Effects of land-use intensity in tropical agroforestry systems on coffee flower-visiting and trap-nesting bees and wasps

Tropical landscapes are dominated by agroecosystems, and most species that survive in forest remnants interact with these agroecosystems. The potential value of agroecosystems for aiding species survival is often ignored. Essential ecosystem services may suffer when functional groups such as pollinators and predators are affected by land use. We used agroforestry systems differing in land-use intensity to examine flower-visiting bees on coffee plants and the community structure of trap-nesting bees and wasps and their natural enemies. The number and abundance of all species of coffee-visiting bees did not show a significant correlation with land-use intensity. The abundance (but not the number of species) of solitary bees increased with land-use intensity, whereas the abundance and number of species of social bees significantly decreased. In a further experiment, abundance and number of trap-nesting species increased with land-use intensity. These results contrast with the common expectation that intensively used agroforestry systems are characterized only by loss of species. Furthermore, they support the idea that many nonpest and beneficial insect species may even profit from agricultural land use. Parasitism and predation of trap-nest inhabitants did not change with land-use intensity, but species diversity (number of enemy species) and ecological function (mortality) were correlated.