Saturday, December 31, 2016
Note: This program first aired on December 31, 2016.
There has been a lot of talk lately about the fact that water is life. We spoke last week about the biochemical reality of that concept, and looked at how water is involved in photosynthesis on a molecular level. Water is key to the reaction that allows plants to transform the energy of the sun from non storable electromagnetic radiation to storable chemical energy. The other great biochemical reaction that life depends on is respiration, the liberation of energy from chemical bonds. And once again, as in photosynthesis, water isn’t the main focus of the chemical reaction, but an extremely useful and in fact necessary bystander, without which the reaction could not occur. The star of the respiration show, the final product that is the real reason for the reaction to occur is called ATP (or adenosine triphosphate), a high energy, unstable molecule that does a good job of temporarily holding on to the chemical energy liberated from the glucose molecule, for a matter of seconds to minutes. Everything that happens in respiration supports the formation of ATP, one way or another.
Typically we think of the respiration reaction as combining glucose and oxygen gas to yield carbon dioxide and water. In reality, we combine glucose, oxygen gas and water to yield carbon dioxide and even more water. We put some water in on the reactant side, and get even more water out on the product side.
Respiration, particularly the aerobic or oxygen using kind we are talking about today, is, just like photosynthesis, a fabulously complicated process with many mind numbing intermediate molecules. The first part of the process, glycolysis, has 10 sub reactions all of its own, just to turn a 6 carbon glucose molecule into two 3 carbon molecules. Those three carbon molecules, get further processed into two 2 carbon molecules, and then enter something you may remember from school, the Citric Acid cycle, or Kreb’s cycle, which uses a series of organic acids to further process the two carbon molecules to their ultimate fate, being turned into carbon dioxide gas. And all along the way, at key steps, electrons are getting moved around, electrons that started in the glucose molecule. Electrons that originally came from water molecules back in the photosynthesis reaction that formed the glucose.
If you are thinking ahead, you can see where this is going. Water plays several roles in respiration. The first is that it is the solvent in which all of these other chemicals are dissolved. Without water, these reactions would have no matrix within which to take place. Secondly, water plays a supporting chemical role in the citric acid cycle, stepping in as a reactant. Water also allows for the initiation of respiration by hydrolyzing or breaking down starch and other more complex carbohydrates into individual glucose molecules. Thirdly, and probably most importantly, water gets formed as a result of all of those electrons getting passed around.
As the electrons get moved from one intermediate carrier molecule to another, conditions inside the cell get set up for the generation of ATP, which remember is the ultimate goal of respiration. Once the stage is set for the ATP generation, virtually all of the useful energy has been wrung from the electrons, and the last hand off, to what we call the terminal electron acceptor, releases the last of the energy. The terminal electron acceptor is oxygen (that is why you need to breathe air with oxygen in it). Oxygen on its own though, with an extra couple of electrons, is what we call a free radical, an unstable and potentially destructive molecule. The destructive power is based on the imbalance of the electrostatic forces in the atom. To counter this, the oxygen quickly joins some hydrogen ions that are available in the cell, and forms water, and the products of respiration are complete. If water wasn’t formed as a result of respiration, we would be left with a free radical form of oxygen which can be destructive to the cell. So once again, the Oscar for best supporting chemical in a biological reaction goes to: water.
As if often the case, any college level Biology text book should cover this in sufficient detail. I use Freeman et al, Biological Science 6th ed. Pearson Higher Ed
Interesting table of free radical https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/table/T1/
From this article in Pharmacology Review: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/
Saturday, December 24, 2016
Note: This program first aired December 24, 2016.
There has been a lot of talk lately about the fact that water is life. That means a great many things to a great many people. To the fishing communities here on the coast of Maine, water provides a living, a work place, a source of income and food. On a hot summer day water provides relief, a place to cool your body. For many people the water is life idea is a spiritual endeavor; water represents the blood of the earth, traveling across the body of the earth, bringing sustenance. Even those recreationalists less spiritually aligned recognize water as a means of direct immersive contact with the natural world. We all understand intuitively that water is life, but few of us understand exactly why. But talk to a biologist, or a chemist, and you will learn that “water is life” has literal concrete molecular meaning.
Water has a specific and intimate role in the most basic biological reactions, playing a key part in both photosynthesis and aerobic respiration. I’ve talked about photosynthesis before on the show, but it is hard to overemphasize the importance of this reaction to the fact that we are all here. It is the means by which all of the energy our bodies use becomes accessible to us; our bodies can’t use light energy, but we can use the chemical energy stored in organic molecules created by plants and transferred up the food web. Virtually our entire economy is based on photosynthesis*, and until a couple of hundred years ago that was all “current photosynthesis”. The advent of the industrial age brought a reliance on fossil fuels, but the “fossil” in fossil fuels is photosynthesis. All the chemical energy stored in oil, gas and coal originated exactly the same way as the energy in your bowl of Wheaties-through an intricate set of biological reactions that move electrons up and down and from atom to atom and result in a final product that has higher potential energy than the original ingredients. Photosynthesis pushes energy up hill. We rely on it utterly. And it relies on water.
The kind of photosynthesis we are talking about, oxygenic photosynthesis is the kind you learned about in school, when you learned that plants can take carbon dioxide and water in the presence of sunlight and make glucose and oxygen. A specific group of bacteria, called cyanobacteria (also known as blue green algae, but this is a misnomer as they are not algae) and certain members of the eukaryotes, a group of organisms that includes us and pretty much everything else you would picture as alive are the organisms that can perform oxygenic photosynthesis. There are other forms of photosynthesis, but they don’t make oxygen, and more importantly for the story today, they don’t use water.
So what role does water play in this most fundamental biological process? There are actually two key roles, Water goes into the photosynthetic reaction and gets deconstructed for parts. The oxygen gas generated as a byproduct of this reaction, the oxygen that changed the composition of the atmosphere and enabled all of the life we see around us is the O in H2O. Take apart a couple of water molecules and you have two oxygen atoms, that bond to each other to create the diatomic oxygen gas we know, love and depend on. But photosynthesis isn’t trying to create oxygen, it is trying to turn electromagnetic energy into storable chemical energy, and to do that it needs some electrons. Electrons are the currency of non nuclear atomic energetics. The light energy that gets absorbed by chlorophyll serves to excite electrons, and the net result of the first part of photosynthesis is that a special chlorophyll molecule called the reaction center loses some of these excited electrons as they are passed on to other molecules in the photosystem. That is its job, to absorb sunlight and pass that energy along to the rest of the system in the form of electrons. To keep doing its job though, the reaction center chlorophyll needs electrons to replace the ones it gave away. Where does it get those replacement parts? You know it already—it gets them from water. That is the reason water is required for photosynthesis, and therefore life—its electrons.
Getting electrons from water isn’t easy to do. Oxygen is an incredibly greedy atom and is loath to relinquish any electrons, chemists call that being strongly electronegative. The only things that can get electrons away from a water molecule are an even more strongly electronegative reaction center chlorophyll molecule, and some very clever enzymes.
So there you have it, water is life, because water is the source of the electrons that provide the medium by which the sun’s energy gets turned into chemical energy, and as a handy byproduct also happens to provide the world with the oxygen it needs. What we need that oxygen, and yet more water for, we’ll talk about next week.
As if often the case, any college level Biology text book should cover this in sufficient detail. I use Freeman et al, Biological Science 6th ed. Pearson Higher Ed
Saturday, December 3, 2016
Note: This program first aired on December 3, 2016.
If you wanted to design an ocean animal that is perfectly constructed to get hit by ships, what characteristics would you include? It should probably be big, and slow moving. Make it dark so it is hard to see. If it is a mammal, it will need to spend time at the surface, so it can breath. It should have to spend long amounts of time feeding on very small food items, again, often at the surface, at night. Make it easily stressed by noise, which decreases its ability to communicate with others of its kind. Put its range right near shore, in major shipping lanes near highly populated areas.
This isn’t just a hypothetical exercise, this animal actually exists. It is called the Eubalaena glacialis, North Atlantic Right Whale, and it is one of the most endangered large whales in the world.
Many people have heard the story of the Right Whale, so called because they were the “right” whale to hunt especially in the early days of whaling. As a species evolved to feed in relatively shallow productive water of the continental shelf, they stay close to shore, which made them accessible to land based hunters in small boats. They could be brought to shore and processed on land, and were an important part of the land based whaling industry, before the more ocean going sperm whale was discovered and chased all over the global ocean on multi year whaling expeditions. Right whales also have enough blubber, or body fat, to lower their overall density enough that they will float when killed, again, making them easier to manage from a small boat. It is hard to know how many Right Whales were around before commercial whaling began, but they received internationally recognized protection starting in 1935, after having been harvested consistently in the northwest Atlantic since the 1500’s, and most likely earlier in European waters. Researchers estimate that there were less than 100 North Atlantic Right whales left in the western Atlantic in 1935. Since that time the population has rebounded, but very very slowly. The most current published population estimate puts the number around 476 individuals, based on direct observation. Though they are no longer hunted, they are still highly endangered.
Why are they still endangered? If we return to our list of characteristics of our vulnerable ocean animal, we can start to see why. They like to hang out where we spend most of our time in the ocean too. They fish where we fish. They travel where we travel. The two big reasons that Right whales die as a result of human activity are 1. They get tangled in fishing gear and 2. They get struck by ships.
The fishing gear entanglement issue is complicated, and unfortunately seems to be a fact of life for North Atlantic Right Whales. Researchers have observed that 83% of these whales have scarring consistent with entanglement, and around half show signs of multiple entanglements. Changes to fishing gear are a start at preventing this problem, but there is further work to do.
On the ship strike side, and because I work at a maritime college I focus more on this end of things, some very positive strides have been taken. In areas where these whales are known to congregate at certain times of the year, speed limits have been imposed for vessels over 65 feet. These zones are called seasonal management areas or SMAs and came into effect in 2008. Compliance on the part of industry has slowly but surely increased since that time. Speed makes a huge difference. If a whale is struck by a ship traveling at 20 knots, mortality is 100%. When ship speed is reduced to 9 knots, mortality is around 20%. And it has had an impact. Before 2008, 87% of the ship strike mortality occurred within or just outside the SMAs, because that is where most of the whales were. Since these slow zones were established, all of the documented ship strike mortality events, averaging 1 per year, occurred outside of the SMAs. So just getting ships to slow down where the concentration of whales is highest has worked to decrease our impact on this population. Not that we should stop and pat ourselves on the back, there is certainly more to do. These whales continue to face the threats of ship strike outside of the SMAs, entanglement in fishing gear, increased stress from noise pollution, and the likelihood of a genetic bottle neck stemming from such low population numbers in the early 20th century. We’ll learn more about what is being done on a future show.
There is a ton of info out there on these whales, including many federal websites, due to the federal regulations stemming from the protections encumbered by the Endangered Species Act.
The study that documented the positive impact of the speed reduction zones: http://www.int-res.com/articles/esr_oa/n023p133.pdf
From the federal government: http://www.nefsc.noaa.gov/publications/tm/tm219/8_NARW.pdf
Saturday, November 19, 2016
Note: This program first aired November 19, 2016.
I know many of you listen to this show because you like hearing about the natural world, learning things you didn’t know before, and getting insights into the amazing mysteries of nature. I know this show, and this radio station as a whole can serve as a respite from the 24 hour news cycle, the information overload and the go go go culture we are awash in, even here in eastern Maine. And I know that after the last two weeks we’ve had, I should be offering you a show about kittens and puppies, just to provide something distracting, hopeful, sweet and kind.
I think you know what is coming. I can’t do that. Not yet anyway. I’m in the camp with the majority of those casting votes in the last election who are not happy with the results of the election. There are so many reasons, but one especially relevant to this show is the appointment of Myron Ebel to lead the Trump administration’s transition at the Environmental Protection Agency, an appointment that many presume will lead to Ebel’s nomination to lead that agency after the transition of power.
Ebel is a known and vocal climate skeptic who directs policy on energy and the environment at the Competitive Enterprise Institute, a think tank that both the New York Times and the National Review characterize as libertarian. While he says that he believes human caused climate change is real, he follows that up with the belief that it isn’t really a big deal, and certainly not something we need to worry about or more importantly, spend any money on right now. The main targets of his derision are the models and forecasts developed and constantly honed by climate scientists, in an attempt to predict the near climate future. And I quote:
*“… the scientific consensus is not based on known scientific facts. It is based on discredited climate model projections, such as the ones promoted by Gavin Schmidt at NASA’s Goddard Institute for Space Studies, and fantasy reconstructions of past climate history, such as the infamous hockey stick.”*
Climate models to have a degree of uncertainty, and scientists work tirelessly to revise the models, using “back casting” as a way to test them (can they run and accurately predict the climate trends we have already experienced? If so, than then you can have a relatively high degree of confidence in the model, within the strict limits of what it is designed to test). The International Panel on Climate Change reports take great pains to report confidence intervals with each of their predictions and prioritizations of climate related problems. So while Ebel seems to delight in denigrating what he calls unfounded climate alarmists, many of the forecasts he is critical of are coming with acknowledgements of the uncertainty.
Ebel’s think tank’s most recent policy position promotes anti regulation legislation, and that seems to be at the heart of this issue. Lowering the regulatory threshold is one of the main pillars of the Ebel’s career, and with climate change, the easiest way to do that is to deny the problem that the regulations are supposed to be addressing. If climate change isn’t really a problem, of course there is no need for the Clean Power Act, or the Paris Climate Treaty. It seems that the answer to when was America Great in the first place is the time before industry faced any kind of regulation. Annoying regulations like the Clean Air Act, and the Clean Water Act.
So for all the reasons to be concerned about the ramifications of the recent election, and there are many, incredibly serious ramifications, this one might be the most important. Climate change doesn’t just screw it up for us in America, it screws it up for everyone on this planet.
Administrator of the Environmental Protection Agency isn’t technically a cabinet level position, but it is high enough in the ranks to require Senate approval. We’ll get back to the trees and fungus and forests, plankton and algae and whales, the plants that run our lives, the winds that bring the weather and yes the kittens and puppies make us smile in the coming weeks. But in the mean time, call your senators. Tell them how you feel about someone who doesn’t take climate change seriously leading the agency tasked with protecting the environment we all share and depend on.
Senator Angus King: Augusta Office: 207 622 8292, Scarborough office: 207 883 1588 https://www.king.senate.gov/contact
Senator Susan Collins: Augusta Office: 207 622 8414, Bangor office: 207 945 0417 https://www.collins.senate.gov/contact
The New York Times profile of Ebel: http://www.nytimes.com/2016/11/12/science/myron-ebell-trump-epa.html?_r=0
The Competitive Enterprise Institute, where Ebel is Director of the energy and the environment policy division https://cei.org/
The Cooler Heads Coalition, a group of climate skeptics and deniers Ebel leads http://www.globalwarming.org/about/
*Source of the quote from the show: Myron Ebel’s blog post about a New York Times article attacking the climate scientist Willie Soon: http://www.globalwarming.org/2015/02/27/new-york-times-repeats-scurrilous-greenpeace-attack-on-willie-soon-without-checking-the-facts/#more-23224
The Clean Power Plan https://www.epa.gov/cleanpowerplan/clean-power-plan-existing-power-plants
Where he said that he thinks anthropogenic climate change is real, but that its not a big deal: http://web.archive.org/web/20161111000552/http://www.eenews.net/stories/1060041292
Really, here it is: http://www.nasa.gov/feature/goddard/2016/climate-trends-continue-to-break-records/
Saturday, November 5, 2016
Note: This program first aired November 5, 2016.
Food anchors us to the land(*), it places us in a landscape and timescape. Food also anchors us in our community. We share a common language with those who eat the same things we do, and food gives us a currency with which to exchange culture with people with different traditions.
I never feel more human than I do when I am eating wild foods. Whether it is incorporating a daily morning berry foraging walk that provides my summer breakfast, harvesting and tincturing a medicinal herb to support a loved one’s health, stumbling on an edible fungus in the fall or collecting favorite algae at the sea shore, nourishing myself from uncultivated yet bountiful sources feeds something as old as time in me.
I don’t as of yet hunt animals, so the wild food gathering I undertake is primarily focused on plants. With this in mind I signed up for a class with Arthur Haines, a well respected botanist here in New England and passionate and generous advocate for the wild food and rewilding movement. Our topic was acorns, how to collect, preserve, process and enjoy this at times prolific nut.
I was delighted to hear Arthur sing the praises of the Northern Red Oak acorn (Quercus rubra), a member of the Black Oak subfamily that includes Scarlet Oak, Pin Oak and many others. I live in a Red Oak forest, the acorns literally drop onto my door step in the fall. Northern Red Oak acorns are distinguished by their nutritional profile, they are nearly 50% lipid (or fat). Crack open a fresh Red Oak acorn and you will feel the oiliness on your fingers. That fat is mainly oleic acid, the same monounsaturated fatty acid that is found in olive oil. The rest of the bulk of the nut is complex carbohydrate, and a small percentage of protein.
The process of using acorns for food begins with gathering and sorting. It turns out not all acorns are created equal. Some are damaged right from the start, fail to develop to full size and are shed by the tree early. Others look like regular acorns, but when hefted in the hand reveal a lighter than average weight. They weigh less because they are hollow, or are in the process of becoming hollow. They are hollow because they are being eaten from the inside out by the larva of the acorn weevil, a small beetle that lays its eggs in the developing acorn. As the acorn approaches maturity, the egg hatches and the tiny larva, now housed inside its own food source, begins to eat. As it eats, it also respires, and just like we exhale carbon dioxide and water, so does the larva. That gas has mass and dissipates through the acorn shell, so as the larva eats the acorn, the acorn gets lighter and lighter. Once the larva has eaten all of the goodness inside, it exits the acorn through a little hole it creates---thus any acorn you find with a tiny circular hole in the side is no good—it is just full of acorn frass. Any acorn you find without the tell tale exit hole, that feels feather light, much lighter than all the others in your hand-if you cracked that one open it is likely you would find a number of acorn weevil larvae still munching away inside.
We can’t just shell an acorn and pop it into our mouths, and this is something aboriginal populations world wide figured out thousands of years ago. Acorns contain tannins, a group of chemicals that yield both a bitter taste and an astringent feel in the mouth. Primarily thought of as a defensive compound for the plant, some tannins have anti nutrient properties, while others (like the ones in tea) have strong nutritionally beneficial anti oxidant properties. The tannins in acorns are of the former variety, and make them in their unprocessed state, an unpleasant eating experience.
The processing may be one reason these native nuts have fallen out of favor, after drying, cracking and shelling, you still have to chop or grind them and then leach out the tannins. The process, though not intensive throughout, takes weeks. The result at the end though is a relatively bland flour, with a high healthy lipid content, and a very low glycemic index, suitable to mixing in with other flours in baked goods, or eating as a hot cereal with maple syrup. If you like getting connected with your food source, aren’t afraid a little work and are up for a culinary adventure, this would be a good year to try eating acorns. For many of us in eastern Maine, they are falling on our doorsteps.
On acorn weevils from Iowa State Extension service: http://www.extension.iastate.edu/news/2007/sep/072107.htm
Encouragement from the Earth Island Journal for eating acorns at Thanksgiving: http://www.earthisland.org/journal/index.php/elist/eListRead/this_thanksgiving_consider_cooking_with_acorn_flour/
Delta Institute of Natural History (and website of Arthur Haines, the botanist and wild food advocate mentioned in the program): http://www.arthurhaines.com/ *The first line of this show (about food anchoring us to the land, comes from Arthur’s description of the acorn workshop)
There are lots of references online for how to process acorns, some using hot water to leach the tannins, others using cold. Some crack the nuts immediately, others dry the acorns first (they are A LOT easier to shell if dry, and can be stored dry in the shell for years). The work shop I attended emphasized making the process efficient, but regardless—go ahead and experiment! There’s lots of info out there to get you started!
Saturday, October 22, 2016
Note: This program first aired on October 22, 2016.
Earlier this fall, a listener contacted me suggesting a topic for the show. He had just replaced his glass hummingbird feeder with a polycarbonate plastic one, in a successful attempt to thwart the yellow jackets that were frequenting the feeder. He wondered though, about the possible contaminants, especially BPA, that the birds might be exposed to. Anticipating the arrival of the ruby throated humming birds in the spring and watching them feed in our yards all summer long rank high among summer pleasures for many Mainers. But with growing awareness that problematic plastic additives show up anywhere, and everywhere, it has been only a matter of time until some one put two and two together and asked this question.
Plastics are polymers, chains of individual units (monomers) strung together chemically. Most plastics are a mix of different kinds of hydrocarbons, with various additives to give them specific physical attributes. These additives have various levels of fidelity to the plastic they are part of, and some readily leach out of the plastic into the environment. Awareness has grown in the past 10 years of this potential problem with the consumer goods and food packaging we contact on a daily basis.
Some chemical additives may be inert, other are quite biologically active and that is the crux of the problem. Bisphenol A, or BPA, the additive my listener asked about, is used in polycarbonate plastic, the kind that lexan water bottles, protective eye wear and DVDs are made of. It has proven itself to be, as many plastic additives are, a potent estrogen mimic, meaning, it binds to the same receptive sites in cells that naturally occurring endogenous estrogen does.
Estrogen is the female sex hormone in all vertebrates, from fish to mammals. It plays the same role throughout the vertebrate group, in carefully timed pulses it guides the development of the reproductive system. The biological or anatomical sex of an individual is the result of the relative balance of estrogen and male sex hormones like testosterone, and the timing of the exposure of cells to these hormones. Through the study of developmental biology, we’ve learned that the critical period for this exposure is very early in embryonic development.
Having an environmental estrogen out there can mess up this system, throwing off the balance of hormones, and the timing of exposure. And that is where most of the permanent impact of chemicals like BPA lies, by mimicking estrogen and flooding estrogen receptors in the cells of vertebrate embryos BPA can interfere with the normal development of the reproductive system of exposed organisms, be they fat head minnows, Japanese quail, or human beings.
Most of the research on the impacts BPA on wildlife has been on freshwater aquatic vertebrates, as it is easy for BPA to get into surface water through municipal water treatment facilities and industrial run off. The research on birds is much more limited, but that which is out there points to embryonic exposure leading to persistent malformations of oviducts and the shell gland (leading to thin and weak shells) in female birds, and changes to brain development in male birds leading to reduced copulatory behavior. These are problems, that, while initiated when the birds were embryos, don’t show up until they reach sexual maturity.
All of this bird research has been on model organisms like Japanese quail or domestic chickens, using exposure vectors like injecting BPA directly into eggs, or dipping eggs in an aqueous solution containing BPA. No one has looked at BPA’s effect on wild birds like humming birds, exposed through the parent’s ingestion of BPA laden sugar water from your new plastic hummingbird feeder. All we can say is that there is a demonstrated estrogenic effect in some birds in experimental conditions, but that the impacts on wild populations with more natural exposure are unknown. If there were negative effects to hummingbirds, I would expect them to be reproductive.
And before you all start writing me telling me that you can get BPA free polycarbonate and other plastics, yes, you can. It turns out that many of the chemicals used to replace BPA are simply other bisphenol chemicals, or are less well studied, and when they are investigated, turn out to have similar biological actions. So just because it says BPA free, doesn’t mean it is necessarily great.
If you are worried about the reproductive health of the hummingbirds who visit your yard, you may want to continue your search for the perfect glass feeder, or better yet, cultivate the original hummingbird feeder, a yard full of flowers.
Excellent review article in Dose Response, focusing on aquatic vertebrates https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4674185/
Full text of a Swedish PHd dissertation from the University of Uppsala on environmental endocrine disruption in birds: https://uu.diva-portal.org/smash/get/diva2:165990/FULLTEXT01.pdf
Environmental Defense Fund on BPA free: https://www.edf.org/health/three-reasons-bpa-free-wont-protect-you?utm_source=ggad&utm_medium=cpc&utm_campaign=gr-bpafree&gclid=COXaxd316c8CFQkkhgodBkkBtg
Other sources on BPA alternatives: http://www.the-scientist.com/?articles.view/articleNo/45789/title/Effects-of-BPA-Substitutes/
And from UCLA http://newsroom.ucla.edu/releases/chemical-used-to-replace-bpa-in-plastic-accelerates-embryonic-development-disrupts-reproductive-system
Saturday, October 1, 2016
Note: This program first aired on October 1, 2106.
I was asked by a listener recently about the place of mosquitos in the world. The combination of news stories about the Zika virus and developing a vaccine on the one hand, and rampant species extinction on the other got him wondering—why don’t we solve the Zika problem by trying to extinct the mosquito? At least that would be an extinction that solves a human problem. If things are going extinct anyway, why not try to get some benefit from that? The real question here is: are mosquitos good for anything?
And the answer is of course, it depends on who you ask. The typical answer to this oft asked question (why can’t we just kill all the mosquitos) is that they provide critical ecosystem services, in the form of being food for other animals in various ecosystems. Scientists are not unified on the impact of eliminating mosquitos (of which there are over 3500 known species, only a couple of hundred of which bite humans). Many say that the positive public health benefits far out weigh any temporary ecological disruption, and that any unoccupied former mosquito niche would be filled immediately by another organism. There are varying opinions and findings about the true role of adult or larval mosquitos in various food webs; they have been on the scene for over 100 million years, allowing plenty of time for elaborate co-evolution with predators, yet food web studies often demonstrate that mosquitos do not make up a large percentage of the food items in the stomachs of insectivorous predators. Male mosquitos do not bite, and feed on the nectar of flowers, and thus serve a pollination role, though none of the plants typically serviced by them are of any economic importance to humans. So the summary on this commonly held wisdom is maybe, perhaps there would be some impact to various ecosystems, and some specialized predators would go extinct, but nothing that we know as of now that would negatively impact humans.
On the other side of this question asks why would we kill all the mosquitos, if we could? Mosquitos are flies, in the order Diptera, a group of insects with mouthparts specialized for piercing and sucking. Their life history requires a blood meal for development of the eggs, hence only the females bite. It is this biting habit that makes them an annoyance, a public health problem and an excellent means of transportation, again, depending on who you ask. Many of the diseases that affect millions of people throughout the world, particularly the economically developing, tropical and sub tropical world, are spread by mosquitos. Malaria, dengue fever, west nile virus, triple E, chikungunya virus, yellow fever, a host of encephalitises, zika, all these are spread either from human to human, or from zoonotic (or animal) host to human, through mosquito bites.
The problem is that mosquitos exploit an ecological niche that includes us warm blooded nutritious humans, and are at the same time exploited by pathogens that use mosquitos to transport them around. Mosquitos are really just a proxy species for the pathogens we would like to rid the world of. A patsy. Purposeful extinction of mosquitos would be an attempt to extinct the pathogens that we would like to avoid. It is these pathogens that kill hundreds of thousands of people, mostly children a year, and sicken millions more. To return to that original question, are mosquitos good for anything—if you were to ask a malaria plasmodium, or a west nile viron, the answer would be a resounding yes.
It was John Muir who once said “When we try to pick out anything by itself, we find it hitched to everything else in the Universe.” * And Aldo Leopold said “To keep every cog and wheel is the first precaution of intelligent tinkering.” ** This classical American environmental thinking argues strongly against taking out an entire family of organisms, it's flipside is the same logic that hunted large predators to near extinction throughout North America. But I doubt the Muir and Leopold were thinking about malaria, and deep human suffering.
I think what my listener wanted to know is if we did succeed in taking out all mosquitos, would it initiate some kind of ecological collapse? Are mosquitos a keystone species? The answer is potentially no, especially when colored with the anticipated reduction in human suffering. With that card on the table it may be difficult to get a truly unbiased assessment. Which is doesn’t even take into account if purposeful extinction would be possible, though people are working hard on this front all the time.
I’d like to see us use our ingenuity to find a way to prevent contact between the disease spreading mosquitos and humans, rather than pursue what are likely to be toxic extermination methods. I think we can go a lot further to reduce human suffering and eliminate, what one scientist called, collateral damage. These are difficult philosophical questions—I appreciate you asking them. Keep them coming.
I include this for the table of mosquito borne diseases part what down the page: https://en.wikipedia.org/wiki/Mosquito-borne_disease
The journal Nature has addressed this very same question: http://www.nature.com/news/2010/100721/full/466432a.html
*From My First Summer in the Sierra
**From Round River: From the Journals of Aldo Leopold
Saturday, September 17, 2016
Note: This program first aired September 17, 2016.
Our bodies are over 60% percent water. We can only live a matter of days without water. Water covers 71% of the surface of this planet.
It should be no surprise that people attempting to live according to traditional, earth centered, non western value systems hold water to be sacred. Call them Indians, native peoples, first nation, aboriginal, tribal, many of these communities still hold to ideals that see water as the sacred blood of the earth, as the first medicine. And so it should be—all life depends on access to clean water.
Water is a polar molecule, making it a wonderful solvent, readily dissolving any substance that has an atomic electrical charge. Liquid water is fluid, and can easily transport any other fluid substance in it, even if that substance is non polar, having no electrical charge, and can’t dissolve in the water. Even if that substance is crude oil.
Crude oil is made up of a mixture of many different fractions of hydrocarbons, ranging from the heavy end with things like asphalt and paraffin, to the light end with things like the methane and propane, some of the constituents of natural gas. Crude oil contains other substances, related to the hydrocarbons we burn in our cars and furnaces, things you might have experimented with in organic chemistry class, like the aromatics benzene, toluene, and xylene. And even though the aromatics come from crude oil, something we typically think of as insoluble in water, these light fractions are soluble in water. They also have a low atomic weight, so they evaporate into the air quite readily as well. And worst of all, they are carcinogenic.
This is the kind of thing you think about when you learn that an oil transporting pipeline is about to be built through a river that is your source of drinking water. You think about the pipeline leaking, and the heavy fraction of the crude oil, being denser than freshwater, sinking to the bottom of the river, virtually impossible to clean up, and the lighter more soluble fractions traveling with the water to be taken up by municipal water systems down stream. You think about how common it is for pipelines to break, and in isolated rural areas how long it takes for people to notice.
These are the things I was thinking about as I stood in the rain attending a solidarity event for the Standing Rock Sioux tribe in North Dakota. The Standing Rock tribe has been protesting the fast track approval of the Dakota Access pipeline, its permitted path through off reservation sacred sites, and its crossing of the Missouri River, the drinking water source for the tribe and rural farmers and ranchers downstream. Native tribes from all over north America have been converging on the protest encampment at the Sioux reservation in a show of solidarity, and events like the one I attended, organized by Wabenaki leaders here in Maine, are popping up nationwide. You don’t have to be Native American to understand that water is sacred, though watching the Wabenaki prayer ceremonies made me realize that I lost the language of sacred connection many generations ago. Nor do you have to be a scientist to understand the linkage of water pollution and illness, and unfortunately I speak that language all too fluently.
Water is not unique in the universe, in fact the only reason we have it hear on Earth is that it came here the same way all the other matter on Earth did, as an aggregation of space dust and rocks. But water is what makes this planet unique, and what makes life possible on this third rock from the sun. The Standing Rock Sioux know it, and so do you.
Yep, pipelines do leak into rivers: https://usresponserestoration.wordpress.com/2014/06/20/as-oil-sands-production-rises-what-should-we-expect-at-diluted-bitumen-dilbit-spills/
People say these pipelines don’t leak. Really? http://www.npr.org/sections/thetwo-way/2016/07/25/487357502/canadian-oil-spill-threatens-drinking-water
Another one: http://news.nationalgeographic.com/news/energy/2015/01/150120-oil-spills-into-yellowstone-river/
A map of the pipelines: https://www.propublica.org/article/pipelines-explained-how-safe-are-americas-2.5-million-miles-of-pipelines
Saturday, September 3, 2016
Note: This program first aired on September 3, 2016.
Last week we talked about fungus, and they ways it makes a living in this world. The mushrooms we see in the forest are just the tip of the fungal iceberg, the vast majority of fungal biomass in the forest is subterranean. These are the bundles of fungal fiber called mycelium, and if the mushroom’s job is reproduction of the fungus, the mycelium’s job is to nourish it.
There are three ways that fungi can get food from the environment; they can parasitize another fungus*, they can decay organic matter, or it can form a relationship with a plant in an “I’ll scratch your back if you scratch mine” symbiosis called mutalism. We covered parasitism and saprotrophism earlier, leaving mutalism for today.
It turns out that many of those mushrooms you see erupting from the forest floor are from fungal biomass that is in direct relationship with the trees that make up that forest. The individual hyphal filaments that make up the mycelium, or all that fungal biomass beneath the surface of the soil, get up close and personal with the tiny root hairs, or rootlets from the tree and form what is called a mycorrhizal relationship, “myco” referring to fungus, and “rrhizal” referring to roots. Trees and their fungus typically form what is called an ectomycorrhizal relationship—meaning the fungus only just barely infiltrates the upper layers of the rootlet tissue, squeezing in between the cells of the root outer cortex, forming a sheath. The conjoining of the tree roots with the fungal mycelium effectively expands the tree’s root system by orders of magnitude, and even directly connects it to other trees of its species if the mycelium forms an ectomycorrhizal relationship with more than one individual.
Typically a fungal species has only one suitable tree species it can pair with, though often trees can have many different fungal partners. Many of the trees I see daily are obligated to form relationships with fungal partners; they cannot grow without the assistance of the fungus. Those groups include pines, oak, beech and spruce. Other tree species are facultative, and can grow without a fungal partner but grow better with one. Examples include maples, juniper, willows and elms.
I said this is an I’ll scratch your back if you scratch mine kind of situation, both partners benefit from this trans species contact. As I noted, the tree gets a major extension of its root system, gaining what one source called “hundreds of thousands of kilometers’ of individual hyphae, collecting water and inorganic nutrients from the soil. Essential nutrients like phosphorous and nitrogen are limited in the terrestrial environment, and the fungus is able to aggregate these and make them more available to the tree than they would be otherwise. The fungus also is able to collect water from the soil, though there can also be instances when the plant gives moisture to the fungus as well. And in some cases the fungus produces plant growth hormones, stimulating tree root growth. What we know for sure the fungus gets out of the relationship is carbon, in the form of sugar. 10 to 15 % of the carbon fixed by the tree gets channeled to the mycorrhizal partner. Both players are able to trade something they are good at getting from the environment for something they need, to the benefit of everyone.
This kind of relationship isn’t limited to trees and mushrooms. Many herbaceous plants and agricultural crops form mycorrhizal relationships as well, relationships characterized by even deeper infiltration of the fungus into the plant tissue. And in a totally different part of the world, coral reefs, we see the mutualistic symbiosis of coral polyps and photosynthetic plankton, swapping carbon in the form of sugar in return for inorganic nutrients. In a great example of convergent evolution, many realms of life species have evolved to swap resources in order to increase their competitive fitness. That is the cool thing about evolution, when something works, it keeps popping up independently on the tree of life.
So many of those mushrooms you see in the woods this fall, are part of a legacy of remarkable biological cooperation.
* or plants or even animals!
Saturday, August 27, 2016
Note: This program first aired on August 27, 2016.
Last week we looked at mushrooms, and talked about how they are the reproductive structures of certain kinds of fungus. Mushrooms are simply the above ground spore making structures of an otherwise underground organism, one made of miles of bundles of filaments called mycelium. If the mushroom’s job is to make spores, then what is the job of the mycelium, all the fungal biomass we don’t see? Just like in other realms of life, different life stages have different jobs for the organism, and the mycelial job is feeding. Fungus are heterotrophs like you and I, they rely on food sources outside of their bodies (unlike plants—which create their own carbohydrates). As heterotrophs we eat food, ingesting the complex material which is then broken down into smaller more accessible biological molecules and absorbed directly into our bodies in our guts. Fungus don’t have mouths or guts, but they still digest food using the same process. They excrete the digestive enzymes onto the material they are eating, and once that material is broken down into smaller molecules, it can be absorbed by the fungal filament. For example neither humans nor fungus can absorb cellulose, one of the primary molecules of wood, and much plant material. When humans eat cellulose, we call it insoluble fiber, and though it has health benefits, we don’t digest it and don’t get any nutrition from it. When the mycelium of certain fungi encounter cellulose, they are able to produce enzymes that break the cellulose down into the individual molecules of glucose it is made from. Fungi can then absorb the glucose, gaining nutrition from the cellulose. The ability to digest cellulose and lignin, the other primary constituent of wood, is one of fungi’s super powers.
There are lots of fungi out there, but we’ve been trying to limit our discussion to mushrooms—so do all mushrooms eat wood? No, in fact there are three different modes of nutrition for the mushrooms that we see out in the woods. The first, and least common, so we’ll get it out of the way, is parasitism. There are fungi that parasitize other fungi! Parasitism is a symbiosis that is typically thought to benefit one partner and have a negative impact on the other. The parasitic fungus benefits by stealing nutrition from the parasitized fungus. In our region the most common parasitic fungus you will see is lobster mushroom, which is a fungus that doesn’t make its own mushroom, but hijacks the mushroom of other species. I’ve talked about Lobster mushroom before on the show.
The second mode of nutrition for mushrooms is to be a decomposer or saprotroph. This is the default or ancestral mode of fungal nutrition, the ability to excrete digestive enzymes into the environment and break down complex organic molecules into simple (and thus absorbable) organic molecules is the hall mark of this kingdom of life. If it weren’t for fungi (and many bacteria as well), we would be overwhelmed with dead organic matter, and in fact life would stop because it would run out of raw materials. Fungi are the recyclers of the biological world, they process millions of tons of organic waste a year, turning dead material back into building blocks like carbon dioxide and individual mineral nutrients that can be used again by plants to make more food. The balance between the carbon taken out of the atmosphere by plants and the carbon put back into the atmosphere by animals, bacteria and fungi is what keeps climate relatively stable*, at least until plate tectonics changes atmospheric circulation** and weather patterns change, and throw that balance out of whack, driving extinction and more importantly evolution. Heady stuff for those little mushrooms along the trail.
I said there are three modes of nutrition for fungi, but we are out of time for today, so we will look at the third, and if you are a plant, most interesting mode, next week.
*Before the geologists get mad at me--Yes, the rock cycle plays a really important part in this as well--carbon going into and coming out of geological sinks like limestone...
**And influences the rock cycle by exposing or burying carboniferous rocks...
All the same ones as last week plus:
About external digestion: http://bugs.bio.usyd.edu.au/learning/resources/Mycology/Feeding/extracellDigestion.shtml
Still one of my favorite theories out there, even if it is now being challenged: www.scientificamerican.com/article/mushroom-evolution-breaks-down-lignin-slows-coal-formation/
Saturday, August 20, 2016
Note: This program first aired on August 20, 2016.
There’s fungus among us. Though it has been a dry summer, in the past few weeks, right after each heavy rain, on the trails I run I see mushrooms pushing their way up out of the forest floor. Russulas and Lactariuses, coral fungus and boletes, an occasional amanita and delicious chanterelles. And those are just the groups I can identify with relative ease.
Mushrooms are the reproductive structures of certain kinds of fungus, ascomycetes and basidiomycetes. There are many other kinds of fungus out there as well, but they don’t make mushrooms (think mold and yeast and a bunch of stuff that is essentially invisible to human eyes). As the reproductive structures of ascomyctes and basidiomycetes, they emerge when environmental conditions favor fungal growth. The timing of these appearances gives a clue as to what those favorable conditions are. It has been a dry summer, dry enough that all of the organic matter that makes up the upper layers of the forest floor is dry, and we’ve experienced a few small forest fires. Scary stuff in our dense, low fire frequency eastern forest. The mushrooms we see emerge after damp weather are the result of the action of billions of fungal filaments below ground in the soil. These filaments, called mycelium make up the bulk of fungal biomass, at least in terms of the mushrooms we see in the forest. The mushrooms are truly only the tip of the ice berg.
Mycelium are made up of even smaller individual filaments called hyphae, and grow through the soil in the forest feeding on organic matter. Like the fine hair like roots of plants, these microscopic fillaments don’t do well when the soil is very dry, their movement and metabolism are aided by the water that makes the soil damp. Hence, a nice flush of rain that wets the forest soil results in a boom of mycelial activity, and it is when compatible mycelium meet up underground that a mushroom results. Rapid increases in mycelium increases the chance of these meetings, hence mushrooms appearing overnight after wet weather. The mushroom’s only job is to create spores, which can result from sexual reproduction between those two compatible mycelia, and are a dispersal mechanism for fungus. Tiny and airborn, spores can travel great distances on air currents, and if they land in the right spot, can germinate and form a new hyphal strand. If that strand of hyphae finds what it needs it continues to grow and becomes multistranded mycelium. If it runs into another mycelium from the same species, and they are compatible mating types, they will merge and share their genetic information, and build a mushroom from this conjoined mycelium. In special cells in the mushroom (typically on the gills underneath the cap) meiosis will occur and the spores that are formed will contain a mix of genetic information unique from either parent.
If that is the job of the mushroom, what is the job of all that mycelium in the forest soil? We’ll answer that question next week.
Mostly books this time around:
David Arora, Mushrooms Demystified
George Barron, Mushrooms of Northeast North America
Lawrence Millman, Fascinating Fungi of New England
Elizabeth Noore-Landecker, Fundamentals of the Fungi, 4th ed.
James, Timothy (2007). "Analysis of mating type locus organization and synteny in mushroom fungi: Beyond model species". In J. Heitman; J. W. Kronstad; J. W. Taylor; L. A. Casselton. Sex in Fungi: Molecular Determination and Evolutionary Implications. Washington DC: ASM Press. pp. 317–331.
Saturday, July 30, 2016
Note: This program first aired on July 30, 2016.
This week’s show originated as a question from my nephew. He was wondering why hair turns gray. I have thought of that myself, as I sport a head full of white hairs, which started losing color far ahead of the curve early in my 20s. And the answer to the question is of course, complicated and partially unknown.
To start we have to look at where hair, and fur color comes from. Hair is made of several layers of a structural protein called keratin (the same thing your finger nails are made of). It grows from collection of cells, which some sources refer to as a mini-organ, called a follicle. The skin of most mammals is studded with hair follicles, it is a defining characteristic of the group. The color of hair is controlled by cells around the follicle called melanocytes, who’s job unsurprisingly is to generate a pigment called melanin. Melanin gives hair its color, by being injected into the filamentous protein we call hair, as it grows. The variety of hair colors we see in mammalian animals is determined by the mix and balance of different types of melanins, broadly speaking, eumelanins are black and brown, and phaeomelanins are lighter, reds and yellows.
Human hair has three develpmental stages: anagen or growth phase, which lasts for years, catagen or transitional phase, as the hair transitions from active growth to being shed, and telogen, a quiescent phase that ends with the hair fiber being shed. While we look mainly at what is going on with the hair itself, these phases represent dramatic differences in the functioning of the hair follicle. As the hair is growing in anagen, the melanocytes are pumping melanin into the hair fiber. When the follicle enters catagen, the first thing that happens is the melanocytes stop melanin production and undergo apoptosis, which is programmed cell death. Individual melanocytes then only get to produce melanin for a single strand of hair. Hair pigmentation shuts off in the transitional phase of hair growth, and if it doesn’t turn back on when the cycle starts over, the resulting hair that grows will be colorless, or white.
Now I said that not only does the melanocyte stop producing pigment, it actually dies, and in order for the next hair that grows to have pigment a new melanocyte has to form. And that is where the root of all this going gray as a normal part of aging happens. The new melanocytes arise from stem cells, melanocyte stem cells, which can mature into a pigment producing cell when needed. These stem cells continually divide and create more stem cells, so there is always a supply on hand when the hair follicle returns to the anagen active growth phase. The current thinking is that mammals go gray as they age because stem cells start to lose their integrity the older they are. The older you are the more damaged the cells in the melanocyte stem cell reservoir are, so the chances of a functional stem cell being able to mature into a pigment producing cell go down. The more times cells divide, the more chances there are for errors in transcription, the copying of genetic information. That is why age impacts cellular health, in general, the older a cell is, the more times it has divided. Cells only have so many times they can divide, before the telomere mechanisms inhibit further cell division and the cell effectively is put out to pasture. When we get very old, we don’t have any melanocyte stem cells left. Normal aging (which really means the changing of our cellular DNA, or shortening of our telomeres, that occurs during cell division) results in this decrease in stem cells, but cellular stress in the form of mutagens that damage DNA can as well, things like Xrays and UV light.
Many questions remain about this going gray business. The diversity of pattens of human graying is thought to be genetic but we don’t know why, and are there implications for other stem cells in the body, do all your stem cells function the same way? Why do dogs go gray around their muzzles but not other parts of their bodies? Why do some mammals not go gray at all? Many questions, fewer answers, but that is actually a good thing. If we had all the answers there would be nothing left to do. So please, keep your questions coming.
More than you ever wanted to know about hair: https://repositorium.sdum.uminho.pt/bitstream/1822/15299/1/2010%20Biology%20of%20Human%20Hair%20Know%20Your%20Hair.pdf
Saturday, July 23, 2016
Note: This program first aired July 23, 2016.
Ecosystems are like salad bars, you fill your plate with lots of leafy greens and then sprinkle lesser amounts of more concentrated food items on top (nuts, olives, bacon bits). Ecosystems have a similar food or trophic structure, at the bottom are the primary producers, the plants and other photosynthetic organisms, as you move up at each level there are fewer and fewer non plant individuals ( herbivores, omnivores and carnivores).
Land plants are the primary producers of terrestrial ecosystems, doing the work of capturing the sun’s energy on dry ground, they are the lettuce on the salad bar of the forest. And it turns out there are bacon bits here in the forest as well, in the form of caterpillars. As herbivores these organisms are able to transfer the energy that plants capture from the sun to higher trophic levels in the forest food web. That is what I learned listening to a talk from University of Delaware entomologist Doug Tallamy when he came to Maine to speak earlier this summer.
Tallamy’s work looks at the relationship between the primary producers, insects and the upper trophic levels, mainly birds. And what he has discovered has profound implications for the way we manage the landscapes directly under our control. It turns out that if you want birds around, particularly migratory song birds, you need insects, specifically caterpillars. These birds migrate thousands of miles to northern North America to breed, because of the plentiful food sources here.
Caterpillars, which are made up of fat and protein, are very nutrient dense and make up a huge proportion of that food for many of these birds. Tallamy recalled watching a pair of birds feeding their young, calculating that the nest of young birds were fed hundreds of caterpillars a day, thousands over the two week period they spent in the nest. And here is where it gets interesting, because if you want caterpillars around, caterpillars being the larval stage of lepidoptreans, the butterflies and moths, you need plants, because caterpillars eat plants.
But not just any plants, caterpillars generally eat specific plants, plants they have a long evolutionary relationships with. Plants do everything they can to not be eaten, evolving elaborate chemical warfare against hungry insects. Insects do everything they can to evolve physiologic means of evading the plant defenses, in an ever escalating evolutionary game, the relationship between the eater and the “eat-ee” gets more and more specific. We have all heard about the monarch butterfly and its host plant common milkweed, but many lepidopterans have this level of specificity with their target food source. Others are less specific and play the field, having relationships with plants in more than one genus. And plants are not monogamous, as the “prey species” in this relationship, they have many different insects trying to eat them, and can play host to tens to hundreds of different kinds of caterpillars.
What Tallamy and his lab have quantified is the number of different lepidopteran species (in the form of the caterpillars—which are the stage in which these insects do the majority of their primary production energy transfer) various genera of plants support. The results are astonishing. In my area, native tree genera like willow (Salix) and oak (Quercus) can support between 300 and 350 different types of caterpillars! Other native tree genera support nearly that many. The corallary to this is that nonnative trees and shrubs, frequently planted as part of “normal” landscaping, support virtually no caterpillars, because no native insects have evolved ways to evade these plants’ defenses. None. Insects are the animal that is responsible for transferring the majority of primary productivity from plants to the rest of the terrestrial food web. Birds, reptiles, amphibians, spiders, and rodents all rely on caterpillars as a food source. So if you don’t have plants that support insects, you don’t have anything else in the food web either. Biodiversity is our life support system, and what I learned from Doug Tallamy is that it starts from the ground up, in an elegant and fundamental relationship between those that eat and those that are eaten.
Doug Tallamy’s book on native plant landscaping in the suburban environment: http://www.bringingnaturehome.net/
Download the data from Doug Tallamy’s studies here: http://udel.edu/~dtallamy/host/
One of Doug’s popular science articles (slightly dated) but with interesting stats: https://www.americanforests.org/magazine/article/backyard-biodiversity/
Our local native plant advocacy group, Wild Seed Project, has lists of appropriate native plants (to Maine) for different environmental conditions: http://wildseedproject.net/using-natives-in-the-landscape-a-comprehensive-plant-list/
The native plant finder at the National Wildlife Federation site: http://www.nwf.org/nativeplants-beta/About (its a beta version--still a little buggy, no pun intended, for example, when I searched my zip code some high scoring trees did not appear, but when I searched them individually they showed up in my zip code…)
Nutritional info on caterpillars: http://healthland.time.com/2013/08/21/why-eating-bugs-is-good-for-you-its-about-the-nutrients/slide/caterpillar/
Want to eat some bugs yourself? Here’s a list of internet resources: https://edibug.wordpress.com/where-to-get-bugs/
Saturday, July 9, 2016
Note: This program first aired on July 9, 2016.
I’ve been spending a lot of time lately thinking about
bumble bees, watching which flowering plants they visit and which they don’t,
looking at them trying to discern one species from the next, and learning when
they like to fly and when they don’t. I’ve volunteered to survey bumble bees
for the Maine Bumble Bee Atlas project and the learning curve has been steep.
The entomologists who direct the project are evidence of the fact that the
rabbit hole you can go down when you open your eyes and start to see the insect
world all around you has no bottom. Arthropods are the most successful phylum
of animals on the planet, and there is no shortage of wonder to be pursued in
their diversity. For me it seems bumble bees may just be the beginning.
|A worker bee, temporarily interrupted from foraging.|
One place to start is with their life history. I’ve kept honey bees on and off for a few years and thought that bumble bees worked the same way, albeit on a smaller scale. I was wrong. Bumble bees, like honey bees are true eusocial insects, meaning they live in colonies that have castes of workers with behavioral specialization, communal care of brood, overlapping generations, and reproduction limited to a few specific individuals (often a single queen and specially raised males). Bumble bees live this eusocial life in a way very different from the European honey bees many of us bee keepers are familiar with.
Bumble bee colonies over winter as queens, the large, mated reproductively active females that are raised and mated the fall before. When the weather turns cool these individuals search out an overwintering spot, in leaf litter at the edge of the forest. These are well fed bees, having been raised on the bountiful nectar and pollen from the late season golden rods and asters. These queens emerge in the spring and are the stock from which the new colonies form. The only bumble bees that survive the winter are the queens, colonies do not over winter, workers do not over winter. Only single bees do, prepared to start a brand new colony of their own the next year.
So those first really big bees you see flying in the spring are the over wintered queens. They emerge and look for a spot in which to nest, a spot that will house their modest colonies for the summer. Old rodent burrows are especially good spots, as apparently are the seat cushions of the old abandoned cars in the woods you see frequently in Maine as early 20th century farmsteads are reclaimed by forest. Once a queen finds a good nest cavity, she lays the first of her eggs (remember she mated the fall before, so she has all the sperm she needs to lay fertilized eggs), She incubates them herself by generating heat shivering, and feeds the larva nectar and pollen when they hatch. One bee foraging to feed several hungry babies though does not quite cut it, so the first round of bees that are produced by the queen are quite small. These are the first worker bees you will see in the spring, they look stunted, and quite literally they are—nutritionally they got enough to survive but not really thrive. Once there are more workers in the colony, the subsequent larvae get fed better, and the resulting bees are bigger. This pattern continues throughout the summer, the queen lays eggs, staying in the nest once there are enough worker bees to do the foraging, the workers out in the field collecting the nectar and pollen needed to sustain the hive. Workers live around 25 days, and a typical hive has between 50-100 bees when up and running during the summer.
At the end of the summer, two different kinds of bees get produced by the hive. The first are males—these come from unfertilized eggs. They have one purpose only, that next year’s queens can get fertilized before hibernating. The others are the new queens. The last batch of worker bee eggs that are laid become the queens for next year. Theoretically the hive is at its highest capacity at the end of the summer, the land is covered with golden rod and asters and thus there is plenty of forage, and many workers able to feed these up and coming queens. Once these very large nascent queens emerge, they mate with the males which also unsurprisingly emerge at the same time. As fall progresses on, the old queen, the founder of the colony, dies. Her daughters, the worker bees, all die. Her sons, the males, all die. The only bumble bees that don’t die are the new queens, well fed and stocked with sperm, ready to over winter in the leaf litter until the process starts over again in the spring.
It’s a pretty remarkable process, and something to consider when you clean up your yard in the fall. Do the bumble bees a favor, leave those leaves where they are until the spring, in doing so you create safe space for the potential bumble bees of the future.
On eusocial insects: https://www.amentsoc.org/insects/glossary/terms/eusocial
The Maine Bumble Bee Atlas project: https://ac41277bd54735c2b85336aff6fdfbfd153fcee3.googledrive.com/host/0B985dSJVRA1maGtVekhDUkJjYWM/
The Maine Bumble Bee Atlas project: https://ac41277bd54735c2b85336aff6fdfbfd153fcee3.googledrive.com/host/0B985dSJVRA1maGtVekhDUkJjYWM/