Mentor: Dr. Neal Williams
Pollination is an essential part of food production. Humans depend on the fruits of flowering plants to fulfill much of their nutritional needs. Because over 66% of pollination relies on insects, primarily bees 1 , their presence is necessary for setting fruit on crops. Most farmers rely on managed honey bee colonies to pollinate their crops. However, recent declines in honey bee populations due to disease, pesticides and other factors have increased the economic burden to maintain these colonies on farms 2 . Although honey bees contribute a large part to crop production, native bees also help in this effort. In addition, some native bees are better pollinators of crops than honey bees. Therefore, an understanding of how native bee populations are contributing to crop pollination will provide an assessment of their role on agricultural lands.
For this project, my collaborators and I will survey native bee species on target crops in eastern PA and western NJ. This survey will quantify the service native bees might be providing through the pollination of these crops. This will be done by observing and collecting bees that visit the crops during specific intervals of time. The target crops are tomatoes, peppers, pumpkins, squash and cucumbers, a diverse set of summer flowering plants with different pollination requirements. For example, flowers from tomato plants have pollen that can only be obtained by high frequency vibrations; thus honey bees cannot collect this reward 2 . As part of the survey I will also quantify the composition of the landscape surrounding the farms (natural habitat or developed land), the management of the farms (organic or conventional) and other variables will be considered for analyzing the diversity of native bee populations and quantifying the amount of pollination the native bees provide.
A recent study done in California concluded that a diverse group of native bees can supply most, if not all, of the pollination necessary for many crops including watermelon 3 . The amount of natural habitat near the farm, management of the farm and other variables are factors that could influence the population of native bees. Organic farms surrounded largely by natural habitat will probably have a larger population and variation of native bees due to the lack of pesticides and availability of nesting areas. The future of honey bee populations is hard to predict. Nonetheless, most of the agricultural industry is still dependent on this one species of bees to pollinate their crops. An economical substitute for honey bees could be native bees. Their presence on farms could supply the farmers with many years of free service. In the long run, this sustainable method may perhaps prove more cost-effective for farmers. Preserving the homes of native bees and their surrounding biodiversity can be justified if native bees can provide an equivalent or superior pollination service than honey bees.
 Roubik, D. W. (1995) Pollination of Cultivated Crop Plants in the Tropics (Food Agric. Org. U.N., Rome ).
2 Kremen, C., Bugg, R.L., Nicola, N., Smith , S.A. , Thorp, R.B., & Williams, N.M. (2002) Fremontia 30, 41-49.
3 Kremen, C., Williams, N.M., & Thorp, R.B. (2002) PNAS 99, 16812-16816.