Posts Tagged: monarch butterflies
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.
Monarch butterfly nectaring on Mexican sunflower, Tithonia, as a territorial male longhorned bee, Melissodes agilis, takes aim. (Photo by Kathy Keatley Garvey)
Monarch butterfly heading toward a butterfly bush. (Photo by Kathy Keatley Garvey)
This is milkweed, the monarch's host plant. (Photo by Kathy Keatley Garvey)
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!
Honey bee foraging on milkweed in the UC Davis Arboretum, near Mrak Hall. (Photo by Kathy Keatley Garvey)
Walk down the garden path, lined with milkweed, and sit on the bench in the UC Davis Arboretum. (Photo by Kathy Keatley Garvey)
But how many people know about its migration?
Steve Reppert, chair and professor of the Department of Neurobiology at the University of Massachusetts Medical School, will speak on "Monarch Butterfly Migration: Behavior to Genes" at the Department of Entomology seminar on Wednesday, Feb. 13 from 12:10 to 1 p.m. in Room 1022 of the Life Sciences Addition, corner of Hutchison and Kleiber Hall drives.
"Studies of the iconic migration of the eastern North American monarch butterfly have revealed mechanisms behind its navigation using a time-compensated sun compass," Reppert says. "Skylight cues, such as the sun itself and polarized light, are processed through both eyes and integrated in the brain’s central complex, the presumed site of the sun compass. Circadian clocks that have a distinct molecular mechanism and that reside in the antennae provide time compensation. The draft sequence of the monarch genome has been presented, and gene-targeting approaches have been developed to manipulate putative migration genes. The monarch butterfly is an outstanding system to study the neural and molecular basis of long-distance migration." (See lab research.)
Hosts are Joanna Chiu, assistant professor of entomology, and Hugh Dingle, emeritus professor of entomology, will host the talk. Dingle, an authority on animal migration, was featured in a National Geographic cover story, "Mysteries of Great Migrations" in November 2010.
Reppert received his bachelor's degree from the University of Nebraska, Omaha, in pre-medicine, and his medical degree from the University of Nebraska College of Medicine. He completed a post-doctoral fellowship in neurobiology at the National Institutes of Child Health (NICHD), NIH, in 1979. He is a professor of pediatrics (neuroscience) at Harvard Medical School (2001 to the present) and since 2000, a pediatrician at the Massachusetts General Hospital.
Reppert became the chair of the Department of Neurobiology, UMass Medical School in 2001, the same year he became the Higgins Family Professor of Neuroscience at UCMass Medical School. He is a fellow of the American Association for the Advancement of Science.
Among his publications on monarchs:
Reppert SM, Gegear RJ, Merlin C (2010). Navigational mechanisms of migrating monarch butterflies. Trends in Neurosciences (TINS) 33:399-406.
Heinze S, Reppert SM (2011). Sun compass integration of skylight cues in migratory monarch butterflies. Neuron 69:345-358.
Zhan S, Merlin C, Boore JL, Reppert SM. The monarch genome yields insights into long-distance migration. Cell 2011; 147:1171-1185.
Reppert's talk will be video-recorded and posted on UCTV at a later date.
Monarch butterflly shares a Tithonia (Mexican sunflower) with a honey bee at the Haagen Dazs Honey Bee Haven, UC Davis, last summer. (Photo by Kathy Keatley Garvey)
However, in wild populations, monarchs are commonly infected "with a specialist protozoan Ophryocystis elektroscirrha; this parasite can be transmitted both vertically and horizontally and causes debilitating infections."
Altizer, an associate professor in the Odum School of Ecology, University of Georgia, Athens, will discuss "Migratory Immunity: Parasite Infection, Host Defense and Fitness Costs in Monarch Butterflies" at the UC Davis Department of Entomology seminar on Wednesday, May 9 in 122 Briggs Hall.
It promises to be well-attended, given the avid interest in monarchs and Altizer's expertise.
What's so special about monarchs?
"Monarch butterflies are known for the incredible mass migration that brings millions of them to California and Mexico each winter," according to an article in National Geographic. "North American monarchs are the only butterflies that make such a massive journey—up to 3,000 miles (4,828 kilometers). The insects must begin this journey each fall ahead of cold weather, which will kill them if they tarry too long."
The National Geographic article points out that "Only monarchs born in late summer or early fall make the migration, and they make only one round trip. By the time next year's winter migration begins, several summer generations will have lived and died and it will be last year's migrators' great grandchildren that make the trip. Yet somehow these new generations know the way, and follow the same routes their ancestors took—sometimes even returning to the same tree."
Altizer's research focuses on the interplay between animal behavior and the spread and evolution of infectious diseases. For the past 15 years, she has studied monarch butterfly migration, ecology, and interactions with a protozoan parasite, asking how seasonal migration of these butterflies affects parasite transmission.
She also researches a number of other projects, including mammalian infectious diseases and songbird-pathogen dynamics, including studies of house finch conjunctivitis, West Nile virus, and salmonellosis.
But we butterfly enthusiasts are happy she's studying the monarchs!
A monarch butterfly foraging on a Mexican sunflower in the Haagen-Dazs Honey Bee Haven, UC Davis. (Photo by Kathy Keatley Garvey)
Surprise: it's in the antennae!
Neurobiologists at the University of Massachusetts Medical School have long wondered how monarch butterflies (Danaus plexippus) can migrate from across eastern North America to a specific grove of fir trees in Mexico.
That's 2000 miles, as a crow flies--or as a monarch flies.
The scientists figured that the key mechanism that steers the monarchs is in the brain.
Nope. It's in the antennae. The antennae aren't just "noses" or "odor detectors."
"We've known that the insect antenna is a remarkable organ, responsible for sensing not only olfactory cues but wind directions and even sound vibration." said Steven Reppert, professor and chair of neurobiology and senior author of the study, published today (Sept. 25) in the journal Science.
"But its role in precise orientation over the course of butterfly migration is an intriguing new discovery, one that may spark a new line of investigation into neural connections between the antennae and the sun compass, and navigation mechanisms in other insects," he said in press release.
For those of us who are navigationally challenged and have long admired how insects migrate from Point A to Point B, this is amazing. There are circadian clocks in the antennae.This study makes us look at monarch butterflies in an entirely different light.
Like the monarchs we spotted nectaring last weekend on the grounds of the Luther Burbank Home and Gardens, Santa Rosa.
Their antennal circadian clocks coordinate sun-compass orientation.
Or, in other words, those antennae are necessary for sun-related orientation.
It's in the Antennae