Insect pollinators in Iowa cornfields: Community identification and trapping methods analysis

Pollination services are crucial to U.S. agriculture and economy.  Understanding how pollinators utilize highly modified and disturbed agricultural landscapes such as those found in Iowa is an important step in creating best management practices for pollinator conservation. Our objectives are to characterize the pollinator community visiting cornfields in Iowa and develop methodology for describing their community diversity and abundance. In 2012, three cornfields were sampled in central Iowa over a six-week period spanning VT toR3 (tasseling to milk stage). Unbaited Pherocon® AM yellow sticky cards (YSC, Trécé Incorporated) and pan traps painted fluorescent yellow, blue, and white (i.e. bee bowls) were used to collect insect pollinators. In 2012 bee bowls described 27 species/morpho-species. 20 from Hymenoptera: Andrenidae, Apidae, Colletidae, and Halictidae; 7 from Diptera: Calliphoridae, Dolichopodidae, Syrphidae, and Tachinidae.  YSC described a subset of this community, representing 9 of the 27 taxonomic units.  The most abundant bee species were Melissodes bimaculata, bees in the Lasioglossum subgenus Dialictus, and Agapostemon virescens.  The most abundant anthophilous flies were from Dolichopodidae. Both traps were deployed at three heights (anther, ear and ground).  Abundance and diversity of pollinators varied across trapping heights and trap type.  Bee bowls deployed at anther height captured significantly more bees than the traps at ear or ground height.  Additionally, bee bowls at anther height represented the most even community of bees.  These results suggest that the community of pollinators foraging in cornfields is best described by sampling with bee bowls at the height of the anther.