- Author: Kathy Keatley Garvey
Why? Hypothesis: the milkweed may have been treated with pesticides before it was shipped to the nursery.
Newly published research led by scientists at the University of Nevada, Reno (UNR), in collaboration with the Xerces Society for Invertebrate Conservation--and appearing in the peer-reviewed science journal Biological Conservation--sheds some light on pesticide contamination of milkweed plants being sold in retail nurseries across the United States.
The article, titled "Milkweed Plants Bought at Nurseries May Expose Monarch Caterpillars to Harmful Pesticide Residues," indicates that every single plant tested in stores across the nation--every single one!--contained multiple pesticides, "even those that were labeled 'wildlife-friendly," according to the researchers, who included co-author Matt Forister, a UNR biology professor.
The team collected leaf samples from 235 milkweed plants purchased at 33 retail nurseries across the United States to screen for pesticides. "Across all samples, we detected 61 different pesticides with an average of 12.2 compounds per plant," they wrote in their abstract. "While only 9 of these compounds have been experimentally tested on monarch caterpillars, 38% of samples contained a pesticide above a concentration shown to have a sub-lethal effect for monarchs."
"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 pesticide but it was surprising to see the great diversity of pesticides found in these plants," Forister told Mike Wolterbeek in a Nevada Today news release. "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."
Forister, who is the Trevor J. McMinn Endowed Professor in Biology, Foundation Professor, holds a doctorate in ecology from UC Davis, where he studied with major professor Art Shapiro, UC Davis distinguished professor of ecology and evolution.
Forister's doctoral student, Christopher Halsch, is the lead author of the paper. “The farther along in the life stage you go, the higher concentration you need to have a sublethal effect," Halsch explained. "For the caterpillars, this means a low concentration can have a more damaging effect than it would have on the butterflies.”
So did the plants labeled "wild-life friendly" have fewer pesticides on the leaves? No.
“That was the most shocking part," Halsch related. "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.”
Thus, it's crucial that those milkweed plants that we purchase in retail stores--and elsewhere--be pollinator friendly and pesticide-free.
AsXerces' Pesticide Program Director Aimée Code, pointed out in the news article: “Everyone can take steps to address the risks we uncovered. 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. 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.”
We asked entomologist and monarch researcher David James of Washington State University today what he thinks of the study: "We all suspected this was the case, given all the reports in social media of caterpillars dying, etc. I'm glad they did this scientific study to confirm it. Pretty shocking, really."
Indeed, scientists fear that the rapid decline of monarchs could lead to extinction. The International Union for the Conservation of Nature (IUCN) placed the migratory monarch butterfly on its Red List of threatened species on July 21, 2022, classifying it as endangered.
"In the 1990s, nearly 700 million monarchs made the epic flight each fall from the northern plains of the U.S. and Canada to sites in the oyamel fir forests north of Mexico City, and more than one million monarchs overwintered in forested groves on the California Coast," according to the Xerces Society. "Now, researchers and citizen scientists estimate that only a fraction of the population remains, monarchs have declined by more than 80% since the 1990s from central Mexico, and by more than 99% since the 1980s in coastal California."
- Author: Kathy Keatley Garvey
But climate change, aka global warming, may be an equal, if not more, of a factor.
So indicates a 10-member team of scientists, including UC Davis distinguished professor Art Shapiro, Department of Evolution and Ecology, in the March 4th Science journal.
The research article, "Fewer Butterflies Seen by Community Scientists Across the Warming and Drying Landscapes of the American West," sounds a crucial alarm, alerting us to try to find new ways of protecting our fluttering friends.
The abstract:
"Uncertainty remains regarding the role of anthropogenic climate change in declining insect populations, partly because our understanding of biotic response to climate is often complicated by habitat loss and degradation among other compounding stressors. We addressed this challenge by integrating expert and community scientist datasets that include decades of monitoring across more than 70 locations spanning the western United States. We found a 1.6% annual reduction in the number of individual butterflies observed over the past four decades, associated in particular with warming during fall months. The pervasive declines that we report advance our understanding of climate change impacts and suggest that a new approach is needed for butterfly conservation in the region, focused on suites of species with shared habitat or host associations."
Lead author is UC Davis alumnus Matthew "Matt" Forister, the Trevor J. McMinn Endowed Professor in Biology, and Foundation Professor, Department of Biology, University of Nevada. Forister received his doctorate in ecology from UC Davis in 2004.
As Pennisi points out, "butterflies are at risk in open spaces, too." She writes: "Art Shapiro, an insect ecologist at the University of California, Davis, and colleagues have shown that over the past 35 years, butterflies are disappearing even in pristine protected areas such as the Sierra Nevada mountain range in the western United States."
"To see whether that finding held up elsewhere, Shapiro and Matthew Forister, an insect ecologist at the University of Nevada, Reno, gathered data from the North American Butterfly Association, which has coordinated community scientist butterfly counts across the United States for more than 42 years. The duo also incorporated 15 years of data from iNaturalist, a web portal that collects sightings of plants and animals, including butterflies. In all, the researchers tracked the fates of 450 butterfly species from 70 locations in the western United States."
The research indicates that the butterfly population in the Western United States has decreased an average of 1.6% per year between 1977 and 2018. "Fifty species declined in at least two of the data sets used, including the Edith's checkerspot (Euphydryas editha), the rural skipper (Ochlodes agricola), and the great copper (Lycaena xanthoides)," Pennisi wrote.
The researchers warn that some species may completely disappear from parts of their ranges in the coming decades, as fall temperatures continue to align with or exceed summer temperatures, impacting breeding cycles and plant dependence.
Back in February, 2019, Shapiro told the Environmental Defense Fund's UC Davis meeting on "Recovering the Western Monarch Butterfly Population: Identifying Opportunities for Scaling Monarch Habitat in California's Central Valley," that it's not just monarchs in trouble.
"Monarchs are in trouble in California--but they're hardly alone," Shapiro told the attendees. "If we act as if this is a 'Monarch problem,' we're in danger of missing the real causes of Monarch decline--factors acting at a much broader scale. We've been monitoring entire butterfly faunas--over 150 species--along a transect across California since 1972. Our monitoring sites are matched with climatological data, allowing us to examine statistical relations between climate and butterfly trends. Based on this data set, our group was the first to document and publish evidence of monarch decline here. That's the only reason I'm here."
"At low elevations—below 1000'—entire butterfly faunas have been in long-term decline. We published several papers showing that these declines were about equally correlated with land-use changes and pesticide (especially neonicotinoid) use, with climate change a significant factor but much less important. Remember, these are correlations, not necessarily demonstrations of causation—but they are strongly suggestive. Monarchs were just one of many species going downhill; three once-common species (the Large Marble, Field Crescent and “Common” Sooty-wing) had already gone regionally extinct or nearly so, with others threatening to follow suit."
See more of Shapiro's comments on the March 4, 2019 Bug Squad blog. Read the Science article here.
- Author: Kathy Keatley Garvey
Newly published research examining more than four decades of data collected in central California by Art Shapiro, UC Davis distinguished professor of evolution and ecology, clearly reveals the effect: a marked difference between how butterfly populations fared at low and high elevations.
It's basically good news for the valley or low-elevation butterflies and bad news for the mountain or high-elevation butterflies.
The research, "Impacts of Millennium Drought on Butterfly Faunal Dynamics," is published in the journal Climatic Change Responses.
Lead author Matthew Forister, a biology professor at the University of Nevada, Reno, is a former Ph.D. student of Art Shapiro's, as are two co-authors James Fordyce of the University of Tennessee, Knoxville, and Chris Nice of Texas State University, San Marcos. UC Davis co-authors, besides Shapiro, are James Thorne and David Waetjen of the UC Davis Department of Environmental Science and Policy.
The six-member team analyzed the data in Shapiro's 10-study site dataset, which dates back to 1972 and encompasses 163 butterfly species. The sites, representing what Shapiro calls the "great biological, geological and climatological diversity of central California," range from the Sacramento River delta, through the Sacramento Valley and Sierra Nevada mountains, to the high desert of the western Great Basin. See his research website. Shapiro walked the study sites every two weeks between 45 and 29 years, noting the presence or absence of all butterfly species. (He still does. Of course, he walks during what he calls "good butterfly weather," when conditions are suitable for insect flight. This is nearly year-around at low elevations but understandable, there's a more narrow period at higher elevations.)
Of the research paper, Professor Shapiro said: "This is the most important contribution from our research group in a while. It documents the responses of entire butterfly faunas to the recent California drought. It demonstrates that, counter to intuition, butterfly faunas near sea level apparently benefited from the drought, temporarily reversing long-term declines, while montane Sierran faunas were severely harmed...the study has broader implications for the biological impacts of climate change."
Bottom line: Climate change, aka global warming, is real. Wikipedia describes it as "the observed century-scale rise in the average temperature of the Earth's climate system and its related effects. Multiple lines of scientific evidence show that the climate system is warming." Indeed, we should all be concerned with the increasing severity and frequency of extreme weather events, such as drought, and the challenges that plant and animal life face.
"Despite ongoing political controversy swirling around climate change, the vast majority of scientists dealing with the subject have no doubt that it is occurring and that its ecological implications are profound," Shapiro told us today. "One way to address potential long-term impacts of climate change on living things is to examine in detail how they are reacting to shorter-term climatic events, especially climatic extremes. The recent 'millennia'-scale California drought affords just such an opportunity. We have been monitoring entire butterfly faunas along the I-80 corridor in California for many years (in some cases way back to the early 1970s), so we have a huge baseline for comparison to data from the drought years. There are very few comparably continuous and extensive data sets on any group of organisms world-wide. As we explain, butterflies reacted to the drought in mostly unexpected and 'counterintuitive' ways. By trying to understand those reactions, we can approach longer-term trends in a much more sophisticated way. Or so we think."
Read the research paper here and learn how the scientists compiled the statistics and obtained the results.
- Author: Kathy Keatley Garvey
UC Davis alumnus Matt Forister, McMinn Professor of Biology at the University of Nevada, Reno (UNR), will return to UC Davis campus on Wednesday, April 25 to discuss the research he and his lab are accomplishing on the "colonization of alfalfa by a focal butterfly (the Melissa blue) as well as other arthropods and microbes."
Forister has titled his seminar, set for 4:10 p.m. in 122 Briggs Hall, "Understanding Host Evolution: A Case Study of Alfalfa Colonists Across the Great Basin." This is part of the weekly spring seminars hosted on Wednesdays by the UC Davis Department of Entomology and Nematology.
"Host range dynamics are central to issues that include diversification, specialization and persistence of populations in the Anthropence," Forister writes in his abstract. "Outstanding questions in this area include the relative importance of different host traits in the colonization process, as well as the underlying genetic architecture associated with the use of alternative host plants. I will cover our attempts to understand the colonization of alfalfa by a focal butterfly (the Melissa blue) as well as other arthropods and microbes. Results will include a detailed look at genetic architecture in the Melissa blue as well as ongoing work on alfalfa phytochemistry to understand how the plant manages host-associated communities." (See his lab research website)
Forister is the co-principal investigator of a 2016-2021 grant from the National Science Foundation to study "Dimensions: Collaborative Research: The Evolution of Novel Interactions within a Network of Plant, Insect and Microbial Biodiversity." The UNR portion of the $1.9 million grant is $540,000.
Keenly interested in monarch butterfly research, Forister also holds a $25,000 U.S. Fish and Wildlife grant titled "Western Monarch and Milkweed Habitat Suitability."
Among his research publications: "The Global Distribution of Diet Breadth in Insect Herbivores," published in 2015 in Proceedings of the National Academy of Sciences; and "Global Weather and Local Butterflies: Variable Responses to a Large-Scale Climate Pattern along an Elevational Gradient, published in 2015 in the journal Ecology.
Forister received his doctorate in ecology from UC Davis in 2004, studying with major professor Art Shapiro, distinguished professor of evolution and ecology. He then worked as a post-doctoral research associate from January 2005 to July 2006 at Stony Brook University, New York, and then headed to the University of Nevada to accept a position as research assistant professor from September 2006 to July 2008 with the Department of Natural Resources and Environmental Sciences.
Forister joined the UNR Biology Department faculty in July 2008 as an assistant professor and was promoted to associate professor in July 2013. His research interests include plant-herbivore interactions; specialization; speciation; hybridization; co-evolution; evolution of diet breadth; niche shifts in herbivorous insects; global change and adaptation to anthropogenic change; analyses of long-term ecological datasets; and monitoring and conservation of insects. His teaching expertise targets ecology, biodiversity, molecular ecology, biodiversity, and biostatistics.
Highly honored by his university, Forister was named the McMinn Professor of Biology in 2015, and selected the recipient of the Hyung K. Shin Award for Excellence in Research in 2014; Regents' Rising Research Award in 2013; the Mousel-Felner Award for Excellence in Research in 2012; and the Stephen Jenkins Mentorship Award in 2012.
The Entomological Society of America honored him in 2005 with the George Mercer Younger Investigation Award for "the most outstanding paper in ecology by a scientist under 40."
Forister made his mark at UC Davis, receiving a $10,000 Faulkner Fellowship, a $11,000 Zolk Fellowship, and a National Science Foundation Graduate Research Fellowship of $86,418.
He and Art Shapiro continue to collaborate on multiple projects.
(Editor's Note: This lecture will be recorded)
- Author: Kathy Keatley Garvey
And he wasn't even looking for it.
A UC Davis graduate student won the “Beer for a Butterfly” contest by collecting the first cabbage white butterfly of the year Saturday morning, Jan. 16 outside his home in West Davis.
Jacob Montgomery, a master's student in ecology, said he was walking out of his home around 10:30, heading for the Farmers' Market, when he spotted the cabbage white butterfly perched on his lavender.
“It was cold and rainy and the butterfly's wings looked bent like it had just hatched,” Montgomery said. “It was not difficult to catch. I picked it up by hand…I had been aware of the contest but not actively searching for the butterflies. It was completely opportunistic.”
Art Shapiro, UC Davis distinguished professor of evolution and ecology who has sponsored the contest since 1972 as part of his four-decade study of climate and butterfly seasonality, identified it as a female with a damaged forewing.
Shapiro awards a pitcher of beer, or the equivalent, for the first cabbage white of the year found in the three-county area of Sacramento, Yolo and Solano. Montgomery collected his prize, Great White beer, on Tuesday night at The Graduate.
The two shared beer and talked butterflies.
The cabbage white (Pieris rapae) probably eclosed or hatched around 7:30 that morning, said Shapiro, who has earlier predicted that the first butterfly of 2016 would be collected in mid-January.
Shapiro's former graduate student, Matt Forister, an associate professor at the University of Nevado, Reno, plots the first-flight dates and also predicted it would be found about now.
Montgomery's catch means that “now we should be seeing more and more of them after three to five days,” Shapiro said.
The UC Davis student studies plankton production dynamics in the delta and how plankton function as a food source for fishes. “More specifically, how do hydrodynamics, land management practices and slough geomorphology contribute to aquatic productivity and influence abundance and distribution of plankton?”
This makes only the fourth time that Shapiro, who is out in the field more than 200 times a year, has been defeated. His graduate student Adam Porter defeated him in 1983; and his graduate students Sherri Graves and Rick VanBuskirk each won in the late 1990s.
“I sort of consider this is a liberation because now I don't have to look for it every time the sun comes out in January—now I can relax,” Shapiro said. “Jacob's win shows that the contest isn't rigged,” he said, smiling. “Some think the contest is all a sham.”
“If this starts happening every year like this, that's when I should retire,” quipped Shapiro, who turned 70 last week.
Shapiro says the cabbage white is “typically one of the first butterflies to emerge in late winter. “Since 1972, the first flight has varied from Jan. 1 to Feb. 22, averaging about Jan. 20.”
Although the first flight of the cabbage white has been as late as Feb. 22, it is emerging earlier and earlier as the regional climate has warmed, the professor said. “There have been only two occasions in the 21st century in which it has come out this late: Jan. 26, 2006 and Jan 31, 2011.”
Shapiro won the 2015 contest by netting a cabbage white at 12:30 p.m.. Monday, Jan. 26 in West Sacramento, Yolo County. The site: a mustard patch near the railroad tracks.
Shapiro does long-term studies of butterfly life cycles and climate. "Such studies are especially important to help us understand biological responses to climate change,” he said. “The cabbage white is now emerging a week or so earlier on average than it did 30 years ago here."
Shapiro, a fellow of the American Association for the Advancement of Science, the Royal Entomological Society and the California Academy of Sciences, maintains a website on butterflies at http://butterfly.ucdavis.edu/, where he records the population trends he monitors in Central California. He and artist Tim Manolis co-authored A Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions, published in 2007 by the University of California Press.
