershed Draws the Line

by bruce stutz
After spreading across Pennsylvania, fracking for natural gas has run into government bans in the Delaware River watershed. The basins of the Delaware and nearby Susquehanna River offer a sharp contrast between what happens in places that allow fracking and those that do not.

Will Tidal and Wave Energy
Ever Live Up to Their Potential?

by sophia v. schweitzer
As solar and wind power grow, another renewable energy source with vast potential — the power of tides and waves — continues to lag far behind. But progress is now being made as governments and the private sector step up efforts to bring marine energy into the mainstream.

The Rapid and Startling Decline
Of World’s Vast Boreal Forests

by jim robbins
Scientists are becoming increasingly concerned about the fate of the huge boreal forest that spans from Scandinavia to northern Canada. Unprecedented warming in the region is jeopardizing the future of a critical ecosystem that makes up nearly a third of the earth’s forest cover.

Northern Forests Emerge
As the New Global Tinderbox

by ed struzik
Rapidly rising temperatures, changes in precipitation, and increased lightning strikes are leading to ever-larger wildfires in the northern forests of Alaska, Canada, and Siberia, with potentially severe ecological consequences.

For U.S. Tribes, a Movement to
Revive Native Foods and Lands

by cheryl katz
On ancestral lands, the Fond du Lac band in Minnesota is planting wild rice and restoring wetlands damaged by dams, industry, and logging. Their efforts are part of a growing trend by Native Americans to bring back traditional food sources and heal scarred landscapes.

e360 digest
Yale Environment 360 is
a publication of the
Yale School of Forestry
& Environmental Studies


Paris Climate Coverage COP21

Donate to Yale Environment 360
Yale Environment 360 Newsletter



About e360
Submission Guidelines

E360 en Español

Universia partnership
Yale Environment 360 articles are now available in Spanish and Portuguese on Universia, the online educational network.
Visit the site.


e360 Digest
Video Reports


Business & Innovation
Policy & Politics
Pollution & Health
Science & Technology


Antarctica and the Arctic
Central & South America
Middle East
North America

e360 VIDEO

The 2015 Yale e360 Video Contest winner documents a Northeastern town's bitter battle over a wind farm.
Watch the video.


The latest
from Yale
Environment 360
is now available for mobile devices at e360.yale.edu/mobile.

e360 VIDEO

A 2015 Yale e360 Video Contest winner captures stunning images of wild salmon runs in Alaska.
Watch the video.

e360 VIDEO

Colorado wildfires
An e360 video goes onto the front lines with Colorado firefighters confronting deadly blazes fueled by a hotter, drier climate.
Watch the video.


A three-part series Tainted Harvest looks at the soil pollution crisis in China, the threat it poses to the food supply, and the complexity of any cleanup.
Read the series.

header image
Top Image: aerial view of Iceland. © Google & TerraMetrics.