Drift and deposition of neonicotinoid contaminated seed lubricants on wild flowers

Populations of honey bees have declined worldwide in recent years.  One suspected cause is the widespread use of pesticides in agriculture, specifically neonicotinoid seed treatments.  When treated seeds are planted using a vacuum controlled planter, talc or graphite is mixed with the seed to serve as a lubricant and to help the seeds properly flow through the system.  The exhaust fan operating this vacuum system blows these seed lubricants as well as minute pieces of seed treatment into the environment where it may interact with foraging honey bees by settling on flowering vegetation.  To access these risks, an experiment was conducted to determine at what concentrations neonicotinoid containing seed lubricant exhaust settles on marigold flowers.  Talc, graphite, and a new experimental fluidity powder were tested using two different rates of clothianidin, 0.5 mg/seed and 1.25 mg/seed.  Marigold flowers were set downwind at distances of 0, 5, 20, 50, and 100 m away from a planter planting corn treated with the two different seed treatment rates.  One marigold pot was set at 20 m upwind of the planter to serve as a negative control.  Flowers from the marigold plants were sampled and tested for clothianidin using liquid chromatography/mass spectrometry.