Neonicotinoids Harm Bees
Source: Environmental Toxicology and Chemistry, DOI: 10.1002/etc.4021
Three groups of in-ground Clethra and Illex x attenuata were treated with a soil drench of dinotefuran (Safari) and imidacloprid (Merit) with three treatments (spring, summer and fall). Nectar was extracted from the flowers in early summer (during bloom) over 2 years and analyzed for insecticide residue in the nectar.
Results suggested that Merit and Safari, when applied at the labeled landscape rates in the fall of year one and spring of year two, can result in an amount of residue detrimental to bees in year two but not in year three. An obvious recommendation is to reduce the application rate so the residue can dissipate quicker, but it is not clear if doing so will reduce the insecticide's effectiveness. And applications are usually not reduced. Another surprise is that application of Merit just after bloom in the summer resulted in low residue concentrations in nectar after one year, but application of Safari at the same time did not. The results highlight the point that neonicotinoids are not created equal. (The study was published in Environmental Toxicology and Chemistry, DOI: 10.1002/etc.4021.)