Action: Leave field margins unsprayed within the crop (conservation headlands)
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Two replicated controlled trials in England showed that conservation headlands do not attract more foraging bumblebees than conventional crop fields. One replicated trial found fewer bees on conservation headlands than in naturally regenerated, uncropped field margins in England.
Supporting evidence from individual studies
Kells et al. (2001) counted bumblebees Bombus spp. and honey bees Apis mellifera on 50 m transects in five 6 m wide field margins managed as conservation headlands, and ten naturally regenerated, uncropped field margins in the West Midlands, England. They recorded averages of less than three bees/transect in conservation headlands, compared to averages of between 10 and 50 bees/transect in naturally regenerated margins.
A replicated controlled trial (Pywell et al. 2005) in East Anglia and the West Midlands, England, found no significant difference in bumblebee species richness and abundance when 16 conservation headlands were compared with paired conventional field margins. In both types of field margin, a few species of plant contributed to the vast majority of foraging visits by bumblebees, mainly creeping thistle Cirsium arvense and spear thistle C. vulgare.
- Kells A.R., Holland J.M. & Goulson D. (2001) The value of uncropped field margins for foraging bumblebees. Journal of Insect Conservation, 5, 283-291
- Pywell R.F., Warman E.A., Carvell C., Sparks T.H., Dicks L.V., Bennett D., Wright A., Critchley C.N.R. & Sherwood A. (2005) Providing foraging resources for bumblebees in intensively farmed landscapes. Biological Conservation, 121, 479-494
- Carvell C., Meek W.R., Pywell R.F., Goulson D. & Nowakowski M. (2007) Comparing the efficacy of agri-environment schemes to enhance bumble bee abundance and diversity on arable field margins. Journal of Applied Ecology, 44, 29-40