Defining the community of insect pollinators found in Iowa corn and soybean fields

In landscapes dominated by agriculture the availability of mass flowering crop species, such as corn and soybean, has a positive effect on the density of generalist, native pollinators. In Iowa, 75% of the arable acres are in row crop production, primarily corn and soybean. To what extent bees and other pollinators use both of these crops is unclear, as one is wind pollinated and the other is self-pollinated, despite producing abundant flowers. There are three general possibilities when considering the similarity of the groups of pollinators that use these crops: 1) the two groups share a few common species, but some are found in only one of the crops 2) the two groups are distinctly different sharing no similar species or 3) all species are common between the two crops.  Overall, we observed a diverse group of insect pollinators in both corn and soybean fields of Iowa.  During 2012 and 2013, we observed over 3,600 individuals representing more than 50 species of bee and flower visiting fly from cornfields and more than 3,000 individuals representing 43 species from soybean fields. Using non-metric multidimensional scaling we determined that there is a distinct community of insect pollinators found in both corn and soybean fields of central Iowa.  This community is comprised mostly of solitary, ground nesting bees.  The most abundant species collected in both crops were Lasioglossum (Dialictus), Agapostemon virescens, Melissodes bimaculata, Toxomerus marginatus, while Apis mellifera was rarely detected over both years.