Bumblebee Declines in the United Kingdom

Bumblebees the world over are threatened. Nowhere perhaps, is this better documented than in the United Kingdom. The level of scientific, public and amateur interest in bumblebees there is among the highest in the world. So the British have good records on their bumblebee populations, some of them dating back over a hundred years, The UK even has a not-for-profit organization dedicated to preserving native populations, The Bumblebee Conservation Trust.

And here's the sad truth that has been discovered. Although the UK currently has a relatively diverse bumblebee fauna, with 24 species, only six of these remain relatively common while over the last 70 years the rest have declined to varying degrees. During that period, two species have become extinct in the region. The survival of a further six species is so endangered they have been designated priority species under the terms of the UK Biodiversity Action Plan.

Local bumblebee supporters are highly active in trying to preserve species that, like the Shrill Carder and Great Yellow Bumblebees, have become rare and exist only in a few isolated populations. And they have discovered, with great delight, that one of the species now extinct in the UK, the Short Haired Bumblebee, still survives in New Zealand, because it was introduced there in the late 19th century in order to pollinate clover crops. Now a conservation group called Natural England is undertaking to transplant individuals of the lost species back into the UK in order to re-establish the former populations.

Other events are on the move as well. A European species called the Tree Bumblebee that was never present in Britain before has now invaded the country from the south coast and is heading northward.

Things are changing fast for crop pollinating bumblebees in the UK and only a vigilant monitoring program will provide enough information to know which bees to try and help, and when.

[The photo is of the Tree Bumblebee, by Rasbak, Creative Commons and GNU licences]

Bumblebee Colors

Colors? What colors? Bumblebees are black and yellow, right?

Well yes, many of them are. But lots of bumblebees have brown, red, and white colors as well.

And even when black and yellow, most bumblebees do not fit our popular, oversimplified image of alternating black and yellow bands around the body.

In fact the patches of color that decorate the bumblebee's generally black body can appear in a vast variety of patterns of varying complexity.

Central to this issue of bumblebee color patterns is the fact that there are many different kinds, or distinct species, of bumblebees. Who knew? When I was a kid, even though I was wise to the different species of butterflies that I saw visiting flowers, I thought all bumblebees were the same. And I'm sure this is true for most people. Scientists, however, have discovered about 250 species worldwide and around 50 in North America alone. The first clue to understanding this tremendous bumblebee diversity is noticing the variety of color patterns they display.

Students of the bumblebee have discovered that most individual species can be identified primarily on the basis of the color pattern. That means that the color patterns of different species are different from each other most of the time. There are a number of factors that tend to confuse the issue, but we'll get to that in a moment. For now, all we need to recognize is that most books, websites and identification guides to bumblebees use color patterns as the most important means of distinguishing one species from another.

Here's how the observation of color patterns works. First we start out with a silhouette of the upper surface of the bumblebee body in diagrammatic form. The silhouette is all black, as that is the basic color of the exoskeleton in these insects. The main body parts shown are the head, thorax and abdomen. The individual segments of the abodomen, six in queens and workers, are numbered from front to back as T1 through T6. In this numbering system, the 'T' stands for 'tergite,' the anatomical term given to the exoskeletal plate that forms the upper surface of each abdominal segment.

Then, on top of the basic silhouette are added a number of colored areas... various shades of yellow, red, brown and white. These colored areas correspond to dense patches of hairs, referred to as pile, occurring on the body. The shape, color and location of these patches is what determines the overall color pattern.
Using this system to take a quick look at some of the color patterns of different bumblebee species not only provides a useful starting point for identification, it is a breathtaking reminder of the diversity of ecologies and lifestyles these pollinators have evolved.

Postscript: The simple correspondence between a single color pattern and a single bumblebee species is complicated by three facts of life in the bumblebee world - polymorphism, Mullerian mimicry and cryptic species. More about these issues in later posts to this blog. [Images copyright (c) Dave Barr, 2010]

Bumblebees on The Web

Not a spider's web, of course. Most bumblebee queens and large workers are strong and heavy enough to extricate themselves from a spider's web. Although the smaller workers could easily be trapped, one seldom sees them suspended from an orb web. Perhaps their defensive sting convinces the spider to cut them out, or perhaps they are just good at sensing and avoiding the spider webs in the first place.

Today's posting is actually about bumblebees on the World Wide Web. Fortunately there is loads of good information out there, and all freely available too.

The place where every bumblebee afficionado should start is Bumblebee.org (http://www.bumblebee.org). This site aims to be the textbook of bumblebee biology, providing detailed information that is well illustrated. Here you can find out about bumblebee anatomy, nests, life cycles, feeding, foraging, behavior, economic importance and much, much more. The focus is on British species, but most of the biological information applies to species found in the rest of the world as well. The color patterns of North American bumblebees are illustrated, so you can make a start at recognizing species on both sides of the Atlantic. That's one of the great photos from Bumblebee.org on the right.

If, on the other hand, you just want a quick overview, try the Wikipedia page: http://en.wikipedia.org/wiki/Bumblebee

Learn about some of the conservation issues for bumblebees, especially in Britain, at the Bumblebee Conservation Trust [http://www.bumblebeeconservation.org/index.htm], and for North America at the Xerces Society [http://www.xerces.org/bumblebees/].

Information on Bumblebees of The World is featured at the Natural History Museum (London) [http://www.nhm.ac.uk/research-curation/research/projects/bombus/]. And you can see some great, hi-res photos at: http://www.cirrusimage.com/Bees_bumble.htm

How Can A Bumblebee Fly? - New Insights

Almost everyone has heard the story (probably meant to discredit science) of how scientists have calculated that the bumblebee cannot fly. All bumblebees, as everyone knows, can actually fly quite well.

Explanations of the origin of this humorous story vary, but it may be based on the principles of flight that apply to the earliest fixed-wing aircraft. In those early planes the weight that could be lifted was roughly proportional to the surface area of the wings. Now bumblebees, when compared to butterflies or locusts have rather small wings in proportion to the size of their bodies. Obviously, any comparison to a fixed wing aircraft is misleading.

Instead, bumblebee wings, as it turns out, seem to have more in common with helicopter blades than with airplane wings. Watch this short YouTube slow motion video to see the bee using its wings to fly up, down, sideways and even backwards as it navigates around a flower blossom - http://www.youtube.com/watch?v=dNZLyW6ZEaY. The wings beat, or oscillate at high frequency and those oscillations create a vortex (like a mini-tornado) in the air above the wing. The vortex produces considerably more lift than a fixed wing, thus allowing the bumblebee to escape the limitations of the Wright brothers' craft.

Like all bees, bumblebees have two wings on each side of the body. But the two wings on the same side are coupled together with a row of microscopic hooks so that they move as one. Using a wind tunnel and smoke streams, biologists at Oxford University have recently demonstrated that in flight the wings on one side operate independently of those on the other side - http://www.sciencedaily.com/releases/2009/05/090507194511.htm. This means that the bee beats its way through the air, rather than gliding forward with a smoothly coordinated rowing or gliding motion.

The flight of the bumblebee may be inefficient, but it probably makes the insect much more manoeuverable, allowing it to turn quickly from one blossom to the next, and weave its way among flowers dangling close to each other. And they seldom fly far. Most foraging flights are less than 500 metres from the nest.

Saving Native Pollinators

This afternoon I attended a webinar given by Ted Leischner who has been a commercial beekeeper and is now actively involved in monitoring and communicating about native pollinator species. To the right you can see one of his slides (used by permission) highlighting the importance of bumblebees.

The webinar, entitled "What Happens When the Honey Bees Disappear," was organized by the Certified Organic Associations of British Columbia (http://bit.ly/aqADU0).

About 75% of the 240,000 species of flowering plants on earth need pollen transfer services from animals to ensure their survival. The equation is a simple one: no pollinators = no fruits and vegetables for we humans. As animal pollinators disappear, so will the plant species that depend on their pollination services.

In agriculture we have come to depend increasingly on commercially managed honey bees to pollinate major crops like almonds, apples, blueberries, canola and peaches. But as Leischner pointed out, honey bees are in trouble. Due to Colony Collapse Disorder and the inroads of Varroa mites and other parasites and pathogens, over 30% of honey bee colonies are being lost each year. So "what happens," Leischner asks, "when the honey bees disappear?"

His answer is simple and direct. We have to be prepared to depend more on native pollinating insects, mostly various species of bees, for help in sustaining earth's ecology and the security of our own food supply. Unfortunately, native pollinators are under pressure and experiencing decline themselves. The 2007, multidisciplinary report on the Status of Pollinators in North America (http://bit.ly/dqxUyu) concluded that many pollinators are in decline and discussed the causes and consequences. The biggest culprits seem to be industrialized, monocultural agriculture and the loss of habitat and food resources everywhere.

Leischner wants us to start now by learning more about native pollinators and their needs. Then we can begin to reverse their decline by providing the habitat and flowering plant resources native pollinators need to survive. Helping them is not only helping the ecosystem, it is helping ourselves as well.

In all of this, bumblebees play a key role. Some species are clearly endangered, threatened with extinction, both in North America and Europe. Bumblebees are major players in the production of human food. They participate in the pollination of some 50 species of crop plants (http://bit.ly/16SG0g). Along with the rest of the native pollinators, we need the bumblebee.

You can get in touch with Ted Leischner at tleisch@telus.net or 250-499-9471.

Meet The Bumblebees

Bumblebees are one of the most familiar insects visiting our gardens and parks. Just about anywhere you find flowers growing in temperate regions of the world, you will find bumblebees. These big, fuzzy, black-and-yellow bees buzz from flower to flower, lapping up nectar with their tongues and collecting the pollen that adheres to the dense layer of hairs covering most parts of their bodies. Almost all of us can recognize a bumblebee on sight.

Bumblebees are pollinators, a critical link in the reproduction of huge numbers of flowering plants, including many of those that supply the fruits and vegetables in the human diet. So bumblebees are part of the web of natural organisms that sustain all life on earth.

But bumblebees are in trouble. Their numbers are changing rapidly and they need our help.

In this blog we will be exploring the world of bumblebees and trying to discover what we have to do to ensure that these native pollinators will continue to fulfill their critical role in the ecosystem we all share.

[Image copyright (c) Dave Barr 2010]