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Are neonicotinoids killing your bees?

 
Above: Neonicotinoids are an effective deterrent for mealybugs. Below: Scale is among the common pests that neonicotinoids target.
Above: Neonicotinoids are an effective deterrent for mealybugs. Below: Scale is among the common pests that neonicotinoids target.
Published Sept. 18, 2015

I don't use poisons on plants for two reasons: I'm cheap and I'm scared to death of them. If my natural remedies don't work, I just get rid of my poor, afflicted friends to prevent their pestilence from spreading.

So, when I started seeing warnings recently from gardeners on social media that buying plants from certain big-box retailers will doom my birds, bees and butterflies because of the pesticides they use, I did a double take.

What?

The insecticides they're talking about, a group called neonicotinoids, have been banned in several U.S. cities and parts of Europe. But big-box stores don't use insecticides — their growers do. So, at least part of the message was wrong. That made me curious about the rest of it.

If you read only this far, rest assured: Buying flowering plants from Home Depot and Lowe's likely won't kill your pollinators. So say two experts I trust: a University of Florida entomologist and a UF-educated horticulturist who supplies Home Depot with annuals and perennials. (Costa Farms, a major Florida grower for Lowe's and Home Depot, declined to comment.)

"These are some of the safest products we have. And by the time you get them into the landscape, they're not active," says Catharine Mannion, a bug specialist and associate professor in UF's Tropical Research & Education Center. "These aren't impacting hummingbirds (and other pollinators). ... It's the bees people are worried about."

Neonicotinoids

Neonicotinoids, a group of seven insecticides that appeared in the early 1990s, kill common nemeses including scales, mealybugs, aphids and white flies. They got bad — and unwarranted, according to many respected experts — publicity three years ago, when a Harvard professor published a study blaming them for the huge decline in honeybees in 2006.

That study had problems, including flawed research, Catharine and many other reputable scientists say. And it doesn't account for the fact that honeybee numbers have been dropping for decades.

"There's been a decline in bees since the 1950s for a lot of reasons: loss of habitat, pesticides in general, diseases — the viruses in bees is a huge issue. Genetic diversity is very poor among the honeybees, so they can get wiped out fast," Catharine says.

Mainstream media snapped up press releases about the study, so consumers around the world got the news from trusted sources, like newspapers. (Well-respected Nature magazine rejected it, according to a 2014 Huffington Post article, which reported the study by Chensheng "Alex" Lu first appeared in a pay-for-publish magazine, the Bulletin of Insectology.)

Some retailers, including Home Depot, now require their growers to certify that they don't use neonics, says Rick Brown of Riverview Flower Farm. He's one of Home Depot's biggest Florida growers and a diehard environmentalist and UF-educated horticulturist. But Home Depot reacted to public alarm — not a real threat, he says.

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"Neonics have replaced so many devastatingly harsh, toxic chemicals that were previously used on food crops worldwide with greater peril to bees, wetlands and people," he says.

"When used properly and according to the label, neonics remain today the least toxic and most widely used safe and effective pesticide in the world. ... We do not use neonics but had excellent and safe results from 1992 through 2013."

Substitutes to insecticides

All insecticides have some negative impact, so if you can avoid them, you should, Catharine says. Here's what she suggests for home gardeners.

Be okay with some pest damage. A few chomps in a leaf is no reason to break out the machine guns.

Try mild remedies. A mixture of dish soap, water and vegetable oil or a jet spray from your hose can blow away many common pests.

Know what you're dealing with. Send photos of your plant and that weird worm to your local UF Extension Service (every Florida county has one) for identification and tips on how to get rid of it, if necessary. Use the right insecticide for the problem, and follow directions carefully!

For major infestations, follow up your shock-and-awe assault with gentler treatments. Once you've made the problem manageable, control it with less toxic strategies.

For those of us whose lives do not depend on the plants we grow, a gentle approach to pest control seems like a no-brainer. But we also depend on farmers, and they depend on their crops.

Buying from certified organic growers helps ensure you have safe plants. If you prefer the convenience and lower prices of big retailers, pesticides will play a role. Nix the safest of these, and we could end up with something far worse.

Contact Penny Carnathan at pcarnathan49@gmail.com; visit her blog, digginfloridadirt.com; and join in the chat on Facebook, Diggin Florida Dirt.