Changes in the gardening industry might be good for pollinators.
A momentous thing happened this year, the first signs of a victory for the environment likely not seen since the EPA banned use of DDT in 1972. Neonicotinoids, one of the most widely utilized pesticides on the planet, are falling out of favor. While we are far from an out-and-out ban, as with DDT, powerful forces, from government agencies to multi-national companies, are beginning to eschew the chemicals known to weaken pollinator insects—creatures that enable plants to make fruits or seeds.
Neonicotinoids (neo-nicotine-oid), a group of chemicals developed by Shell and Bayer in the mid-1990s, are powerful neurotoxins that easily penetrate and attack the central nervous system of insects but, according to the EPA, early tests demonstrated to be much less toxic to birds, mammals and other vertebrates. Almost always used as a seed treatment for commercial crops like corn and canola, this point-specific application eliminated the need for broadcast spraying of mature plants. As the treated plant grows, poison remains inside the plant and, hypothetically, only affects the pests that feed on the treated crops.
Within a decade of widespread use, however, signs showed that neonics were not as harmless as they first seemed.
Passed on through pollen
By 2006, neonicotinoid pesticides were widely considered to be a factor contributing to Colony Collapse Disorder, possibly by weakening the immune systems of beneficial pollinators. Yet by 2010, neonicotinoid use was continuing on an upward trajectory and represented some of the most popular and widely used insecticides, accounting for 27% of the world’s total insecticide use ranging from urban landscaping to agricultural systems.
While we often acknowledge and understand the widespread use of neonics on crops like corn and canola (95% of these crops are treated with neonics in the U.S.), soybeans and sugar beets, research from the Yale School of Forestry and Environmental Studies shows more surprising applications on “the vast majority of fruit and vegetable crops, including apples, cherries, peaches, oranges, berries, leafy greens, tomatoes, and potatoes” as well as cereal grains, rice, nuts, and wine grapes.
For workers in the field, neonicotinoids are safer than other pesticides. In fact, neonics are a problem only in regard to trees and plants that produce blossoms pollinators like—and only when the treated plant is flowering. It’s the pollen that holds traces of neonics, which foraging pollinators ingest. This powerful neurotoxin can be detected at some level in the pollen of a treated plant or tree for several years.
A study reported last year by Science News shows that neonicotiniods are turning up in honey. The global survey tested 198 honey samples from all six continents and found that almost half the samples contained more than one type of the pesticide (86% of samples from North America contained measurable amounts). While the pesticide level for humans consuming honey is smaller than negligible, honey is the primary food of bees.
Neonics in the environment
Even as use of neonics grows, research confirming their danger is also accumulating. A 2014 paper, published by the U.S. National Library of Medicine, by J.M. Bonmatin, a researcher of molecular biophysics, found that neonicotinoids often accumulated in soils and waterways and that the chemicals persisted in the environment for extended periods of time. With a half-life in many cases of 1,000 days, these chemicals often persisted in soils for years. They further accumulated with repeated use.
Bonmatin and his team found clear evidence of neonicotinoids also being taken up by area pollinators. According to the study, “food stores in honey bee colonies from across the globe demonstrate that colonies are routinely and chronically exposed to neonicotinoids. Other nontarget organisms, particularly those inhabiting soils, aquatic habitats, or herbivorous insects feeding on non-crop plants in farmland, will also inevitably receive exposure.”
While on the subject of degradation of neonics: Breakdown of neonics accumulated in soil depends on factors such as soil type, moisture, temperature and pH. According Bonmatin’s research, the half-life of neonics is almost 10 times longer under dry conditions and that breakdown is insignificant during the colder months. Sounds like Utah is not the place for neonicotinoids.
Common sense alternatives
After much deliberation, the U.S. Fish and Wildlife Service, at their 2017 national conference, banned neonicotinoid use on national wildlife refuges. This may be just the start. According to the National Wildlife Federation, the U.S. Environmental Protection Agency (EPA) is reviewing the safety of five neonics, with draft risk assessments scheduled to be released this year and has already issued recommendations to reduce their use. The private sector is following suit with companies from Home Depot to Costco swiping neonic-treated plants from their landscaping products.
With the toll that neonics are taking on our pollinator populations, and considering the long-lasting presence of these chemicals in the environment, it’s nice to know that alternatives are being seriously considered. The most interesting suggestion might prove at once the easiest and the most difficult: Just stop using them. It seems that the need for neonics has been blown out of proportion. But other practices would need to be put in place, which are not immediately compatible with Big Ag.
In 2009, the European Union adopted a compulsory approach called Integrated Pest Management. The directive requires some common sense. Before deciding to use poison on crops, for example, the impact of predatory insects must be monitored; treatment with pesticides will only be recommended if and when “the assessment has found that [pest damage] levels are above predetermined economic thresholds for crop protection.” Additionally, if crops show significant stress and damage due to pests, the IPM plan calls for chemicals as a last resort. The first line of defense is standard organic farming practices such as crop rotation—often sufficient for heading off large pest infestations.
In the U.S. additional IPM practices are making their way into regulatory language, if not actual practice. Last year, the EPA put out new guidelines designed to protect pollinators from pesticide exposure such as temporarily halting the approval of new outdoor neonicotinoid pesticide use.
Though pesticide use in Big Ag is something we should all be concerned about, home gardeners also need to be aware that neonicotinoids are the active ingredient in most pesticides you can buy in your local store. (See sidebar for details.)
Luckily, some change is happening on the home front as well. The 2016 Greenhouse Grower’s State of the Industry report showed a big bump in the number of growers eliminating neonicotinoids.
According to the report, 64% of growers (who sell to garden retailers, nurseries and landscaping companies) reported no longer using neonics — up from 52% the year before. Since plants from these growers find their way onto store shelves, from mom and pop gardening centers to big chain stores, these changes are trickling into most companies. Two of the largest home improvement retailers in the world, Home Depot and Lowe’s, are now committed to phasing out neonics in their gardening centers by this or next year. Whole Foods, Walmart, Ace Hardware, True Value Hardware and Costco have also made similar commitments.
In Salt Lake City, many reputable garden centers carry plants and trees from Monrovia. The company has reduced its use of neonics by 80% since 2012 and is practicing Integrated Pest Management, using neonics as last resort and following “stringent and conservative guidelines.” A Dave Wilson Nursery spokesman says they, too, have significantly cut back on their use.
Local nurseries that grow their own plants, such as Lambert Growers, do not use neonics at all.
Still, if you want to rest assured that you are not buying plants or seeds treated with neonics, or any harmful chemical, buy organic.
While we’re on a roll with good news
There might be a new little pollinator getting ready to do some heavy lifting for the gardening industry. Commercial greenhouses have long used bumble bees to pollinate their indoor plants, but like the honey bee, these little creatures (specifically the Bombus occidentalis) have recently been in decline. Now researchers from Utah State University are looking at Bombus huntii (Hunt’s bumble bee), native to the Western U.S., as a promising new alternative for Western greenhouses. B. Huntii is a generalist pollinator, so he’s not a picky eater—an important trait for a bee whose job will have him bouncing around a warehouse of thousands of different plants.
There is always more that we can do for our pollinators. The Xerces Society for Invertebrate Conservation has called for increased federal regulation of neonicotinoids including a prohibition of neonic application on bee-attractive plants during bloom and strengthening pesticide warning labels. Yet much good work is already being done. With bee-advocating researchers like those at USU, and with a growing shift in industry practices, our pollinators might get a second chance.
For the home gardener
A philosophical approach
Don’t freak out. Many trees and shrubs, including all conifers, are wind pollinated and are not usually visited by bees.
Because pollinators range widely, the presence of a neonicotinoid insecticide in one plant will be diluted when they feed on untreated plants.
Flowers bought in flats should be completely safe. Besides, bees don’t even much like petunias or marigolds.
The longterm benefit to pollinators from even treated perennial flowers and flowering shrubs and trees outweighs the harm.
A practical approach
Avoid spraying insecticides in the yard and garden as much as possible, and never spray flower blossoms. If you have a problem with caterpillars chewing too many holes in the leaves of some plants, use a product containing Bacillus thuringensis (B.t.).
Another bee-friendly option is to use horticultural oil or an insecticidal soap. Used properly, they are effective on most soft-bodied insects.
If you’ve acquired a bee-friendly perennial or flowering trees or shrub that was treated, you can remove the flowers during the first summer. Also, you can water it thoroughly, and continue to run the water for another 10 minutes. This will flush any neonicotinoid insecticide residue that is not tightly bound to the organic matter in the soil.
— Dave Smitley, entomologist Michigan State University
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You won’t find the word “neonicotinoid” on any product label. The five specific neonic chemicals you may encounter are Imidacloprid, Clothianidin, Thiamethoxam, Acetamiprid and Dinotefuran. In general, avoid anything that sounds lethal: bugs B gon, insect killer, GrubZ out, systemic insect spray, etc. Bayer and Ortho make a long line of objectionable products. For a detailed list of specific products to avoid, check out Xerces Society’s “Neonicotinoids in your Garden” webpage.
Katherine Pioli is CATALYST’s associate editor.