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Cornell scientist casts doubt on efficacy of ubiquitous pesticide that's toxic to bees

A honeybee on a bluish purple flower
LightShaper/Getty Images/iStockphoto
A honeybee (Apis mellifera) sips nectar from an aster in a butterfly garden.

Lawmakers in the Vermont House are weighing a bill that would largely ban seeds coated with neonicotinoid pesticides in Vermont.

If H.706 becomes law, Vermont would follow New York and Quebec, who have already adopted bans.

The policy is supported by environmental groups in the state, including the Vermont Public Interest Research Group, as well as by beekeepers, who told lawmakers they frequently lose 50% of their hives each year. And while parasites and climate change are driving factors, beekeepers say pesticides are also a major threat.

Testifying Tuesday, Cornell Professor Scott McArt confirmed those concerns — sharing data from what he said is the largest ever literature review on the topic.

Evidence of harms and limited benefits of treated seeds

In addition to raising concern about the well-documented impact of neonicotinoid pesticides on bee and pollinator health, some have also raised questions about how effective treated seeds are.

McArt compiled a literature review of studies examining this on behalf of New York state lawmakers.

He looked at more than 300 peer-reviewed studies examining the impacts of neonicotinoids on pollinators — namely honeybees. Additionally, his lab did a benefits analysis for growers, looking at more than 5,000 published trials that compared the economic, pest and crop yield differences between fields planted with neonicotinoid coated seeds and those planted with untreated seeds.

“We created the largest summary of the literature that has ever been done on this topic,” McArt told lawmakers.

The review found strong evidence that neonicotinoids adversely impact pollinator behavior and reproduction, which impacts their population size.

“If bees are able to reproduce better, their populations can grow,” he said.

When it came to efficacy, McArt found that neonicotinoids were very effective at promoting crop yields for fruit, vegetables and turf — but that there are alternatives that work well, too.

However, for corn and soybean, which account for the vast majority of neonicotinoid use in Vermont, McArt’s review found that in most cases, coated seeds had a limited impact on crop yield — and in the vast majority of studies, that impact wasn’t great enough to offset the additional cost incurred from buying a coated seed.

“There was surprisingly limited evidence of benefits from neonics on corn and soybean seeds,” he said. Specifically, just 12% of trials found higher crop yields from coated corn seed compared with controls, and 14% of trials found higher crop yields from coated soybeans compared with controls.

A corn field standing tall with the mountains in the background.
Amy Kolb Noyes
VPR File
A corn field in East Montpelier.

Studies in Quebec and Ontario have found even lower rates of yield increase from planting coated seeds.

And McArt says corn yields have not declined in the European Union since coated seeds were banned there in 2013, according to Euro Stat Agricultural Production data, and crop yields have increased in Ontario and Quebec.

Despite Cornell data, Agency of Agriculture urges caution

Still, some dairy farmers in the state have joined the Agency of Agriculture in urging caution, saying in their view, more research is needed about how a ban would affect crop yields in Vermont.

Steve Collier, with the Agency of Agriculture, Foods and Markets, told lawmakers Tuesday the bill proposes an overly simple fix for a complex problem.

“We definitely have problems with pollinators, no question about that,” Collier said. “And we agree that it needs to be addressed. The question is how.”

Collier said the department supports continued study of the impacts of neonicotinoids and how a ban would affect the dairy economy.

"Part of the whole issue from our perspective is we operate in a national economy. We're not an island of Vermont, we don't operate separated from everyone else," Collier said. "So when you're evaluating the tools that are available, and you're evaluating our farmers' competitive place in the market, we have to keep our relative role in that market in perspective."

He said the Agency of Agriculture feels Vermont should wait for a federal ban, and lawmakers should put their energy towards petitioning the state’s congressional delegation over the issue, rather than legislating it locally.

Some lawmakers in committee pushed back on the notion Vermont should wait for federal action.

People dressed in homemade bee costumes hold yellow and black signs calling for lawmakers to protect pollinators.
Abagael Giles
Vermont Public
Members of the Honeybee Steelband showed their support at the Statehouse this week for a bill that bans neonicotinoid coated seeds.

Right now, the University of Vermont Extension estimates 99% of corn seed in the state is treated with neonicotinoids, as is the vast majority of soybean seed.

The Agency of Agriculture has raised concern that seed companies will refuse to supply treated seeds to Vermont farms, or will only supply a limited inventory.

“The primary pest we’re worried about is the seed corn maggot,” said Steve Dwinell, the director of public health for the Agency of Agriculture.

Dwinell told lawmakers that seed companies told the Agricultural Innovation Board they will not sell uncoated seeds in Vermont.

But at arecent panelhosted by the University of Vermont Extension, dairy farmers from Quebec told Vermont farmers that this hasn’t been an issue for them since Quebec’s ban went into place a few years ago.

Renaud Peloquin farms about 1,300 acres of corn, soybeans, winter wheat and winter rye.

“Vermont friends, don’t be fooled,” he said, speaking via a translator. “All the seed suppliers can turn around and provide insecticide-free seeds very quickly. There are a lot of marketing strategies to scare people into the need to use neonics, but you shouldn’t be bothered with that.”

Though Peloquin and other Quebec farmers said having a hyper-local seed distributor that custom coats their seeds made that particularly easy — and the province paid them $18 per acre to switch away from treated seeds.

'Vermont wouldn't go first'

The Agency of Agriculture has warned that Vermont represents a tiny share of the corn seed market nationally. If lawmakers adopt a ban, Vermont would be one of two states requiring uncoated seeds — and Dwinell and others have raised questions about whether big seed companies will be willing to create a special supply chain for such a small share of their customer base.

But Paul Burns with the environmental advocacy nonprofit Vermont Public Interest Research Group (VPIRG) says Vermont’s proximity to New York should be a boon for sourcing seeds.

“I just don’t think anybody can make a credible case that seeds won’t be available in Vermont, as long as we stick with a timeline that would be right in line with New York’s, and that would be our expectation here — Vermont wouldn’t go first,” Burns said.

In testimony this week, the Champlain Valley Farmer Coalition, which represents 75 farms in Addison and Chittenden counties, echoed support for adopting New York’s timeline — which phases out coated seeds by 2029.

In a memo to lawmakers, Executive Director Vijay Nazareth said their members have concerns about the availability of untreated seeds and would like to see additional research into alternatives to neonicotinoids. However, Nazareth said, “The New York bill allows a five-year timeframe for these issues to be addressed, which we think is appropriate.”

Close-up of a beekeeper collecting honey on a honeycomb of bees.
Frazao Studio Latino/Getty Images
Close-up of a beekeeper collecting honey on a honeycomb of bees.

NOFA Vermont has come out in strong support of a ban. Last week, policy director Maddie Kempner told the House Agriculture and Forestry Committee that the warnings about seed supply were just a scare tactic.

And she says the use of pre-treated seeds harms organic farms in the state by disrupting their efforts to ward off pests through investments in soil health.

“In a place like Vermont where our land base is small, organic and conventional farms are often side by side,” Kempner said. “The persistent negative impact of neonicotinoids on soil health and bees actually works against organic farmers and lots of others who may not be certified organic.”

A political 'minefield'

In testimonyto lawmakers earlier in the session, the American Seed Trade Association voiced their support for the use of treated seeds, saying that treated seeds enable farmers to plant earlier and that following the instructions on labels for treated seeds mitigates the risk to pollinators.

They contested the notion that farmers are being denied a choice in buying untreated seeds, but that “for certain crops, farmers who wish to purchase non-neonicotinoid treated seed will need to discuss their order in advance because seed companies begin production 9-12 months prior to planting.”

In concluding his testimony, Scott McArt from Cornell warned lawmakers to be wary of disinformation as they consider the policy further.

“Since releasing our risk benefit report in 2020, numerous people have attempted to sow doubt on the science that I’m showing you here,” McArt said, saying he and his data have been “attacked” by scientists representing chemical manufacturer BASF and the Competitive Enterprise Institute, CropLife America, the New York Agribusiness Association, and other entities.

“This is is just the science,” he said. “You guys do what you want, right? This is just the data.”

He urged lawmakers to consider who funded any research presented to them and called the landscape of people invested in the topic of neonicotinoids “a minefield.”

“I would just caution you, whatever you decide to do on this topic, just be aware that there is quite a bit of disinformation out there.”

Have questions, comments or tips? Send us a message.


Updated: February 16, 2024 at 9:19 AM EST
The headline of this story has been updated to lead with the data shared in testimony Tuesday to the House Agriculture and Forestry Committee. It previously read "Some Vermont dairy farmers, state officials urge caution about buzzy bill to ban neonicotinoids."

Additionally, discussion of the data compiled by Cornell and New York state around the efficacy of neonicotinoids and their impact on honeybees has been moved further up in the story.
Abagael is Vermont Public's climate and environment reporter, focusing on the energy transition and how the climate crisis is impacting Vermonters — and Vermont’s landscape.

Abagael joined Vermont Public in 2020. Previously, she was the assistant editor at Vermont Sports and Vermont Ski + Ride magazines. She covered dairy and agriculture for The Addison Independent and got her start covering land use, water and the Los Angeles Aqueduct for The Sheet: News, Views & Culture of the Eastern Sierra in Mammoth Lakes, Ca.