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Wednesday, January 17, 2018

Bee Bedevilments: Colony Collapse Disorder and More

      Colony Collapse Disorder (CCD) was one of the most striking mysteries in the news 11-12 years ago; honeybee workers were vanishing fast for no clear reason. To this day, that puzzle has never been entirely solved, researchers say.

     And perhaps it never will be. Colony collapse disorder has faded in recent years as mysteriously as it began. It’s possible the disappearances could start up again, but meanwhile bees are facing other problems.

     CCD probably peaked around 2007 and has faded since, says Dr. Jeff Pettis, who during the height of national curiosity was running the Beltsville, MD, honeybee lab for the U.S. Department of Agriculture. Five years have passed since Dennis vanEngelsdorp, who studies bee health at the University of Maryland  has seen a “credible case” of colony collapse (see below in the lower part of the image.)

     Beekeepers still report some cases, but Dr. Pettis and Dr. vanEngelsdorp aren’t convinced such cases really are colony collapse disorder, a term that now gets used for a myriad of things that are bad for bees. To specialists, colony collapse is a specific phenomenon. An apparently healthy colony over the course of days or a few weeks loses much of its workforce, while eggs and larvae, and often the queen herself, remain alive. Also food stores in collapsing colonies don’t get raided by other bees as a failing colony’s treasures usually do.

      “I think I know what happened,” says Dr. Pettis, now in Salisbury, MD, consulting on pollinator health. His proposed scenario for CCD, like those of some other veterans of the furor, is complex and doesn’t rest on a single exotic killer. But so far, no experiment has nailed a proof.

     Looking back, Pettis realizes he had heard about what might have been early cases of CCD, described as colonies “just falling apart,” for several years before the phenomenon made headlines. Then in November 2006, Pennsylvania beekeeper David Hackenberg, as usual, sent his colonies to Florida for the winter. They arrived in fine shape. Soon after, however, many buzzing colonies had shrunk to stragglers. Yet there were no dire parasite infestations and no dead bee bodies in sight.

      “It was, ‘OK, something weird just happened,’ ” remembers Dr. Jay Evans of the USDA’s honeybee lab in Beltsville. “It looked like a ‘flu,’ something that kind of swept through miraculously fast.”

      No single menace, however, could be tightly linked to every sick colony, or only to sick colonies. Varroa mites, small hive beetles, Nosema fungi, deformed wing virus, unusual signs of pesticide exposure, for instance —screening techniques at the time just weren’t picking up a clear pattern in any of these bee bedevilments.

     Entomologists were hounded by the press, not to mention leaned on by politicians and pursued by would-be entrepreneurs. “For me, what made it rewarding,” Dr. Pettis says, “was that people were learning about the value of pollination.”

      A Columbia University researcher who had identified pathogens in mysterious human disease outbreaks looked at the problem. Dr. Ian Lipkin had never worked with bees, but he and his lab collaborated with entomologists and other bee specialists to search for any genetic signature of a pathogen appearing only in collapsing colonies. The approach of searching through mass samples, with their messy traces of gut microbes and random parasites, is now familiar as metagenomics. At the time, this way of searching for pathogens was groundbreaking, says collaborator Diana Cox-Foster, then at Penn State U. The resulting paper, in Science, pointed to several viruses, especially the previously obscure Israeli Acute Paralysis Virus, or IAPVThat emphasis on IAPV, which got a lot of attention at the time, hasn’t held up well. “It’s not 100 percent ruled out,” Evans says. But the explanation’s main problem is shared by other threats proposed as a single cause of CCD. After finding IAPV or another presumed single menace in sick bees in one place, he says, “you could go to other apiaries that were collapsing and not find it, or you could find it in healthier colonies.”

      As an apiary inspector for Pennsylvania at the time, vanEngelsdorp monitored for signs of collapse in over 200 hives. “We tried to watch it happen but we couldn’t,” he says. None collapsed. Even finding the sickest bees in collapsing colonies was a challenge. Doomed bees presumably flew off in multiple directions, and birds or other scavengers usually found the bees before scientists could.

     Dr. Pettis now sees the disaster as a two-step process. Various stressors such as poor nutrition and pesticide exposure weakened bees so much that a virus, maybe IAPV, could quickly kill them in droves. Evans, too, sees various stressors mixing and matching. When pressed for his best guess, he says “all of the above.”

       Dr. Cox-Foster has managed to re-create part of the process, the vanishing effect that marked the end for stressed bees. When she infected honeybee colonies in a greenhouse with a virus, the sick bees left the hive but were trapped by the greenhouse walls before dispersing too far to be found. (Of course, this experiment doesn’t demonstrate how colonies with no sign of a virus died.

     That tendency for sick bees to leave hives, Dr. vanEngelsdorp proposes, could have developed as a hygiene benefit. “Altruistic suicide,” as social-insect biologists call it. Flying away from the colony could minimize a sick bee’s tendency to pass disease to the rest of the hive.

     Colony losses each year are still running higher than beekeepers say would be acceptable (gray bar in the image below). Even though hives can be split so numbers eventually build up again, the slowdown and expense raise the costs of pollination.

      Today, hive losses remain high even with CCD waning or gone, according to national surveys by the Bee Informed Partnership, a nonprofit bee health collaboration. Beekeepers typically note that they either expect or can tolerate annual losses between 15 and 20 percent of their total number of colonies. Yet from April 2016 until March 2017, losses across the United States ran at about a third of hives. And that was a so-called good year, the second-lowest loss in the seven years with data on annual losses.

      Classic CCD may not be as much of a threat these days, but the “four p’s” — poor nutrition, pesticides, pathogens and parasites — are, says Dr. Cox-Foster, now at a USDA lab for pollinating insects in Logan, Utah. Coping with the four p’s may not fire the imaginations of armchair entomologists. But it’s more than enough of a challenge for the bees.

       Answer? Choose B (but it's still a confounding mystery.)

Bee well,

Monday, January 1, 2018

2017: 74 Interesting Science, Technology, and Health Links

     Here are 74 interesting science, technology, and health stories in this 2017 year-end article from The Atlantic. Enjoy all the links from how flamingos easily stand on one leg (#2). . .

in formation. . .

to a large waterfall in Antarctica where the Nansen Ice Shelf meets the sea (#19). . .

to the way hummingbirds drink nectar using tongues that are so long that, when retracted, they coil up inside the birds’ heads, around their skulls and eyes (#59). . .

to genetically distinct uptown versus downtown rats in New York City (#60). . .

to the oldest rocks on earth (4 billion years old having fossil traces in them in the Torngat Mountains in Canada (#67) to. . . wherever the links take you.

      Which links were most intriguing for you? Which did you skip past quickly (#13 for me)?

      I'll leave the mole rats and their oxygen needs for you to discover (#74).

All the best for a healthy, happy, and scientifically stimulating 2018!

Friday, December 15, 2017

Something to Crow About: Happy Hooking, a Relatively New Tool Skill

      New Caledonian crows are the only species besides humans known to manufacture hooked tools in the wild. These birds produce these remarkable tools from the side branches of certain plants, carefully 'crafting' a crochet-like hook that can be used for snagging insect prey.

      The study, published in Current Biology on December 7, 2017, reveals how crows manage to fashion particularly efficient tools, with well-defined 'deep' hooks.

      The hook is widely regarded as one of humankind's most important innovations, with skillful reshaping, a useless piece of raw material is transformed into a powerful tool. While our ancestors started making stone tools over 3 million years ago, hooks are a surprisingly recent advance; the oldest known fish hooks are just 23,000 years old.

         Project leader Dr. Christian Rutz has conducted field research on New Caledonian crows for over a decade. His team recently noticed that crows' hooked tools vary considerably in size and shape. While some tools only exhibit a small extension at the tip, others have deeper hooks.

     Dr. Rutz explains: "We suspected that tools with pronounced hooks are more efficient, and were able to confirm this in controlled experiments with wild-caught crows. The deeper the hook, the faster birds winkled (to extract with difficulty) bait from holes in wooden logs."

     This finding raised the intriguing question of what it takes to make such well-formed hooks. The researchers started planning their study by imagining how humans would approach a comparable task. "When a craftsperson carves a tool from a piece of wood, two things ensure a quality product: good raw materials and skill," Dr. Rutz said.

      Researchers found that the same, apparently, applies to New Caledonian crows. The researchers discovered that the depth of the hook was influenced by both the properties of the plant material, and the technique crows used for detaching branches. When birds made controlled cuts with their sharp bills, the resulting hooks were significantly deeper than when they used a 'sloppier' alternative method of simply pulling off branches. Careful cutting may leave more wooden material at the tip of the stick from which the hook can subsequently be 'sculpted'.

     Surprisingly, adult crows, which are expected to have considerable tool-making experience, did not produce the deepest hooks and regularly employed the 'quick-and-dirty' manufacture technique. Dr. Rutz notes that making very deep hooks may not be the best strategy in the wild: "It probably takes more time and effort to make such tools, and experienced birds may try to avoid these costs. It is also possible that deep hooks break more easily when inserted into narrow holes and crevices."

      Dr. Christophe Boesch, a world-leading chimpanzee expert and Director of the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, comments: "We have recently discovered that chimpanzees routinely use naturally-hooked stems to fish for algae, but they don't actively craft these hooks. The crows can reshape plant material with their pointed bills, which act like 'precision pliers', but this would be very difficult for chimpanzees with their large fingers."

     The present study is the first to examine in a non-human animal what factors determine the morphology of crafted tools, and as a consequence, their foraging efficiency. Paleo-anthropologists try to understand how our ancestors produced relatively complex tool shapes from basic raw materials, such as wood, bone or seashell, but they face the challenge that the manufacture process cannot be directly observed.

      The New Caledonian crow, with its remarkable ability to fashion hooked tools from plant stems, provides a fascinating window into humans' evolutionary past.

Hooked on Crows,

Wednesday, November 29, 2017

Where All the Women Are Strong: Bone Strength Comparison

     A new study comparing the bones of central European women who lived during the first 6,000 years of farming with those of modern athletes has shown that the average prehistoric agricultural woman had stronger upper arms than living female rowing champions.

     Researchers from the University of Cambridge's Department of Archeology say this physical prowess was likely obtained through tilling soil and harvesting crops by hand, as well as the grinding of grain for as much as five hours a day to make flour.

      Until now, archeological investigations of past behavior have interpreted women's bones solely through direct comparison to those of men. However, male bones respond to strain in a more visibly dramatic way than female bones.

     The Cambridge scientists say this has resulted in the systematic underestimation of the nature and scale of the physical demands borne by women in prehistory.

     "This is the first study to actually compare prehistoric female bones to those of living women," said Dr. Alison Macintosh, lead author of the study published this month in the journal Science Advances.

     "By interpreting women's bones in a female-specific context we can start to see how intensive, variable and laborious their behaviors were, hinting at a hidden history of women's work over thousands of years."

     The study used a small CT scanner in Cambridge's laboratory to analyze the arm (humerus) and leg (tibia) bones of living women who engage in a range of physical activity: from runners, rowers and footballers to those with more sedentary lifestyles.

     The bone strengths of modern women were compared to those of women from early Neolithic agricultural eras through to farming communities of the Middle Ages.

     "We can forget that bone is a living tissue, one that responds to the rigours we put our bodies through. Physical impact and muscle activity both put strain on bone, called loading. The bone reacts by changing in shape, curvature, thickness, and density over time to accommodate repeated strain," said Dr. Macintosh.

      "By analyzing the bone characteristics of living people whose regular physical exertion is known, and comparing them to the characteristics of ancient bones, we can start to interpret the kinds of labor our ancestors were performing in prehistory."

      Over three weeks during trial season, Macintosh scanned the limb bones of the Open- and Lightweight squads of the Cambridge University Women's Boat Club, who ended up winning this year's Boat Race and breaking the course record. These women, most in their early twenties, were training twice a day and rowing an average of 120 kilometers a week at the time.

      The Neolithic women analyzed in the study (from 7400-7000 years ago) had similar leg bone strength to modern rowers, but their arm bones were 11-16% stronger for their size than the rowers, and almost 30% stronger than typical Cambridge students. {Bone scan is at left, above, vs. x-ray to the left}.

     The loading of the upper limbs was even more dominant in the study's Bronze Age women (from 4300-3500 years ago), who had 9-13% stronger arm bones than the rowers but 12% weaker leg bones.

     A possible explanation for this fierce arm strength is the grinding of grain. "We can't say specifically what behaviors were causing the bone loading we found. However, a major activity in early agriculture was converting grain into flour, and this was likely performed by women," said Dr. Macintosh.

      "For millennia, grain would have been ground by hand between two large stones called a saddle quern. In the few remaining societies that still use saddle querns, women grind grain for up to five hours a day." {The mano and metate is a variety of saddle quern used for nixtamalization or grinding.}

     "The repetitive arm action of grinding these stones together for hours may have loaded women's arm bones in a similar way to the laborious back-and-forth motion of rowing."

     However, Macintosh suspects that women's labor was hardly likely to have been limited to this one behavior.

     "Prior to the invention of the plough, subsistence farming involved manually planting, tilling and harvesting all crops," said Dr. Macintosh. "Women were also likely to have been fetching food and water for domestic livestock, processing milk and meat, and converting hides and wool into textiles.

     "The variation in bone loading found in prehistoric women suggests that a wide range of behaviours were occurring during early agriculture. In fact, we believe it may be the wide variety of women's work that in part makes it so difficult to identify signatures of any one specific behavior from their bones."

     Dr. Jay Stock, senior study author added: "Our findings suggest that for thousands of years, the rigorous manual labor of women was a crucial driver of early farming economies. The research demonstrates what we can learn about the human past through better understanding of human variation today."

Where all the women are strong,
Steph (former member of Smith College Crew)

Monday, November 6, 2017

Even Mammoth Males Took More Risk!

     You may know why/how I came up with this week's Partial Ellipsis of the Sun topic.

      "Male mammoths really had to watch their steps. More than two-thirds of woolly mammoth specimens recovered from several types of natural traps in Siberia came from males, researchers report November 2, 2017, in Current Biology."

      "Paleogenomicist Patrícia Pečnerová of the Swedish Museum of Natural History in Stockholm and her colleagues examined genomic data recovered from 98 mammoth bone, tooth, tusk and hair shaft specimens and found that 69 percent of their owners were male." 

      "Sex biases in fossil preservation are rare, and the sexes were almost certainly balanced at birth. So the researchers considered whether social and behavioral patterns might have meant that male mammoths more often died in such a way that their remains were buried and preserved, such as becoming trapped in a bog or falling through thin ice."

     "In modern elephants, herds of females and young live together, led by an experienced female, whereas males are more likely to live in bachelor groups or alone. That could result in more risk-taking behavior for those males." 

       "Woolly mammoths, the distant cousins of modern elephants, may have had the same social structures, the researchers suggest."

     "The study, the authors say, highlights how fossil genomic data can help illuminate the past social structures and behavior of extinct animals — and how existing fossils may not fully represent the original population. . ."

      And that risky behavior in males, be they mammoths or human beings, happens. . .

Woolly, Boolly, Woolly, Boolly,


Monday, October 23, 2017

Happy Birthday Earth (at 9 a.m.): Birthday Cake Served Up on a New Plate

     Archbishop Ussher declared today, October 23rd, 4004 B.C. (at 9 a.m.) to be the Earth's birthday. Geologists everywhere will raise a glass this evening to celebrate. . .and serve up a piece of birthday cake on a "brand new" tectonic plate, the Malpelo plate, off the coast of Ecuador. The Malpelo plate is that thumb-like protrusion on the northeast corner of the Nazca Plate (seen below in light blue).

      "Researchers led by Rice University geophysicist Dr. Richard Gordon discovered the microplate while analyzing the junction of three other plates in the eastern Pacific Ocean. Their research is published in Geophysical Research Letters.

     The Malpelo plate, named for an island and an underwater ridge it contains, is the 57th tectonic plate to be discovered and the first in nearly a decade. "Mal pelo" means "bad hair" in Spanish (making the Malpelo plate the patron saint of bad hair days?)

     How do geologists discover a plate? In this case, they carefully studied the movements of other plates and their evolving relationships to one another as the plates move at a rate of millimeters to centimeters per year.

     The Pacific lithospheric plate that roughly defines the volcanic Ring of Fire is one of about 10 major rigid tectonic plates that float and move atop Earth's mantle, which behaves like a fluid over geologic time. Interactions at the edges of the moving plates account for most earthquakes experienced on the planet. There are many small plates that fill the gaps between the big ones, and the Pacific Plate meets two of those smaller plates, the Cocos and Nazca, west of the Galapagos Islands.

     One way to judge how plates move is to study plate-motion circuits, which quantify how the rotation speed of each object in a group (its angular velocity) affects all the others. Rates of seafloor spreading determined from marine magnetic anomalies combined with the angles at which the plates slide by each other over time tells scientists how fast the plates are moving."

      When you add up the angular velocities of these three plates, they ought to sum to zero," Dr. Gordon said. "In this case, the velocity doesn't sum to zero at all. It sums to 15 millimeters a year, which is huge."

       That made the Pacific-Cocos-Nazca circuit a misfit, which meant at least one other plate in the vicinity had to make up the difference. Misfits are a cause for concern -- and a clue.

      Knowing the numbers were amiss, the researchers drew upon a Columbia University database of extensive multibeam sonar soundings west of Ecuador and Colombia to identify a previously unknown plate boundary between the Galapagos Islands and the coast. The Malpelo plate is moving independently of the Nazca plate.

     "Since we're trying to understand global deformation, we need to understand where the rest of that velocity is going," he said. "So we think there's another plate we're missing."

      Let's discover yet another tectonic plate today to serve up that birthday cake! Enjoy, bad or good hair day!