Bee Visitation to Crops and other Flowers Planted as Bee Food

Farms that require insect pollination and reside in diverse landscapes benefit from pollination by native bees. However, populations of native bees and honey bees are generally in decline and this threatens food production. Documentation of crop pollination as an ecosystem service is needed to identify potential impacts from declining bee populations. This study identifies communities of bees providing pollination and how they vary across different crops and environmental conditions. Managing landscapes to provide additional food sources for bees may improve the health of wild and managed bees. This study also evaluated the attractiveness of bees to selected species of plants that could be used to provide food sources.

In 2008-09, bee visitation was measured on 10 different crops among 12 farms in Tennessee. On one of these farms, visitation was observed for 24 different flower species that could be used for supplemental bee forage. Bees visiting flowers were organized within a classification scheme of 10 taxonomic groups. Environmental data for each observation was recorded including the type of flower, the date, time, location, farm and plot size, if the farm was organic or conventional, and the number and sex of flowers when appropriate.

Nonmetric multidimensional scaling and linear models revealed that native bees are important visitors to crop flowers, but their abundance and composition depend on the type of flower. Within a flower type, other environmental effects can shift the community composition. Plants selected for habitat enhancement can be chosen based on the similarity of the community of bees which utilize them as compared to crops.