- Author: Kathy Keatley Garvey
Professor Louie Yang's monarch and milkweed research at the University of California, Davis, is quite celebrated.
Yang, a community ecologist and professor in the Department of Entomology and Nematology, is involved in monarch conservation science and planning, in collaboration with the Western Monarch Conservation Science Group, U.S. Fish and Wildlife Service, the Xerces Society of Invertebrate Conservation, Monarch Joint Venture, Environment Defense Fund, and the National Monarch Summit in D.C.
- Science Friday, National Public Radio, interviewed him in February 2022 about his monarch-milkweed research. (Listen to the archived interview.)
- He was one of 12 invited scientists nationwide who delivered a presentation during the two-day Monarch Butterfly Summit, held in June 2022 at the Capitol, Washington D.C. He has presented invited seminars at Purdue University and the University of Nevada.
Another feat: Yang launched the Monitoring Milkweed-Monarch Interactions for Learning and Conservation (MMMILC) project in 2013 for students in the environmental science program at Davis Senior High School or those associated with the Center for Land-Based Learning's Green Corps program. He taught more than 150 high school-aged participants. Their tasks: monitoring milkweed-monarch interactions in a project funded by the National Science Foundation. He organized and led a 135-member team, and supported them all as co-authors of the paper, “Different Factors Limit Early- and Late-Season Windows of Opportunity for Monarch Development,” published in July 2022 in the journal Ecology and Evolution. The 107 co-authors included high school students, undergraduate and graduate students, and community members.
But did you know that Professor Yang excels at teaching and mentoring?
Described as “a phenomenal teacher, mentor and an incredibly strong advocate for students,” Yang is the newly announced recipient of the UC Davis Academic Senate's 2024 Distinguished Teaching Award, Undergraduate Student category.
And so well-deserved.
“I have watched him engage, inspire, and challenge his students, fostering creative and critical thinking like no one else I've ever seen,” Joanna Chiu, professor and chair of the department, wrote in her nomination letter. “We deeply appreciate and admire his innovative and inclusive teaching, his exemplary work ethic, his welcoming demeanor, his dedication to his students, and his nationally recognized ecology expertise. Louie has received many well-deserved teaching and mentoring awards for his teaching contributions on and off campus.”
Professor Yang is one of the three co-founders and co-directors (along with Professor Chiu and UC Davis distinguished professor Jay Rosenheim) of the campuswide, one-of-a-kind Research Scholars Program in Insect Biology (RSPIB), launched in 2011 to help students learn cutting-edge research through close mentoring relationships with faculty.
Yang, who holds a bachelor's degree in ecology and evolution (1999) from Cornell University, and a doctorate in population biology (2006) from UC Davis, joined the UC Davis faculty in 2009. UC Davis distinguished professor Walter Leal, then chair of the entomology department, remembers recruiting and hiring him, on the recommendation of community ecologist Richard "Rick" Karban.
In 2012, as an assistant professor, Yang was selected a Hellman Fellow and then received a 2013-2018 National Science Foundation Faculty Early Career Award. In 2015, he won a Chancellor's Teaching Fellow Award and the Atwood Colloquium Rising Star Award in Ecology, University of Toronto. Currently he chairs the Entomology Graduate Program and also serves as interim vice chair while community ecologist and associate professor Rachel Vannette is on sabbatical.
Since 2009, Yang has taught more than 600 undergraduates and more than 90 graduate students in his formal classes. His courses include Insect Ecology, Community Ecology, Experimental Ecology and Evolution in the Field, He has taught two National Science Foundation Graduate Research Fellowship Program (GRFP) grant writing workshops, and the Population Biology Graduate Group core course for three years.
Professor Rosenheim, recipient of the 2011 Academic Senate Distinguished Teaching Award, Undergraduate Level, has observed Yang's innovative teaching. “His class sessions were impeccably organized, his presentations deeply insightful, and the discussions highly engaging," he wrote. "Louie alternated lectures with class sessions in which large blocks of time were devoted to structured debates. For the debates, Louie drew names at random and assembled two 3-person teams of students, one arguing the 'pro' side of the issue, the other arguing the 'con' side. After an initial period when positions were presented and rebuttals given, the whole class was invited to join in the discussion. What was truly remarkable was the high level of participation that Louie is able to elicit, both during the debates and during his lectures. Louie inspires the confidence of his students, and they reciprocate with their willingness to take risks during class by contributing, even when discussing topics that are new to them. This is not an easy thing to accomplish; Louie's ability to gain such strong student participation is perhaps the strongest evidence of Louie's talent in connecting with students. I was so impressed with the success of Louie's methods that I decided to incorporate structured debates into one of my own classes as well."
In unsolicited comments in Rate My Professors, his students wrote:
- “One of the best instructors at UC Davis. Class on insects was very interesting…He is super cool, and lectures are never boring.”
- “Louie honestly might be my favorite professor on campus. He is cool and smart and engaged with his students…”
- “Really one of the most intelligent people I've met in college. It's apparent just talking to him, which I'd highly recommend.”
- “I loved this seminar, Ecology Outdoors! I learned so much from Louie, and he's really good at encouraging creativity and experimentation. He's a very hard worker and plans the class well.”
- “Really cool guy, made the class interesting. gave a lot of real-life example, so students can relate the subject to real world.”
A tip of the insect net to Professor Louie Yang!
- Author: Kathy Keatley Garvey
Where do Western monarchs go after leaving their overwintering sites along coastal California in February?
An observation: They didn't stop in the spring or summer to deposit eggs on any of our four species of milkweed in our Vacaville pollinator garden.
Spring? Zero. Zilch. Nada.
Summer? Zero. Zilch. Nada.
Fall? Yes.
Why not spring and summer? Did the monarchs passing through Vacaville opt for "a better habitat" in the cooler Pacific Northwest and beyond (British Columbia)?
"I wish I knew," commented UC Davis distinguished professor emeritus Art Shapiro, who has monitored the butterfly populations of Central California since 1972 and maintains a research website, Art's Butterfly World.
Beginning in September, as many five monarchs a day began fluttering into our garden. Some laid eggs.
To date, we've spotted some 20 eggs and caterpillars.
"This is generally consistent with the pattern we've seen in previous years," said UC Davis Department of Entomology and Nematology professor Louie Yang, who researches monarchs. "Even in Davis, we've been seeing more caterpillars in the late summer/fall. I think this is probably because some are stopping to lay eggs on the return migration, and the fall population is much larger than the spring migration population. Looking very carefully, we did also see eggs in the spring each year, but very few of them developed into large caterpillars." See the Louie Yang et al, research paper, "Different Factors Limit Early- and Late-Season Windows of Opportunity for Monarch Development," published in July 2022 in the journal, Evolution and Ecology.
The availability of food resources, such as tropical milkweed (Asclepias curassavica) that can overwinter in warmer climates, doesn't deter them from migrating, said UC Davis emeritus professor Hugh Dingle of the Department of Entomology and Nematology. Dingle, an internationally known expert on animal migration who has studied monarchs for more than two decades, said: "Migration and the diapause that accompanies it in the fall are determined by shortening photoperiod and temperature (warm temps can override short days hence the issue with climate change)."
Said UC Davis professor Elizabeth Crone of the Department of Evolution and Ecology: "Monarchs may behave similarly in spring, but the spring population is probably much smaller than the fall one, so they are less likely to happen across your garden. Our estimate is that the population increases 2-3x each generation (so it's about 100-200x larger in Fall than Spring), then resets each year due to mortality during Fall migration and overwintering. There is some research from Sonia Altizer's lab in Georgia showing that monarch butterflies that encounter milkweeds during fall migration will leave reproductive diapause and breed. It is unknown whether these monarchs are effectively lost from the migratory population, or whether they or their offspring (the caterpillars in your yard) will continue on to the overwintering sites."
"The egg-laying females you are seeing now are likely migrants that have eschewed reproductive dormancy for reproduction," says entomologist David James, an associate professor at Washington State University who researches migratory monarchs. "This has probably always happened to some extent but is likely more significant now because of warmer falls."
"The lack of activity in summer in Vacaville was probably a function of most of the population having dispersed further east and north, maybe more than usual? They surely did pass through Vacaville in spring on their way north but clearly didn't stop to use your milkweeds. It does seem that some years they are more prone to frequent stopping/oviposition on their way north and east, yet in others they just keep flying. There's evidence that the latter was the case this year... with as many migrants making it to BC as to Washington... Normally they stop in Washington and only a handful make it to BC."
"The many mysteries of monarchs," James added.
James is the author of a newly published book, The Lives of Butterflies: A Natural History of Our Planet's Butterfly Life (Princeton University) with colleague David Lohman of the City College of New York. The book, released in the UK on Oct. 3, 2023, will be available in the United States starting Jan. 9, 2024.
Irish scientist Éanna Ní Lamhna recently interviewed the WSU entomologist in a podcast on RTÉ, or Raidió Teilifís Éireann. The book, she said, "showcases extraordinary diversity of world's butterflies, while exploring their life histories, behavior, conservation and other aspects of these most fascinating and beguiling insects." (See Bug Squad blog)
Listen to the butterfly podcast here: https://www.rte.ie/radio/radio1/clips/22294525/
Meanwhile, are you seeing fall breeding and egg-laying in your garden? We have for more than a decade, with some monarchs eclosing in November and December.
- Author: Kathy Keatley Garvey
Western monarchs are now settling in their overwintering sites along coastal California, but the iconic butterflies showed up in force at the Bohart Museum of Entomology's recent open house--in the form of specimens, photographs, books, maps and displays.
Some 650 visitors arrived to talk to the scientists, see the displays, and take home native milkweed seed packets, provided by community ecologist Louie Yang, professor of entomology, UC Davis Department of Entomology and Nematology (ENT-NEM). Yang shared seeds of narrow-leafed milkweed, Asclepias fascicularis.
Statistics show that the overwintering population of western monarchs along coastal California has declined by more than 99 percent since the 1980s, according to the Xerces Society for Invertebrate Conservation, but the population has been showing a mini-boom in recent years. Scientists blame habitat destruction, pesticide use, and climate change as the primary causes of the decline.
Scientists participating in the open house were:
- UC Davis distinguished professor emeritus Art Shapiro of the Department of Evolution and Ecology, who has studied butterfly populations in central California since 1972 and maintains a research website, Art's Butterfly World.
- UC Davis emeritus professor Hugh Dingle, a worldwide authority on animal migration, including monarchs. He is the author of Migration: The Biology of Life on the Move (Oxford University Press), a sequel to the first edition published in 1996. (See news story on the ENT-NEM website.)
- UC Davis professor Louie Yang, who does research on monarchs and milkweed and has been featured nationally. (See news story about his work.)
- UC Davis professor Elizabeth Crone of the Department of Evolution and Ecology, formerly of Tufts University, who researches monarchs. (See news story about the declining monarch population on the ENT-NEM website.)
In addition, the Bohart Museum showcased monarch photography by Larry Snyder of Davis and Kathy Keatley Garvey of ENT-NEM.
Yang and Crone were among the 12 nationally invited scientists who delivered presentations during the two-day Monarch Butterfly Summit, held last year at the Capitol in Washington D.C. and organized by Sen. Jeffrey Merkley of Oregon, During that summit, the Department of the Interior announced a $1 million award to the National Fish and Wildlife Foundation's Monarch Butterfly and Pollinators Conservation Fund, and the U.S. Fish and Wildlife Service announced a Pollinator Conservation Center. (See news story)
In another project, Yang organized and led a three-year study of wild monarch butterflies and milkweed in rural Davis. The project, funded by two of Yang's National Science Foundation grants, involved UC Davis, Davis Senior High School and the Center for Land-based Learning, Woodland. The 135-member team included 107 high school students, a K-12 teacher, 18 UC Davis undergraduates, three graduate students and two postgraduate researchers.
"This study collected a high-resolution temporal dataset on milkweed-monarch interactions during the three years prior to the precipitous single-year population decline of western monarchs in 2018,” Yang said. From 2015 through 2017, the team monitored the interactions of monarchs, Danaus plexippus, on narrow-leafed milkweed, A. fascicularis, planted in December 2013 on city-owned property.
“This study has three key findings,” Yang related. “First, we documented early and late seasonal windows of opportunity in the wild, migratory western monarch population. Second, our data suggest that early and late seasonal windows were constrained by different factors. Third, climatic and microclimatic variation had a strong effect on the timing and importance of multiple factors affecting monarch development. Broadly, we hope that this study contributes to a more temporally detailed understanding of the complex factors that contribute to year-to-year variation in monarch breeding success.” (See news story on ENT-NEM website)
In February of 2022, Yang appeared on Science Friday, National Public Radio, in an interview titled "How Long Will California's Butterfly Boom Last?"
Hugh Dingle. Professor Dingle, an internationally known expert on animal migration, has researched animal migration for some 50 years. In the last two decades, he has focused on monarch butterflies. National Geographic featured him in its cover story on “Great Migrations” in November 2010. LiveScience interviewed him for its November 2010 piece on “Why Do Animals Migrate?”
Dingle says:
- "There is not enough tropical milkweed planted to have much influence (see the amount of A. syriaca and A. fascicularis throughout the American West not to mention various other species like A. erosa, cordifolia, californica, etc.) Yes, there are parasites on A. curassavica as there are on ALL milkweeds."
- "There are populations of monarchs that are doing just fine feeding exclusively on A. curassavica (e.g. on many Pacific Islands, such as Guam where I have studied them."
- "Migration and the diapause that accompanies it in the fall are determined by shortening photoperiod and temperature (warm temps can override short days hence the issue with climate change). There is no significant influence of food plant."
Elizabeth Crone. Crone focuses her research on population ecology, "especially of plants and insects, and plant-animal interactions. Specifically, I am interested in how environmental changes translate to changes in population dynamics in animals. I was also one of the first ecologists to use generalized linear mixed models to parameterize stochastic population models." She co-authored "Why Are Monarch Butterflies Declining in the West? Understanding the Importance of Multiple Correlated Drivers," published in 2019 in Ecological Applications, Ecological Society of America.
Art Shapiro. Professor Shapiro shared several handouts, including "Comments on Monarchs." He co-authored research (lead author Anne Espeset and six other colleagues) titled, "Understanding a Migratory Species in a Changing World: Climatic Effects and Demographic Declines in the Western Monarch Revealed by Four Decades of Intensive Monitoring," published in Population Ecology.
"None of my group is a Monarch specialist, and that includes me," Shapiro wrote in the handout. "Since 1999 I have done counts of all butterfly species at 4 Valley sites (Suisun, West Sacramento, North Sacramento and Rancho Cordova) using standard 'Pollard walk' methods, slightly modified. As a result we have a quantitative picture of Monarchs in breeding season over 14 years. Such data are very rare. Population estimates of Monarchs are typically based on the overwintering (non-breeding) aggregations and we know from published material that what breeding-season data exist routinely diverge from the overwintering data. That is, trends in population size as measured by overwinter animals are not routinely reflected in the summer numbers. There can be a variety of explanations for this. To me the most likely is that as a very mobile species, the Monarch may breed in different places in different years, so that a monitoring program like mine, based on a limited number of fixed, Intensively-monitored sites, is unlikely to capture this stochasticity in where Monarchs breed."
Over the last 50 years, "Suisun has had the highest counts (of monarchs), partly but not entirely reflecting coastward migration from farther inland early in the season, but these high numbers have effectively disappeared—perhaps reflecting a systematic change in migratory trajectories."
Also at the open house, entomologist Jeff Smith, who curates the Bohart's Lepidoptera collection, and colleague Greg Kareofelas showed visitors drawers of monarch and other butterfly specimens.
Two origami monarchs, the work of UC Davis alumnus Kevin Murakoshi of Davis and a gift to the Bohart Museum, drew special attention. Murakoshi earlier crafted origami praying mantises, ticks and bed bugs for Bohart Museum open houses.
One of the books displayed at the open house was UC Berkeley professor Noah Whiteman's newly published work, "Most Delicious Poison: The Story of Nature's Toxins--from Spices to Vices" (Little Brown Spark, Oct. 24, 2023) It includes information on the toxicity of milkweed.
The Bohart Museum, directed by UC Davis distinguished professor Lynn Kimsey, is located in Room 1124 of the Academic Surge Building, 455 Crocker Lane, UC Davis campus. It is the home of a global collection of eight million insect specimens. It also houses a live "petting zoo" (including Madagascar hissing cockroaches, stick insects and tarantulas) and a gift shop.
- Author: Kathy Keatley Garvey
And just like that, a female monarch butterfly fluttered into our Vacaville pollinator garden this morning, Aug. 10, and left a dozen or so calling cards: precious eggs.
We earlier saw a male monarch patrolling the garden on the morning of July 23, but he left to go find the girls.
So, total number of monarchs sighted in our garden so far this year: 2. (In 2016, we counted more than 300 eggs and caterpillars.)
Ms. Monarch deposited eggs on three milkweed plants: a narrow-leafed milkweed, Asclepias fascicularis, and two tropical milkweeds, Asclepias curassavica. She favored a lone tropical milkweed thriving in a planter. It's already attracted honey bees, leafcutter bees, syrphid flies, crab spiders, cabbage white butterflies, Gulf Fritillaries, mourning cloaks, gray hairstreaks, Western tiger swallowtails, ants, aphids, and a young praying mantis lying in wait.
Ms. Monarch totally ignored the showy milkweed, Asclepias speciosa, that towers over the garden. Not for me, she seemed to say. Ditto on the butterflyweed, Asclepias tuberosa.
We managed a few images of Ms. Monarch in flight, several images of her laying eggs, and a couple of the ever-so tiny eggs clinging beneath the leaves.
Welcome, Ms. Monarch. Now go tell all your buddies where to find the milkweed of your choice, and the rich nectar sources such as Mexican sunflowers (Tithonia rotunifola).
And you better warn them about that praying mantis...
- Author: Kathy Keatley Garvey
Apparently so, from personal observation.
Over the years, we've grown multiple species of milkweed in our pollinator garden in Vacaville, Calif. We give them a choice. The species include:
- Narrow-leafed milkweed, Asclepias fascicularis
- Showy milkweed, A. speciosa
- Pleurisy root, A. tuberosa
- Tropical milkweed, A. curassavica
- Hairy balls or balloonplant, Gomphocarpus physocarpus
Which species do they prefer? Tropical milkweed, hands down. But it's a plant that's become highly controversial in California. Friends unfriend friends, and the unfriended lash out with how "bad" tropical milkweed is and how "uneducated" the messenger is. "Don't you know about Ophryocystis elektroscirrha (OE)?" they ask. "How dare you plant tropical milkweed? Yank it out!"
Meanwhile, the monarchs keep monarching. And we keep observing them.
Consider the male monarch spotted lying in the middle of a residential street in west Vacaville the morning of Jan. 3. It was there despite the rain, the cold and the passing cars. What will happen to it? Will it find a mate? Will its mate be able to find a milkweed to deposit her eggs? She certainly won't find native milkweed, such as A. fascicularis and A. speciosa, but she might find A. curassavica.
If. She. Is. Lucky.
Mona Miller, administrator of the educational Facebook page, Creating Habitat for Butterflies, Moths and Pollinators, recently shared a post that should be "food for thought" (for us) and that should result in "more food" (milkweed) for the monarchs. Her Facebook page focuses on "the preservation and protection of North American butterflies, moths and pollinators, particularly the Monarch butterfly."
"All milkweeds get Ophryocystis elektroscirrha (OE)," Miller wrote. "There are native milkweeds that are viable in the fall and winter. Tropical milkweed, due to their high level of toxins (cardenolides), are very medicinal. Monarch females choose tropical milkweeds over less toxic native plants to self-medicate. In October 2022, there was a discussion on the Monarch Watch email list. Dr. (Orley "Chip") Taylor (founder and director of Monarch Watch and a professor in the Department of Ecology and Evolutionary Biology at the University of Kansas) said that tropical milkweed does not stop the migration. He said more native and tropical milkweed should be planted. He said the more milkweed that is available the less spores will be left on all milkweeds. Fewer milkweeds leave monarchs visiting available milkweeds and leaving more spores. You can read the discussion here, there are several posts: https://lists.ku.edu/pip.../dplex-l/2022-October/012192.html."
"Actually, the best strategy is to plant more milkweeds, both native and tropical," Professor Taylor wrote, explaining that "First, the interactions between monarchs, milkweed and O.E. are frequency and density dependent. What this means is that spore loads on foliage are dependent on the abundance of milkweed relative to the number of ovipositing females. The O.E. infection rate is a function of this dynamic. Second, because of these relationships, O.E. cycles. That is, it increases and then declines only to increase again. There is a seasonal pattern to these cycles with low rates in the spring and higher rates about 3-4 generations. Third, the interactions that contribute to cycling involve spatial relationships that include distances between resources (milkweed patches) and the search capabilities of the butterflies. There is a time component as well."
"Here is the scenario that could play out from San Diego to Ventura counties and parts of Marin as well," Taylor wrote. "Due to warmer conditions more and more native milkweeds (mostly fascicularis) remain green during the winter. This appears to be happening over a broad area. With the sale of tropical milkweed (hereafter TM) being prohibited and homeowners being discouraged from growing TM, what is the likely outcome? With fewer milkweeds overall, the O.E. spore count will go up on both native and TM. OE will become more common rather than less. Further, the reduced distribution of milkweeds will reduce the opportunity for O.E. to cycle. Cycling depends on part of the milkweed distribution being relatively free of spores for the monarch population to recover. Overall, there will be fewer butterflies surviving the winter and therefore a lower starting population in the spring. If that happens, there will be fewer monarchs through the entire season. So, instead of leading to lower O.E. and more butterflies, the elimination of TM is likely to reduce the monarch population--in effect taking the butterflies away from the people. Again, in addition to cutting back TM from time to time to reduce O.E., an alternative solution is to grow TM and to see that it is hyper-dispersed in gardens, etc. through the 5-county area. The same strategy would involve A. fascicularis and other native milkweeds."
"Some of the reaction to TM is simply based on the notion that it is non-native," Taylor wrote. "We can agree on that point. However, it does not naturalize and therefore is not invasive. Our gardens are filled with such plants. TM supports populations of monarchs as far south as Peru and in most, if not all, places where monarchs have been introduced. Also, since this species flowers nearly continuously through the growing season, it is a source of nectar for a large number of pollinating species. TM supports monarchs--full stop! Let's learn to live with it. More milkweeds equal more monarchs and less O.E. overall."
Taylor went on to say that TM does not cause monarchs to break diapause and become reproductive. "Dingle suggests that it is temperature that causes monarchs to break diapause and that is exactly what I have been saying for years. Hormone production is a function of temperature--head temperatures--and not contact with plants. The major driver in the West has been and will continue to be weather/climate. It starts with the conditions that determine the size and distribution of the overwintering female numbers and their reproductive success."
However, the California Department of Food and Agriculture (CDFA), influenced by conservation groups, has categorized A. curassavica as "a noxious weed," and county agricultural commissioners have banned the sale of the plant in nurseries in Marin, Contra Costa, San Mateo and Ventura counties.
Professor Dingle bears to differ. "No one should rush out and pull out their tropical milkweed as it would be a waste of time and effort," he says. "Nurseries should also be able to continue to sell it." He points out:
- "There is not enough tropical milkweed planted to have much influence (see the amount of A. syriaca and A. fascicularis throughout the American west not to mention various other species like A. erosa, cordifolia, californica, etc.) Yes, there are parasites on A. curassavica as there are on ALL milkweeds."
- "There are populations of monarchs that are doing just fine feeding exclusively on A. curassavica (e.g. on many Pacific Islands, such as Guam where I have studied them.
- "Migration and the diapause that accompanies it in the fall are determined by shortening photoperiod and temperature (warm temps can override short days hence the issue with climate change). There is no significant influence of food plant."
UC Davis distinguished professor Art Shapiro, who has monitored butterfly populations in central California since 1972, says the "anti-curassavica propaganda is total hogwash. I have been saying so for years."
Curious, isn't it, that a plant can be so controversial? Four states, California, Arizona, New Mexico and Texas, border Mexico. On the California side, inches away from the Mexican border, tropical milkweed is considered a "noxious weed" per the CDFA definition. On the other side, in Mexico, it's simply a great host plant for monarchs.
What does 2023 hold for the iconic monarch and its host plants? For one thing, more scientific research is needed.