According to media accounts, neonicotinoid seed treatments are taken up by plants and expressed in pollen and other reproductive parts, thus contributing to the much-publicized declines in honeybees in recent years.
But new research by Mid-South university entomologists indicates that’s not necessarily the case, as Gus Lorenz, Extension entomologist with the University of Arkansas explained in this video report from the Beltwide Cotton Conferences in New Orleans.
“When we look at the literature and the Internet, what it says is that neonicotinoids applied as seed treatments are then taken up into the plant and expressed in the pollen and in the nectar,” said Lorenz. “That’s what everyone is telling us. That’s the press that we get. Well, that’s not so much what we found.”
In their studies in corn, for example, six of the tests they conducted were positive for the neonicotinoid clothianidin with a range in the samples of 0 to 23.1 parts per billion and a mean of 2.3 ppb. The positive tests for imidacloprid, another neonicotinoid, were zero and for thiamethoxam, three positives with a range of 0 to 0.5 ppb and a mean of .1 ppb.
“So we’re not seeing that expression of the material in the corn pollen,” he noted. “When we look at cotton pollen, it’s even better. What we have is a very low percentage and very low numbers in the treatments.”
They tested soybean flowers at three locations and found no traces of neonicotinoid insecticides. The same was true of nectar in cotton. “So it’s not being expressed in the reproductive parts of the plants.”
Lorenz said the findings are important because activists groups and some beekeepers are using claims such as those he cited on the Internet to call for the withdrawal of tolerances for compounds such as Transform, which was recently registered for use in cotton.
“We can’t grow cotton in the Mid-South without Transform and similar compounds,” said Lorenz. “It is not economically feasible given the levels of insects we’re seeing.
For more about bee health issues: Honey bees - take a walk on the light side