Defining the Insect Pollinator Community Found in Iowa Corn and Soybean Fields: Implications for Pollinator Conservation

Although corn (Zea mays L.) and soybeans (Glycine max L.) do not require pollination, they offer floral resources used by insect pollinators. We asked if a similar community of insect pollinators visits these crops in central Iowa, a landscape dominated by corn and soybean production. We used modified pan traps (i.e., bee bowls) in both corn and soybean fields during anthesis and used nonmetric multidimensional scaling (NMS) to compare the communities found in the two crops. Summed across both crops, 6,704 individual insects were captured representing at least 60 species, morphospecies, or higher-level taxa. Thirty-four species were collected in both crops, 19 collected only in corn and seven were collected only in soybean. The most abundant taxa were Lasioglossum [Dialictus] spp., Agapostemon virescens Cresson, Melissodes bimaculata (Lepeletier), and Toxomerus marginatus (Say), which accounted for 65% of the insect pollinators collected from both crops. Although social bees (Apis mellifera L. and Bombus spp.) were found in both crops, they accounted for only 0.5% of all insects captured. The NMS analysis revealed a shared community of pollinators composed of mostly solitary, ground nesting bees. Many of these species have been found in other crop fields throughout North America. Although corn and soybean are grown in landscapes that are often highly disturbed, these data suggest that a community of pollinators can persist within them. We suggest approaches to conserving this community based on partnering with activities that aim to lessen the environmental impact of annual crop production.