D3217: (1st Place) Floral resource use by native and non-native bees on the Luther College campus

The objective of this study was to perform a baseline survey of the floral resources used by bee species in landscaped flower beds and prairie plantings on Luther College campus in Decorah, Iowa. To see which plant species were visited by bees, timed 30 minute surveys were conducted at 25 locations (10 planted prairies and 15 landscaped flower beds) on campus from early June to the end of August 2022. We observed a significant difference in bee abundance on native flower species (n= 61) compared to non-native flower species (n=37). 100% of native flower species were used by native bees (n=1,296), which also used 35 of the 37 species of non-native flowers. Comparatively, only 65% of the non-native flower species were used by native bees while 43% of non-native flower species were used by non-native bees. The most frequently visited floral resource was Penstemon digitalis, a native wildflower found in both prairie plantings and landscaped flower beds. However, in landscaped flower beds non-native wildflowers such as Salvia yangii and Spiraea japonica were used by a significant number of native bees. The pollinator network of native bees was dramatically more complex than the pollinator network of non-native bees. Native floral resources not only support native bee species but also provide resources for non-native bee species. Whereas non-native floral resources support significantly fewer bees and bee species