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When Monarch Butterflies Skip Meals
Got milkweed?
If not, monarch butterflies are in a heap of trouble.
An interesting study just published in journal PLOS One by researchers at the University of Jamestown, North Dakota, and the University of Georgia, Athens, Georgia, revealed that the larvae of monarch butterflies that skip meals (host plant, milkweed) will become adults with a smaller wing size, as much as 2 percent smaller.
That's important because monarch butterflies (Danaus plexippus) are migratory animals that travel long distances, and without milkweed, Asclepias spp., their migration will be adversely affected.
In their research, “Does Skipping a Meal Matter to a Butterfly's Appearance? Effects of Larval Food Stress on Wing Morphology and Color in Monarch Butterflies,” Haley Johnson of the University of Jamestown and her colleagues also found that monarch larvae deprived of food became adults with a different wing coloration: paler wings.
This study nails home the point why we need to plant milkweed. As the Xerces Society for Invertebrate Conservation says on its website: “The loss of milkweed plants in the monarch's spring and summer breeding areas across the United States is believed to be a significant factor contributing to the reduced number of monarchs recorded in overwintering sites in California and Mexico. Agricultural intensification, development of rural lands, and the use of mowing and herbicides to control roadside vegetation have all reduced the abundance of milkweeds in the landscape.”
To address this seed shortage, the Xerces Society launched Project Milkweed to produce new sources of milkweed seed “where seed has not been reliably available: California, the Great Basin, Arizona, New Mexico, Texas, and Florida."
Bottom line, the Xerces Society is:
- raising public awareness about milkweeds' value to monarchs and native pollinators
- promoting the inclusion of milkweeds in habitat restoration efforts
- developing milkweed seed production guidelines, and
- building new markets for milkweed seed.
The Xerces website also offers sources of native milkweed seed in your state.
Meanwhile, the butterflies that overwintered in Mexico are on the move and in Texas. For more information on butterfly migration, see Monarch Butterfly, Journey North.
Monarch butterfly sightings are becoming more uncommon. (Photo by Kathy Keatley Garvey)
Monarch butterfly grabbing a sip of nectar from lantana. (Photo by Kathy Keatley Garvey)
Monarchs 'n Milkweed
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.
A monarch butterfly nectaring on a zinnia. (Photo by Kathy Keatley Garvey)
This is a milkweed, the host plant of the monarch. This photo was taken in the Melissa Garden, Healdsberg. http://www.themelissagarden.com/ (Photo by Kathy Keatley Garvey)
Where Have All the Monarchs Gone?
As the world mourned the Jan. 27th death of 94-year-old folk singer Pete Seeger and hummed his signature song, "Where Have All the Flowers Gone?", the question has now turned to: "Where Have All the Monarchs Gone?"
The monarch butterfly (Danaus plexippus) is in trouble.
It has been in trouble for a long time.
Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis, says the monarch situation is not surprising, really, due to "changing ag practices, urbanization and drought/freezing."
Monarchwatch.org reported today that "the overwintering numbers are in from Mexico and once again it's bad news."
In his blog, Chip Taylor mentions three factors have "contributed significantly to the loss of monarch and pollinator habitats: the adoption of herbicide tolerant (HT) crops, the ethanol mandate, and development."
"In much of the corn-belt," Taylor wrote, "farming is from road to road with little habitat for any form of wildlife remaining. Grasslands--including some of the last remaining native prairies, rangelands, wetlands, and 11.2 million acres of Conservation Reserve Program (CRP) land--have been plowed under to produce more corn and soybeans. Most of these acres formerly contained milkweeds, monarchs, pollinators and other forms of wildlife. They are gone and the total loss of these habitats since 2008 exceeds 24 million acres (an area about equal to the state of Indiana)."
Milkweed is the monarchs' host plant.
"Development consumes about a million acres of farmland a year," Taylor noted, "and the conversion of woodlands and other landscapes to shopping malls, housing and roadways consumes another million acres a year. Overall, the loss of various habitats due to development probably exceeded 34 million acres since 1996."
Taylor estimates that "that at least 167 million acres of monarch habitat has been lost since 1996."
"Not all of the corn and soybean acreage occurs within the summer breeding range for monarchs so the total loss of monarch habitat due to HT crops is lower (150 million) than the total area (174.5 million) planted in 2013. The 24 million acres of grasslands, etc. converted to croplands since 2008 have been included in the estimated loss to HT crops. Add to this number the estimated loss due to development and the total is 167 million acres lost but this could easily be an underestimate since there are losses such as roadside management that we can't account for."
Be sure to read his informative blog, and his charts. Taylor ends with "...let's plant milkweed--lots and lots of it."
The Xerces Society of Invertebrate Conservation's Project Milkweed is raising public awareness and promoting the use of milkweeds in restoration habitats. Xerces' role also includes developing milkweed seed production guidelines and building new markets for milkweed seed, according to its website.
Monarch butterfly nectaring on lantana on Oct. 27, 2013 in Vacaville, Calif. (Photo by Kathy Keatley Garvey)
A glorious sight: monarch on the move. (Photo by Kathy Keatley Garvey)
Saving the Monarchs
If you think people don't care about monarch butterflies, think again.
A recent survey published in Conservation Letters showed that Americans are willing to spend at least $4.78 billion to help conserve monarchs (Danaus plexippus), one of the most recognizable of all insects. Indeed, what is more spectacular than the multigenerational migration of monarchs heading from their breeding grounds in northern United States and southern Canada to their wintering grounds in central Mexico and coastal California?
The study of 2,289 U.S. households, led by Jay Diffendorfer of the U.S. Geological Survey, Geosciences and Environmental Change Science Center, Denver, found that we Americans love monarchs so much that we're more than willing to plant milkweed, their larval host plant, to save them.
Yes!
The article, published Oct. 28 and titled National Valuation of Monarch Butterflies Indicates an Untapped Potential for Incentive-Based Conservation, calls attention to the destruction of the monarch's habitat and the importance of conservation.
"Since 1999, the size of the overwintering colonies in Mexico and California have declined, and the 2012 survey in Mexico showed the lowest colony size yet recorded, which prompted wide-scale media reports," the authors wrote. "Habitat loss in the overwintering sites in Mexico and California is well-documented, although no direct empirical link between declining overwintering habitat and monarch numbers exists. In addition, the growing use of glyphosate-tolerant genetically modified crops has reduced larval host plant (milkweed, Asclepias spp) abundances in farm fields across United States and Canada. Increasing acreage of glyphosate-tolerant corn and soybeans are negatively correlated to monarch numbers, with the area of milkweed in farm fields in the United States declining from an estimated 213,000 to 40,300 ha."
Biologist Hugh Dingle, emeritus professor of entomology at UC Davis, is among those studying their migration. (Read his quotes in the National Geographic cover story, "Mysteries of Great Migrations," published in November 2010. Dingle is now working on a much-anticipated book on migration from his headquarters in the Sharon Lawler lab, UC Davis Department of Entomology and Nematology.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at UC Davis, monitors butterflies in Central California. Here's what he has to say about monarchs on his website, Art's Butterfly World.
Meanwhile, a day before Conservation Letters published the survey, a lone monarch butterfly fluttered into our backyard to sip nectar from lantana. It lingered for 10 minutes.
What a treat to see!
A monarch butterfly on lantana last week in Vacaville, Calif. (Photo by Kathy Keatley Garvey)
Monarch taking flight. (Photo by Kathy Keatley Garvey)
Mighty Monarchs Gone Missing
The news is not good.
Scores of Monarch butterflies (Danaus plexippus) are now migrating toward their overwintering zone in Mexico but they're doing so in dwindling numbers.
"Monarch butterflies appear headed for a perhaps unprecedented population crash, according to scientists and monarch watchers who have been keeping tabs on the species in their main summer home in Eastern and Central North America," wrote reporter Daniel Schwartz of CBC News in a Sept. 24 news article.
"There had been hope that on their journey north from their overwintering zone in Mexico, the insects' numbers would build through the generations, but there's no indication that happened."
We spotted six Monarchs nectaring on lantana on Sept. 14 in south Vacaville. "I think the numbers are up regionally, but I've seen no breeding at all in the Central Valley," said butterfly expert Art Shapiro, distinguished professor of evolution and ecology at UC Davis. "They bred like mad in Nevada this year."
Shapiro writes on his butterfly monitoring website: "The Monarch overwinters on the central coast and moves inland, typically in early March."
In his book, The Handy Bug Answer Book, entomologist Gilbert Waldbauer, professor emeritus of the University of Illinois at Urbana-Champaign, points out that Monarchs are the most famous of the "insect migrants that make a return trip."
Which begs the question: "Do the overwintering monarchs in Mexico feed?" Responds Waldbauer: "Practically none of them feed. On warm days, they leave the trees to drink water, but the few flowers near the overwintering sites are sucked dry of nectar by the first few monarchs that find them."
They survive, he writes, "on large stores of energy-rich body fat that they acquired as they migrated south. On average, their bodies consist of about 50 percent fat. Their fat supply lasts through the winter because, inactive in the cold climate of the high mountains, they use up very little energy."
A Monarch butterfly nectaring on lantana. (Photo by Kathy Keatley Garvey)
A Monarch butterfly filling up on nectar from lantana. (Photo by Kathy Keatley Garvey)
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