(Editor's Note: An earlier announcement indicating that this seminar was postponed was an error. It will be held at the same time, date and place.)
Those amazing monarch butterflies!
We're looking forward to a seminar on UC Davis-based research on monarchs in the Pacific Islands.
"The monarch butterfly is an iconic insect in North America largely because of its long-distance migration to precise overwintering sites in Mexico and subsequent return," says Hugh Dingle, emeritus professor, UC Davis Department of Entomology and Nematology.
"Less well known is the fact that it has been introduced to islands across the Pacific and into Australia in the last 200 years or so," he points out. "This presents a great opportunity to study contemporary evolution and adaptation along a migrant/resident axis."
Dingle and graduate student Micah Freedman of the UC Davis Population and Biology Group will present a seminar, sponsored by the UC Davis Department of Entomology and Nematology, on Wednesday, Nov. 9, on "Monarchs in the Pacific: Contemporary Evolution or Local Ecology?" The seminar, open to all interested persons, will take place from 4:10 to 5 p.m. in 122 Briggs Hall, Kleiber Hall Drive. Plans call for video-recording the seminar for later posting on UCTV.
"Here we assess orientation capabilities in island residents vs California migrants and patterns of wing shape presently and over time (from museum collections) for comparison to migrants and residents in North and Central America and the Caribbean," Dingle says in the abstract. "This is a work in progress so queries, suggestions, and critiques will be welcomed."
Dingle, who received his bachelor's degree in zoology from Cornell University and his doctorate in zoology from the University of Michigan, served on the faculty of the UC Davis Department of Entomology (now the UC Davis Department of Entomology and Nematology) from 1982 to 2002, achieving emeritus status in 2003. He is a past president of the Animal Behavior Society and former secretary of the International Society for Behavioral Ecology. Following his retirement, he lived in Brisbane, Australia until 2010, accepting an honorary appointment at the University of Queensland. He returned to Davis in 2010 and shares space in Professor Sharon Lawler's lab.
Dingle published the second edition of Migration: The Biology of Life on the Move (Oxford University Press) in November 2014. It is the sequel to the widely acclaimed first edition, published in 1996. National Geographic featured Dingle in its cover story on Great Migrations in November 2010. LiveScience interviewed him for its November 2010 piece on Why Do Animals Migrate?
Freedman, a graduate student in the UC Davis Center for Population Biology for the last two years, is a graduate of Cornell. He received his bachelor of science degree in entomology and plant sciences.
Dingle speculates that the monarchs arrived in the Pacific Islands with their host plant, milkweed, which was valued at the time for its medicinal properties. Some of the islands are extremely isolated, he said.
An analysis of a monarch population in Hawaii shows that resident monarchs have shorter, broader wings than the long-distance migrants, Dingle says. The Hawaii butterfly wings were shorter than the eastern U.S. long-distance migrants, but “not so short-winged as the residents in the Caribbean or Costa Rica, which have been present in those locations for eons, rather than the 200 years for Hawaii.”
“If there are indeed wing shape changes associated with evolution in isolation, are there other changes that may have occurred under selection and local adaptation for residency?” Dingle wonders. “Are there other changes that may have occurred under selection and local adaptation for residency? Examples of such traits might be changes in flight muscle physiology, changes in photoperiodic diapause response, changes in the characteristics of orientation ability and its relation to antennal circadian rhythms, or changes in the reproductive capacity or tactics (re-colonization of ‘empty' habitats is no longer part of the life cycle).
“Diapause and fat storage, necessary to support migration, are triggered by short photoperiods,” Dingle said, “and the butterflies orient using a sun compass synchronized to a circadian rhythm in the antennae." Overwintering sites in North America include the Transvolcanics Mountains of central Mexico, and the California Coast, particularly Santa Cruz, Pismo Beach, and Pacific Grove.
So here it is Monday, Oct. 10 and the monarch butterflies are still laying eggs on our milkweed in Vacaville, Calif.
"Mrs. October" fluttered down to our tropical milkweed at 4:30 p.m. today and began laying eggs on three tropical milkweeds (Asclepias curassavica).
We grow three other species--showy milkweed, Asclepias speciosa; narrow-leafed milkweed, Asclepias fascicularis; and butterfly milkweed, Asclepias tuberosa. All are looking quite healthy, but Mrs. October chose the tropical milkweed.
As she tended to her maternal business, several migrating monarchs glided down to sip some nectar (flight fuel) from Mexican sunflower (Tithonia) and butterfly bush (Buddleja davidii) in our pollinator garden. Other monarchs seemed interested in finding partners. In October? Apparently so. Temperatures have hovered around 90 degrees for the last several days.
And here I was just telling the family, "My monarch-rearing season is almost over. I have two chrysalids left (in our indoor habitat). If monarchs eclose, that will make a total of 50 monarchs reared and released this season." (This is my small-scale conservation project to help the declining monarch population.)
Not so fast. We now have four monarch eggs, four eggs rescued from assorted predators (lady beetles, milkweed bugs, spiders, ants, and other critters looking for a tasty bit of protein. Pathogens, tachinid flies, wasps, assassin bugs and birds also "interrupt" the natural life cycle of a monarch. (See enemies of monarchs from monarchprogram.org.)
With any luck, the monarch eggs will become caterpillars, then chrysalids and then adults, thanks to Mrs. October's unexpected gift.
However, it's not good to count your chickens before they hatch...or the monarchs before they eclose.
Presidential candidate Herbert Hoover campaigned for "a chicken in every pot and a car in every garage." (Now we have free-range organic chicken on every barbecue grill, and as many as three fuel-efficient cars with sophisticated high-tech gadgets in every multi-car garage.)
Marco Gutierrez, founder of the group "Latinos for Trump," warned that we might have a "#taco truck on every corner." (That's a slogan that backfired; who doesn't love tacos?)
So, "chicken in every pot," "car in every garage" and "taco truck on every corner."
What about a slogan for our monarch butterflies (Danaus plexippus)? If we all planted milkweed, the monarch's host plant (monarchs lay their eggs on milkweed and their caterpillars eat only milkweed), that would be ideal. And even more ideal, if we all provided some flight fuel (floral nectar) for migrating monarchs.
In the 1990s, nearly 700 million monarchs made the epic flight each fall from the northern plains of the U.S. and Canada to sites in the oyamel fir forests north of Mexico City, and more than one million monarchs overwintered in forested groves on the California Coast. Now, researchers and citizen scientists estimate that only a fraction of the population remains, a decline of more than 80% has been seen in central Mexico and a decline of 74% has been seen in coastal California.--Xerces Society for Invertebrate Conservation.
Public awareness could go a long way in helping to boost our monarch population:
- "Milkweed on every corner" or hashtag it: #MilkweedOnEveryCorner.
- "Tithonia in every garden" or hashtag it: #TithoniaInEveryGarden.
Meanwhile, you can't go wrong with Mexican sunflower or Tithonia, which anchors many pollinator gardens in California from early spring through fall. In addition to monarchs, we've seen Gulf Fritillaries, Western tiger swallowtails, mourning cloaks, pipevine swallowtails, skippers, buckeyes, acmon blues, painted ladies and other butterflies sipping nectar from Tithonia. That's not to mention the other pollinators drawn to the colorful orange flower. Among them: bumble bees, carpenter bees, sunflower bees, leafcutter bees, blue orchard bees, sweat bees, syrphid flies or hover flies, and hummingbirds.
Imagine a world with #MilkweedOnEveryCorner" and "TithoniaInEveryGarden." Imagine more monarchs...
Oh, the joy of rearing monarchs...from an egg to a caterpillar to a chrysalis to an adult...
However, the ultimate joy is not in rearing them, but releasing them--from their confined and well-protected indoor habitat to that Spectacular Spacious World Without Boundaries. Some soar majestically 80 feet into the air, never looking back. Some decline to leave your hand and just cling there on your finger. And some leave your hands only to hang around the yard for five hours. Hey, do I have to go? Can't I just stay awhile?
It's been said that in Nature, 97 percent of monarch eggs don't reach adulthood. Or, to put it another way, the survival rate is 3 percent. Conservation, even on a mini-scale (we've reared and released 22 this year) is what it's all about.
Another joy is this: documenting them as they fly off or nectar on nearby flowers. Monarchs may live from minutes to hours to several weeks, depending on predators, diseases, deformities, food supply and migratory mishaps. Some live several months as they overwinter along coastal California and in Central Mexico.
Speaking of life span, we were rather surprised that a video of a monarch being released--and then eaten by a diving bird--emerged as one of three $100,000 America's Funniest Videos. Funniest? Not funny. True, that's what birds do, and do well, but the humor escapes many of us. It was more of an "Oh, No!" moment.
On a more pleasant note, it's good to see an increasing number of citizen scientists planting milkweed. They know that milkweed is the host plant of monarchs; that monarchs will lay their eggs only on milkweed; and caterpillars will eat only milkweed. No milkweed. No monarchs.
For more information on monarchs (Danaus plexippus) and planting milkweed, check out the wealth of information on the Xerces Society's monarch website. And read the news release by the Xerces Society's Emma Pelton on the 74 percent decline in the monarch in the number of monarch butterflies overwintering in coastal California.
How times change with the advancement of knowledge.
It's long been known that when honey bees—as well as other insects—get trapped in the milkweed's pollinia, or sticky mass of pollen, many perish when they are unable to free themselves.
So when we were perusing the book, ABC of Bee Culture, published in 1890 and written by noted beekeeping innovator/entrepreneur A. I. Root (1839-1923) of Ohio--with information “gleaned from the experience of thousands of beekeepers from all over the land”--we came across a surprising recommendation.
The surprising recommendation: If you want to kill off bees where they are not wanted, plant milkweed. In one reference, milkweed is described as a “useless weed.” (Actually, it's the only larval host of the monarch butterfly and without milkweed, no monarchs.)
Excerpt from ABC of Bee Culture:
"Milkweed (Asclepias cornuti). This plant is celebrated, not for the honey it produces, although it doubtless furnishes a good supply, but for its queer, winged masses of pollen, which attach themselves to the bees's feet and cause him to become a cripple, if not to lose his life. Every fall, we have many inquiries from new subscribers in regard to this queer phenomenon. Some think it is a parasite, others a protuberance growing on the bee's foot, and others, a winged insect enemy of the bee.” (Note that foragers are referred to as male, but all foragers are female.)
“It is the same that Prof. Riley alluded to when he recommended that the milkweed be planted to kill off the bees when they become troublesome to the fruit grower. The folly of such advice—think of the labor and expense of starting a plantation of useless weeds just to entrap honey bees---becomes more apparent when we learn that it is perhaps only the old and enfeebled bees that are unable to free themselves from those appendages, and hence the milkweed can scarcely be called an enemy. The appendage, it will be observed, looks like a pair of wings, and they attach themselves to the bee by a glutinous matter which quickly hardens so it is quite difficult to remove, if not done when it is first attached.”
There's a wealth of information in the encyclopedic ABC of Bee Culture, even the 126-year-old edition, but planting milkweed to kill bees and describing milkweed a "useless weed" aren't two of them.
How times change with the advancement of knowledge.
(Editor's Note: The newest edition of the ABC of Bee Culture is The ABC and Xyz of Bee Culture: An Encyclopedia of Beekeeping, 40th Edition. It's published by the A. I. Root Co.)