Early-season mass-flowering crop cover dilutes wild bee abundance and species richness in temperate regions : A quantitative synthesis

Pollinators benefit from increasing floral resources in agricultural landscapes, which could be an underexplored co-benefit of mass-flowering crop cultivation. However, the impacts of mass-flowering crops on pollinator communities are complex and appear to be context-dependent, mediated by factors such as crop flowering time and the availability of other flower resources in the landscape. A synthesis of research is needed to develop management recommendations for effective pollinator conservation in agroecosystems. By combining 22 datasets from 13 publications conducted in nine temperate countries (20 European, 2 North American), we investigated if mass-flowering crop flowering time (early or late season), bloom state (during or after crop flowering) and extent of non-crop habitat cover in the landscape moderated the effect of mass-flowering crop cover on wild pollinator abundance and species richness in mass-flowering crop and non-crop habitats. During bloom, wild bee abundance and richness are negatively related to mass-flowering crop cover. Dilution effects were predominant in crop habitats and early in the season, except for bumblebees, which declined with mass-flowering crop cover irrespective of habitat or season. Late in the season and in non-crop habitats, several of these negative relationships were either absent or reversed. Late-season mass-flowering crop cover is positively related to honeybee abundance in crop habitats and to other bee abundance in non-crop habitats. These results indicate that crop-adapted species, like honeybees, move to forage and concentrate on late-season mass-flowering crops at a time when flower availability in the landscape is limited, potentially alleviating competition for flower resources in non-crop habitats. We found no evidence of pollinators moving from mass-flowering crop to non-crop habitats after crop bloom. Synthesis and applications: Our results confirm that increasing early-season mass-flowering crop cover dilutes wild pollinators in crop habitats during bloom. We find that dilution effects were absent late in the season. While mass-flowering crop cultivation alone is unlikely to be sufficient for maintaining pollinators, as part of carefully designed diverse crop rotations or mixtures combined with the preservation of permanent non-crop habitats, it might provide valuable supplementary food resources for pollinators in temperate agroecosystems, particularly later in the season when alternative flower resources are scarce.

Bibliographic Details

Main Authors:	Riggi, L.G.A., Raderschall, C.A., Fijen, T.P.M., Scheper, J., Smith, H.G., Kleijn, D., Holzschuh, A., Aguilera, G., Badenhausser, I., Bänsch, S., Beyer, N., Blitzer, E.J., Bommarco, R., Danforth, B., González-Varo, J.P., Grab, H., Le Provost, G., Poveda, K., Potts, S.G., Rundlöf, M., Steffan-Dewenter, I., Tscharntke, T., Vilà, M., Westphal, C., Berggren, Lundin, O.
Format:	Article/Letter to editor biblioteca
Language:	English
Subjects:	dilution effects, floral resource, landscape composition, mass-flowering crops, pollinator abundance, pollinator richness, seasonal effects,
Online Access:	https://research.wur.nl/en/publications/early-season-mass-flowering-crop-cover-dilutes-wild-bee-abundance
Tags:	Add Tag No Tags, Be the first to tag this record!