Biology: The coffee pest's Achilles heel

Gut microbes are responsible for the breakdown of caffeine in the most devastating insect pest coffee, reveals a new study in Nature Communications this week. Caffeine would otherwise be toxic to the coffee berry borer, Hypothenemus hampei, and this newly identified role of microbiota may provide novel strategies to help control the pest.

H. hampei is responsible for decreasing coffee crop yields worldwide by up to 80% and is the only known insect that completes its life cycle exclusively within the green coffee bean. The socioeconomic consequences of H. hampei infestation have stimulated research into pest control methods; however, the insect’s basic metabolism was poorly understood until recently.

Javier Ceja-Navarro, Eoin Brodie and colleagues show that the gut of H. hampei specimens from seven major coffee-producing countries are inhabited by a common, core population of gut microbes, including certain Pseudomonas species. Experimental inactivation of H. hampei gut microbiota by treating with antibiotics eliminates the insect’s ability to detoxify caffeine, which ordinarily acts as a potent pesticide, and resulted in significant and substantial declines in numbers of viable insects, relative to controls. Moreover, reinoculation of the antibiotic-treated insects with one of the gut-derived Pseudomonas strains allows the insects to thrive on caffeine again. The results from this study may help develop new biocontrol methods targeting the microbes’ ability to allow H. hampei to survive on a caffeine-rich diet.