13
Sep
Multiple Pesticides Detected in All Store-Bought Milkweed, Threatening Further Monarch Declines
(Beyond Pesticides, September 13, 2022) Every store-bought milkweed sample tested in a recent study contains multiple toxic pesticides, placing monarchs reliant on these plants in harm’s way at a time the species can ill afford any further loss to its population. Pollinator declines have influenced many residents throughout the U.S. to take action into their own hands and transform their home yards or businesses into an oasis for bees, birds, and butterflies. Yet the recent study published in Biological Conservation finds that many retailers are dousing their ‘wildlife-friendly’ plants with pesticides that put this vulnerable species in further danger.
“That was the most shocking part,” said lead author Christopher Halsch, a doctoral study at University of Nevada, Reno. “The fact that plants labeled as potentially beneficial or at least friendly to wildlife are not better and in some cases might be worse than other plants available for purchase. This research sheds light on how pesticides may impact western monarchs, but many other butterflies are facing even steeper population declines, and pesticides are likely one driver.”
Testing was conducted by purchasing milkweed plants at 33 different stores spanning 15 different states. A sample of each plant was cut after purchase, and then sent to the lab for chemical analysis. Screening was conducted for 92 different pesticides, including insecticides, fungicides, herbicides, and the synergist piperonyl butoxide.
Out of the 92 pesticides tested, 61 compounds were discovered in milkweed samples. Every sample contains at least two pesticides, though certain plants contain over 25 different chemicals. Despite the importance of this iconic species, data on harmful effects of most pesticides on monarchs is sparse or lacking. Only 9 of the 61 compounds detected have been tested for their impact on monarch health. Yet for the data that is available, researchers find that 89 samples exceed levels associated with sublethal effects in monarchs — exposures that may not outright kill a monarch, but may increase the likelihood of death in the wild. These sublethal effects were seen in 17 of 25 locations, driven primarily by the elevated presence of the fungicides azoxystrobin and trifloxystrobin. Milkweed sold from larger retailers generally contain more pesticide than those sold at smaller stores, but the effect was not statistically strong.
“In a previous study in California that primarily looked at milkweed in agriculture and urban interfaces, we had looked at a small number of plants from retail nurseries, and found that they contained pesticides,” study coauthor Matt Forister, PhD, said. “So we were prepared for this much larger sample of nursery plants to again uncover contamination, but it was surprising to see the great diversity of pesticides found in these plants. In many ways, they are as contaminated or even worse than plants growing on the edges of agricultural fields. That was a surprise, at least to me.”
Prior investigations from the same research team did find wild milkweed growing in a range of habitats to be ubiquitously contaminated with pesticides. Published in 2020, their study found 262 different pesticides from over 200 milkweed samples collected from around 20 sites within California’s Central Valley. “From roadsides, from yards, from wildlife refuges, even from plants bought at stores—doesn’t matter from where—it’s all loaded with chemicals” Dr. Forister said of the previous study.
Monarchs on both sides of North America are fairing extremely poorly in the face of multiple interacting stressors, including climate change, habitat destruction, and pesticide exposure. Eastern populations have declined by 80% since 2005, and western monarchs have shrunk an astounding 99.9% from their population of over 10 million in the 1980s. These numbers pose a significant risk of migratory collapse, and with it, potential extinction.
Despite this dismal state of affairs, Aimee Code, study coauthor and pesticide program director at the national nonprofit Xerces Society, notes that, “Everyone can take steps to address the risks we uncovered.” In the context of this study, it’s important get active in your purchases and the milkweed plants being sold in your community. “Consumers can let their nurseries know they want plants that are free from harmful pesticides. Nursery outlets can talk with their suppliers and encourage safer practices, and government agencies can improve oversight,” she said.
Instead of immediately ripping out your milkweed, Ms. Code indicates there are steps that can be taken to protect butterflies from the likely contamination. “And it’s important to keep gardening for pollinators for the long term, just take steps to reduce pesticide exposure: cover new plants the first year, water heavily, discard the soil before planting, as it may be contaminated, and avoid pesticide use.”
It is critical that every possible step is taken to protect these iconic pollinators before it is too late. While the international conservation group, International Union for the Conservation of Nature (IUCN), is listing the monarch as endangered, the U.S. government has not taken similar action. The U.S. Fish and Wildlife Service (USFWS) determined in 2020 that monarchs were eligible for protection under the endangered species, act but their listing was “precluded by higher priority actions..” Is the ubiquitous threat of pesticides throughout the monarch habitat the reason USFWS is dragging its feet? In another recent listing, concerning the officially endangered Rusty-Patched bumblebee, USFWS declined to declare the species’ critical habitat, precluding rules that could place restrictions that protect the species from toxic pesticide exposure. Some conservationists speculate that the federal government is failing to take action on pollinators as a result of the significant implications of listing would cause to the pesticide industry.
Meaningful action at the federal level will take immense pressure from local residents and communities. Join Beyond Pesticides in telling U.S. Fish and Wildlife to officially list monarch butterflies as endangered species, so that they have access to additional protections needed to recover the population.
All unattributed positions and opinions in this piece are those of Beyond Pesticides
Source: University of Reno press release, Biological Conservation
Thank you for this informative article.
July 24th, 2023 at 9:52 amI want to help the Monarch Butterflies.
1. how can I be sure I have purchased pesticide free Milkweed from small nurseries.
2. if I collect seeds from a common nursery plant that likely used pesticides, do the seeds also carry the pesticides in growing the next plant? How can I plant “clean” seeds and plants?
3. I live in a condo unit. What info is helpful to persuade the condo leaders to cancel pesticide sprays?
4. Cancel perfect looking green lawns.
How can a National movement begin that brings us back to healthy yards with dandelions ? Begin with posting a sign in the yard?
“My yard is free of chemicals”. This yard is safe for all humans and animals” etc…
I have not looked at your website yet. I hope some of my questions will be answered there. Thank you, Lee Ann