Researchers trying to gain a better understanding of declines in bee populations have found higher concentrations of neonicotinoid insecticides in the foliage of wild flowers located along field borders than they expected.
Activists groups have been saying neonicotinoid insecticides from seed treatments are being taken up into the pollen and nectar of plants and that dust from the talc used to help seed flow through the planter tubes is leaving insecticide seed treatment residues on foliage of nearby plants.
Extension experts from Mid-South universities have found little evidence that the “neonic” insecticides are in the reproductive parts of the plants in cotton, corn and soybean fields, says Gus Lorenz, Extension entomologist with the University of Arkansas. The possibility of insecticides being transferred by planter dust could be another matter, however.
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“When we started this study what we were hearing was there were huge clouds of neonicotinoid dust floating across the landscape at planting time,” Lorenz said in a presentation at the Beltwide Cotton Conferences in New Orleans. “We kind of laughed that off because we really didn’t think there was anything there.”
Instead of stopping at that point, the specialists conducted studies in wildflowers along field borders in 2012 and in 2013, taking a total of 78 plant samples from 49 fields in Arkansas and Tennessee and analyzing them for insecticide residue. More than 15 species of plants were assayed.
“We found that percent detections (greater than or equal to 1 ppb) ranged around 23 percent,” said Lorenz. “So there is some neonicotinoid dust floating across that landscape. It is out there”
Based on the 2012 study, the Extension specialists expanded their approach in 2013. In a test in Arkansas, they found that about 70 percent of the wildflowers around a cotton field had detectable levels of a neonicotinoid insecticide. Studies were also conducted using potted soybean plants in west Tennessee.
Mississippi State University researchers, meanwhile, compared the use of talc and graphite vs. an experimental compound to determine if a new lubricant would result in less dust being dispersed from planters. The experimental material lowered the amount of dust from that produced by talc significantly.
“This is part of this mitigation issue,” said Lorenz. “We realize now there is a dust issue with the planter, and we need to start looking at some ways to reduce the neonicotinoid drift across the landscape. I think that it’s nothing we can’t fix with some engineering and some additional products that maybe can help us reduce that neonicotinoid dust.”
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