- Author: Kathy Keatley Garvey
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."
Louie Yang
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.)
- Author: Kathy Keatley Garvey
"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.
He will speak in person. The lecture also will be broadcast simultaneously on Zoom. The Zoom link: https://ucdavis.zoom.us/j/99515291076.
"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 ssiddique@ucdavis.edu for any technical issues involving the Zoom connection.
- Author: Kathy Keatley Garvey
"The population, counted by citizen scientists at monarch overwintering locations in southern California, dropped from around 300,000 three years ago to just 1,914 in 2020, leading to an increasing fear of extinction. However, last winter large populations of monarchs were found breeding in the San Francisco and Los Angeles areas. Prior to last winter, it was unusual to find winter breeding by monarchs in those locations."
So begins a news release, "New Monarch Butterfly Breeding Pattern Inspires Hope," posted on EurekAlert by the communications specialists at Washington State University, Pullman, Wash., in citing the peer-reviewed research of WSU entomologist/associate professor David James. He's been studying monarchs for 43 years and spearheads a migratory monarch tagging program in the Pacific Northwest.
The WSU news release quotes the monarch scientist: "There's more to it than just counting overwintering butterflies. It seems that monarchs are evolving or adapting, likely to the changing climate, by changing their breeding patterns."
The impetus for the news release? James recently authored "Western North American Monarchs, Spiraling into Oblivion or Adapting to a Changing Environment?" in the journal Animal Migration. He called attention to the huge declines of monarchs--and their resiliency--in Australia when he was working on his PhD dissertation there 40 years ago.
James says that climate-wise, San Francisco is very similar to the area around Sydney. And he thinks that monarchs will adapt well to the changing climate in the western United States, just as the monarchs in the Sydney area have.
The WSU entomologist is now connecting with citizen scientists in California to collect more data on winter breeding that "can show this evolution and adaptability." His research includes data on what milkweed species the monarchs frequent. They include tropical milkweed, Asclepias curassavica, which has thrived in California for more than 100 years. Some advocate a "no grow" policy, declaring that A. curassavica impedes migration and carries more of the Ophryocystis elektroscirrha (OE) spores than the native milkweeds because it can survive the winter in many areas of California, while native milkweed species usually go dormant. Others argue that tropical milkweed is not the cause of the declining milkweed population--that habitat loss and pesticides are. "Just cut it back before the fall migration or cut it back when monarchs are no longer laying eggs" to limit the transfer of OE, they say. Still others insist on planting a variety of milkweed species, including tropical, to give monarchs a choice, that "monarchs know what they want."
When we contacted the WSU entomologist earlier this week, he pointed out that "the milkweeds that monarchs were using during winter last year in Santa Clara County were not solely tropical. There are good numbers of Gomphocarpus physocarpus and Gomphocarpus fruticosus being used as well, although these two species are difficult to tell apart."
- Author: Kathy Keatley Garvey
She came, she saw, she oviposited, she nectared and she left.
That's the extent of our sole monarch sighting in our Vacaville pollinator garden this year. This occurred Oct. 9.
But the good news is that more monarchs are gathering on the overwintering sites along the California coast than this time last year. And this is occurring during a major drought year.
In an article, Monarch Butterflies Return to Pacific Grove. And the Drought May Be the Reason for Their Rebound, published yesterday (Oct. 21) in the San Francisco Chronicle, Tara Duggan wrote:
"For once there is some promising news for western monarch butterflies: Around 2,600 of the migratory insects were counted at Pacific Grove Thursday, after zero were observed at the famed Monterey County sanctuary last year. And overall, conservationists estimate the current population that has arrived in its annual wintertime migration to the California coast to be around 10,000 compared to 1,900 last year.
"One possible reason for the rebound: this year's drought, since warm and dry conditions in early spring can help with their migration."
Many others haves noticed the uptick, too. On Oct. 14, entomologist David James of Washington State University wrote on his Monarchs Butterflies of the Pacific Coast Facebook page: "Another exciting and encouraging update on monarch arrivals at the California overwintering sites. Combining all the reports I've received over the past few days there are an estimated 1500 butterflies at 5 overwintering sites from Santa Cruz to Pismo Beach. And still the butterflies are arriving... The highest number at one site is about 700 at a site in the Pismo beach area. This exceeds the highest number seen at one site in 2020 (550 at Natural Bridges). Pacific Grove is reported to have about 200 butterflies. This is especially notable since none were recorded at this site in 2020. Inbound migration will continue for a few more weeks yet but even at this early stage we are close to exceeding the entire population counted at overwintering sites in 2020. Good news, indeed!"
Volunteers counted only 1900 on the overwintering sites along the California coast in 2020, according to the Xerces Society for Invertebrate Conservation. Compare that to approximately 29,000 in 2019 and almost 200,000 in 2017.
"But on Wednesday (Oct. 20) volunteers counted 8,000 of the butterflies at two groves in Pismo Beach, compared to 300 last year," wrote Duggan.
Scientists, including Art Shapiro, UC Davis distinguished professor of evolution and ecology, say the main reasons for the decline of the monarchs are habitat loss and pesticides.
Plant milkweed, plant nectar sources and lose the pesticides.
(Editor's Note: Due to UC ANR server issues, images aren't visible. Click on the icon to see the image)
- Author: Kathy Keatley Garvey
Our showy milkweed (Asclepias speciosa) is putting on a show.
The towering plant--a good eight feet--anchors the garden as we patiently wait for monarch butterflies to arrive and lay their eggs.
It's mid-August and it appears the monarchs are not coming here to our little pollinator garden in Vacaville, Calif. Maybe we'll see some during their late summer or early fall migration--on their way to their overwintering sites along coastal California.
Meanwhile, the speciosa has more than its share of lady beetles (aka ladybugs) and aphids.
But now we have a new visitor, well, maybe a permanent resident.
A praying mantis, Stagmomantis limbata (as confirmed by mantis expert Lohit Garikipati, a UC Davis graduate and Bohart Museum of Entomology associate now attending graduate school in Towson University, Maryland) has arrived.
For the first several days, Ms. Mantis hung upside down and did not eat (at least in our presence). She watched the bees buzzing around but made no effort to snag one. We think she was yawning. "Okay, I know you're there. I don't care and I'm not hungry."
Then we found her exoskeleton on one of the speciosa leaves.
A mantid's "skeleton," you know, is outside its body and it's known as an "exoskeleton." It reminds us of a suit of armor, for protection, support and form (is it a "suite of amour" when love abounds?).
A young mantis eats and outgrows its exoskeleton and then it molts (sheds it). Scientists say some species of growing mantids may lose their exoskeletons as many as 10 times.
And, according to Garikipati, a mantis that has just molted may not eat for two or three days.
Did you hear that, bees?
So, bottom line, no monarchs on the milkweed.
But we do have assorted lady beetles, aphids, and one praying mantis and her exoskeleton.
Wait, correct that. Just one mantis. A breeze just swept away the exoskeleton.