Wild bee communities contribute over $ 3,000 per hectare to the annual production of insect-pollinated crops, says Professor David Kleijn from Wageningen University in the Netherlands, who led the study. Amazingly, the majority of these pollination services are provided by a very small subset of wild bee species: a mere two percent of the wild species studied accounted for 80 percent of the pollination services.
The good news is that these dominant pollinator species can easily be enhanced by simple conservation measures. The study found that biodiversity-enhancing management more than tripled the abundance of crop-visiting bees. Among the measures studied were habitat-creating activities such as planting wildflowers, or establishing grass margin strips. Restricting the use of crop protection products failed to increase the density of dominant crop pollinators.
A Plea for Diversity
The study also looks into the impact of agriculture on different wild bee species. As could be expected, the crop-foragers persist with the expansion and intensification of agriculture, while non-crop forager bees are the first to decline with higher intensities of land use.
Non-crop forager bees thrive in more extensively managed farmland, preferring semi-natural habitats like non-flowering crops, grassland, old fields, or hedgerows. Their number and species richness decline with decreasing semi-natural habitats. As a result, they will not benefit from conservation measures in highly intense agricultural landscapes, simply because they are absent in these regions. Measures to enhance these species would have to be taken into the areas where they are found, says the study.
The authors conclude with a plea for maintaining the diversity of all bees – including those who are crucial for the ecosystem, while less so for agriculture. They warn conservationists that they may undermine their own argument by promoting a purely economic argument for the protection of bee biodiversity.
Bayer has been promoting the planting of blooming strips for years. So far, the different initiatives have led to the planting of almost 1,000,000 m² of wildflowers. Read more about it in our magazine BEENOW
The study “Delivery of crop pollination services is an insufficient argument for wild pollinator conservation” by David Kleijn et al. was picked up by the Guardian:
If you'd like to read the study, you can find it here: