The coffee berry borer is the most devastating coffee pest in the world. The tiny beetle is found in most regions where coffee is cultivated, and a big outbreak can slash crop yield by 80 percent. It's also a caffeine fiend. The insect is the only coffee pest that uses the caffeine-rich bean as its sole source of food and shelter. It bores into the bean and spends most of its life tucked inside, where it's exposed to what should be an extremely toxic amount of caffeine for its mass: the equivalent of a 150-pound person downing 500 shots of espresso. Caffeine is harmful to most insects and is believed to act as a natural pest repellant. So how does the coffee berry borer thrive in such a hostile environment? 

It relies on the bacteria in its gut, according to new research by scientists from the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), the U.S. Department of Agriculture (USDA), and Mexico's El Colegio de la Frontera Sur (ECOSUR). Their study appears July 14 in the journal Nature Communications. 

The scientists discovered that coffee berry borers worldwide share 14 bacterial species in their digestive tracts that degrade and detoxify caffeine. They also found the most prevalent of these bacteria has a gene that helps break down caffeine. Their research sheds light on the ecology of the destructive bug and could lead to new ways to fight it. 

"Instead of using pesticides, perhaps we could target the coffee berry borer's gut microbiota. We could develop a way to disrupt the bacteria and make caffeine as toxic to this pest as it is to other insects," says Javier Ceja-Navarro, a scientist in Berkeley Lab's Earth Sciences Division and lead author of the paper.