Although solitary bees and flies are important pollinators, little information is available on the nectar rewards of flowers they visit or their consumption of them, because small quantities of nectar are difficult to extract and measure. We studied five such plants in deciduous forests and agricultural fields in west-central Indiana, USA: three native forest herbs [Claytonia virginica L., Dentaria laciniata Muhlenb. ex Willd., Erigenia bulbosa (Michaux) Nutt.] and two exotic agricultural weeds [Barbarea vulgaris R. Br., Stellaria media L. (Vill.)], which often grow in close proximity. Using spectrophotometry, we measured daily sugar accumulation (in caged flowers) and standing crops (in uncaged flowers) at two sites on four dates per species. Dentaria laciniata was the most rewarding species (mean daily accumulations: 185–404 µg sugar/flower), followed by moderately rewarding B. vulgaris and C. virginica (24–113 µg sugar/flower) and low-rewarding E. bulbosa and S. media (7–38 µg sugar/flower). The presence of species with similar rewards in both habitats suggests that generalist bee and fly species can be expected to forage in both. Each flower species showed much variation in mean sugar accumulation per flower among population samples and among individual plants. Solitary bees were the most common visitors to all species (47 to 81% of visitation), followed by flies and honey bees. Insects consumed much, but not all (45 to 90%) of daily nectar accumulation by the five species. The more sugar a flower population secreted, on average, the higher its standing crop; visitation did not reduce rewards to a common level.
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. 133 • No. 4