Reporter Lizzie Wade, Science's Latin America correspondent based in Mexico City, led with: "It started with the best of intentions. When evidence emerged that monarch butterflies were losing the milkweed they depend on due to the spread of herbicide-resistant crops in the United States, people across the country took action, planting milkweed in their own gardens. But a new paper shows that well-meaning gardeners might actually be endangering the butterflies' iconic migration to Mexico. That's because people have been planting the wrong species of milkweed, thereby increasing the odds of monarchs becoming infected with a crippling parasite."
Wade pointed out that "tropical milkweed—at least when planted in warm environments like southern Texas and the U.S. Gulf Coast—doesn't die back in the winter like native milkweed does. When presented with a place to lay their eggs year-round, many monarchs don't bother making the trip to Mexico at all." Some think the year-round tropical milkweed is "an even more direct threat to the butterflies. Milkweed hosts a protozoan parasite called Ophryocystis elektroscirrha (OE). As caterpillars, monarchs ingest the parasite along with their normal milkweed meals, and when they hatch from their chrysalises they are covered in spores."
She quoted a butterfly scientist as saying that infected monarchs are much weaker than their healthy counterparts and don't live nearly as long. And if an OE-infected monarch tries to migrate, it will probably die long before it arrives in central Mexico, she wrote.
Shapiro has been monitoring and studying populations of butterflies in central California for more than four decades and posts the information on his website. In an email response to inquiries from a UC Master Gardener and Farm Advisor (initially sent my way), wrote: “The story is basically correct, but there has to be more to it. Monarchs are normally in 'reproductive diapause' in winter, which means their sex organs and sex drive are inactive; this condition (as in migratory birds) is believed to be induced by seasonal day-length changes. We never used to get attempted winter breeding. Tropical milkweed has been in gardens in California for decades, but only very recently are we seeing attempted winter breeding, first in Southern California and now in the Bay Area. Many of us would like to understand why these animals are NOT in diapause! There have been unexplained changes in the seasonal geography of monarch breeding: for example, here in the Sacramento Valley, there is now virtually no spring breeding (as before) but tons of fall breeding (which didn't use to happen; the animals migrating coastwise were generally in reproductive diapause)."
The reference to OE is correct, Shapiro said. "However, there is an easy 'fix' that nobody talks about for some reason: just cut the plants to the ground a few times a year. This will encourage new growth, which will be cleaner, prettier, more nutritious, and uncontaminated with OE. There is nothing inherently 'bad' about winter breeding if it's clean. Infected winter breeding is a population sink. The animals are often too feeble to fly, and may be unable to expand their wings. But perfectly healthy ones are being produced right now in the East Bay on clean plants."
Many of the public comments that people posted about the research, Shapiro said, show a large amount of ignorance. “Observation: the commonest eastern (Asclepias syriaca complex) and Californian (A. fascicularis) milkweeds are usually almost if not quite non-toxic, which means the monarchs that feed on them will be edible to birds. If you want to breed monarchs as bird food, by all means plant those! But if you want to breed nasty monarchs that will make birds vomit and never try one again, plant one of the more toxic species! There is no good evidence that the females discriminate between high-and low-cardenolide milkweeds, or that larvae do better on one than on the other. There is no garden equivalent of "one size fits all." You want to use species that make sense where you are located! That's what gardening 'zones' are there for...The genus Asclepias extends south to Argentina (the s-most species, A. mellodora, is the major host of the South American Monarch, Danaus erippus) so yes, there are milkweeds in Mexico…. There are so many resources readily available, but people are lazy, don't know how to search properly, or prefer to create their own 'facts' a la Fox News...it gets discouraging. God bless Master Gardeners and Farm Advisers!”
When a monarch butterfly comes fluttering through your yard, grab your camera. Marvel at it beauty, celebrate its presence, and keep it in your memory. It may be become an endangered species the way things are going.
The Xerces Society for Invertebrate Conservation recently reported that the monarch population has declined by more than 90 percent in under 20 years. And, “during the same period it is estimated that these once-common iconic orange and black butterflies may have lost more than 165 million acres of habitat — an area about the size of Texas — including nearly a third of their summer breeding grounds.”
So a trio—Center for Biological Diversity, Center for Food Safety, and the Xerces Society—filed a legal petition asking the U.S. Fish and Wildlife Service for Endangered Species status to protect the monarch (Danaus plexippus).
The widespread loss of milkweed, the butterfly's host plant, especially throughout the Midwest, is troubling.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at the University of California, Davis, says there's plenty of milkweek in Northern California. “The problem is that nobody's there to breed on it.” For example, he sees large spreads of milkweed (Asclepias speciosa) around his many monitoring sites, including one by the Vacaville (Calif.) Transit Center. “Probably 75 stems, but I have never ever seen a monarch there, let alone any evidence of breeding." (See his entry on monarchs on his website.)
So, a monarch's solo visit to our little bee garden seems like a major event. When we see one, as we did Sept. 17, it heads straight for the Mexican sunflower (Tithonia).
Backlit, the monarch resembles a stained glass window. What a gorgeous butterfly, worthy of the royal name, “monarch!”
The only question is: will we consider it worthy enough to save it?
- Plant milkweed, its host plant.
- Avoid insecticides or herbicides.
- Become a citizen scientist and help record sightings.
- Support conservation efforts.
- Promote public awareness.
The Xerces Society for Invertebrate Conservation issued news today that is both disturbing and hopeful.
Disturbing in that the monarch butterfly population (Danaus plexippus) has declined by more than 90 percent in under 20 years.
Hopeful in that the monarch may receive federal protection through the Endangered Species Act.
The Xerces Society, the Center for Biological Diversity, the Center for Food Safety, and monarch scientist Lincoln Brower, have filed a legal petition with the U.S. Fish and Wildlife Service to protect the monarch through the Endangered Species Act. The agency must respond within 30 days as to whether the petition warrants further review.
“Monarchs are in a deadly free fall and the threats they face are now so large in scale that Endangered Species Act protection is needed sooner rather than later, while there is still time to reverse the severe decline in the heart of their range,” related Lincoln Brower, preeminent monarch researcher and conservationist, who has been studying the species since 1954.
Tragicallly, the monarchs have lost more than 165 million acres of habitat, including nearly a third of their summer breeding grounds that contain their host plant, milkweed. The female monarchs lay their eggs on milkweed and this is the only food their larvae eat.
As Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis, told us today: "Might be too little too late but they have to preserve/conserve milkweeds (Asclepias spp.) That's more important than the butterfly itself."
Xerces earlier sounded the alarm on the critical role that milkweeds play in the monarch's life cycle.
Senior scientist Tierra Curry of the Center for Biological Diversity, hammered home this point in the news release: “The 90 percent drop in the monarch's population is a loss so staggering that in human-population terms it would be like losing every living person in the United States except those in Florida and Ohio.”
And the loss of habitat is equal in size to the state of Texas.
The news release said that the butterfly's dramatic decline is "being driven by the widespread planting of genetically engineered crops in the Midwest, where most monarchs are born. The vast majority of genetically engineered crops are made to be resistant to Monsanto's Roundup herbicide, a uniquely potent killer of milkweed, the monarch caterpillar's only food. The dramatic surge in Roundup use with Roundup Ready crops has virtually wiped out milkweed plants in midwestern corn and soybean fields."
Science policy analyst Bill Freese of the Center for Food Safety was quoted as saying: "The widespread decline of monarchs is driven by the massive spraying of herbicides on genetically engineered crops, which has virtually eliminated monarch habitat in cropland that dominates the Midwest landscape. Doing what is needed to protect monarchs will also benefit pollinators and other valuable insects, and thus safeguard our food supply.”
Monarch butterflies are known for their spectacular multigenerational migration each year from Mexico to Canada and back, the news release said.
"The population has declined from a recorded high of approximately 1 billion butterflies in the mid-1990s to only 35 million butterflies last winter, the lowest number ever recorded," according to the release. "The overall population shows a steep and statistically significant decline of 90 percent over 20 years. In addition to herbicide use with genetically engineered crops, monarchs are also threatened by global climate change, drought and heat waves, other pesticides, urban sprawl, and logging on their Mexican wintering grounds. Scientists have predicted that the monarch's entire winter range in Mexico and large parts of its summer range in the states could become unsuitable due to changing temperatures and increased risk of drought, heat waves and severe storms."
Endangered species director Sarina Jepson of the Xerces Society worries--and rightfully so--that the monarch may become extinct, just like the passenger pigeon.
We are, too. We've seen only two--two--of these majestic butterflies fluttering in our family bee garden this year.
Folks are planting milkweed for the monarchs.
The milkweed (genus Asclepias) is the host plant (larval food) for the monarch butterfly (Danaus plexippus). No wonder the monarch is sometimes called "the milkweed butterfly."
The perennial plant is so named for its milky juice, consisting of a latex containing alkaloids and other complex compounds. Carl Linnaeus named the genus for the Greek god of healing, Asciepius.
But milkweed is also a favorite bee plant. It's an important nectar source.
The UC Davis Arboretum has a beautiful milkweed patch near Mrak Hall and on any given day, you'll see honey bees foraging. Be prepared to see as many as four or five honey bees on one bloom. The fragrance is delightful and so are the bees!
Monarchs and milkweed are in the news again.
As well they should be.
The declining monarch population, coupled with the decreasing scarcity of their host plant, the milkweed, is disturbing. The larvae of the monarch butterfly (Danaus plexippus) feed exclusively on milkweeds. No milkweed, no monarchs.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at UC Davis, says the problem hasn't totally reached California yet. "The 'dearth of milkweed' problem is primarily an East/Midwest problem, due to increased use of Roundup since the introduction of 'Roundup-ready' GM crops. It's quite real. There is no such problem out here--at least yet--but there is a new milkweed pathogen that may cause one! Dave Rizzo (UC Davis Department of Plant Pathology) and I hope to publish on it shortly. No harm in planting milkweeds, but the problem isn't a California one, at least not yet."
Journalist-photographer Alessandra Bergamin, writing in the Feb. 18 edition of Bay Nature: Exploring Nature in the San Francisco Bay Area, says that "the number of monarchs overwintering in Mexico's Oyamel fir forest has reached an all-time low," quoting the World Wildlife Fund in Mexico. "The reports suggest that factors such as loss of habitat, climate change and use of insecticides have contributed to the decline."
The situation in California, however, looked better than bleak last year. A little better. "Monarch butterfly populations in California's coastal overwintering sites showed a slight — and surprising — rebound in 2013 after more than a decade of dwindling numbers," Bergamin wrote. "The 2013 Western Monarch Thanksgiving Count tallied 211,275 monarchs at 162 sites from Sonoma County to San Diego County, up from 144,812 the year before."
Over the past two decades, however, the Western monarch population has dramatically declined in California, she pointed out in her article, "Western Monarch Population Hanging On." The downward trend is expected to continue.
Meanwhile, the Xerces Society for Invertebrate Conservation, headquartered in Portland, Ore., has posted a seed finder resource so folks can find milkweed seed in their state and plant the seeds in their gardens, parks, landscapes, restoration areas and on farms.
Oakland parks supervisor Tora Rocha is taking it one step further. She is collecting the monarch caterpillars, rearing them, and releasing the adults in the Lakeside Gardens at Lake Merritt. Her newly formed Pollinator Posse has sparked the interest of volunteers, who range from school children to city council members. They all want to save the monarchs.
Rocha bans pesticides and herbicides from her pollinator gardens. “For the past fifteen years the gardens have had a pesticide-and herbicide-free policy,” Rocha told writer Constance Taylor of Wild Oakland, which offers free, Oakland-centered environmental education. “We also rely on volunteers contributing thousands of hours to keep our parks maintained--about 75% of the work is done by volunteers.”
Rocha says it's not enough to be a custodian of the land: it's important to be a steward of the land and protect the pollinators. She's created a video, posted on YouTube, that explains what she and the other Pollinator Posse members do.
Rocha and colleague Eddie Dunbar of the Insect Sciences Museum of California and a fellow Pollinator Posse member, recently visited UC Davis to share information with Shapiro and native pollinator specialist Robbin Thorp, emeritus professor of entomology.
Another person keen on butterflies is Sally Levinson of Berkeley, who writes a blog on butterflies and is publishing educational videos, including "Secret Lives of Monarchs" and "In the Company of Wild Butterflies." As a graduate student at UC Riverside, Levinson studied with major professor Bruce Hammock, now a distinguished professor of entomology at UC Davis. (He maintains a joint appointment with the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center.)
As an aside, the Bohart Museum of Entomology at UC Davis offers a "Got Milkweed?" t-shirt spotlighting the monarch and its host plant. The work of doctoral candidate Fran Keller and Bohart volunteer/naturalist Greg Kareofelas, the t-shirt is available online or at the museum, located in Room 1122 of the Academic Surge building on Crocker Lane.
Want monarchs? Plant milkweed.