Insect pollinators in corn and soybean agricultural fields
Iowa's landscape is dominated by row crop agriculture with the majority of acres being in corn and soybean production, and as a result is spatially uniform and functionally homogenized. In landscapes dominated by agriculture, such as those found in Iowa, the availability of mass flowering crop species show strong positive effects on the density of generalist, native pollinators. While soybean, a self-pollinated plant, and corn, a wind pollinated plant, do not require physical pollination for fruit production, they can be a source of nectar and/or pollen for insect pollinators. The first objective is to develop methodology to accurately describe the in-field abundance and diversity of insect pollinators associated cornfields in Iowa. The second objective is to define the community of insect pollinators using Iowa row crops as a potential resource. Over 2012 and 2013, 3,617 insect pollinators representing 51 species were captured using bee bowls in cornfields. Traps deployed at the height of the tassels describe a more abundant and species rich community of pollinators than traps at ear height (2x as many individuals) or ground height (4x as many individuals). Blue bowls captured more bees than white (2.75x as many individuals) or yellow bowls (3.5x as many individuals); and yellow bowls captured more flies than white (2x as many individuals) or blue (2.3x as many individuals). Over the two field seasons 3,087 individual insect pollinators were collected using bee bowls in soybean fields. These individuals represented more than 43 species (or morphospecies) of insect pollinators. Summed across both years and crop types, 6,704 individual insect pollinators were captured representing more than 56 species or morpho-species. A common group of 34 species use both crops.