Holland J. M., Sutter L., Albrecht M., Jeanneret P., Pfister S. C., Schirmel J., Entling M. H., Kaasik R., Kovacs G., Veromann E., Bartual A. M., Marini S., Moonen A.-C., Szalai M., Helsen H., Winkler K., Lof M. E., van der Werf W., McHugh N. M., Smith B. M., Wallis D. W., Cresswell J. E.
Moderate pollination limitation in some entomophilous crops of Europe.
Pollination services to crops may be worsening because of declines in farmland pollinators, but the consequences
for yields have been uncertain. We therefore investigated pollination limitation in four entomophilous crops
(oilseed rape, sunflower, pears and pumpkin) by quantifying the difference in harvestable mass between openpollinated
and saturation-pollinated (hand-pollinated) flowers. We also examined whether pollination limitation
in the four crops was associated with the number of flower visits by insects. Across 105 commercial fields in six
European countries, the average decrease in harvestable mass due to pollination limitation was 2.8 %
(SE=1.15). Among crops, the highest decreases were in sunflowers (8%) and in one of three oilseed rape
production regions (6%). We observed substantial variation among crops in the numbers of insect visits received
by flowers, but it did not significantly correspond with the levels of pollination limitation. Our results suggest
that yields in these crops were not severely pollination-limited in the regions studied and that other factors
besides visitation by pollinators influenced the degree of pollination limitation.