Are seed treatments ending up in water? Western Producer

by Robert Arneson  download

Like many others, John Gavloski is troubled by neonicotinoid seed treatments.

Some scientists and environmentalists are worried that neonico-tinoids are a threat to bees, but Gavloski, a Manitoba Agriculture entomologist, is more concerned that the insecticides are accumulating in puddles, ponds and larger water bodies near agricultural land.

Gavloski told a presentation at Manitoba Ag Days in January that prairie growers should reduce their use of neonic seed treatments. If that doesn’t happen, government regulation of neonics is a possible outcome.

“They (neonics) are being overused. They are being used to the point where we’ve got these levels showing up in surface water that we don’t want to be seeing,” he said.

“I personally see the surface water residue as probably the issue … that’s probably the thing that’s going to push it (regulations).”

Neonicotinoid seed treatments are applied to almost all of the corn and canola seed in North America and a majority of soybean seeds.

In 2015, University of Saskatchewan toxicologist Christy Morrissey published a review of neonico-tinoids, their concentrations in ponds and related risk to insects.

Neonics, a class of insecticides, are highly soluble. When it rains, a neonic can move from the soil to water bodies near, or within, agricultural land.

After reviewing 29 studies on neonics in nine countries and published data on neonics toxicity to insects, Morrissey concluded that insecticide seed treatments do pose a risk to aquatic insects.

“Concentrations of neonico-tinoids in surface waters worldwide are well within the range where both short- and long-term impacts on aquatic invertebrate species are possible over broad spatial scales.”

If neonics are killing aquatic insects, it could diminish the food supply for wild birds who feed on those insects, Morrissey said.

The risk of insecticide “pulse” following a rain is higher in parts of Manitoba where corn, canola and soybean, grown with neonic treated seed are the dominant crops.

“You’re going to have some municipalities where the majority of your fields have a neonic,” Gavloski said.

“That’s just a huge source to be getting into the water bodies.”

CropLife Canada is also paying attention to neonics and surface water concentrations .

“We’re spending a lot of time on this issue … because the Ministry of Environment in Quebec released a surface water monitoring program in their corn and soybean growing regions,” said Pierre Petelle, CropLife Canada vice-president of chemistry.

Petelle said Quebec used a threshold of 8.3 parts per trillion for surface water concentrations of neonics, based on research done in the Netherlands. 

“The threshold bar was set so low that any little detection exceeded that threshold,” Petelle said.

“What we found is that 8.3 parts per trillion goes back to one study in the Netherlands. That researcher has re-done his work three additional times and never come up with such a low level (for) impact on aquatic insects.”

Morrissey has recommended a surface water threshold for chronic exposure to neonics of 35 parts per trillion.

Health Canada is re-evaluating the safety and efficacy of neonics with a focus on bees. Surface water concentrations and impact on insects will likely be part of the review, but recommendations on threshold levels may not happen for years.

“In the interim, especially if scientists like John and others are raising questions, we may need a separate process to focus on this,” Petelle said.

“It’s important to get the levels (thresholds) right…. We, very clearly, want our products to stay where they’re supposed to do their work. They’re no good to the farmer if they’re off the field.”