A mid-life chrysalis?

Well, maybe not mid-life, but definitely out of season.

A female monarch butterfly eclosed today in our little indoor butterfly habitat. Two weeks ago, we “rescued” the caterpillar from a narrow-leafed milkweed plant in our Vacaville pollinator garden and brought it inside.  Our goal: conservation. We sought to protect it from prey, including the resident scrub jays.

So, this morning, we lost a chrysalis and gained a butterfly. She was right on schedule: Eclosure after 10 days as a chrysalis.

When the temperature hit 61 degrees at around 1 p.m., we released her. She fluttered a bit, and then soared straight up, a good 80 feet high. Usually when we release the monarchs, they flutter around, sometimes touching down on a bush and sometimes soaring over it. This one wasted no time.

On its way to Santa Cruz?

Not sure. At 3:30 p.m., we spotted a monarch butterfly--same one?--roosting on our African blue basil as a dozen honey bees buzzed around, gathering nectar.

Meanwhile, the fellow members of her species are winging their way to their overwintering sites: the monarchs east of the Rockies to the Sierra Madre Mountains in Mexico, and those west of the Rockies to the California coast, including the Natural Bridges State Beach in Santa Cruz, and Pacific Grove in Monterey County.  They cluster in eucalyptus, Monterey pines, and Monterey cypresses.

Monarchs do not fly at night. They travel only during the day and then find a roosting spot for the night. "Roost sites are important to the monarch migration," according to the U.S. Department of Agriculture's Forest Service. "Many of these locations are used year after year. Often pine, fir and cedar trees are chosen for roosting. These trees have thick canopies that moderate the temperature and humidity at the roost site. In the mornings, monarchs bask in the sunlight to warm themselves."

How many miles can monarchs travel a day? Between 50 to 100 miles, the Forest Service says. "It can take up to two months to complete their journey. The farthest ranging monarch butterfly recorded traveled 265 miles in one day."

Monarchs use a combination of directional aids, including the magnetic pull of the earth and the position of the sun. They take advantage of the air currents and thermals as they head toward their overwintering sights. 

To think that we humans can barely make it out of the neighborhood without our GPS devices!  

As of 5 p.m., the monarch roosting on the African blue basil is still there. The bees are gone, back to the warmth of their hives.

Tomorrow, our little buddy will warm her flight muscles, sip a little nectar, and take flight.

Safe travels,  Miss Monarch!

Abbas Mohamed

Brian Johnson

Rachel Vannette

There's exciting news today out of the Department of Entomology and Nematology, University of Califoirnia, Davis.

A team of researchers--two faculty members and a graduate student--just published a paper on bee immunity and toxin metabolism today (Nov. 9) in Scientific Reports, part of the Nature Publishing Group. The team: assistant professor Rachel Vannettte; and assistant professor Brian Johnson and his graduate student, Abbas Mohamed.

The journal article is titled Forager Bees (Apis mellifera) Highly Express Immune and Detoxification Genes in Tissues Associated with Nectar Processing. 

When honey bees shift from nurse bees to foragers, or from caring for the brood to foraging for nectar and pollen, the bees “turn on” gene expression with products that protect against microorganisms and degrade toxins, they discovered,

“First, the results suggest that forager bees may use antimicrobial peptides—short sequences of amino acids with general activity-- to reduce microbial growth in stored food resources,” said Vannette, who joined the faculty in September as assistant professor after a postdoctoral fellowship at Stanford University. “This would be a largely unrecognized way that bees protect honey and potentially other stored resources from microbial spoilage. Second, this work shows that forager bees produce toxin-degrading enzymes in nectar-processing tissues.”

“This may allow forager bees to degrade many different kinds of compounds in nectar, before it is stored,” Vannette said. “Bees also vary in their ability to do this—foragers have a greater ability to degrade a variety of compounds than nurses. This may have implications for hive health and management.” 

The scientists found the change in nectar-processing tissues, but not in the gut.   The scientists surmised that the exposure to bacteria or yeasts in the environment may trigger this change, but they did not examine it in the study. it in the study.

"Nice paper,” said Gene Robinson, director of the Institute for Genomic Biology and Swanlund Chair of Entomology, University of Illinois at Urbana-Champaign, who was not involved in the research. “It had been well known that the division of labor in a honey bee colony is supported by extensive differences in brain gene expression between bees that perform different jobs. This new research shows nicely that this genomic differentiation extends beyond the brain; different complements of active genes in a variety of tissues make each bee better suited for the job it needs to perform."

The team plans to follow up with functional assays to examine the potential of these gene products to (1) reduce microbial growth and (2) degrade a variety of natural and synthetic compounds. 

So, we're anxiously awaiting to hear more! 

Monarch caterpillar eating a narrow-leafed milkweed. Note the aphids. (Photo by Kathy Keatley Garvey)

In research published Nov. 4 in the Proceedings of the Royal Society B, Professor Agrawal and colleague Georg Petschenka, also of Cornell, found that monarch butterflies (Danaus plexippus) have "evolved" the ability to store toxins, known as cardenolides, that are poisonous to birds. The title of their research article: "Milkweed Butterfly Resistance to Plant Toxins Is Linked to Sequestration, Not Coping with a Toxic Diet."

Lepidopterans and butterfly enthusiasts know that caterpillars digest the toxins in milkweed plants and that they  retain that poison not only as caterpillars, but as chrysalids and adults.

Birds dislike the toxicity and learn to avoid the monarchs. Of course, birds still eat the caterpillars, chrysalids and adults, but not as many.

The take-home message in lay terms? "We learned that the evolutionary pressure of predation can be so strong, that it drives the way insects eat plants, and to eat more toxic plants," Agrawal told us this afternoon.

What about the oleander aphids that suck the juices out of milkweed plants and the lady beetles, aka ladybugs, that eat the aphids?

"The toxicity does impact both the aphids and lady beetles … they don't like it!" Agrawal said. "Well, it is sort of a coevolutionary argument… the aphids have specialized on the milkweeds, so that family is all they eat… but in response, the plants produce cardenolides that do bother them."

Writer Geoffrey Giller published an article, "Butterflies Weaponize Milkweed Toxins" today in The Scientist.

"Scientists," wrote Giller, "have long known that milkweed cardenolides, which in most animals disable a vital sodium-potassium pump enzyme if they are absorbed into the blood, serve to make caterpillars and butterflies dangerous meals for their predators, but whether that acquired toxicity was a side effect of an adaptation that allowed monarchs to eat milkweed or had developed separately as a defensive mechanism was unclear."

The paper is being called a landmark. 

And those toxins are also "landmark" weapons. Toxic weapons.