Reed, C. 1993. Reconstruction of pollinator communities on restored prairies in eastern Minnesota. Final report to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 88 pp.
I observed and collected insects visiting flowers on 4 relatively undisturbed prairie sites and 4 reconstructed prairies (farm fields recently replanted to prairie plants) in south central Minnesota during the summers of 1991 and 1992. Bees, flies, wasps, Lepidoptera and beetles visited flowers. Over 1100 observations of insects per flower revealed no consistent differences between the native prairie sites and the reconstructions over all, although insects per flower varied among forb species. A total of 279 insect species were identified among the 4000 insects collected; 83 species were found on native sites only, 68 on reconstructions only, and 128 species on both native sites and reconstructions. Species richness of sites ranged from 40 to 111 flower-visiting species per site; both the highest and the lowest value were observed on reconstructions. All sites contained both specialist and generalist insects.
Bee species richness of sites was related to forb species richness, not to site area, reconstruction age or total number of flowers or inflorescences in bloom. Reconstructions and native sites were comparable in their bee species richness, but bee distribution was quite patchy. Only 8 of 125 bee species were found on all 8 sites, and each site had at least one unique bee species found on no other site.
These results imply that prairie reconstructions can be valuable sites for insect conservation; to increase this value, managers should plant a wide variety of forbs from several families, and include forbs which bloom early and late as well as mid-season species. Native prairie sites can support many insect species; even small remnants should be preserved.
Areas of greatest interest for further research include the adequacy of pollination by various insect groups for plant reproduction; the distribution of bees over larger areas including the protected sites; and the interactions among plants, their pollinators, and the other factors which allow high pollinator diversity on some sites.