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Coffee threatened by beetles in a warming world

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


    * Erica Westly for Yale Environment 360, part of the Guardian
Environment Network
    * guardian.co.uk, Friday 27 August 2010 11.46 BST

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 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, 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 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.

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."