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..