Silene spaldingii S. Watson (Spalding's catchfly) is a threatened wildflower that relies on insect-mediated pollination. However, its pollination ecology is not well understood, particularly in the Zumwalt Prairie of northeastern Oregon, which contains the largest known S. spaldingii population. Our objectives were to: (1) describe the principal insect visitors to S. spaldingii in the Zumwalt Prairie, (2) quantify the available pool of pollinators in the area, and (3) determine whether the visitation rate to individual plants is associated with the density of S. spaldingii at the patch scale, as predicted by the resource concentration hypothesis, and/or by the density and composition of non-S. spaldingii blooming plants, as predicted by the facilitation and competition hypotheses. We recorded insect visits to S. spaldingii during peak bloom at 30 patches and characterized the local bee community using blue vane traps. We quantified the patch-scale density of S. spaldingii and the composition and abundance of other blooming species at each patch. Two bumble bee species comprised all observed visits, although they constituted only 20% of the total bees sampled on the prairie. Bumble bees showed a high degree of host fidelity even when other blooming plants were present. Per capita visitation rates increased with catchfly density and blooming plant abundance at the patch scale, supporting the resource concentration and facilitation hypotheses. Silene spaldingii in the Zumwalt Prairie appears to rely on a narrow pool of pollinators that may preferentially visit it over other blooming plants, and more dense patches of S. spaldingii may increase pollination efficiency.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 34 • No. 2