Comparison of two release techniques for the use of Cephalonomia stephanoderis (Hymenoptera: Bethylidae), to control the coffee berry borer Hypothenemus hampei (Coleoptera: Scolytidae) in Soconusco, southeastern Mexico

Cephalonomia stephanoderis Betrem (Hymenoptera: Bethylidae) is one of the few known natural enemies of the coffee berry borer (CBB), Hypothenemus hampei Ferrari (Coleoptera: Scolytidae), the most important pest of coffee throughout the world. The response of this parasitoid to its host, in field cages and small field sites, was shown to be highly variable and unpredictable and between 62% and 96% of all parasitioids released did not enter a target CBB-infested coffee berry. The parasitoid did not respond differently to aggregations of 2, 6, or 12 CBB-infested berries. However, the performance of C stephanoderis released as a culture of parasitized hosts was up to five times better than when the parasitoid was released in the traditional manner as adults because a greater proportion of the parasitoids released as a culture entered and remained within target berries. Individual performance was, however, similar for both release methods; a single parasitoid killed, on average, by a combination of parasitism and predation, between 3.75 and 18.74 individual CBB. The release of C stephanoderis as a culture offers an important step forward in the technology for the use of this parasitoid. However, estimates indicate that, even when released as a culture, very large numbers of parasitoids (e.g., 59 million per hectare, to control a 65% CBB infestation in a densely planted, productive plantation, towards harvest time) would be necessary to control CBB. This method of CBB control is unlikely therefore to be economically viable. (C) 2002 Elsevier Science (USA). All rights reserved.