While researching an entirely different subject, I found my attention captured by Dan Gunderson's story on Minnesota Public Radio, Study finds pesticides in plants used as butterfly habitat:
A new study finds milkweed plants from retailers across the country contain pesticides that could harm the monarch butterflies attracted to the plants.
Milkweed is a host plant for monarchs, and many people plant it in gardens to provide breeding habitat. Eggs laid on the plant hatch into caterpillars which become butterflies.
“We looked in 15 different states, including in Minnesota, and we looked from very small retailers to large, big box stores,” said Aimée Code, pesticide program director at the Xerces Society for Invertebrate Conservation, and one of the study authors. . . .
Read the rest at MPR.
I grew curious about the details and tracked down the study via a Xerces Society press release. The screenshot at the top of this page is taken from the study, Milkweed plants bought at nurseries may expose monarch caterpillars to harmful pesticide residues, published this month in Biological Conservation (a PDF of the entire paper is available at the link).
The news reminded us of the 2014 law passed by the Minnesota legislature regulating pollinator-friendly plant labeling by retailers. The then new language put into statues states:
Pollinator lethal insecticide.
"Pollinator lethal insecticide" means an insecticide absorbed by a plant that makes the plant lethal to pollinators. Pollinator lethal insecticide includes, but is not limited to, the neonicotinoid class of insecticides that affect the central nervous system of pollinators and may cause pollinator paralysis or death. . . .
(e) A person may not label or advertise an annual plant, bedding plant, or other plant, plant material, or nursery stock as beneficial to pollinators if the annual plant, bedding plant, plant material, or nursery stock has been treated with and has a detectable level of systemic insecticide that: (1) has a pollinator protection box on the label; or (2) has a pollinator, bee, or honey bee precautionary statement in the environmental hazards section of the insecticide product label. The commissioner shall enforce this paragraph as provided in chapter 18J.
Neonicotinoids are a type of systemic poison. Of the insecticides listed in the chart above for Minnesota, four show up in the Xerces Society Searchable Systemic Insecticides List. One is a neonic.
Were milkweed plants in the study sold as "pollinator friendly"? As we tweeted earlier, we hope the Minnesota Department of Agriculture, which has authority to enforce the law, looks into the labels on the insecticides and the plants--and future sales as well.
2/2 If so labeled, were plants with these 4 insecticides on them sold as "pollinator friendly"? If so, that violated 2014 law #mnleg passed on bipartisan basis. Maybe @MNagriculture, which has enforcement authority, can look into this #mnpollinatorshttps://t.co/GNqbk5OuQZ
— Sally Jo Sorensen (@sallyjos) September 5, 2022
Unfortunately, that law only covers truth-in-labeling with regard to systemic insecticides. Perhaps it's time to update the law to be more comprehensive.
In the meantime, Gunderson's report at MPR offers this advice:
. . . Monarch populations are in decline and many people plant milkweed in backyards and other locations in an effort to help the butterfly. Code said the study does not mean every milkweed plant sold at a retailer is contaminated, but it does mean consumers must be aware of potential pesticide contamination.
“We still need to put these plants in our garden, but we need to make sure that these plants are safer,” said Code.
"If you buy a plant to the store, and you don't know if it was contaminated or not, that doesn't mean you throw out the plant, especially a milkweed which can last for many years, but it means that you take steps to avoid pesticide exposure," she said.
Code said protective steps might include removing the soil in the pot the plant was purchased in. It might mean placing a net over the plant for a year to keep butterflies from landing on it until the pesticides on the plant break down.
A final note: the milkweed plants in my gardens are self-starters--and have been pesticide-free before and after a helpful person trespassed and zapped the largest patch with an herbicide just as the plants were loaded with monarch caterpillars. Both the plants and caterpillars died. Uffda.
Related posts:
- HF2798, pollinator-friendly plant labeling bill, scheduled for House vote on Tuesday, April 29
- Nurseries, neonicotinoids and HF2798/SF2695
Screenshot: From Milkweed plants bought at nurseries may expose monarch caterpillars to harmful pesticide residues, published this month in Biological Conservation.
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