OOS 46-3
Ecosystem services, pest control, and shade management in coffee agroecosystems: Ecology and application
Shade coffee systems, where coffee shrubs grow under a native or planted tree canopy, have received considerable attention over the past 20 years for their ability to protect biodiversity and contribute to conservation in tropical agricultural landscapes. Further, shade coffee systems, or the biodiversity harbored therein, can provide important ecosystem services such as pollination, pest control, nutrient cycling, and climate regulation. However, shade coffee is not a homogeneous category, and can represent a variety of agroecosystems, from those with dense canopy cover (80-90%) and high tree species diversity, to those with sparse canopy cover (20-25%) and a single introduced tree species. Differences in canopy cover and tree diversity may very well affect the degree to which the agroecosystems or biodiversity can provide ecosystem services. We reviewed 42 studies that have directly measured the ecosystem service of pest control in coffee agroecosystems varying in vegetation management style, and examined where pest control services were maximized. Specifically, we reviewed studies that examined predator or parasitoid abundance or richness, herbivore, prey, or pest abundance or removal, and plant damage in two or more systems differing in canopy cover, or another aspect of the shade tree canopy (including sun coffee systems with no canopy).
Results/Conclusions
Pest control services in coffee agroecosystems is provided by an array of organisms including ants, spiders, birds, bats and lizards. Generally, predators provide effective control of the coffee berry borer, the coffee leaf miner, and of coffee herbivores. Predation services can improve yields, and can increase revenue for coffee farmers. Although pest control services were common, they were enhanced in coffee systems with more complex vegetation. In approximately 60% of the comparative studies examined, we found higher levels of pest control ecosystem service provision in the more shaded coffee agroecosystem. In the more shaded treatment, natural enemy abundance was higher in 11 studies (~58%), and richness was higher in 6 studies (~67%). Pest or prey abundance was lower and prey removal was greater in 17 studies (~57%). Plant damage created by pest species was lower in sites with greater shade in the one study that measured this factor. Fewer than 20% of studies documented negative effects of shade on pest control. Although most studies document greater pest-control-providing organisms or services with shade, some did not. Thus factors other than shade (e.g. landscape surroundings, chemical use) likely also influence the level to which conservation biological control is provided in coffee agroecosystems.