Fight invasives or protect pollinators: Neonicotinoids present tough choice

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The U.S. Fish and Wildlife Service designated the rusty-patched bumblebee as endangered in early January, a first for any bee species. Image: Dan Mullen

By Ian Wendrow

Neonicotinoids, a class of insecticides frequently used in agriculture, gets plenty of bad press for killing pollinators like honeybees.

But they’ve also emerged as an important combatant of the emerald ash borer, an invasive insect that has devastated ash populations all over the United States with the highest risk localized to the American Midwest and the northern half of the Eastern seaboard.

Map showing where emerald ash borer is most likely to appear and pose the greatest threat in the continental U.S. Image: Forest Health Technology Enterprise Team

For pollinator protectors in Michigan, that’s a problem.

With the recent designation of the rusty patched bumble bee as endangered by the U.S. Fish and Wildlife Service – the first time any bee species in the U.S. has landed on such a list – the race for effective conservation tactics has accelerated.

That includes proposed bans on neonicotinoid use for personal and professional application. They draw upon recent studies linking neonicotinoids to instances of colony collapse disorder in honeybees. The disorder occurs when most worker bees abandon an otherwise healthy hive.

Former Michigan Rep. Gretchen Driskell, D-Saline, introduced a bill last November that would have banned on neonicotinoids. It focuses on a class of the insecticide  found in the majority of those used against the emerald ash borer.

“We introduced this legislation kind of thinking that it’s a pretty harsh bill but a good starting point to have the conversation to maybe tailor it more to specific purposes than an all out ban,” said Annika Doner, the legislative director for Driskell.

Similar bills are proposed around the U.S. as part of pollinator protection plans. Maryland is the first state to ban consumer products containing neonicotinoids such as weed killers sprays and other lawn control products. It is slated to go into effect at the start of next year. The law still allows certified parties such as farmers and veterinarians to continue using products with these chemicals, but environmental activists are celebrating the partial ban as a crucial first step.

Entomologists remain on the fence.

“I do think that the situation with neonics can be complex,” said Deborah McCullough, a professor of entomology at Michigan State University and co-author of “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer,” a book funded in part by the U.S. Department of Agriculture and the National Institute of Food and Agriculture’s North Central Integrated Pest Management Center.

“There’s clearly places where neonics shouldn’t be used,” she said. “Anything that flowers, where you know that plant has every evolutionary reason in the world to attract pollinators, is not really a great place to use neonicotinoids.”

Ash don’t rely on flowers to help them reproduce, limiting direct exposure to pollinators. However, there is concern that the repeated application of neonicotinoids to ash  increases the chance of it affecting bees and other pollinators in less obvious ways over a longer period of time.

Since 2002, when the emerald ash borer was first discovered in Michigan, neonicotinoids have been used to treat infected ash trees. Part of this practice,  McCullough said, was due to a scarcity of other treatment plans.

Today there are other insecticide options to tackle emerald ash borer that may pose less of a threat to pollinators, McCullough said.

Recently, more and more professional applicators have switched from neonicotinoid based pesticides, which require annual sprays and trunk injections, to emamectin benzoate based products which only require tri-annual application, according to McCullough.

Still, the conflict between pollinator protection and emerald ash borer eradication remains.

For one, the science surrounding neonicotinoid toxicity to pollinators is far from settled, as is the potential toxicity of emamectin benzoate. An EPA risk-assessment published January 12 found that nitro class neonicotinoids, when applied properly, “do not pose significant risks to bee colonies.”

An EPA summary of its registration review for emamectin benzoate published in 2011 noted a data gap in the ecological toxicity database for emamectin benzoate. The EPA’s timeline for the review states that it will issue a decision on emamectin benzoate this year, following a three month public comment period that ended December 2016.

Those developing Michigan’s Pollinator Protection Plan have no intention of banning consumer products containing neonics, said Jeffrey Zimmer, the deputy director of the Michigan Department of Agriculture and Rural Development’s Pesticide and Plant Pest Management Division.

“When we started developing the plan in Michigan we made an effort to identify all sorts of stakeholders, beekeepers of course, agricultural producers, pesticide applicators, large area land managers and so on,” Zimmer said. “We wanted to ask them, ‘What practices do you think will be helpful for protecting managed pollinators from pesticide residue?’”

Meghan Milbrath, a research associate within Michigan State’s Department of Entomology who is helping develop that plan, suggests using neonicotinoids conservatively. Pest management strategies that employ cultural, physical and biological controls should be tried first, she said.

Another problem further complicating the neonicotinoid debate is sublethal effects, she said.

Sublethal refers to factors outside of neonicotinoids that contribute to the honeybee’s struggles. The waxy makeup of hives gradually accumulates heavy metals, pesticide dust and other contaminants over time.

The build up weakens the immune system of bees, the effects of which can be seen in emerging infectious diseases that afflict them. Environmental pollutants also inhibit bees’ dance communication and their ability to navigate back to their hives after foraging, Milbrath said. Habitat loss further diminishes the available nutrients for bees, creating a web of threats in which neonicotinoids are but one factor.

“You can’t really separate them, because maybe the neonics wouldn’t be as bad if the bees weren’t so terribly affected, or maybe the diseases wouldn’t be so bad if neonics weren’t present,” Milbrath said. “They all kind of work together which is why it’s been an issue for decades.”

It is why the Michigan Pollinator Protection Plan Committee is hesitant to go after neonicotinoids in earnest. Pesticide labeling will still be a prominent component of the pollinator protection plan, Zimmer said.

But that’s something Milbrath also expresses concern about.

“The EPA’s started to do labeling on some of the most toxic ones, which is good,” she said. “One of the kind of negative issues that stems from that is that a lot of people are saying ‘Well, it’s not labeled, therefore it’s bee safe’ and they’re being sold as bee-safe.”

The committee will have a draft of the plan available for public comment between March 10 and April 14. You can sign up to receive updates on the Michigan Pollinator Protection Plan.

Correction: A prior version of this story misidentified Jeffrey Zimmer as the deputy communications director of the Michigan Department of Agriculture and Rural Development. His title has been fixed in the story above.

Editor’s Note: A clarification to this story was added on Tuesday, February 14, 2017 that notes professional pesticide applicators have been shifting towards using more emamectin benzoate based pesticides over neonicotinoid based ones.

2 thoughts on “Fight invasives or protect pollinators: Neonicotinoids present tough choice

  1. I would love an update on the science that has evolved over the last four years. I am concerned about the decline in bee colonies.

  2. While Imidicloprid was included in the study published by Deb McCullough, no one uses it for treatment of EAB anymore as far as I know. The product of choice is emamectin benzoate (Trade name TREE-age) and is NOT a neonicitinoid, it’s a macrycyclic lactone . It still has bee toxicity though. The article is misleading as it refers to treatment of EAB using neonicitinoids, which is not true. There may be rare exceptions by uninformed companies. I’ve personally treated over 2,800 Ash trees in the last 4 years with TREE-age.
    David Williams
    ISA Certified Arborist
    Williams Lawn Care, Inc

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