Establishment of exotic parasitoids of the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae) in Colombia through farmer participatory research

A participatory project was conducted with small-scale coffee growers from Quindío Department, Colombia. In 34 coffee lots in three municipalities, growers implemented an integrated management programme against the coffee berry borer (CBB) Hypothenemus hampei Ferrari, based on improved cultural harvesting and sanitation practices (to remove breeding habitats) and releases of exotic parasitoids. Growers released over 10 million Cephalonomia stephanoderis and 5 million Prorops nasuta (both Hymenoptera: Bethylidae) over 2 years. Populations of the CBB declined from a range of 7–14% infested berries (Quimbaya), 10–13% (Montenegro) and 15–48% (Buenavista) prior to the integrated pest management programme, to an average of 2.1 ± 0.2% infested berries in Químbaya, 3.5 ± 0.2% in Montenegro and 2.8 ± 2.1% in Buenavista, over the following 25 months. Damage to parchment coffee similarly declined during this period. Six months after the final release of parasitoids had been made, we found both parasitoid species established in all three municipalities. However, P. nasuta were recovered more frequently (in 71.4% of lots where they were previously released) compared with C. stephanoderis (recovered in 30.8% of release lots). Average parasitism rates remained low, i.e. 3.7% for P. nasuta and 2.9% for C. stephanoderis. This low rate was probably due to the frequent manual removal of mature berries containing developing parasitoid larvae. In addition, the entomopathogenic fungus Beauveria bassiana was observed on average on 9.5% adult CBB in Montenegro, compared with mean infection rates of 4.3 and 4.4% in Quimbaya and Buenavista, respectively. Cultural harvesting and sanitation is an important component of CBB control, although it may limit the impact of the pest's parasitoids.