Measuring the foraging distance of the alkali bee, Nomia melanderi, using transgenic pollen as a marker

Pollination is essential for seed set in alfalfa seed production.  Alkali bees (Nomia melanderi) are native, solitary bees that nest in dense aggregations called bee beds. The Washington State Department of Transportation is proposing an upgrade of US Highway 12 that passes through the Lowden-Touchet-Gardena seed growing district of southeastern Washington. The proposed four-lane highway could pose negative impacts to the bees and seed yield in the area due to bee mortality from vehicular traffic. N. melanderi significantly increase seed yields in this area through their pollination services. In 2011, the USDA deregulated Round Up® Ready (RR) alfalfa.  At present, roughly 25% of the alfalfa being produced for seed in the area is genetically engineered with the RR gene. Alkali bee foraging distance has been documented as 1.6 km but bees have been found up to 11 km away from their nesting sites. To study flight distances, we focused on thirteen alkali bee beds with high populations. All surrounding alfalfa fields were mapped as genetically-engineered or non-genetically-engineered. Fifty bees were collected from each bee bed per week of bee foraging. The bees were analyzed for the presence of RR alfalfa pollen through PCR analysis. The minimum distance between the bee bed tested and the closest RR alfalfa field was measured. By using the RR transgene to determine the minimum N. melanderi flight distance, we can attempt to minimize the impacts of vehicular traffic from the new highway and understand the potential for cross-pollination from conventional seed to RR seed fields.