The response of three distinct pollinators to alfalfa floral volatile emissions

Plant-insect interactions are often mediated by floral scents. Plants release volatile organic compounds (VOCs), which can attract insect pollinators. In an agricultural setting, pollinators could move genes between different plant varieties, or between cultivated plants and feral populations.  Alfalfa is a widely planted forage crop, commercially pollinated by honey bees and alfalfa leafcutting bees and commonly visited by wild bumble bees.  The flowers of alfalfa produce a strong scent. We collected, identified and quantified the volatile organic compounds (VOCs) of the floral scent of 18 alfalfa varieties from Round-up Ready and conventional stock, as well as from 20 populations of wild alfalfa plants.  Using three distinct bee species, honey bees, bumble bees, and leaf cutting bees we will determine the electro-physiological response of the bees to these compounds through electroantennogram trials.  Wind tunnel binomial choice tests will allow the examination of behavioral responses to the compounds.  Initial results of VOC collection revealed the presence of three main volatile chemicals, E-beta ocimene, Z-beta ocimene, and cis-3-hexenyl acetate.   E-beta ocimene was documented as a honey bee pheromone, indicating the possibility of attraction to this compound. The results of this study not only increase basic understanding of how three pollinator species respond to the components of alfalfa volatiles, but also allow the development of useful strategies for managing pollinators to limit gene flow among patches of genetically modified Round-Up Ready crops to conventional, organic, or wild alfalfa.