- Author: Kathy Keatley Garvey
Fact: Without milkweed, no monarchs.
Yet a milkweed species that's been thriving in California for more than a century is getting a bad rap. The California Department of Food and Agriculture (CDFA), apparently influenced by conservation groups, has categorized Asclepias curassavica, commonly known as tropical milkweed, as "a noxious weed."
That means, among other things, that county agricultural commissioners can ban the sale of tropical milkweed in nurseries. Indeed, several counties, including Marin, Contra Costa, San Mateo and Ventura, already have.
Banned for sale in nurseries? Says entomologist Jeff Smith, who curates the Lepidoptera collection at the Bohart Museum of Entomology: "There are PLENTY of other 'noxious' weeds sold in nurseries (eucalyptus?) that don't seem to raise the hackles of these counties, so it appears more political than factual, and coming up with the supposed pathogens-on-the-plants scenario looks like they searched for an excuse."
Fact: Infected monarch butterflies can deposit microscopic protozoan parasites, Ophryocystis elektroscirrha or OE, on milkweed. That's ALL species of milkweed, not just tropical. Tropical, however, does not die back in the winter in some parts of California, and that, some argue, encourages monarchs to continue to breed and impedes their migration to overwintering sites. Some blame this "continued OE exposure" to the decline of the monarch population.
Hugh Dingle, distinguished professor emeritus of entomology, behavior and evolution at UC Davis and now a Marin County resident, is an internationally known expert on animal migration. He's researched animal migration for some 50 years. In the last 20 years or so, he has focused on monarch butterflies. He has authored two editions of Migration: The Biology of Life on the Move and some 100 papers. National Geographic featured Professor Dingle in its cover story on “Great Migrations” in November 2010. LiveScience interviewed him for its November 2010 piece on “Why Do Animals Migrate?” (See news story that includes his biographical information)
Professor Dingle responded to a recent front-page article in a Marin County paper about the ban on tropical milkweed. Banning tropical milkweed will NOT save the monarch, Dingle told the reporter in an email. In fact, he said, the ban will "essentially have zero effect on monarchs" and "no one should rush out and pull out their tropical milkweed as it would be a waste of time and effort. Nurseries should also be able to continue to sell it."
The contents of his email, which the professor shared with Bug Squad, include:
- "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."
They Should Know Better! Dingle said some of the advice that CDFA received to categorize A. curassavica as a "noxious weed" came from conservation groups. "They should know better!" he declared.
Art Shapiro, UC Davis distinguished professor of evolution and ecology, has been researching the butterfly populations (including monarchs) of central California for more than 50 years. He co-authored the well-cited research article, "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 online in March of 2016 in the journal, Population Ecology.
Professor Shapiro shared this email with Bug Squad:
So, What Happened? We asked Professor Dingle how tropical milkweed went from total acceptance to a bad reputation. "I don't know why tropical milkweed got such a bad reputation," he responded in an email. "A couple of possibilities: in some places tropical milkweed seems to have more of the Oe parasite than temperate species which die back in winter--ergo, butterflies pick up more parasites (Fact is not enough to have much influence on migration or breeding although in some places there can be a little. But over the whole range of monarchs . . .naaah!) Second possibility is since tropical is around longer, butterflies can feed on it longer and so might 'keep butterflies from migrating.' BUT...migration is a photoperiodic phenomenon (occurs with short days) so feeding is irrelevant. Besides during migration monarchs will feed on almost any plant with nectaring flowers!"
"Monarch butterflies are dependent upon milkweed as its host plant. They lay their eggs on milkweed and their caterpillars eat milkweed. In the past, monarchs in California spent the winter roosting in trees along the coast of California. They did not breed during the winter. They moved inland during summer months where they bred."
"Because of global warming, monarchs have begun to breed during the winter months in California and the existence of tropical milkweed in gardens in coastal California has made that possible...The Nature Police have succeeded in getting the sale of tropical milkweed banned in Contra Costa, Marin, San Mateo and Ventura counties. Academic entomologists have pushed back against this harmful ban in an article published by The Monterey Herald, San Jose Mercury, Marin Independent Journal, and East Bay Times.
The milliontrees.me website also points out that:
- Hugh Dingle, a retired University of California at Davis entomology professor who has studied monarch butterfly migration for more than two decades, said the bans are “basically a wasted effort” and that the focus should be on larger threats such as pesticide and herbicide use. All species of milkweed carry parasites that can affect monarch populations."
- “Arthur Shapiro, a UC Davis professor who has studied monarch butterflies for the past six decades, described the rationale behind the bans as “hogwash.” Shapiro, Dingle and other researchers said winter breeding among monarch butterflies is a relatively new behavior and one influenced by warmer winter temperatures caused by climate change.”
- “David James, an associate entomology professor at Washington State University who has studied monarch butterfly breeding and migration in the Bay Area, said there is a case to be made about the tropical milkweed as being a vital resource for the monarchs in a changing climate.”
- “Leslie McGinnis, a UC Berkeley doctoral candidate studying monarch populations and working with gardeners in the East Bay, said the bans take a 'simplistic view' of the threats that monarchs face, including the fact that many native milkweed plants supplied to nurseries can also be sprayed with pesticides. The bans, she said, can work to disenfranchise or demonize people that have tropical milkweed who instead could be partners in working to help restore monarch populations.”
Indeed, the website minces no words: "Native plant advocates are wedded to a past that is long gone. The climate has changed and it will continue to change. Monarchs and other animals are trying to adapt to the changed conditions. Their survival depends on their ability to adapt. The native plant movement has become a form of climate change denial. Their irrational hatred of introduced plants is damaging the environment with herbicides and harming wildlife. There is no evidence that tropical milkweed is harmful to monarchs."
Mona Miller, who administers the popular Facebook page, Creating Habitat For Butterflies, Moths, & Pollinators, related in a recent post: "Monarch are resilient insects, they have so many strategies to increase their population, but they do have their limits. We must stop pulling out tropical milkweed and cutting it back. Washing off all milkweed should suffice to clean off the OE spores. I emailed several scientists, no one could tell me that OE (Ophryocystis elektroscirrha is a protozoan parasite) has any way to attach to milkweed leaves other than getting caught in the hairs. Tropical milkweed has smooth leaves. Tropical milkweed has been in California since 1909, that is over 100 years. Totally eradicating tropical milkweed, just like totally eradicating all the eucalyptus trees, would have a detrimental effect on the monarch population, perhaps it already has." (Both eucalyptus and tropical milkweed are non-natives.)
Personal Experience. As an aside, our family has provided several species of milkweed in our pollinator garden in Vacaville for more than a decade. The species now include narrowleaf milkweed, A. fascicularis; butterflyweed, A. tuberosa; showy milkweed, A. speciosa; and tropical, A. curassavica. One season we counted more than 300 eggs and caterpillars on the milkweed. Almost all favored A. curassavica. Second choice: A. fascicularis. Some scientists say that perhaps tropical milkweed offers more toxins, and monarchs "know what they want and need."
We continue to plant both natives and non-natives in our thriving garden. The practice now seems so highly controversial that sometimes we feel as if we must mark ourselves "safe" from negativity. But as Professor Shapiro told Bay Nature in June 2022: "I am sick to death of being told you must use natives, especially if a butterfly has no more interest in it than a fire hydrant."
Additional Resources:
- Milliontrees.me:
The Consequences of Putting Plants into 'Native' Strait-Jackets - "Monarch Butterfly Experts Fault Marin Tropical Milkweed Ban," published in, among others:
Ukiah Daily Journal
Marin Independent Journal
Chronicles Live - Xerces Society of Invertebrate Conservation
Monarchs in Decline
Native Milkweeds - Bug Squad:
What's Happening with Our Western Monarch?
- Author: Kathy Keatley Garvey
The invasive species, repeatedly introduced in California and eradicated, "was first found in Central Mexico in 1863, and by the early 1950s flies were found along the California-Mexico border," according to the USDA. "The pest has since been detected in Arizona, California and Texas. A large number of commercially grown crops, including avocado, grapefruit, orange, peach and pear, would be threatened if the Mexican fruit fly became established."
The California Department of Food and Agriculture's fact sheet relates that:
- The Mexican fruit fly (MFF) is among the world's most destructive pests and can destroy many types of fruit, including oranges, grapefruits, apples, peaches and pears.
- Female fruit flies lay their eggs in ripening fruit. The eggs hatch into larvae that eat the flesh of the fruit, causing it to rot.
One of the scientists who does research on the genomics of this fruit fly and other pests in the family Tephritidae is Julian Dupuis, an assistant professor at the University of Kentucky. He'll speak on “Developing Genomics-Based Molecular Diagnostic Tools for Recurrently Invading Tephritid Pests” at a seminar hosted by the UC Davis Department of Entomology and Nematology on Wednesday, Oct. 12 in 122 Briggs Hall.
The seminar, both in-person and virtual, will begin at 4:10 p.m. The Zoom link is
https://ucdavis.zoom.us/j/95882849672
“With increased global trade and transport, anthropogenic movement of non-indigenous, pestiferous species is becoming more coming,” Dupuis writes in his abstract. “Effective management and prevention of these invasions relies on accurate species identification and geographic pathway analysis (that is, what is it and where did it come from?) However, many of these pests belong to highly diverse groups of closely related species that are difficult or impossible to delimit using traditional taxonomic methods, and traditionally used molecular markers have proven ineffective for these tasks. Here, I will present ongoing efforts to use genomic data to inform and develop molecular diagnostic tools for the highly diverse and economically damaging true fruit flies of the family Tephritidae. These efforts combine foundational phylogenomics and population genomics with highly applied uses of these data for phytosanitary purposes, with the ultimate goal of providing highly sought after tools to regularly agencies such as USDA-APHIS."
Dupuis received his bachelor's degree in biology in 2009 from Northern Michigan University and his doctorate in systematics and evolution in 2016 from the University of Alberta. His research interests include insect systematics, speciations, evolution, genomics, phylogenomics and population genomics.
“We are broadly interested in insect speciation and systematics and use an integrative approach to study these phenomena with a large emphasis on genomic approaches,” he writes on his website.
He served as the lead author of research, "Range-Wide Population Genomics of the Mexican Fruit Fly: Toward Development of Pathway Analysis Tools," published in May 2019 in the journal Evolutionary Applications.
Emily Meineke, assistant professor of urban landscape entomology, UC Davis Department of Entomology and Nematology, coordinates the department's seminars for the 2022-23 academic year. All 11 seminars will take place both person and virtually at 4:10 p.m. on Wednesdays in Room 122 of Briggs Hall except for the Nov. 9th and Dec. 7th seminars, which will be virtual only, she said. (See list of seminars)
For further information on the seminars or technical difficulties with Zoom, contact Meineke at ekmeineke@ucdavis.edu.
- Author: Kathy Keatley Garvey
Benson, internationally known for her entomology and horticulture illustrations, will be honored by Srdan Tunic, a UC Davis graduate student studying for his master's degree in art history, at a special talk, "Plants, Insects and Art: Mary Foley Benson's Scientific Illustrations," from 11 to 11:50 a.m., Saturday, Oct. 15 in the Teaching and Learning Complex, 482 Hutchison Drive.
The event, open to the public, is being held during Aggie Spirit Week.
Benson (1905-1992) served as scientific illustrator for the U.S. Department of Agriculture's Bureau of Entomology and the Smithsonian Institution. Later, as a resident of Davis, she engaged in other projects, including working for UC Davis entomologists. Much of her work appears in campus buildings, including Briggs Hall, home of the Davis Department of Entomology and Nematology, and the Bohart Museum of Entomology. (See research story on Mary Foley Benson by forest entomologist Malcolm Furniss)
"I will focus on the visual material, and start by saying a few words about the museum, and then talk about Mary's life and art chronologically, paying special attention to her work at UC Davis," Tunic said. "At some point I will briefly touch on scientific illustration and how artists make this sort of work, and near the end mention other illustrators I encountered during this process, and wrap up motivating people to dive into their local collections."
Tunic is a freelance curator and researcher. A graduate of the University of Belgrade and University of the Arts in Belgrade, Serbia, he holds degrees in both art history and cultural management. He anticipates receiving his master's degree from UC Davis in June 2023.
"A few months later, my art history department granted me the opportunity to do an internship there and I have been diving deep into the life and work of Mary Foley Benson since the spring quarter of 2022. It's really like detective work! I have been surrounded by insects, books and artworks for this whole time--which sounds great in my world--and I am thankful for the whole Bohart Museum team for making this possible."
Tunic has been working independently and collaborating with various art and education initiatives since 2012. He is a co-founder of Trans-Cultural Dialogues (as part of Cultural Innovators Network), Kustosiranje/About and Around Curating, and Street Art Walks Belgrade. He collaborates with art professionals, researching fields such as contemporary art, curatorial practices, street art and graffiti, science fiction, art appropriation, cultural diversity, experiential learning, independent cultural scene and self-management. His work has been published in a number of magazines and journals.
Since 2018, Tunic has been a contributing editor for Not Afraid of the Ruins, especially contributing to the open call Local Science Fictions (2019) and the forthcoming NAOTR anthology (2022). More about his work is at http://srdjantunic.wordpress.com/
- Author: Kathy Keatley Garvey
Never be late for dinner or it might be all gone.
Take the case of the Mexican sunflowers, Tithonia rotundifola, that we planted last April for the monarchs. Monarchs seem to favor Tithonia more than any other nectar source in our pollinator garden. Second choice: the butterfly bush, Buddleia davidii.
May, June, July, and August came and went. The invited (and expected) guests were a "no show." Didn't they make reservations? Or did they forget?
The Tithonia drew honey bees, long-horned bees, syrphid flies, a praying mantis, and assorted butterflies. No monarchs.
In September, entomologist David James of Washington State University, who studies migratory monarchs, announced the monarchs are on their way from the Pacific Northwest to their overwintering sites along coastal California. "They're coming," he said.
Finally, on Sept. 16, a single monarch glided in, sipped some nectar on the Buddleia for a few seconds and left. Another monarch stopped by on Sept. 26, nectared on the Tithonia for a couple of seconds and vanished.
Where are all the dinner guests?
Finally, at 4:30 p.m. on Oct. 3, a male monarch arrived for dinner. And what a 12-course dinner it was on the Tithonia's remaining 12 flowers. He paused once to sample nectar from the Buddleia, but he obviously preferred the Tithonia.
Frankly, it's not been a good year for monarchs in our pollinator garden. Monarchs totally ignored the milkweed, their host plant, and almost disregarded the nectar sources. In comparison, back in 2016, monarchs laid about 300 eggs on our milkweed. In the migratory season, it was not uncommon to see seven monarchs in our garden at one time.
If any more monarchs arrive, they'll not get much Tithonia or Buddleia to fuel their flight to the overwintering sites. They'll have to settle for what's left of the nectar sources: African blue basil, catmint, lion's tail, Mexican petunia, and honeysuckle.
We're just glad one dinner guest showed up, although he was almost too late for dinner.
- Author: Kathy Keatley Garvey
You'll want to register for a class on "I Planted a Bee Garden: Now What?," offered Saturday, Oct. 29 by the UC Davis Bee Haven, part of the Department of Entomology and Nematology.
The class, taught by Christine Casey, academic program management officer of the Bee Haven, is set from 9 a.m. to 10:30 a.m. in the Bee Haven, located on Bee Biology Road, next to the Harry H. Laidlaw Jr. Honey Bee Research Facility. It also will be offered online. Registration for the class, which covers a light breakfast and course materials, is $50. Proceeds will support the operation of The Haven.
Topics will cover turf removal and weed control, best bee plants for new gardeners, and turf vs. bee garden maintenance. Enrollment is limited to 25. To register, access
http://registration.ucdavis.edu/Item/Details/870.
https://registration.ucdavis.edu/Item/Details/871.
UC Extension apiculturist Elina Lastro Niño of the Department of Entomology and Nematology serves as the faculty director of the half-acre garden, planted in the fall of 2019 under the direction of interim department chair Lynn Kimsey, director of the Bohart Museum of Entomology. Häagen-Dazs was the primary donor. (See timeline and history of the garden.)
The garden features art projects by the UC Davis Art/Science Fusion Program, co-founded and co-directed by the duo of entomologist/artist Diane Ullman, professor and former chair of the UC Davis Department of Entomology, and self-described "rock artist" Donna Billick of Davis. Billick created the 200-pound ceramic-mosaic bee sculpture, Miss Bee Haven, that anchors the garden.
The Haven is open daily from dawn to dusk. Admission is free. For more information access the website, Facebook page, Casey's Bee Gardener blog on the UC Agriculture and Natural Resources website, the Instagram account or the Twitter account.
