For the sake of protecting crops against the numerous insects that beat people to the plate by eating those crops in the field, many companies now coat their seeds with insecticides. One popular class of insecticide, neonicotinoids, has proven effective against a variety of potential pests that feast on roots, stems and leaves alike. But that very strength sometimes manifests as a weakness: Neonicotinoids can also harm both the pests’ natural predators and the bees, butterflies and other pollinators critical to agriculture worldwide.
That unintended consequence usually arises when the pesticide particles of treated seeds scrape off during the planting process. Water and wind can then carry those free particles to other plants, where pollinators and other beneficial insects consume the insecticides via nectar or pollen. Still, little research has tried to quantify how much of the seed-treated insecticides are spreading through the air — or refine new tools to better measure that spread.
The Department of Entomology’s Judy Wu-Smart and Surabhi Gupta Vakil recently teamed with the Nebraska Water Center’s Daniel Snow to do just that. As part of a three-year study at the Eastern Nebraska Research and Extension Center near Mead, Nebraska, the team planted 17 wildflower-covered, pollinator-friendly plots next to corn and soybean fields. Over that time, the researchers also constructed and placed 51 sticky traps: adhesive-coated microscope slides that they mounted on posts roughly 5 feet tall.
The team quantified insecticide concentrations by dividing the insecticide residue on each sticky trap by the surface area of the trap itself. A lab-based analytical technique then allowed the team to identify 12 specific seed-treated compounds captured by the traps. Two particular neonicotinoids — clothianidin and thiamethoxam — were found in 98% and 80% of the samples, respectively.
That combination of simple, low-cost sampling method and sensitive, well-established analysis could help researchers learn more about the fates and potential consequences of airborne, off-target insecticides, the team said.
More details at: https://link.springer.com/article/10.1007/s00128-022-03627-y