Biological Control of Coffee Berry Borer: the Role of Dna-based Gut-content Analysis in Assessment of Predation

The coffee berry borer, Hypothenemus hampei, is the most important pest of coffee worldwide, causing an estimated $500 million in damage annually. Infestation rates from 50-90% have been reported, significantly impacting coffee yields. Adult female H. hampei bore into the berry and lay eggs whose larvae hatch and spend their entire larval life within the berry, feeding on the coffee bean, lowering its quality and sometimes causing abscission. Biological control of H. hampei using parasitoids, fungi and nematodes has been reported but potential predators such as ants and predatory thrips, which have been observed in and around the coffee berries, have received little attention. This study reviews previous H. hampei biological control efforts and focuses on the role of predators in H. hampei biological control, an area in which tracking trophic associations by direct observation is not possible in part due to the cryptic nature of the biology of H. hampei, spending its life cycle inside the berry. The use of molecular methods to detect the presence of small amounts of prey in the digestive tracts of predators is the primary focus of this research program, and ultimately elucidating food web structure and making recommendations for biological control. We designed H. hampei-specific primers to demonstrate that H. hampei DNA can be detected in DNA extractions of a predatory thrips species, Karnyothrips flavipes, which preys on H. hampei. We demonstrate the potential of this molecular technique to unravel the trophic interactions that occur inside the coffee berry.