Natural enemy diversity reduces temporal variability in wasp but not bee parasitism.

Biodiversity may enhance and stabilise ecosystem functioning, but little evidence exists for diversity-function relationships involving multitrophic interactions in real landscapes. In multitrophic communities diversity may vary at different trophic levels, with either synergistic or antagonistic effects on ecosystem functioning. Intensification of land-use systems is often found to reduce diversity, which in turn may lead to reduced associated ecological functions in natural food webs, such as host-parasite interactions.

Caveats to quantifying ecosystem services: fruit abortion blurs benefits from crop pollination.

The recent trend to place monetary values on ecosystem services has led to studies on the economic importance of pollinators for agricultural crops. Several recent studies indicate regional, long-term pollinator declines, and economic consequences have been derived from declining pollination efficiencies. However, use of pollinator services as economic incentives for conservation must consider environmental factors such as drought, pests, and diseases, which can also limit yields.