The Latest Neonic Research
Wednesday, January 17, 2018
A newly published research article compared the uptake and dissipation of two neonicotinoid residues in nectar and foliage of Ilex and Clethra. The research was led by Dr. Dan Potter, University of Kentucky, and partially funded by the Horticultural Research Institute (HRI) through the Pollinator Stewardship Initiative.
The two neonicotinoids evaluated were imidacloprid and dinotefuran. Though both are neonics, the two insecticides have different properties that impact their behavior in plant material. Both are systemic and able to move through plant material from roots to the upper canopy, but the speed of that movement is different. Dinotefuran, for example, moves much more quickly. This has led researchers to speculate that dinotefuran would be less persistent in plant tissues.
Dr. Potter tested three application timings, autumn (postbloom), spring (prebloom), and summer (early postbloom). Results showed that concentrations in nectar were found to be higher than levels known to adversely affect honey bees. However, summer applications of imidacloprid reduced concentrations. Results also indicated that dinotefuran may be more persistent than originally thought.
Translating these results into practices impacting pollinator protection would be a bit premature. No regulatory limit has been identified for imidacloprid or dinotefuran in woody plants. When considered in landscape settings, assessing potential exposure to bees becomes even more complex.
Most bees collect pollen and nectar from a variety of flowering plants, potentially diluting the effects of occasional, sublethal exposure to neonicotinoid-treated plants. The length of bloom period and the percentage of plants in a neighborhood treated with neonicotinoids both impact bees’ exposure. Dr. Potter’s group has previously shown that most woody landscape plants typically bloom for one to two weeks, as opposed to a crop such as canola where the bloom period can last up to six weeks.
Brought to you by Lighthouse, an AmericanHort Program. Article by Jill Calabro, PhD. Photo courtesy of AmericanHort.