Crop Pollination by Bees as a Function of Farm Surroundings

Posted May 26th, 2010 at 2:43 pm.

Lauren Kurtz

Mentor: Dr. Neal Williams

Pollination is essential for crop production; the quality and amount of pollination directly affects the quality and amount of resulting crops, and thus the profit a farmer can make from a given harvest. Crop pollination is provided primarily by managed colonies of honey bees and a diverse set of native bees. The contributions of the latter remain largely unrecognized and for the most part have not been quantified. These native bees can be viewed as providing a potentially valuable benefit to humanity, a so called ecosystem service. The diversity and of bees on farms has been shown to be affected by surrounding landscape. More complicated and developed land results in a lower diversity and abundance of bees (Klein et al. 2000; Steffan-Dewenter et al. 2001). There is evidence that this ultimately results in lower quality pollination (Kremen et al. 2002).

As a first step in exploring the contributions of different bees to crop pollination, I propose to measure the diversity and abundance of native and non-native bee species visiting selected farm crops as well as each individual species’ visitation rate to “target” crop species. I will also assess how abundance and diversity of bees are affected by the composition of the surrounding landscape. In collaboration with Princeton researchers, I will study bees on organic and conventional farms in Pennsylvania (Berks, Bucks and Montgomery counties) and New Jersey (Mercer and Hunterdon counties). Target plants-tomato, pepper, squash, eggplant, melon and cucumber-have been chosen because of their economic importance and pollination matters; self-pollination is inferior or impossible and these crops require specific pollination strategies. Each farm will be divided into standard sized plots by crop. To measure visitation, abundance and species diversity, I will sample numbers of individuals visiting each plot during standard timed samplings.

To assess how landscape composition affects bees, I will look at how abundance, diversity and productivity vary by farm. I will then use state GIS data to determine the land use in 1km and 2.5km radii around each farm. Based on previous research conducted in other areas, I expect to see results vary according to landscape use. Farms located in more developed areas will have lower bee species diversity and that bee species present will not necessarily be the most effective pollinators (Klein et al. 2000; Steffan-Dewenter et al. 2001; Kremen et al. 2002). I also anticipate that organic farms and farms that use fewer pesticides will have a greater bee abundance and species richness. Since these farms will have a greater diversity of bees present, then they will also be more likely to have bees specialized in pollinating specific crops.

If my expectations are correct, then farmers in less developed areas with few pesticide applications will have an advantage, with respect to crop pollination by native bees. These findings would be helpful to farmers, because of pollination benefits found by switching to more organic pest controls. It would also encourage the preservation of natural habitats, which would improve the state of pollination, in addition to a multitude of other ecosystem services, such as preservation of biodiversity, water purification and waste decomposition.

Filed under: 2004,Kurtz, Lauren,Williams, Dr. Neal by Ann Dixon

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