Evaluating bee (Hymenoptera: Apoidea) diversity using Malaise traps in coffee landscapes of Costa Rica

Even though Arabica coffee (Coffea arabica Linnaeus, Rubiaceae) can self-pollinate, bees are important pollinators, without which there is lower fruit quality and yield. We studied bee diversity in coffee agroecosystems in Costa Rica during two coffee flowering seasons (2005 and 2006). Malaise traps were used as a passive sampling method to collect bees during coffee blooms. We collected 1012 bee individuals from three different site types: nonagricultural fields and shaded and unshaded coffee farms. Unshaded coffee farms had significantly higher species richness (S) and number of bee individuals (n) than did the shaded coffee farms and nonagricultural sites. Overall bee diversity did not differ among site types but evenness (J′) was significantly lower in unshaded coffee farms. Using a more detailed community analysis, there was a significant association between functional groups and habitat type with more species and individuals of small-bodied ground-nesting bees (Lasioglossum (Dialictus) Robertson) associated with unshaded coffee farms. A large proportion (49%) of bees collected were of this subgenus, which was never before reported as common in coffee agroecosystems. Further studies should establish whether Dialictus is important in coffee pollination. We propose strategies involving conservation of native bees through simple habitat management for small-scale coffee farms that may improve crop quality and quantity. Bien que le caféier d'Arabie (Coffea arabica Linnaeus, Rubiaceae) puisse s'autopolliniser, les abeilles sont d'importants pollinisateurs sans lesquels la qualité et la production des fruits sont moindres. Nous avons étudié la diversité des abeilles dans les agroécosystèmes de caféier au Costa Rica durant deux saisons de floraison du caféier (2005 et 2006). Des pièges Malaise ont été utilisés comme méthode passive d’échantillonnage afin de récolter les abeilles durant la floraison du caféier. Nous avons récolté 1012 individus sur trois différents types de sites : des champs non-agricoles et des plantations de caféiers ombragées ou non. Les plantations de caféiers sans ombre possédaient une richesse d'espèces (S) et un nombre d'individus d'abeilles (n) significativement plus grands que les plantations de caféiers ombragées et les sites non-agricoles. La diversité globale des abeilles ne différaient pas entre les différents types de sites, mais l’équitabilité (J′) était significativement plus basse dans les plantations de caféiers sans ombre.