On Friday, Aug. 26, he met with success. He spotted four within half an hour.
It all began with his stroll through the UC Davis Arboretum and Public Garden, "where construction at Wyatt Deck was finally completed and the paths have been reopened," he related in a group email.
"It was my first time there in about 3 weeks. As usual, I scoped out the big Asclepias speciosa clone and found...nothing." He then crossed over Arboretum Drive to the Environmental Horticultural gardens where he knew of another small clone of A. speciosa. "By now it was 4:30 p.m. and the area was in dappled light and shade--and there were two brilliantly fresh-looking male monarchs chasing each other in the trees above the milkweed!"
"I looked over the plants for evidence of larval feeding and found absolutely none; I can't believe they were 'born' there despite being so brilliantly fresh-looking. I then walked west on Arboretum Drive, intending to turn north toward Mrak Hall, when an old, worn male monarch flew directly in front of me near eye level. It was now 4:50.
"As I went to turn toward Mrak (Hall) a fresh-looking one--sex undetermined--was cruising up in the trees near the bridge. I believe I saw four different individuals within half an hour. That's almost as many as I've seen in Davis all year."
Then, on Aug. 29, Shapiro ventured to north Davis where Professor Louie Yang of the UC Davis Department of Entomology and Nematology and collaborators had planted several dozen narrow-leaf milkweed, Asclepias fascicularis, several years ago for their research projects. "Nearly all the plants are in seed; I only found three still in bloom," Shapiro said. "And one had a beautiful, fresh-looking male monarch nectaring at it at 11.55 a.m. I didn't try inspecting all those plants but on casual inspection, I noted no evidence of larval feeding, nor pupae nor pupal exuviae."
That's good news on The Monarch Front.
Shapiro's colleague and former doctoral student Matt Forister, the McMinn Professor of Biology at the University of Nevada, Reno (UNR), alerted him to more good monarch news: "They're passing through Reno with increasing frequency. I am personally seeing ~1 per day now. All stopping for nectar, and heading your way, Art. Looks like the production in the desert has been good." (See latest research by Forister and colleagues on "Milkweed Plants Bought at Nurseries May Expose Monarch Caterpillars to Harmful Pesticide Residues," published in the science journal Biological Conservation.)
As you may know, Shapiro has been studying the butterfly populations at 10 sites in Central California for 50 years and maintains a research website, Art Shapiro's Butterfly Site, aka Art's Butterfly World.
The North American Butterfly Monitoring Network (NABA) website praises his work as "the longest continually running butterfly monitoring project in the world":
"Art Shapiro began monitoring 10 transects in 1972 and has been conducting bi-weekly monitoring of those sites ever since. He also monitors an additional site as part of NABA's Seasonal Count Program! Art's program is the longest continually running butterfly monitoring project in the world, predating even the British Butterfly Monitoring Scheme."
Elsewhere in Davis, Bohart Museum of Entomology associate Greg Kareofelas has seen monarchs in his Davis backyard three times this year: May 6, May 11, and in early June. "A couple of days ago, in the Inner Coast Range, Glenn county I saw nine or ten adults and that many larvae."
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."
The good news? That the iconic monarch landed on the Red List, which means opening safeguards to protect it.
The bad news? Being on the list means that it's closer to extinction. The other bad news? The U.S. Fish and Wildlife Service, has not yet listed it as endangered or threatened, only that it's a candidate for its list of endangered and threatened wildlife.
The sad news? The IUCN Red List now includes 147,517 species, of which 41,459 are threatened with extinction.
IUCN, the global network conservation authority based in Switzerland, is comprised of more than 1,400 member organizations, with input from some 15,000 experts.
Percentages punctuate the story of the declining monarch population. "The western population is at greatest risk of extinction, having declined by an estimated 99.9%, from as many as 10 million to 1,914 butterflies between the 1980s and 2021," according to the IUCN news release. "The larger eastern population also shrunk by 84% from 1996 to 2014. Concern remains as to whether enough butterflies survive to maintain the populations and prevent extinction."
IUCN fittingly called attention to climate change, pointing out that "climate change has significantly impacted the migratory monarch butterfly and is a fast-growing threat; drought limits the growth of milkweed and increases the frequency of catastrophic wildfires, temperature extremes trigger earlier migrations before milkweed is available, while severe weather has killed millions of butterflies."
So here we are, our favorite butterfly "teetering on the edge of collapse," as IUCN monarch butterfly assessment leader Anna Walker so accurately put it. Yet, Walker, a member of the IUCN Species Survival Commission's Butterfly and Moth Specialist Group and Species Survival Officer at the New Mexico BioPark Society, sees signs of hope, as people and organizations come together to try to protect the monarch and its habitats.
So much to do...
Meanwhile, have you seen any monarchs lately?
You can participate in the sixth annual International Monarch Monitoring Blitz, set from July 29 to Aug. 7. You're invited to look for milkweed plants and report their observations of monarchs (eggs. caterpillars, chrysalids and adults) to Journey North:
- Learn how to participate: view and download our instructional flyer»
- Read the press release»
- Learn more about the Monarch Blitz»
Over the last several years, we've seen dozens of monarchs in our family's pollinator garden in Vacaville. In 2020, we observed some 300 eggs and caterpillars. So far this year: Zero, zip, nada.
Let's hope that the monarch doesn't go the way of Franklin's bumble bee, the bee that Robbin Thorp (1933-2019), a UC Davis distinguished emeritus professor of entomology, monitored for decades in its small range of southern Oregon and northern California. He was instrumental in placing the bumble bee, Bombus franklini. on the IUCN Red List of Threatened Species in 2008. He also worked to place it on the U.S. Fish and Wildlife Service's Endangered Species List, which occurred in 2021.
Thorp, the last known person to see Franklin's bumble bee in its native habitat, spotted it in 2006 near Mt. Ashland. The bee inhabits--or did--a 13,300-square-mile area confined to five counties--Siskiyou and Trinity counties in California; and Jackson, Douglas and Josephine counties in Oregon. Every year biologists, citizen scientists, volunteers, landowners and students form a search party to look for it. This year more than 70 people participated. Sadly, it's feared extinct.
California's 2021 western monarch Thanksgiving count, directed by the Xerces Society of Invertebrate Conservation, recorded 250,000 overwintering monarchs, as compared to a mere 2000 in 2020.
Executive producer and host Ira Flatow of Science Friday set out to "unpack the news" for his listeners. On Feb. 4, he interviewed community ecologist Louie Yang, professor, UC Davis Department of Entomology and Nematology, and a faculty member of the Center for Population Biology. (Listen to the interview, 'How Long Will California's Butterfly Boom Last?')
"OK, so how did the population bounce back so dramatically?" Flatow asked. "And is this number a blip on the radar or the start of better times for the beleaguered butterfly? Here to help us unpack the news, Dr. Louie Yang, a professor and ecologist at the Department of Entomology and Nematology, UC Davis."
"It seems reasonable to say that an increase of this magnitude would probably require a series of fortunate conditions throughout the breeding season that would sustain population growth across multiple generations," the UC Davis professor told him, adding "What we've seen is a long-term trajectory of declining populations, even before the recent population variability."
Yang focuses his research on "understanding the seasonal dynamics of milkweed-monarch interactions. How do monarch caterpillars develop on their milkweed host plants? And what are the conditions that allow them to develop well and survive to adulthood? And what are the conditions that cause lower survivorship?"
Bottom line. The 100-fold increase in monarch population may or may not be a sign of what's to come. As Yang said: "So we shouldn't be complacent or assume that populations will always bounce back from low densities...I think a lot of folks are breathing a sigh of relief that the population has increased as much as it has over the past year. And I think we all share that sense of relief and joy that the population has increased. But also, there is that note of caution that there is a lot about the dynamics of this population that we don't yet understand and we're still working on."
Social media responses to the podcast included: "Great podcast! I learned even more today about the timing of milkweed availability and monarch eggs--now I understand why late season eggs have a higher percentage of survivorship. Everyone should listen to Professor Yang's interview. It's just a little over 10 minutes, but packed full of information."
Yang, who joined the UC Davis faculty in 2009, holds a bachelor's degree in ecology and evolution from Cornell University, (1999) and a doctorate from UC Davis (2006).
Lauded for his advising and teaching skills, in 2018 Yang received an international award from NACADA, also known as the Global Community for Academic Advising. He co-founded and co-directs the campuswide program, Research Scholars Program in Insect Biology, with UC Davis distinguished entomology professor Jay Rosenheim and professor Joanna Chiu, vice chair of the UC Davis Department of Entomology and Nematology,
Yang, born in Australia but raised in West Virginia, says on his website: "When I was in elementary school, I wanted to be a pet shop owner. In high school, I wanted to be a veterinarian. As a college freshman, I thought I wanted to make nature documentary films. As it turns out, I was really interested in ecology and evolution. After I graduated, I traveled and started a PhD. I've been faculty at the University of California, Davis since 2009. I'm still learning new things all the time."
His current research?"I am working to develop a temporally explicit view of ecology that examines how ecological communities combine complex, coordinated and changing interactions over time. I am particularly interested in the effects of climate change on species interactions, community responses to strong perturbation events, phenological cues and phenological shifts, and seasonal changes in the nature and outcomes of species interactions. I study several different organisms in a wide range of ecological communities, each of which contributes to a broader understanding of how species interactions change over time." (See The Yang Lab website.)
So, in today's Bug Squad, a brief spotlight on Professor Yang:
Question: "How long have you been doing scientific research on monarchs?"
Answer: "I visited the overwintering monarch population at the Coronado Butterfly Preserve in Santa Barbara in 2006, and I started doing research with them shortly afterwards."
A: "Because monarch can travel long distances, it struck me that when they leave their overwintering grounds they might not have very good information about the environmental conditions at their destination. It seems like this lack of information could create the potential for phenological mismatches between the monarch and its host plant."
Q: "What are some of the results?"
A: "Broadly, our results indicate that western monarchs show “seasonal windows of opportunity”--periods in the year with increased developmental prospects. These seasonal windows are constrained by a combination of abiotic (i.e., climatic), bottom-up (i.e., host plant-related), and top-down (i.e., natural enemies-related) factors. In our region, we see two windows of opportunity (late spring/early summer and late summer/early fall) separated by a 'mid-summer slump' on their most common host plant, narrow-leaved milkweed (Asclepias fascicularis). However, plant traits matter: for example, the defensive traits of showy milkweed (Asclepias speciosa) tend to increase across the season, and the monarchs on this species only seem to show one early season window. On showy milkweed, success in the late season window seems to be constrained by host plant defensive traits. Our work has also shown that these seasonal windows appear to be constrained by different factors in the early and late part of each breeding season, and that climatic variation strongly shapes the timing and relative importance different limiting factors."
Q: "What is the role of tropical milkweed, Asclepias curassavica, in monarch conservation?"
A: "I've not studied this in detail myself, but there is a concern that tropical milkweed could change the life history of western monarchs and expose them to more diseases. Unlike our native milkweeds, tropical milkweeds don't senesce during the winter. They continue to grow year-round and are very attractive to monarchs. As a result, this non-native host plant might encourage monarchs to continue breeding longer into the winter than the would normally. In addition, because these milkweeds persist year after year, there are concerns that they can build up higher densities of Ophryocystis elektroscirrha spores, exposing monarch caterpillars to a greater risk of disease."
Q: "What can area residents do to help in monarch conservation?"
A: "I'd encourage folks interested in helping monarch conservation to learn as much as they can about the many and complex factors that can affect monarch populations. Recent variability in the western monarch population illustrates the potential for rapid declines and resilience in this population, but it also shows us the limits of our current understanding about the ecology of western monarchs. Ecology ain't rocket science--it is much more complicated. There is a lot we don't yet know, but there is also a lot that has become clearer over time. We probably know enough now to say that the combined and interactive effects of climate change, land use change, novel environmental chemicals and the global transport of organisms have played a role in the decline of monarch butterflies and many other insects. Scientists will continue working to understand this in more detail, but working now to limit those drivers makes sense."
Q. "What milkweed do you recommend folks should plant in Central California?"
A. "I'd encourage folks to learn about and cultivate the species of milkweed that grow wild in their local area. California has a remarkable diversity of milkweed species, and each occupies a unique niche. Websites like iNaturalist can help folks learn about the species that grow naturally in their area. Visiting established populations of wild milkweed will give folks a sense for the specific habitats that these milkweeds need to survive and thrive. The Xerces Society has also compiled some great information how and where to cultivate milkweed in California." (See Xerces Society website.)
"Scientists now understand how certain animals can feed on picturesque, orange monarch butterflies, which are filled from head to abdomen with milkweed plant toxins.
"In high enough concentrations, milkweed can kill a horse, or a human. To be able to eat this plant, monarchs evolved a set of unusual cellular mutations. New UC Riverside research shows the animals that prey on monarchs also evolved these same mutations.
"A Current Biology journal article, published Nov. 22, 2021, describes the research that revealed these mutations in four types of monarch predators — a bird, a mouse, a parasitic wasp, and a worm." --EurekAlert.
The leading author of that research article, evolutionary biologist Simon "Niels" Groen, an assistant professor at UC Riverside, will discuss "Plant Toxins and the Evolution of Host-Parasite Interactions" when he presents a seminar to the UC Davis Department of Entomology and Nematology at 4:10 p.m., Wednesday, Feb. 2 in 122 Briggs Hall.
"Plants interact with incredibly diverse groups of animals including plant-feeding insects and nematodes as well as their natural enemies," Groen says in this abstract. "These interactions are influenced by toxic defensive chemicals that plants make. In my talk, I will focus on how plants evolved variation in production of these defensive chemicals and how animal parasites in turn evolved mechanisms enabling them to handle such toxins."
Groen, who joined the UC Riverside faculty in July 2021 following his postdoctoral research position (2014 to 2021) in the Noah Whiteman laboratory, Department of Ecology and Evolutionary Biology, University of Arizona, focuses his research on "understanding molecular mechanisms of adaptation in the context of species interactions and fluctuating environmental conditions."
A native of the Netherlands, he received his bachelor's degree and masters degree in biology from Wageningen University, Netherlands, and his doctorate in plant sciences from the University of Cambridge, UK.
Groen served as a visiting researcher from 2007 to 2008 in the Department of Multi-Trophic Interactions, Netherlands Institute of Ecology, and as a visiting researcher from 2008 to 2012 in the Department of Organismic and Evolutionary Biology, Harvard University.
"Growing up in The Netherlands, I became fascinated with plants and their responses to ever-changing environmental conditions while working as a 'ziekzoeker' in tulip fields outside of school hours," he writes in an author profile on the American Society of Plant Biologists website. The site featured him as the first author of “Evolutionary Systems Biology Reveals Patterns of Rice Adaptation to Drought-Prone Agro-Ecosystems," published Nov. 15, 2021 in the journal Plant Cell.
"A 'ziekzoeker' looks for diseased plants and I searched in particular for variegated white and red tulips--the ones you'd recognize from a golden-age Dutch still life painting," Groen related. "I learned how these tulips are infected with an aphid-transmitted virus and during my PhD in the group of John Carr at the University of Cambridge, I would further investigate the molecular mechanisms of how virus infections would change plant interactions with aphids and pollinators. I was gripped by the role that plant defensive chemicals play in shaping species interactions and I continued to study these as a postdoc with Noah Whiteman at the University of Arizona and the University of California, Berkeley.'
On the author page, he chronicled his previous work on the interactions between milkweeds and the monarch butterfly "and found out how the monarch evolved resistance to the cardenolide toxins that milkweeds make. While this work mostly revolved around a single gene of large effect, typically several or many genes are involved in organisms' evolutionary responses. As a Gordon and Betty Moore Foundation fellow in the group of Michael Purugganan at New York University, I learned about the latest developments in evolutionary genomics and systems biology while investigating patterns of natural selection on gene expression in rice populations that we grew under wet and dry field conditions with our collaborators at the International Rice Research Institute in The Philippines."
"The current paper (Plant Cell) is a culmination of this research," Groen related. "We found that under field drought rice plants do not just respond to changes in water availability, but also to concomitant changes in abundance of soil microbes that they interact with. As assistant professor in the Department of Nematology at the University of California, Riverside, I will continue to study rice and milkweed as well as plants from the nightshade family and look at the complex evolutionary tug-of-war between these plants and parasitic nematodes. Combining laboratory and field experiments, we will zoom in on the central role that plant chemicals play by using approaches from evolutionary and systems biology like the ones we describe in our paper."
Nematologist Shahid Siddique, assistant professor in the Department of Entomology and Nematology, coordinates the winter quarter seminars. He may be reached at email@example.com for any technical issues involving the Zoom connection.