Hibernate like the Bees

The turkey’s been stuffed.  The first snow has hit the pavement.  Ambitious merry folk in white-trimmed red-felt hats are already weighing down conifers in their living rooms with glass globes and tinsel.  Yes, ’tis the season when one naturally begins to wonder, “Hey, where do all the bees go in winter?”  Good question!  After all, this is the time of year when we worry about the homeless and the hungry, so shouldn’t we take a moment together to worry about the bees too?  It’s only right.  And turns out it’s pretty interesting too.

Keeping with the spirit of the holiday season, I would love to tell you that the bees are hibernating, tucked away in the furry warmth of some backwoods cave, slumbering gently until spring when they will flutter their wings once more.  I would also love to describe to you how they are being peaceably tended in these starlit caves by amicable shepherds and angels, but then you would know I was lying.  What, in good faith, I have to tell you is this: The bees are dead.  (Call the press!  No…don’t.)  The adult native (non-honey) bees of summers gone are dead.  But their squishy larvae babies are currently noshing on bee bread, cycling through instars, spinning cocoons, and stretching out tiny veins through new delicate webs of wing (all without the aid of shepherds or angels).  They are busy with all these activities right under your nose, hunkered down in underground cells meticulously crafted from mud, leaves, petals, wax.  Ensconced in a chamber of secrets, solitary bees are nowhere and everywhere in winter, absent from their usual aerial haunts, but tunneled into every bare ground patch, hollowed shrubby stem, and vacant wooden cavity around you.  They could even be nesting in the walls of your house.  (Call the exterminator!  No…don’t.)  So while we can’t accurately imagine most bees as iconically hibernating like Yogi or Smokey or anyone else, what the bees are up to these days is at least as endearing, intriguing, and worthy of cartoon caricature and idolatry.

Adorable dormouse overwintering strategy.
http://www.bbc.co.uk/nature/adaptations/Hibernation#intro

Animals have a variety of strategies for surviving the winter, collectively termed ‘overwintering.’  Many birds, some large mammals, certain charismatic insects, and many of our very own geriatrics migrate long distances to avoid having to fatten up and hunker down through the cold months.  Other adorable creatures embrace hibernation, spending autumn preparing their hibernacula (‘tent for winter quarters’ in Latin) in which to cuddle up and sleep the winter away, assuming an impressively boring state of torpor and suppressed metabolism for months on end.  As mentioned above, most adult native bees do not survive the winter and so are not concerned with hibernacula feng shui, but of course there are exceptions.  Queen bumblebees are born at the end of the summer and are the only ones from their hive to survive the winter.  After embarking on a late summer mating flight in the early weeks of their lives, they load up on as much nectar as their little honey stomachs can hold, locate a north-facing slope in a good neighborhood with soil that holds just the right amount of moisture, and excavate their very own hibernacula.  Here the once and future queens will exhibit a level of patience achieved by no other queen in history, suspending all activity until warming soil temperatures in the spring spell promises of abundant floral bloom awaiting them at the surface.  But before this thawed blessing arrives, the queens, like all those on the brink of greatness, must perform a heroic feat of mad science.  To prevent damage to their internal tissues from crystallization in extreme low temperatures, they transform their own blood chemistry by producing and inoculating themselves with the anti-freeze agent glycerol.  This impressive display of self-mastery allows them to pass the winter unfazed by the elements, emerging into the spring with all the youthful vigor they possessed last fall.  Select few superhumans have been documented as having the strange ability to manufacture ethanol from carbohydrates in their own guts, a blessing or a curse termed auto-brewery syndrome.  Try as I might to alter my own blood chemistry every winter, I have not yet been able to endure extreme cold with the same impunity and composure as these bumblebee queens.

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Queen bumblebee overwintering strategy.
http://entomology.unl.edu/bumbleboosters/biology.shtml

Speaking of self-mastery, honeybees go all winter without taking a poop.  Next time someone tells you they think insects are gross, you can throw that little nugget at them.  Honeybees pass the winter inside their hives, huddled together for warmth, unable to leave the hive due to snow cover and dangerous temperatures, and refusing to defecate inside the hive lest they foul the common living space.  Instead, their rectums become distended with feces during the coldest parts of the winter.  Beekeeper Sue Hubbel reports in A book of bees that “on a winter day warm enough for [the bees] to fly out, the snow in front of their hives is spattered with yellow droppings which have been retained inside their bodies.  If they do not have a flight day every few weeks, they will sicken rather than eliminate their metabolic wastes within their hive.”  They also use warmer days during winter to remove their deceased sisters from the hive.  Although adult honeybees will live longer lives during the winter than their overworked summer siblings, individual adult honeybees cannot expect to experience both a summer and a winter, though the hive as a whole is active year-round.  Bees that attain adulthood in the hive during the fall typically have access to more pollen than those reared in the spring when stores are low and activity high.  Because of the additional fat and protein bestowed upon them during development and early adulthood, and because they avoid the foraging sweatshop their spring sisters are born into, these autumn bees generally live long enough to help the queen start her spring brood at the end of a long winter of punctuated dormancy.  Unlike the fasting, motionless animals tucked away in hibernacula, the honeybee hive will survive the winter by consuming its honey stores and exercising flight muscles to generate heat inside the hive.  Stocking the pantry with these winter preserves is, after all, what they work so hard collecting nectar for all summer.  If you open a honeybee hive during the winter, which is apparently not advised if you want your honeybees to survive, you will observe them progressively clustered together in different areas of the comb as they pace their way through consumption of their winter stores.  This overwintering behavior has, of course, been bred into honeybees to some extent.  There are varieties of tropical honeybees who tend to migrate away from food and water shortages instead of enduring this long winter frugality.  But the honeybee strains we know and love have largely been selected by agriculture to stick around for the winter in the hives we provide, so we can orchestrate their migration ourselves to the crops we need pollinated in the spring.

honey-bee-frozen

This is not a good overwintering strategy.
http://blog.vermontlodgingproperties.com

Neither stowed away in hibernation like the bumblebee queen, nor subsisting at a semi-dormant state like the honeybee hive, solitary bees are engaged in an entirely different game throughout the hostile winter months.  They are using their winter chambers as wombs, progressing from egg to larva to pupa to adult in silent isolation while they wait out the photosynthetic drought.  As we’ve discussed before, diversity among native bees is immense, and likewise the nesting strategies of these furtive pollinators is expansive.  Above ground, bees make use of pithy stems, decaying wood, tree cavities, and old beetle burrows to lay the foundations of their winter homes.  The term ‘ground-nesting bees’ describes a wide range of digging habits of bees who employ their mandibles, claws, and the pygidial plates found at the ends of some species’ abdomens to burrow into sand, soil, gravel, and mud at various aspects and slope angles to depths of a few centimeters to a few meters.  Before going about collecting pollen for their young, bees make use of their corbicula (‘pollen baskets’ made of special hairs on their hind legs) to transport resin and other nest building materials.  Some bees use tibial spines and basitibial plates to give them traction along the internal walls of their burrows while they push out dirt or rotten wood from the excavated hole.  Ain’t that the bees’ knees?!  (Literally, it is.)  Lacking proper mini jackhammers, bees may activate their flight muscles to send vibrations through their mandibles to loosen and remove rocks in the tunnel path.  Often times bees use their glossa (long mouthparts) and penicillus (a brush-like structure on their hind legs) to coat burrow walls with liquid wax and antimicrobial secretions to ensure the correct humidity and infection-free environment for their babies through the long winter.

During a summer at Pinnacles National Park in California, I watched a ‘wool carder’ Anthidiine bee push tiny rocks out of her burrow and carry them between her front legs to discard on the adjacent hillside (perhaps to avoid giving away the nest location with an obvious tumulus, or nest debris pile).  I flagged the nest and returned several weeks later to find her at the concluding end of this process.  Carefully retrieving select pebbles from where she had deposited them only weeks before, she made methodical counterclockwise flights from the hillside to her nest where she rolled the toted pebbles into the burrow opening to shelter and conceal her offspring below.  A week after that, I made a final visit with a yard butler gardening tool and  fine forceps to retrieve the mysteries she had left behind.  Deep into the hardened ground, I slowly unearthed several balls of insulating fuzz (‘wool’ made from gathered plant fibers), each enclosing a hardened capsule with a developing bee larva inside: a winter coat and a mother’s final wishful oblation.  I kept the unopened capsules in a fridge during the winter and on my desk that following spring in hopes that they might continue their development and validate their mother’s labors.  Unfortunately, the fluffy spoils of my dig remained lifeless, but there are millions more Anthidiine larvae nestled into the their home-made wool coats who remain safe from my yard butler.

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Anthidiine bee carrying a pebble back to her nest to help close and conceal the entrance hole. Photo J. Meiners.

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Undoing the bee’s hard work, pebble by carefully selected pebble. Photo J. Meiners.

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Inside the nest there were a series of these hardened egg capsules, each enclosed in a sheath of ‘wool’ fibers laboriously scraped from plant leaves. Photo J. Meiners.

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Open the capsules and see all the larvae! Photo J. Meiners.

Once burrow excavation is completed, there are many ways adult female native bees go about constructing the finer points of their external winter womb.  Megachilid, ‘leaf-cutter’ bees, collect tiny leaf pieces, precisely excised with their hardy mandibles, and cement them together with oral secretions to create cryogenic capsules suited for nursing their young through the winter.  Bee nest biology expert Jerry Rozen led a team of melittologists in 2009 on a trip to Turkey where they discovered the gorgeous, immaculately crafted nesting cells of Megachilid Osmia avosetta, built entirely from petals (see pictures below!).  On a less endearing note, it has been speculated that some tropical Trigona spp. construct their nest cells out of carrion and feces.  Usually these capsules hold a single oblong, opaque egg, delicately laid on top of the pollen/nectar provisions just before that capsule is sealed and construction of the next one vertically up the burrow begins.  In the case of most Bombus spp. (bumblebees) and Megachilids like Megachile policaris and Lithurge fiscipennis, however, large cells are built to hold several young which grow through the winter together.  Perdita spp. make unlined cavities in the sand for their offspring, while Xylocopa spp. drill their burrows into wood and masticate wood pulp to create masterfully carpentered cell divisions between individual egg chambers.  Anthophorini bees close their nest cells with spirally constructed mud and a small hole in the center.  When you look out your windows this winter at the blanket of white snow that appears to have superseded all signs of life and color, remember these bright and intricate capsules, buried beneath it all, incubating the bees of spring.

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Nest cell (and an egg) of Osmia avosetta, made entirely from petal pieces.  Has your mother ever constructed something so beautiful for you?  Photo J. G. Rozen.

Univoltine native bee strategy.

Stem-nesting native bee overwintering strategy.
http://hort.uwex.edu/articles/pollinators

So while our favorite cuddly mammals are curled up in their hibernacula doing exactly nothing all winter, and we are bemoaning having to scrape our windshields each morning, native bees are busy reinventing themselves in elaborate underground caverns.  The bee activity we witness during the summer months is only a small fraction of the work it takes to be a bee.  Morphing from a tiny, curved egg, through five instar stages as a larva, including spinning a cocoon inside the nest cell for many species of Apinae and Rophitinae, and then slowly adopting the articulated form of a prepupa or unpigmented adult is a lot to get done in a few short months.  And this is to say nothing of the plight of cuckoo bee eggs, laid by their parasitic mothers in the nest cell of another unsuspecting bee, who must hatch before their host egg, steal its food, fight it to the death with only its meager piercing mouthparts, and then grow into stealthy adulthood next to the sticky remains and neighboring sibling cells of its victim.  (Check out this paper for some images of a cleptoparasitic Stelis ater bee larva attacking its host Osmia chalybea larva and stealing its nest provisions.)  These truly impressive life transformations and micro bee warfare are all going on underneath your serene snowshoe hike.  And as we know, once the bees make it to spring, the struggle only picks up from there.

beecycle

Hardly hibernation.

Let’s briefly review the accomplishments of the average native bee, and take a quick look at our own:  From the moment of initial emergence from their natal home to the time when their wings have literally shred to pieces from overwork about four weeks later, native bees achieve more than many of us mere humans will in decades.  Upon reaching sexual maturity, solitary bees leave the home their parents built for them and never return.  (USA today reports that, as of 2012, 43% of 20-24 year old Americans live with their parents, 19% of those between 25-29, and 9% of those 30 -34.)  Ground-nesting adult female bees will spend their first weeks of life searching out a suitable nest site and excavating their own new home by hand (er, claw), laboriously scraping out a cavity in the ground with their mandibles, carrying out the debris pebble by pebble, packing down the walls with their pygidial plates, and cementing the foundation with homemade waterproofing and antimicrobial secretions.  Many bees will then furnish the burrows with artfully crafted leaf, petal, or wax capsules to cradle their young.  (A 2012  Gallup Poll reports that only 62% of Americans own their own homes.  No statistic on how many build their own homes.)  Bee mothers will collect and provide all the food their children will need for their entire immature development and package it all neatly for them before the winter sets in.  (Baylor College of Medicine reports that in 2013, only 38% of American children bring a lunch packed by their parents to school.)  The mother will then gracefully depart the scene, and the young bees will take control of their own development, pushing through infancy, adolescence, and into maturity with solitary resolve (Do we need a statistic for this one?).  Winter for bees is hardly a long peaceful nap in cushy hibernacula, nor is it a seasonal trip to the beach with their flock.  Though you can’t see them and their buzz is missing from the cold December air, bees are up to something incredible this winter.  Inside wool coats and petal casings, with altered blood chemistry and full rectums, they are pacing themselves through the frosty nights, building their strength and molding their bodies into forms equipped to facilitate the fantastic wildflower shows we will be expecting come spring. What are you doing this winter?

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This is my overwintering strategy.  Photo R. Choi.

*This post is dedicated to my grandmother, Marilyn Meiners, an enthusiastic reader and supporter of my writings and life pursuits.  She passed away on October 17, 2013 at the age of 91.  I will miss seeing her underline every sentence of this post with her red teacher’s pen.*

grandma

Henry, Marilyn, and Joan (me) Meiners, back when everything seemed possible.

Sources:

Baumgartner, D.L. and Roubik, D.W.  1989.  Ecology of Necrophilous and Filth-Gathering Stingless Bees (Apidae: Meliponinae) of Peru.  Journal of the Kansas Entomological Society, Vol. 62, No. 1, pp. 11-22.

Hubbell, Sue. A Book of Bees: –and How to Keep Them. New York: Random House, 1988. Print.

Michener, Charles D. The Bees of the World. Baltimore: Johns Hopkins UP, 2007. Print.

Michener, Charles D.  The Social Behavior of the Bees.  A Comparative Study.  Massachusetts: The Belknap Press, 1974.  Print.

Potts, Simon G. et al.  2005.  Role of nesting resources in organizing diverse bee communities in a Mediterranean landscape. Ecological Entomology.  30, 78-85.

Rozen. J.G. et al.  2010.  Nests, Petal Usage, Floral Preferences, and Immatures of Osmia (Ozbekosmia) avosetta (Megachilidae: Megachilinae: Osmiini), Including Biological Comparisons with Other Osmiine Bees.  American Museum Novitates.  Number 3680, 22 pp., 44 figures, 1 table.

Strange, James P.  Raising Bumblebees at Home: A Guide to Getting Started.  <http://www.ars.usda.gov/SP2UserFiles/Place/54280500/BumbleBeeRearingGuide.pdf&gt;

Posted in Bees, Behavior, Native bees, Nesting | 3 Comments

Pollination is Not your Pacific Island Vacation Destination (unless you happen to own a Magic Schoolbus)

Let’s go study pollination here.  xdesktopwallpapers.com

For some reason, whenever I say “Pollination Ecology,” in relation to explaining what I am studying in graduate school, people often seem to think I am saying “Polynesian Ecology.”  I don’t know why this is, maybe I can’t enunciate, but I know pretty much nothing about Polynesian Ecology (though I certainly wouldn’t mind learning if anyone is going…).  Polynesia is a group of islands in the central and south Pacific, technically including Hawaii, New Zealand, American Samoa, and Fiji (as a Melanesian outlier).  I’ve heard these islands offer fantastic scenery, alluring trails, and cultural enchantments, and I have personally designated New Zealand as my emergency escape route from graduate school (don’t tell anyone), but that’s essentially all I think you need to know about Polynesia at the moment.  I do, however, believe everyone should know a thing or two about Pollination Ecology.  And since I recently was shocked to find out that my own grandmother did not have a clear understanding of why pollination might be interesting enough to study for six years, I am compelled to answer that question for any other soft-spoken doubters right here, right now.  Pollination is beautiful, lyrical, complicated, fragile, powerful, and essential.  So let me tell you about the birds and the bees, the flowers and the trees.

pollinationdoodle

Pollination, not Polynesian, doodles.

Pollination is beautiful.  A labyrinthine aerial dance choreographed by millennia of evolution, pollination unites sessile plants, entrenched in the earth but stretching skyward to offer decorative petals and nutritious rewards, with free-roaming, but ever-searching solicitors of floral recompense.  The elaborate corolla displays and scents we love are loved also by these flying insects and countless other pollinating animals.  The entire radiation of angiosperm floral diversity is thought to exist for the sole purpose of enticing these visitors ever closer, even drawing them into the flowers’ own inner chambers.  Once a bee twists and contorts its body to access the often hidden, but sometimes freely offered, pool of nectar, it emerges handily dusted in pollen, a precious package it will deliver unknowingly to the next outstretched flower down the line.  Enacted over and over with different mobile players and new varieties of floral baits, this cross-species courtship dance intertwines and perpetuates the existence of landscape communities.  Lest they chance scattering their seed to wind and water, angiosperm plants must somehow tacitly enlist passing pollinators to deliver miniscule male sex cells (pollen) to receptive female flowers of the correct species, at the correct time.  They cannot deliver this message nor court their mates themselves, they must stay rooted in place and trust in their peripatetic neighbors to facilitate this imperative cargo transfer.  Pollinators, in turn, often cannot survive without their proverbial giving trees.  Many animal pollinators, including some flies, beetles, butterflies, hummingbirds, bats and lemurs, rely on sugary nectar as an energy source.  Most bees cannot reproduce without concocting a specific blend of protein and carbohydrates from floral pollen and nectar, respectively.  Some bees are even developmentally dependent on a narrow range of floral pollens and must have access to those species to feed their young.  Stitched together by their divergent talents for motion or food production from only the sun’s light, and refined over generations of evolution, plants and pollinators perform daily rituals full of vibrant color, pleasing fragrance, and aerial acrobatics more stunning than perhaps any other show on the planet.  For a visual reminder of the wonders of something you’ve walked by a thousand times, but maybe never stopped to observe, watch Louie Schwartzberg’s TED talk video on the “Hidden Beauty of Pollination.”

Pollination is lyrical.  CorollaPerianthCalyxPetioleAndroeciumApiaryAroliaOcelliBasitarsusBrevystylousPapilionaceousHyalineSubrugoseMesopleuraMelittophilyChiropterophilyPsychophily.  PalynologyPollexPolliniaPetalSepalTepalStriaeStigmaStyleSternaTergaTegulaTessellateTestaciousTristylousTomentoseVespertineViolaceous.  What’s not to love in that list, or to study for years on end?  One of my favorite authors, Barbara Kingsolver, adds her lyrical style and also her weight to the importance of pollination in the following excerpt from her excellent book, The Bean Trees:

I tracked down my father, who had wandered a little distance from the garden and was sitting against a tree trunk.  In his fingers he carefully stretched out something that looked like a wasp, still alive.  It was as broad as my hand, and had a yellow “8″ on each clear wing, as plain as if some careful school child or God had painted it there.  My father looked like he’d just had a look down Main Street, Heaven. He told me, “There aren’t any pollinators…no insects here to pollinate the garden.  Look at this thing.  How would it know what to do with a Kentucky Wonder bean?”  I couldn’t know if he was right or wrong.  I only faintly understood about pollination.  I did know that the industrious bees did the most of it.  “I guess we should have brought some bees over in our pockets too.”  He looked at me like I was his spanking newborn baby; as if he loved me terribly but the world would never be what any of us had hoped for.  “Rae Ann, honey,” he said, “you can’t bring the bees.  You might as well bring the whole world over here with you, and there’s no room for it.”

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Illustrating terms helps, and is fun.

Pollination is complicated.  Beetles may be useful pollinators to some plants, but voracious herbivores to others.  Bees with broad floral predilections (we call them generalists) and little floral constancy may take the pollen from one plant and carelessly deliver it to an unrelated plant, squandering that chance for a fruitful encounter and possibly clogging up the stigma (female landing pad for male pollen) of the second plant with the wrong kind of pollen, hindering its opportunity to produce viable seeds also.  Specialist bees, on the other hand, may be so adept at grooming off pollen collected in their specialized hairs to take home to their nest that they bear little for delivery to the next flower.  Nectar robbers are pollinators that have learned to bypass the arduous work of climbing into a flower past the anthers full of pollen dust, and instead just slit the throat, so to speak, of the flower from underneath to drain its nectar without making contact with the plants’ reproductive parts.  Rewardless flowers, in turn, employ false floral advertising to draw in pollinators to where they can transfer their pollen package, but neglect to expend the energy to fill their nectar reservoirs for them.  I may have painted you a pretty picture above of pollination as a harmonious partnership between disparate organisms in a harsh world, but, like most every thing else in cruel nature, it is a constant “arms race” to take more and give less.  This, of course, makes it all the more interesting, as we are now talking about an elaborate game of intrigue, deception, and carefully balanced manipulation, all for the chance of a sexual encounter between two plants across a field from each other.  Hearten up, though, there are exceptions.  True mutualisms do exist.  The yucca moth (Prodoxidae), for example, actively collects yucca pollen grains using its modified elongated mouthparts, then climbs into another yucca flower and forces them into a receptive female stigma.  She then uses her ovipositor to pierce the flowers’ ovary and deposit her eggs, which upon hatching rely exclusively upon fertilized yucca seeds to fuel their development.  This mutualism is so highly developed that some yucca plants cannot reproduce without the purposeful labors of their particular yucca moth, and the yucca moth will rear no young in the absence of reproducing yucca plants.  Yucca flowers even offer protective refuge to these small, white moths, as you will find if you pull the petals apart and peak in some summer day.  Even still, there is a balancing act going on between these two players.  If the moth lays too many eggs so that too high a proportion of yucca seeds will be consumed by them, the plant will abort that flower and cease to invest resources in it.  So the checks are in place and the partnership continues.

Yucca moth caught in the act.  www.fs.fed.us

Yucca moth caught in the act. http://www.fs.fed.us

Pollination is fragile.  As you might imagine, obligate mutualisms like that of the yucca and yucca moth described above are risky.  If either suffers a sudden parasite or habitat loss, it spells certain doom for the other, as no substitute will do in this highly specialized relationship.  Pollinator limitation is another risk plants face when contracting out the transfer of their reproductive goods.  Successful pollination is not simply a matter of a pollen grain or two hitting its mark and smooth sailing to next year’s baby plants (seedlings) from there.  Quality pollination often requires substantial deposition of exactly the right kind of pollen–not too similar (self), but not too different (heterospecific)–for plant populations to maintain healthy genetic transfer and achieve high seed set.   Since these two communities of plants and pollinators support each others’ growth and reproduction year after year, shaving down or otherwise impeding the abundance of one may whittle down the other as well.   The term ‘Allee effect‘ describes a concept of positive density dependence in populations, where individuals fare better when local abundance of their species is high (as opposed to competitive interactions leading to negative density dependence).  When habitat fragmentation, due most often to land degradation and development, leads to plant populations becoming isolated in patches too small to nourish and sustain their pollinator populations, the whole house of cards can collapse.  Sometimes one population of plants is actually propped up by the existence of an unrelated group of plants that supports the same pollinators earlier in the season, as is the case with Delphinium flowers nourishing alpine hummingbirds, whose retention in the same meadows is required by later-blooming Ipomopsis flowers.  Pesticides and exotic species may also introduce enough stress into a pollination network that the delicate balance of resource transfer and production between original mutualistic members topples to its end.  Migrating pollinators, such as bats, depend on the persistence of rich corridors of nectar to sustain them along their entire journeys.  A field of corn where they expected a stand of nocturnally blooming cacti may halt their progress in its tracks and leave the cacti further down the line equally wanting.  Not only in space, but unexpected shifts in time can be catastrophic to the fluidity of pollen transfer as well.  Among its many other endearing qualities, climate change has been shown to be inducing phenological shifts in bloom times of alpine plants in relation to the flight times of their pollinators.  When solitary bees emerge from their underground overwintering nests to find that the flowers expecting their services, and upon which they depend, have already withered or are yet to bud, an emergency state comes into play for both parties, the outcome of which we have yet to discern.

Still, pollination is powerful.  Charles Darwin called the origin of angiosperms “an abominable mystery.”  From what we now understand, the near infinite diversity of flowering plants is thanks largely to the behavioral bents of their pollinators.  Perpetually seeking to attract more pollinators than its neighbors, plants are constantly evolving new floral colors, shapes, fragrances, and other attributes to help them stand out among the competition.  Because pollinators’ refined floral search images allow them to focus on a particular group of plants and transfer conspecific pollen appropriately, a higher diversity of plants can coexist than is feasible among plants banking on highly density-dependent wind pollen transfer.  The geographic distribution of many plants is also directly connected to the wanderings of their pollinators, who may bring pollen to the outer reaches of a plant population and allow it to extend its range by radiating seedlings in new directions.  If, on the other hand, pollinators neglect to connect two detached populations of a plant species, the reduced gene flow between them may induce allopatric speciation.  But the circle of influence does not stop there.  Herbivores have preferences too, as do the carnivores that eat them and structure our landscapes in many other ways.  The existence of such a variety of blooming plants has allowed for specialization and diversification all the way up the food chain.  Bees and their pollinating brethren, you could say, lay the groundwork for the much of the macroscopic biodiversity on earth, supporting plants that prevent habitat erosion while they shelter and support herbivores, who feed and drive the movements of carnivores.  The camel, for example, before it was fed grass by its domesticators, relied on sparse and thorny xeric plants likely pollinated by desert-loving bees.  Now thanks in part to bees, you can ride a camel to a beautiful sandy vista and enjoy a camel lasagna and camel ice cream picnic on a camel hair blanket.  Pretty impressive, huh?

This camel brought to you by pollination.  http://www.amplifiqa.com

Pollination is essential.  In addition to providing fodder for delightful creatures such as the camel above, pollinators are also key players in the production of many primary agricultural crops and cultivated livestock feed…meaning that pollinators fuel your delightful existence too, and that understanding the ways in which diverse pollinators interact with their environments is connected to the security of our food system.  The squash bee, Peponapis pruinosa, is an important pollinator of wild and cultivated squash and pumpkins.  Alfalfa, a major livestock feed crop with distinctively shaped pea-family flowers, receives efficient pollination services from alfalfa leafcutter bees, Megachile rotundata, uniquely effective at “tripping” alfalfa flowers in such a way that the keel petal pops up and deposits pollen onto the bee’s head before allowing access to nectar.  (The common honey bee declines to play this game and will often cut into the flower from below to rob nectar stores, skipping pollen transfer all together.)  Infamous honey bees are credited with providing valuable pollination services to such crops as almond, blueberry, apple, asparagus, avocado, broccoli, watermelon, canola, cherry, beets, and many other products you would miss.   It has been estimated that one in three mouthfuls are thanks to pollinators (elsewhere this is cited as thanks specifically to bees), and certainly the variety and color on our plates would suffer in the absence of pollinators.  Einstein has been (probably mis-) quoted as saying that if all the bees died tomorrow, humans would have only four years to live.  And they would be four years of bland, grain-based diets, anemia, maybe scurvy, not to mention angry, constipated neighbors and possibly zombies.  The US Department of Agriculture deems pollination ecology important enough to fund a dozen scientists to hang out in Logan, Utah and look at dead bees under a microscope all day, and to support the maintenance of a collection of over one million bees from all over the world, carefully curated in glass drawers so heavy I worry about it falling through our building floor onto the water lab people below one day.  The idea behind this use of your tax dollars is that, since pollination is essential, the more we can unravel about the mysterious life histories, distributions, and foraging habits of the vastly diverse pollinators, the better equipped we are to avoid coming home one day to find our scurvy-ridden friends raiding our pantries for fruit preserves.  Pollinators, and specifically bees, are the shoulders (technically terga) upon which our entire food system stands.  If we are unable to resurrect the honey bee to its former pollinating glory, it will be critical to understand ways in which we might enlist special-ops pollinators like the alfalfa leafcutting bee and the squash bee.  So aside from the beauty, lyricism, complexity, fragility and power of pollination, its essential connection to food production might be the most obvious reason to study and revere pollinators.  Perhaps I should apply for funding from the US Department of Defense.  Knowledge is power.  And, clearly, bees are the anti-Apocalypse.

In case you’re still dubious, you would have a hard time getting leid in Polynesia without pollination.   http://www.polynesia.com

Sources:

Bartomeus, I., Ascher, J.S., Wagner, D., Danforth, B.N., Colla, S., Kornbluth, S., and Winfree, R. (2011). Climate-associated phenological advances in bee pollinators and bee-pollinated plants. Proc. Natl. Acad. Sci. 108, 20645–20649.

Buchmann, S.L., and Nabhan, G.P. (1996). The forgotten pollinators (Island Press).

Chittka, L., and Thomson, J.D. (2001). Cognitive Ecology of Pollination: Animal Behaviour and Floral Evolution (Cambridge University Press).

Delaplane, K.S., and Mayer, D.F. (2000). Crop Pollination by Bees (CABI).

Waser, N.M., and Ollerton, J. (2006). Plant-Pollinator Interactions: From Specialization to Generalization (University of Chicago Press).

Willmer, P. (2011). Pollination and Floral Ecology (Princeton University Press).

Posted in Pollination, Uncategorized | 9 Comments

Happy New Year, Happy New Park – 105 years in the making.

Pinnacles in the early mist from the North Wilderness Trail. Photo J. Meiners.

Pinnacles in the early mist from the North Wilderness Trail. Photo J. Meiners.

As the clock rolled over into 2013, Pinnacles National Monument was on the cusp of an overdue transformation. Originally established in 1908 by President Theodore Roosevelt, Pinnacles National Monument has nestled quietly in California’s San Benito and Monterrey counties, receiving about 175,000 annual visitors to nearby Yosemite National Park’s 3.4 million. For years, Pinnacles employees and fans have lobbied to raise the area to National Park status to increase visitation and receive recognition as one of the country’s most stunning natural areas. On January 10, 2013, President Barack Obama granted that wish, making Pinnacles the 59th National Park and the closest to the San Francisco Bay area.

View of the iconic 'Pinnacles' from the start of the Juniper Canyon Trail.

View of the iconic ‘Pinnacles’ from the start of the Juniper Canyon Trail. Photo J. Meiners.

Paul Rogers reports in the Mercury News that the title change will not increase the size of the park or its budget, but is expected to increase visitation and “put Pinnacles on the map,” as Wilderness Society campaigns director Paul Spitler puts it. Pinnacles should see exponentiating traffic as it comes to be recognized among California’s other revered National Parks: Yosemite, the Channel Islands, Death Valley, Joshua Tree, Lassen, Redwood, Sequoia and Kings Canyon. Whereas National Monuments can be declared relatively easily by a US President, National Park designation must be approved by Congress and usually confers a higher level of protection for a ‘variety of nationally significant resources.’ For a protected area that predates the establishment of the U.S. National Park Service in 1916, and is a primary recovery and release site for the endangered California Condor, the elevation to Park status seems warranted.

Aside from the bald-faced scavengers with ten-foot wingspans that have won the hearts of many conservationists and the malice of many tax payers, Pinnacles National Park has become known for its astonishing diversity of native bees. Thanks to opportunistic trail collecting in the 1990s by my adviser, Terry Griswold, and his student Olivia Messinger, and to my recent plot-based community sampling efforts throughout the park, Pinnacles has been discovered to house over 400 different species of bees. With a maximum sampling area of about 26,000 acres, or about 36 square miles, this density of bee diversity in such a small area has not been documented anywhere else in the world (to my knowledge–please let me know if you discover otherwise!). I won’t give away all my research punchlines just yet, but we attribute this phenomenal biodiversity to the immense variety of habitats within Pinnacles’ boundaries.

Small enough to hike from east to west over the dividing Pinnacles rocks and back again in one day, the Park’s location and geologic history have brought a diverse collection of soil and vegetation types together under a dynamic climate regime. Pinnacles straddles the San Andreas Fault line, which has resulted in soil types and seed banks from the north and south being brought together in one place. The Park’s namesake rocks form a dividing wall between the east and west side that results in coastal influences being largely restricted to the west half of the park, while the drier east harbors some riparian zones. Both sides are dominated by chaparral vegetation typical of California Mediterranean habitats, but the Park is also dotted with woodlands and grasslands across its rolling hills and canyons. The ‘High Peaks’ of the Park sit about 1000 feet above its lowlands, which makes for some steep hikes and large variations in daily temperatures across areas of the park just a mile or two away from each other. It is not uncommon for summer temperatures to range from 50 degrees (F) before sunrise to 100 degrees in exposed areas at noon on the same day, while temperatures in the talus caves hover in the refreshing 50s. There are records from as early as 1881 of local Californian picnickers taking refuge from the day’s heat in the Pinnacles Balconies caves, now one of the Park’s most popular trails and a regular part of my daily commute between my sampling sites.

The reason this habitat variety translates into such impressive variety in bees has to do with the high resource specialization and relatively rapid evolution common among insects. Because insect lifespans are so short (for animals), genetic changes between generations in reaction to environmental changes in their habitat become evident in the population relatively quickly. Once a group of bees find success with and begin preferring a particular set of nesting or floral resources, it will differentiate itself from its relatives with other preferences and eventually separate species will evolve that are no longer reproductively compatible. With such a plethora of available soil and stem types in which to nest, and an even greater variety of flowers from which to collect nectar and nutritionally unique pollens, Pinnacles spurs and supports many diverse taxa of bees. Such dynamic coexistence among bee species presumes complex community interactions and partitioning of resources among these neighboring species. Detailed recording of floral bloom and habitat characteristics, coupled with repeated collection of bee species inhabiting specific areas should allow us to shed some light on ecological relationships between the 400 species crowded into Pinnacles 26,000 acres. Stay tuned for more results. In the meantime, take a trip down California’s I-5 or Hwy 101 this summer and veer off onto the twisty, narrow roads leading to our nation’s newest National Park, also one of its oldest recognized natural areas, and the home of the world’s densest diversity of native bees. There are many treasures to discover at Pinnacles National Park, from threatened bats hiding in the cool talus caves, to majestic condors circling above the High Peaks, to baby birds nestled among rattlesnakes in the tall, undulating grass. Watch your step!

Heading into the Balconies Cave -- Flashlights required, picnic recommended.

Heading into the Balconies Cave — Flashlights required, picnic recommended. Photo J. Meiners.

The rarely visited and under-appreciated McCabe Canyon.

Author collecting in the rarely visited and under-appreciated McCabe Canyon. Photo P. Lamperty.

A Blue Oak Woodland on the West side of the Park.

Therese Lamperty collecting in a Blue Oak Woodland on the West side of the Park. Photo P. Lamperty.

Up in the High Peaks, amidst circling California Condors.

Up in the High Peaks, amidst circling California Condors. Photo J. Meiners.

Hidden gems in Grassy Canyon.

Hidden gems in Grassy Canyon. Photo J. Meiners.

Tunnel Trail back down to the West side parking lot at the end of a long collecting day.

Tunnel Trail back down to the West side parking lot at the end of a long collecting day. Photo J. Meiners.

Hiking in the High Peaks.

Hiking in the High Peaks. Photo J. Meiners.

Watch where you step.  This nest was carefully concealed by the mother twisting the tall grass around the top of the nest.

Watch where you step. This nest was carefully concealed by the mother twisting the tall grass around the top of the nest. Photo J. Meiners.

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Report on a BioBlitz!

Last month I participated in Rocky Mountain National Park’s ‘BioBlitz’ Species Inventory.  When I took German in high school, I learned that “Blitzkrieg” means “lightning war,” so that is what came to mind when my friend and fellow melittologist, David, asked if I wanted to join him at this event.  And in fact, “lightning war” isn’t too far off as a way to describe this weekend biology frenzy.  On Friday, August 24th, 2012, hundreds of scientists and naturalists and thousands of citizens and students descended on the normally protected landscapes of Rocky Mountain National Park to search and pillage for species.  Well, count me in!

When I followed David’s link to register for this event, I was hesitant to designate myself as ‘an expert’ in entomology.  What do I know about Colorado pollinators?  It is, I admit, my home state and I’ve been to Rocky Mountain National Park many times, but that was before my bee-wrangling days.  I’m just a measly grad student!  And the majority of my bee knowledge has come from distant, different California.  But David, and also my adviser, convinced me that I was up to the task…or at least I should be.  So I packed my collecting nets, killing jars, and data book and boarded a plane for Denver.

The Biodiversity Festival is the tailgate party for a Bioblitz.  It boasts “a full schedule of music, ranger programs, live animal demonstrations, photography workshops, poetry, and talks by leading scientists.”  I met David in the parking lot and we wove our way through the crowd and into the tent of biodiversity.  I picked up a biodiversity map, some fliers on bats, and a few note cards about whales, but I was most impressed by the decks of cards National Geographic was handing out, each card with a cartoon and description of a National Geographic Explorer’s contribution to science and adventure around the world.  From discovery of deep sea bioluminescent animals previously unknown to science, to inventive research on bees in Kenya, fifty-two are not enough!

Time to get down to bee business.  We collect our name tags, official stylish NatGeo denim shirts, and head out to find “Upper Beaver Meadows” our assigned collecting location.  Unfortunately, our assigned collecting time was 4pm, or in other words ‘bee quittin time.’  This I knew to be especially true in the Colorado Rockies, where you can almost set your watch by the afternoon storm clouds.  Contrary to their reputation (often deserved) of being perpetually busy, bees are also fickle creatures.  They don’t like to work when it’s too cold.  They stay at home when it’s too windy or wet.  And they usually don’t bother to do much when it’s cloudy.  When I decided to work on bees for graduate school, I thought this sounded like an ingenious field schedule for me too (I did not, however, consider that bees LOVE to fly when it’s 110 degrees, which means I get to chase them around then too.)  Despite the cloud cover, David and I set out our pan traps, for a chance at passive collecting, and navigated towards the meadow blooms with our nets.

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I am ready, but the bees are nowhere to be found. Photo D. Drons.

When the busload of visitors who signed up for the ‘BeeBlitz’ arrives, we still don’t have much to show them.  We caught a few Megachile, a couple Dialictus, an Anthidiine, a parasitic Coelioxys, and what I like to call the ‘stalker wasp:’ a large, very fast greenish-yellow insect that seems to like to dart around you while you are trying to focus on collecting and is infuriating to try to catch (actually called a Bembix).  The eager citizen scientists don’t seem to mind our measly collection though.  We gather them in a circle, break out some of our favorite illustrated bee texts, and explain the world of bees:  “There are nearly twenty thousand different species of bees in the world.   Some are bright green or metallic blue, some are the size of ants.  Most of these are solitary and live only one bloom season.  This also means that most bees do not make honey, which is intended to sustain a hive through the winter.  The solitary female works diligently during her 3-4 week lifespan to dig and provision a nest for her young, which will overwinter underground and emerge to do the same the next year.  Many species of bees have very specific floral preferences.  Without bees our diets and wildflower displays would be very bland.  And no, unfortunately they don’t generally come out when it’s cloudy.”  We give them a quick introduction to a taxonomic key, and pass around the few specimens we’ve garnered so far.  We then show them some collecting technique and let them try out the nets.  Then, all of a sudden, the sun comes out!

One of the young girls in the group turns out to be a sharp collector and almost immediately nets several Megachile that seemed to appear out of nowhere with the sun.  We get them into a collection vial and show her that the underside of the female’s abdomen is covered with bright yellow pollen.  Rather than packing pollen onto ‘pollen baskets’ or bare spots on her hind leg as a honey bee does, this bee has its scopal pollen-collecting hairs on its abdomen, a less efficient but visually striking mode of pollination.  She is likely collecting pollen to provision a nest that she has laboriously hollowed out from the ground or a twig.  She may have already constructed a cell, much like an empty pill capsule, out of leaves in which she will place this pollen food and lay her egg.  She will try to fashion and stock as many of these cells, all arranged in a column in the nest, as she can before she, or the flowers, die.  It is possible that, while she is here in our vial, a cleptoparasite is entering her nest and laying its own egg that will hatch, kill hers, and consume this pollen instead.  Catching this bee tells us a story about this meadow and how its parts weave together to create this habitat.  At least we have one show-and-tell story on this cloudy afternoon.  The girl is thrilled and runs off to hunt down another discovery.

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David answering questions like a pro (because he is one). Photo J. Meiners.

At the end of the day, we only have 13 specimens to turn in to the BioBlitz Species Inventory, a disappointment for two seasoned collectors.  But ours adds to the collections pouring in from other denim-clad scientists sent to other reaches of the park.  In total, the Rocky Mountain BioBlitz tallied 489 species of plants and animals in a 24-hour period.  Pretty solid work for a cloudy day.  And, having been able to answer everyone’s questions and inspire a group of aspiring naturalists to pay attention to the smaller things in the field, I can pack up my collecting supplies with a sense of accomplishment too.  Though I’ve been visiting it much of my life, Rocky Mountain National Park has now shown me a few more of its secrets and allowed me the joy of sharing them with you.  Hail the biology lightning war!

Posted in Bees, Collecting | Leave a comment

Tale of Two Trachusa: Confessions of a Nest Voyeur

Last week I killed a bee family.  I had been watching them for months.  I broke into their home while the mother was out and removed her five little ones, one by one.  I don’t feel great about it.  But it was actually pretty cool.

I first noticed “Stacy” bee (Yes, I named her before I killed her family.  Sadistic and shockingly unscientific, I know.) about four weeks ago while scanning a dry, rocky, exposed area near one of my sampling plots for bee activity.  She flew into the area in a hurry, with some sort of package in tow, and disappeared into a previously invisible hole in the ground.  I kept my eyes glued to the indistinct, dusty area where she had disappeared and was rewarded to see her emerge several minutes later, pause for just a split second at her doorway, and then zoom off in the opposite direction.

I set up camp.  Nestled into the sun-baked red rocks about three feet away from the tiny nest entrance hole, I pulled out my field notebook, pen, and camera, and waited for her to return.  A grueling thirty minutes later, once I had started to wonder if I was going too cross-eyed to even catch her arrival and had rechecked several times that I was indeed staring at an actual nest entrance hole, she reappeared on the scene.  I watched her dart left and right around the area, perhaps unsure of the dangers posed by my looming figure, a new addition to her visually recorded neighborhood.  I sat stark still, waiting for her to recognize the subtle visual cues directing her to her nest entrance: the bent blade of grass, the discarded insect skin, the triangle-shaped rock.

Despite my hovering, Stacy-bee finally made a dash for her entrance hole and I was able to catch a glimpse of her package: a small ellipsoid piece of dark green leaf that she clutched underneath her body with her four front legs.  She was building her nest.

Stacy peeking out from her nest entrance, perhaps to see if the coast is clear for another foraging flight. Photo J. Meiners.

Several weeks earlier, somewhere in these hills in a similar soil type and lined with the same type of leaves, Stacy herself emerged from a nest like this.  Perhaps she was one of several larvae packed away vertically into a hole in the ground and had to wait for her siblings to finish developing and then chew and squirm their way out of the nest before she could make her own clean exit from below them.  Perhaps one of her younger, more shallowly nested siblings hadn’t survived the winter and Stacy had to crawl through the empty, grave-like chamber with the sticky remains of her un-metamorphosed brother to find the world above.  Perhaps she was the only one who survived.

As Stacy climbed from her nest cell into her first rays of sunshine, she was likely bombarded by at least one eager male courtier.  Deposited last, and thus highest, by their mothers in the columnar nests, the males of solitary bee species typically emerge before their conspecific mates and spend this head-start searching out other nest entrances of their species.  In the early spring, if you pay close attention to aerial movements along patches of  seemingly barren ground, you may notice male bees patrolling these discovered nesting sites in low, pacing flights.  Once they detect (most likely by scent and visual cues) a good spot to pick up females, they lurk in wait to pounce on adult females during their first emergence into the world, ensuring that they pass on their genes when she builds and fills a nest of her own.

This is the fleeting love tale of, in this case, two Trachusa (my guess of the Genus in question though, without catching and interrupting our nest-builder, it is difficult to be sure).  Sadly, it is a short affair: a brief, unsolicited delivery of gametes (reproductive haploid cells, i.e. sperm) after which Stacy goes on to a life of hard work and little company while her mate likely flies off to try his luck at another nest entrance, then heads off in search of delicious nectar and ends up spending the night in a flower.

Yes, it’s true.  Males are deplorably unhelpful and undisciplined in the world of bees.  They have no work ethic.  They offer no loyalty.  They display a complete lack of commitment or investment in the future of their offspring.  They hunt and attack naïve virgin females and then promptly flee the scene to spend the rest of the day drinking sweet nectar and passing out in flowers.  I’m not just telling you this because I happen to be a Seven Sisters Scholar and a graduate of the country’s first institution of higher education for women, still a single-sex establishment.  It’s just the way it is, scientifically speaking.  But the males never know what they’re missing.  Stacy is about to have a far more interesting life.

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View from near Stacy’s nest entrance at Pinnacles National Monument. Photo J. Meiners.

The day I first met Stacy, I could only stay and watch her work for approximately ninety minutes.  During this period, she returned to the nest site three times with leaf pieces, each carefully selected and meticulously cut using her strong and precise mandibles, a defining anatomical feature of her taxonomic family of bees, the Megachilidae, which includes the appropriately named “leaf-cutter bees”.  She spent about four minutes inside the nest each time, presumably arranging the leaf pieces into a series of pill-capsule-sized cells that would each protect and house one of her offspring over the coming year.  But before she got to this stage, before I first encountered her, she had to excavate this hole in the ground herself, pushing out tiny rocks and dirt bit by bit and digging the nest deep enough to fill it with as many offspring as she was likely to have time to provision for in her short, busy, several-week life.  It was crucial that she make the nest deep enough to fit as many eggs as she had time to lay, yet shallow enough that her offspring were not presented with a daunting depth from which to crawl when they themselves begin to emerge as adults.  She must make her nest at the right angle into the ground, on the preferred slope aspect, and in the correct soil type to ensure that her young are incubated at the proper temperature and humidity over the changing seasons during their development over the coming year.  If she miscalculates any of this (or has the misfortune to build her nest under the intrigued eye of a new bee scientist) the odds that she will succeed in passing on her genes to the next generation plummet.  I never saw Stacy in this excavation stage, but I have witnessed other species of bees making tireless, repeated circular trips to and from their nests to pick out a single pebble from their nest tunnel and fly it a few feet away to discard on the hillside.  I have also seen the opposite action, at the end of the nesting process, when the female bee collects tiny rocks, carefully selecting them one by one from her nearby surroundings, with which to slowly plug up and conceal her nest tunnel.

The nesting site with my rock cairn marking above.

The nesting site with my rock cairn marking above. Photo J. Meiners.

At the end of this first observation period, I made a little rock cairn uphill and to the left of Stacy’s nest entrance so that I could find it and check on her progress later.  About two weeks after this initial encounter, I returned to check on Stacy’s progress.  I sat and waited eagerly a few feet from her nest entrance.  After several minutes I was thrilled to see her arrive with a bright yellow load of pollen on the underside of her abdomen.  Megachilid bees, including Trachusa Stacy, are known for having their scopal (pollen-collecting) hairs on the underside of their abdomen instead of arranged into ‘pollen baskets’ on the hind legs where we are used to seeing many other bees, such as honey bees, carry their pollen.  Their ability to collect and carry the dynamically-shaped pollen grains using these elongated, branched hairs on the ventral surface of their abdomens makes leaf-cutting female bees with bright yellow ‘bellies’ relatively easy to identify on the wing.

At this middle-aged stage in her life, Stacy is busy stocking the pantry of the carefully constructed leaf capsule she built in the previous chapter.  Once she has completed digging her nest to the appropriate depth, has made several trips to collect leaf pieces from just the right plant (likely Ceanothus cuneatus or “Buck Brush” in Stacy’s case), and has glued them together with oral secretions into the perfectly shaped, waterproofed leaf capsule nursery, she beginnings provisioning it with food.  Many solitary bees are considered “specialists” and are picky about the type of pollen they feed to their young.  Stacy has been collecting pollen, mixing it with nectar, and forming it into a “pollen ball” or “bee bread” as many melittologists like to call it.  She will leave this packet of goodies (similar in purpose to the yolk of a chicken egg) for her young to consume as it grows from larva to pupa to adult all alone in its sealed leaf capsule underground.  Stacy will not be there to supervise.  She must get everything prepared ahead of time.

Once the bee bread is in place, Stacy will lay a small, oblong-shaped egg delicately upon it and carefully seal away her young, never to see it again.  She will not see this bee grow and she will not be alive when it crawls its way into the sunshine of this rocky, sun-baked hillside.  But such is the tale of a Trachusa, and hundreds of other solitary bee genera.  Stacy is building her own time capsule, leaving her legacy.  She will construct and provision as many of these leaf capsules, each containing one new Trachusa bee, as she can in her short life.  Once finished here, she may try to start another nest if her energy remains, but one day she won’t return from her foraging flight to finish this task and the inhabitants of that unfinished nest, left unconcealed, may not survive.  Whereas the production of honey by social bees is a strategy to sustain the active colony throughout the winter (not a gift to humans as we like to think), solitary bees stuck (evolutionarily) to a simpler strategy of shorter life cycles and just one generation per year.  By not making honey or orchestrating division of labor among themselves, solitary bees have no chance at surviving the winter and must arrange everything ahead of time for their young to endure a long period of very minimal activity.  Stacy’s young will remain underground in isolation and silence for the next eleven months, under rain and frost and thaw, while they consume the bee bread and grow and wait.  That is, they would have if I had been able to let them.

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Beginning nest excavations…for science! Photo T. Lamperty.

On June 15, 2012, I returned to visit Stacy for what would be the last time.  I found the cairn marking the nest and settled in to wait for her to arrive and show me the labors of her next project.  But upon closer inspection of her nest, I discovered that it had been sealed up, impressively filled in and concealed with leaf pieces and grass and dirt.  Whatever her fate at that time, Stacy had finished her work here and would not be returning to greet me.

After several pictures and a moment’s sincere appreciation of her work, I dug out my forceps and digging tools and began to slowly unravel her life’s work (for science!).  One by one, I peeled back a couple centimeters of carefully layered fresh leaves, each precisely cut with Stacy’s mandibles.  Then came a thin layer of dirt and the first leaf capsule containing her youngest larvae.  With some guilt, I used my forceps (sharp tweezers) to tease apart the intricate leaf capsule and reveal a tiny white grub perched on a generous pollen ball.  Not wanting to squander this sacrifice, I snapped a few pictures and added the nest contents to a collecting jar.  Kept at the proper conditions, there would be a small chance for this larva to continue its meal and develop in the lab.  The next lowest capsule contained a slightly larger white grub, feasting on a slightly smaller pollen ball.  To reach the final three, and oldest, leaf capsules I had to dig further down into the nest through some hardened dirt where Stacy had laboriously tunneled out and beautifully smoothed the inside of her drinking-straw shaped nest cavity.  I saved two of the middle capsules undisturbed in my collecting jar and opened the deepest one to find, as expected, the largest larva and only a small remaining portion of Stacy’s first pollen/nectar concoction.  After about an hour of carefully chipping away soil clumps bit by bit in the 100 degree heat and blistering sun, I had collected all five of Stacy’s offspring and excavated all 15 centimeters of her custom built home, constructed at about a 30 degree angle into a west-facing slope and insulated with the choicest materials.

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Removing the first leaf piece plugging up the nest entrance. Photo J. Meiners.

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Piece of the nest cavity inner wall. Photo J. Meiners.

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A leaf capsule with developing larva and pollen ball inside. Photo J. Meiners.
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A disassembled leaf capsule and the most developed (lowest placed) of the larva. Photo J. Meiners.

Thus concludes this tale of two Trachusa, though Stacy far outshone her momentary mate in this story.  Her brief life was rich with exploratory flights, prized goods, meticulous craftsmanship, and motherly care.  It amazes me how specific and disciplined are the actions of a female solitary bee: fresh into the world, having known only darkness and solitude followed by a brief encounter with a male of her species, she embarks on a daunting quest with precision and artistry to continue the cycle of wild bee pollination and propagation.  I like to think that in lauding her accomplishments here, her efforts were not in vain.  Thank you Stacy, for letting me into your world.

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Honey Bee *CRASH*

mimulusbees2

Although this blog is decidedly not about honey bees, the media has so successfully publicized their plight in recent years that it is now difficult to enter into a discussion about bees without addressing the dreaded “Colony Collapse Disorder” (CCD).  Therefore, even though I am a member of the USDA Logan Native Bee lab, which includes several melittologists who delight in rolling their eyes whenever the common honey bee is brought up in conversation, I dedicate this post to the widely recognized, historically revered Apis mellifera, as honey bees are known to the scientific community.  As off-topic as it can sometimes feel for me to be asked to talk in circles about CCD with people when they hear I study bees, I love working with an organism to which people feel a connection and have a basic understanding of its global importance (as opposed to when I was the odd, inexplicable “ant researcher girl” on a former project at a Marine Corps Base).  I am happy to discuss honey bees, their fascinating hive dynamics, honey flavors, and the pervasive impacts they have on our ecosystem and agricultural functioning.  Then I am even happier to shift the conversation to the under-appreciated, under-studied native bees and watch your eyes grow wide with plans to fine tune your wildlife vision the very next time you step outside (see previous post).

But, yes, honey bees…

Honey bees rented and transported for pollination services buzz around their hive at a California farm, now a common sight each spring.
http://www.npr.org/blogs/thetwo-way/2011/07/12/137798639/truck-crash-released-14-million-angry-bees-and-honey-on-highway

The issue of CCD is as real as it is mysterious.  In 2006 U.S. beekeepers began reporting alarming and sudden declines in their hives, beginning with David Hackenberg of Florida who woke up one morning to find 85% of his 3000 hives nearly empty.  But after six years of feverish research in the US and Europe, scientists have yet to pinpoint a singular culprit and outline a solid plan of attack to bring A. mellifera back to its former glory.  And with several USDA-ARS labs across the country tasked with resurrecting these commercial pollinators, this is not for a lack of effort or expertise.

That is not to say, of course, that no progress has been made.  Cell phones and cell phone towers, for example, have been exonerated of responsibility for this crime, as has the air pollutant ozone.  Correlations of bee declines with genetically modified crops or the use of high fructose corn syrup to supplement bee colonies, while objectionable on other grounds, does not hold up to scrutiny.  And recent publications compiling current knowledge on causes of CCD have named specific neonicotinoid pesticides as being particularly suspicious in their undocumented dangers towards bees, if sometimes only at  sub-lethal levels.  Research has shown certain pesticides to cause bees to become disoriented while on foraging flights, forcing them to endure more stress and fatigue in their efforts to return to the hive.  Other pesticides seem to not to affect adult bees, but may cause a myriad of developmental problems in larvae, burdening the hive in the next generation. However, since much of the research done on these chemicals is conducted by scientists on the pesticide manufacturers’ payroll who are usually running short-term tests to demonstrate that lethal doses for adult bees are higher than levels found in the environment, such implications are currently inconclusive and a solution to CCD remains stubbornly elusive.  Marla Spivak, Director of the Bee Lab at the University of Minnesota, and Gene Robinson, head of the University of Illinois Bee Research Facility, recently explained in an interview on Minnesota Public Radio that the mass destruction of honey bees seems to be the result of a combination of human-induced factors that have been gradually stacking the deck against these nonnative (imported from Europe long ago) pollinators for many years.

In an effort to maximize profits, our agricultural system has increasingly become one of massive monocultures, resulting in a dearth of pollen and nectar diversity for many miles on end.  Honey bees are known as generalist pollinators, preferring to visit many types of floral hosts.  Being geographically limited to just one type of crop is likely no better for them than a diet of only carrots, though a singular healthful choice, would be for us.  Yet this is what we are offering our managed honey bees when we increasingly support a system that sends them, tightly packed on semi trucks, thousands of miles across the country to be liberated for short stints into vast, isolated groves of almond trees, for example, before being herded up again and transported to the next crop of almond blooms.  Not only is the stress of highway travel not something to which Apis mellifera has had the chance to adapt, but this practice extends the natural range of honey bees many times over, at great cost to their immune capabilities, just as rapid travels through foreign lands sampling all the local food, water, and microbes might send you straight home to your doctor.  Honey bees are typically known to limit foraging to a few mile radius of their hives, only encountering the pathogens, pesticides, and environmental contaminants within a relatively small and familiar area.  When hives are brought from Florida to California to Maine in a single flowering season, the load of new pesticides, parasites, and stressors they encounter is more than they are biologically equipped to resist, especially in their malnourished, disoriented state.  Up against the insurmountable odds of this new, jetsetter lifestyle, hive defenses weaken and intruders such as the wax moth and the varroa mite move in, which are then transmitted via flowers to nearby native bees and local, wild honey bees in the areas to which these hives are introduced.

So the problem of CCD quickly became a problem of limited local crop pollinator availability, which then rapidly necessitated a trend of trucking bees back and forth across the country, which appears to be resulting in a crash of the entire system…literally.  In May, 2010 a truck carrying about 17 million honey bees on a flatbed trailer crashed in Dakota County, MN, releasing thousands of bees onto highway accident victims.  In April 2011, highway workers piled hundreds of honey bee hives on the side of the road and burned them after they spilled from a truck on a highway near Casper, WY.  A “river of honey” flowed across a road in Island Park, Idaho in July, 2011 when yet another semi driver lost control of his buzzing cargo.  And the beehive state joined in on the action in October, 2011 when a highway accident near St. George, Utah released 25 million bees into the air.  The problem of honey bee trucking accidents is apparently so prevalent that the University of Tennessee Institute of Agriculture produced a document on “Preparing for Honey Bee Emergencies in Tennessee,” in which they instruct workers on how to contain and kill honey bees that have escaped in truck accidents, including instructions to “call for wrecker gear and forklifts to move hives” and “maintain several protective umbrella sprays on obvious sources of bees.”  Perhaps another document is in order, detailing how to restructure our farming practices so that we don’t need to bring honey bees thousands of miles in order to sustain our factory-line crops?

Truck accident with bee release and response personnel, an increasingly frequent occurrence on U.S. highways.
http://nbba.wordpress.com/2011/05/01/truck-loaded-with-honey-bees-spills-hives-closing-highway-in-wyoming-accident/

Enter Claire Kremen (UC-Berkeley), Neal Williams (UC-Davis), Rae Winfree (Rutgers) and others working to solve this very problem with brilliant ideas on transforming our monocultures.  They suggest installing pollinator-specific hedgerows and other sources of native bee habitat near larger crops, and establishing small, organic crops to boost native bee abundance and help offset our alarming dependence on managed, transported honey bees.  The three researchers mentioned above, along with Jonathan Dushoff of McMaster University, completed a study in 2007 on the ability of native bees to provide ‘biological insurance’ against ongoing honey bee losses.  Using field measurements of watermelon pollination, along with a simulation model to differentiate between the pollen provided by honey bees and that provided by native bees, they determined that wild, native bees could provide 90% of the necessary pollination in the absence of the honey bees now rented for the job at the farms studied….IF their habitat requirements are factored in to the neighborhood plan.

In dramatic conclusion, native bees emerge the heroes of this sad tale of unresolved honey bee decline.  (Didn’t see that coming?  Didn’t I promise I would bring the conversation back to native bees?)  There is evidence that native bees could be poised to swoop in and save pollination, and thus the diversity of our food and landscapes, if only we can sufficiently restructure our agricultural system to support them.  This is a daunting enough challenge in itself, but it is also necessary to address the very scary concept that, though we may find ways around our heavy dependence on honey bee pollination and we could learn to live without honey (though we really wouldn’t want to), the truth about what Colony Collapse Disorder means for us is even worse than the total loss of honey and the vital ecosystem services provided by its producers.  Spivak and Robinson reminded listeners on MPR that, through CCD, the honey bee has revealed itself as a “poster child” for the current state of our ecosystems.  They are what is known in ecology as an “indicator species,” indicating, like a canary in a coal mine, the quality of the habitat in which we are all living.  So the fact that the cause of CCD remains unclear and is thought to be a combination of a multitude of deplorable conditions for bees is damning news for the chemical and biological state of our world.  There are thousands of beekeepers managing billions of bees, keeping a very close eye on them and poised to raise the alarm when they show signs of trouble.  What might be the condition of the millions of other species (including native bees) on whom we don’t have such thorough surveillance?  Are we standing in the middle of a rapidly disintegrating system, unaware of the vanishing pieces of our ‘biological insurance?’

I found the quote below in a book about honey variety around the world (Honey and Dust by Piers Moore Ede).  With all the recent buzz about how bees support our agricultural system, which often turns into calculations of their economic value as pollinators, I think Tolstoy makes an important point about the outrageous arrogance of trying to define the purpose of any living being from the standpoint of any other.  The more we can learn about our cohabitants on this planet, the better we can respect the complex web of species interactions within which we are cradled during our short time on Earth.  Let us hope we don’t have to discover the vital ecosystem contributions of many species more obscure than Apis mellifera by experiencing the harsh sting of the consequences of their absence.

A bee settling on a flower has stung a child.  And the child is afraid of bees and declares that bees exist to sting people.  A poet admires the bee sucking from the chalice of a flower and says it exists to suck the fragrances of flowers.  A beekeeper, seeing the bee collect pollen from flowers and carry it to the hive, says that it exists to gather honey.  Another beekeeper who has studied the life of the hive more closely says that the bee gathers pollen dust to feed the young bees and rear a queen, and that it exists to perpetuate its race.  A botanist notices that the bee flying with the pollen of a male flower to a pistil fertilizes the latter, and sees in this the purpose of the bee’s existence.  Another, observing the migration of plants, notices that the bee helps in this work, and may say that in this lies the purpose of the bee.  But the ultimate purpose of the bee is not exhausted by the first, the second, or any of the processes the human mind can discern.  The higher the human intellect rises in the discovery of these purposes, the more obvious it becomes, that the ultimate purpose is beyond our comprehension.

-Leo Tolstoy, War and Peace

Sources:

Ede, Piers Moore. (2005) Honey and Dust: Travels in Search of Sweetness. Bloomsbury Publishing, London.

Ghazoul, Jaboury. (2005) Buzziness as usual? Questioning the global pollination crisis.  Trends in Ecology and Evolution, Vol. 20 No. 7.

Kaplan, J. Kim. (2012) Colony Collapse Disorder: An Incomplete Puzzle. Agricultural Research, Vol. 60, No. 6.

Krebs J.R. et al. (1999) The Second Silent Spring? Nature, Vol. 400.

Pilatic, H. et al. (2012) Pesticides and Honey Bees: State of the Silence. Pesticide Action Network North America <www.panna.org>

Potts, S.G. et al. (2010) Global pollinator declines: trends, impacts and drivers. Trends in Ecology and Evolution, Vol. 25 No. 6

Stokstad, Erik. (2007) The Case of the Empty Hives. Science, Vol. 316.

Winfree, R. (2008) Pollinator-Dependent Crops: An Increasingly Risky Business. Current Biology, Vol. 18 No 20.

Winfree, R. et al. (2007) Native bees provide insurance against ongoing honey bee losses. Ecology Letters, 10:1105-1113.

 

Posted in Bees, Honey Bees (Apis) | Tagged , , , , , | 1 Comment

Newsflash: Not All Bees Make Honey!

I think it appropriate to kick-start this blog by debunking some surprisingly common myths about the wondrous world of bees.  While out on the trails conducting bee surveys here in California, I often run into hikers who, upon seeing me and my intern walking with large mesh insect nets, usually exclaim something like “Wow!  Are you collecting butterflies?”  Once we explain to them that, no, in fact we are doing biodiversity surveys for bees, they usually follow with some variation on “Great!  I love honey!” or even occasionally “Oh, I hate bees!  They sting me!”  Depending on how pressed for time we are to arrive at our next sampling location, I then try to spend a few minutes pulling aside the curtain on the real world of native, solitary, (mostly) non-aggressive bees to give them a glimpse of the insect complexity that gives rise to a diverse array of wildflowers and shockingly little honey.  The result is usually one of appreciative awe that makes me want to grab every hiker I see on the trail and show them the delicate contents of my net.

I love honey too.  It is my sweetener of choice for tea, oatmeal, and warmed tortillas (yum…).  I am certainly not immune to the intrigue of the altruistic societies and wiggling communications of the honey bees, the subject of a devoted middle school research paper of mine.  I still consider it a high point of my life when I took my eighth grade science fair project on the antioxidant content of honey of various nectar sources to the Colorado State Science Fair and won third place overall in the Physical Sciences category.  In fact, it’s a little embarrassing to admit, but I included a picture of me in knee-high socks and penny loafers, sporting my third place ribbon in front of my cardboard project display in my application to graduate school.  My point is: I’m not here to knock honey bees.  But it’s a tragedy that their enchanting wiggle dances, painful stings, and penchant for sweet, sticky liquids to get them through the winter is all the word “bee” means to most people.  It is just the beginning, my friend.  Or rather, it’s the end since social bee behavior evolved from the multitudes of solitary bees.  So it is actually the vast and important beginnings we are missing.  Let’s get to it.

Maybe you have heard that there are over 20,000 known species of bees in the world?  (I got that off of a fact card I wrote for my middle school research paper—why I still have those cards is more difficult to explain.)  Honey bees are approximately nine of those species, so we can just pretend they don’t even count.  Can you even imagine 20,000 different types of bees?  Take a minute.  To be fair, some of the different species are visually indistinguishable except to a few very diligent experts with expensive microscopes.  But there is still almost unfathomable morphological variety in the fuzzy Hymenopteran pollinators zooming around our planet right now.  There are bees that are an inch long and completely black, even to the tips of their powerful wings.  There are bees that are so small we have to use the tiniest dab of Elmer’s glue to attach them to a pin or a point (piece of paper that is then pinned) for display since running even the thinnest metal pin through their mesosoma would likely split the bee right down the middle.  Some bees are bright metallic green with red-tipped abdomens, some are a dull shiny blue, and some display a rainbow of bright colors cascading down their bodies (when I first saw a museum specimen of this type, I have to admit, I wanted to steal it).  There are also, of course, some bees that are orange or yellow with black abdominal stripes.

Anthophora sp.
(Bee! (“crazy eye bee!”))
http://www.treknature.com/gallery/photo241305.htm

(NOT a Bee)

With morphological variety often comes behavioral variety, and among these 20,000 different kinds of bees there are as yet innumerable pollination strategies and specific floral preferences.  Fortunately for herbivores and wildflower lovers alike, this has directly resulted in (and been the result of) the evolution of an incredible modern variety of angiosperms, the flowering plants.  This mutualism between bees and flowers, each adapting in shape and seasonality to one another over millions of years, is one of the most classic, dominant, and elegant examples of co-evolution on Earth.  For example, the anatomy of certain orchid flowers is such that when an Orchid bee squeezes through a tailor-made passageway, it causes part of the flower to bend down and affix a pollen packet to the backside of the bee in such a particular place that it cannot be removed until the bee squeezes through another Orchid of the same species.  Some bees in New Zealand have adapted to be able to access the nectar and pollen of certain flowers by biting and pushing open flower buds that are unable to open themselves.  But the behavioral variety among bees doesn’t stop with floral interactions.  Last August in southern Arizona I watched bee expert Jerry Rozen spend over an hour patiently puffing away tiny clumps of sand with a reverse aspirator to reveal the thin, almost meter-long tunnel descending to the nest of a particular solitary bee mother.  At the bottom we found a delicate little pill-sized capsule made of meticulously cut pieces of leaf pasted together to enclose a single egg and a hard-won lump of pollen and nectar.  The effort this single mother had expended in her short (3-5 week) life to collect this food and nest material and slowly excavate such a deep cavity in which to keep it safe makes the Egyptian pyramids look like a slop job.  Other bees are known to use multi-colored pieces of flower petals to construct their egg cases, making tiny works of art more precious than most bearing price tags, in my opinion.  Some bees laboriously tunnel into wood to make their homes, or camp out stealthily in the hollowed-out stems of their favorite  host plants.  There are also bees that, while declining to actually work together in creating a hive and dividing up the tasks of rearing young, are not as hermitic as some of their ancestors.  Some bees live in “apartment style” dwellings, each mother master of her own nest domain, but sharing a common entryway and hallway.  This allows for some shared labor in tunneling out the main passageway and provides a “neighborhood watch” type of security against parasites lurking to pounce when the mothers heads out to forage.  Dr. Rozen may never be able to retire his aspirator with the wonders of bee nest-building that are yet to be discovered.

What all this solitary, hidden bee nesting means for most of you is that the vast majority of bees actually have no interest whatsoever in stinging you.  So you should not hate nor fear them.  With no grand hive to guard and each solitary bee mother working exclusively in her own self interest and with her young in mind, she is very unlikely to charge and impale you at the cost of her own life.  Among the social bees who do live in hives, one major group is actually known as the “stingless bees,” and therefore cannot do you any harm while crusading for their hive.  In fact, there are many species of bees who don’t even have the ability to sting or whose stings serve only as endearing, pin-prick reminders that we are Goliath here.  And since the stinging apparatus is a modified egg-laying organ and therefore only present in females, male aggression is not something you need concern yourself with in bees.  I know melittologists (bee researchers) who, when they recognize a long-antennaed male bee in their net, go ahead and pluck it out with their fingers, so confident are they in its inability to inflict any harm.  (Most of the time their assessments are correct, but an occasional misidentification can come with a painful admonishment.)  So frolic in the meadows at will and feel free to enjoy the pollinating insects you observe at close range.  You’ll know a honey bee when you see or hear one and it probably won’t want to sting you and eviscerate itself either as it heads off over the hills, laden with the pollen of a hundred flower visits.  And just so we’re clear on one more thing: Yellow-jackets?  They are wasps: the mostly predatory, hairless, thin-waisted, devious cousins of bees.  So I make no excuses for their painful stings.  Just look twice in your soda can before you take another drink.

Image

Digging up a bee nest in southern Arizona. 105 degrees out!

I think that wraps up the first installment of bee basics.  If I see you out on the trail, I’ll net you a few bees and show you how friendly and interesting and fuzzily cute (on par with puppies and baby seals, I’d say) they can be(e).  And then we can talk about how much we all like honey.

 

Posted in Bees, Native bees | Tagged , , , , | 4 Comments