Friday, December 24, 2010

Merry Christmas from the Home Bug Garden

The Dragonfly Woman has a nice post on what insects you might see on a white Christmas. The only one of those true insects that we have recorded in the Home Bug Garden, a winter stonefly in the family Taeniopterygidae, is from the day after the last frost on 5 May 2005. Although the Last Spring Frost has since moved closer and closer to the end of May (with a light frost on 1 June of this year) along with the snow, we like to think that we will some day see early springs and winter snowflies without snow again. Meanwhile, we really should start looking for ‘snow fleas’ (aka springtails, Collembola). With the snowpacks we have been getting, it is highly likely that lots of tiny arthropods are going about their business under the snow where temperatures may be hovering around freezing and that some of these will follow the tiny channels to the surface where they can offer us a bit of diversion over the long, long winter.
Meanwhile, on reviewing the HBG portfolio, it looks like the beetles are the bugs with the most Christmas colour, so here follows a small sampling of festive red, white, and green from over the years. We’d also like to wish all of our fellow bug bloggers, those obsessed few who have challenged the stereotype of blogs as cesspools of political invective and made each morning’s readings an uplifting experience, a Merry Christmas & Happy New Year. Among that long list, we’d especially like to thank Ted MacRae at Beetles in the Bush – our first visit each morning; The Bug Whisperer – our local hero, the multi-talented Adrian Thysse; the anonymous, always interesting, and often annoying Bug Girl’s Blog; and finally, the master of bug blogging, the one and only Myrmecos (aka Alex Wild). To each and all bug bloggers a joyous and interesting bug-filled New Year.

Saturday, December 11, 2010

Rugged up until Spring: A Mammalian Digression

 By the calendar it isn’t winter yet, but winter weather closed down the last lingering greenery in the Home Bug Garden in November. Temperatures plunged to -29 C (-20 F) and the North Saskatchewan River froze over 3-4 weeks ahead of schedule. Other than the occasional fungus gnat in the bathroom or spider in the basement, that is it for this year’s bugs: same for the Moose Pasture. Last weekend the snow at the MP wasn’t quite deep enough for snowshoes, but the thermometer had registered -32 and even birds were few and far between. The only sign of insects were the honeybee hibernation hotels. So, my choice this Saturday morning is either shovel the snow off the driveway or invent a post on the HBG. If only all of life’s choices were so easy!
 One thing still in evidence at the Moose Pasture last weekend were its mammals. And since there were mammals, of course, there were arthropods, because mammals are a year-round tropical beach for their arthropod ectoparasites. Well, at least for those that take up residence, as opposed to just stopping by for a meal (fair weather fiends). Ditto for the Home Bug Garden’s mammals or at least those that live outside. We HBGardeners like to think of ourselves as bug-free zones and, except perhaps for the transient mosquito and resident follicle mites (and let’s just not think about them) we are and so are our house-bound cats. But that isn’t true of the ‘native’ mammals: each is the potential home to several species of lice, fleas, mites and ticks.
 So, let’s take Middle Earth Garden’s question one step further and see how similar the HBG is to the MP in terms of mammal habitat for bugs. Now, we don’t actually do much mammal collecting, so our estimate will be mostly theoretical, but it seems a reasonable comparison (and much better than shoveling the driveway).
 If you were to look out at the front of the HBG this morning, you’d see a garden covered in snow and crisscrossed with tracks. Among these are a few cat paws, bird claws, and squirrel scratches, but the vast majority are contributed by one animal: the White-tailed Jackrabbit (Lepus townsendii).
 Jackrabbits are born ready to run and adults don't make burrows, but get by with resting in a slight depression in the soil or snow, so their contribution to the arthropod fauna would be limited to their ectoparasites (mammals that den or burrow are much more arthropod friendly). These are big hares – to 5.4 kg (12 lbs) and over 2 feet in length – and they pay no attention to cats and little attention to people. Dogs do give chase, but with top speeds of over 70 kph (Wood et al. 2006), one tends to feel sorry for the dogs (unless they are trampling the garden). If a dog, or more likely a coyote, does get close, jackrabbits are capable of sudden near 90 degree turns – and their black tipped ears go one way while their bodies go the other, with the coyote left snapping at a vanished ear and the jackrabbit vanishing in the other direction.
 While limited to open areas and rare outside the City (<1 per 4 km2), White-tailed Jackrabbits thrive in residential areas of Edmonton with densities averaging about 4 per km2 in the winter (Woods et al. 2006) or about 1300 shrub snipping hares. I regularly see a half dozen or more of these nocturnal munchers during my pre-dawn walk to work. Anything in the Rosaceae except spiny roses seem to be a preferred winter browse, so every autumn I have to spend a day putting wire cages around the saskatoons, cherries, crabapples, and chokeberries or they will be eaten down to the snowline by spring. In comparison, the Moose Pasture has no jackrabbits at all, but does host a few Snowshoe Hares (Lepus americanus). These also are nocturnal, but somewhat smaller and prefer forested cover. I sometimes see one in the River Valley and we often see their tracks at the Moose Pasture, but they do not make it into the HBG.
Coyotes (Canis latrans), however, do occur both here and at the MP, although only as transients in the HBG. Some estimate that 600 reside in the City. I see one every now and then on the way to work or coming home late at night and always make a point of giving it a chase (well, I try to look threatening anyway). Attacks on people, usually children, joggers, or someone walking a meal (aka small dog) are rare but increasing in frequency as coyotes learn to associate people with food rather than fear (Timms et al. 2004). Coyotes may eat more house mice than house cats, but the telephone poles littered with posters of missing cats bear mute testimony to another aspect of their diet. At the MP coyotes are very common - it sounds like 4 packs (probably male-female pairs with young) are within howling distance - and their tracks, turds, and the occasional bloody remains of dinner are everywhere. Since coyotes also dig dens, as well as produce feces and bits of carrion, they contribute significantly to the arthropod fauna of the Moose Pasture. We watch them watch us, but in the country they know that people are dangerous, so we camp amongst them with little concern.
That attitude would be inappropriate for the two largest carnivores in the region. Both cougars and black bears wander through the Edmonton River Valley on occasion, but were generally considered extirpated south of the River. That is no longer true and our MP neighbours, especially the beekeepers, were treated to a bit of ursine drama two summers ago. Fortunately, no one was hurt and losses were limited to bees (wiped out) and damage to homes (and to bears) and to Disneyesque views of Nature. The new hives are now protected by scarebears (apparently somewhat effective), electric fence (ineffective), and relocation to the middle of cleared agricultural areas (very effective if you have such land).
The cougars have yet to cause a problem (but see David Barron’s excellent book) and probably subsist primarily on the large population of White-tailed Deer (Odocoileus virginianus). Mule Deer should also be in the vicinity, but we have yet to see any. Larger, but not as numerous, is the largest member of the deer family: the Moose (Alces alces). We have at least 5 moose that wander the MP, but fortunately for our shrubs, none in the HBG and only rarely have we seen deer nearby. In the spring after the snowpack melts, the ground at the MP is covered with piles of decomposing moose and deer pellets that support a diversity of beetles and flies (and fungi).
 Although moose are potentially dangerous, they are more likely to hurt us if we crash our car into them, then if we upset them some other way. In Alberta, you are far more likely to be killed or maimed by a car, then by all of the wildlife put together (including West Nile Virus vectoring mosquitoes). However, the Moose Pasture does have one significant wildlife danger to those camping there – being crushed by a beaver-felled tree.
Of all of the mammals in Alberta other than people, beavers clearly have the greatest impact on the environment. They also probably contribute more to arthropod diversity than any other mammal. They build and inhabit large, permanent lodges along with their fleas, parasitic beetles, and a host of detritivores. The meadows they flood eliminate some insects, but the new marshes support hosts of dragonflies, damselflies, water bugs, beetles, and more.

The trees beaver fell are a bonanza for beetles, flies, parasitic wasps, and anything that likes to nest or hide in decomposing wood. Beaver love aspen and will clear it as far from water as they feel safe. This opens up browse for moose and deer, but also spots for herbaceous perennials to bloom and feed more bees, wasps, beetles, butterflies, and moths. The cleared, sun-warm ground is a boon for ants and ground nesting bees and wasps. If you like arthropods, then you should love beavers – just don’t set your tent up anywhere near an aspen or poplar.
 Muskrat benefit from the marshes beavers create and smaller rodents benefit from the open areas covered in herbs and grasses. Deer Mice build burrows and our bumblebees like the abandoned burrows for nesting sites. Voles with their mites and fleas graze on the grasses and herbs that sprout amongst the stumps and most everything is both changed and generally more diverse when beaver are present.
This beneficial effect is especially true during one of the frequent droughts in the Parkland when lush, verdant areas are restricted to around beaver ponds. Porcupines may benefit indirectly, since they like birch and beaver don’t, so the prevalence of birch may increase with beaver present (and with that all the birch-loving insects).
 Beaver are a bit ornery and noisy (it takes a lot of gnawing to bring down a tree – which can make for a restless night), and if you like trees and meadows they are harder to appreciate, but as far as mammals go, they seem a boon for arthropod biodiversity.
Well, I suppose that is enough effusion about beavers for the moment. The Home Bug Garden has no Castor canadensis and few of the other mammals that inhabit the Moose Pasture. Alberta has about 90 species of 'native' mammals and almost half of them (>40) show up at Elk Island National Park, so several more of these will show up at the Moose Pasture if we get serious about finding them.
Not all of these would be welcome in the Home Bug Garden, and I would put deer and Deer Mice at the head of that list.
Even without these peculiarities of taste, mammal-driven biodiversity gets short shrift in the Home Bug Garden. Except, of course, for the only mammal more potentially arthropod biodiversity friendly than the beaver: the naked ape! In my own small way (and usually well clothed) I have made this small lot more diverse and bug-friendly and I guess that will just have to do for the mammal contribution for the moment. Good fences make for good neighbours, and the fewer mammals in the HBG, probably the better for all.
Baron D. 2005. The Beast in the Garden: The True Story of a Predator's Deadly Return to Suburban America. W. W. Norton & Company.

Timm RM, Baker RO, Bennett JR & Coolahan CC. 2004. Coyote Attacks: An Increasing Suburban Problem. pp. 47-57, in: Proc. 21st Vertebr. Pest Conf. (R. M. Timm and W. P. Gorenzel, Eds.) Published at Univ. of Calif., Davis.

Wood JR, Krenz J & Boyd-Zhang T. 2006. Urban White-tailed Jackrabbits of the Edmonton Region (1992-2002). pp. 119-133, in: RW Wein (Ed). Coyotes Still Sing in My Valley. Spotted Cow Press.

Friday, November 26, 2010

Aculeata Agonistes: Bombus Squared & Gone?

Herein, I begin my bumbling through the subgenera and species of Bombus in the Edmonton area with what seemed like an easy start: Bombus (Bombus). Thanks to the online resources that Paul Williams has created at the British Museum of Natural History website, I know that only 11 of the 250 or so recognized species of bumble bee belong to the nominate subgenus – less than 5%. Also, selecting the Nearctic Region from the key, I can reduce this to 4 possible species, albeit with 21 different colour forms. However, according to Richards (1978 – see citations at end) Alberta is abuzz with 21 species of Bombus – how can I tell if any of my bees are Bombus (Bombus)?
The best solution would be to ask a specialist on Bombus and preferably one with knowledge of the local fauna. Alas, no one I know will admit to such knowledge. I could try Calgary – there are bumble bee ecologist there - but here the response from the hymenopterists here has been to bugger off and learn them myself, they have more than enough to do already (which is probably what the Calgary ecologists would say). This is called a ‘taxonomic impediment’ (TI) – a well-known problem to overworked taxonomists and frustrated people who need identifications, but seemingly of limited interest to most of the world. For example, Google comes up with less than 60 thousand hits for ‘taxonomic impediment’, but 27 times as many (1,610,000) for ‘bee decline’.
For those who haven’t heard of TI before, here’s a definition from an Australian source that is more than 15 years old: “The taxonomic impediment to progress in the study of biodiversity is linked to a worldwide shortage of taxonomists who can be called upon to identify species, describe species that are new to science, determine their taxonomic relationships, and make predictions about their properties.” And, 15 years later, if you are interested in how Canada is dealing with TI, then you are in luck: last week the Council of Canadian Academies released Canadian Taxonomy: Exploring Biodiversity, Creating Opportunity. You can download the 4mb pdf for free – but to make a long story short: “Job openings in taxonomy have virtually ceased’ ‘Canada’s ranking [in taxonomic publications] dropped from 6th in the 1980s to 14th in the 2000s’ ... [and most relevant to this post] ‘pollinators provide a crucial ecosystem service (via fertilization of crops) to agriculture, yet there is a growing taxonomic expertise gap in pollinator identification.”
Okay, I get the point – the Government may tut-tut about the shortage of taxonomists every decade or two, but better look elsewhere for a solution. Is there a generous specialist from some more enlightened elsewhere with a pro bono bombology streak? Well, one could submit pictures to BugGuide where John Ascher seems to have the talent to name that bee. For example, The Bugwhisperer’s recent spectacular photo of a Bombus melanopygus ménage à trios now resides name and all on BugGuide. The BugGuide route is tempting, but Dr Ascher probably has more than enough to do as it is. In theory, I have some skill with arthropods, small though it may be, and it’s not like I’ll be seeing any new bumble bees before May. If I could make a small, local contribution to the pollinator expertise gap, then it would be a pleasant break from shoveling snow.
So, what lies ahead? Richards (1978) reported that 15 species of Bombus could be found in Aspen Parkland in southwest Alberta. That is a pretty good diversity considering that Donovall & van Engelsdorp (2010) found records for only 17 species of Bombus in the entire state of Pennsylvania and Grixti et al. (2009) only 16 for Illinois (and four of these appear to be locally extinct). I don’t know if a similar diversity survives in the lower elevation (~700 m) former Aspen Parkland of the Home Bug Garden, but this is mostly because we HBGs have been loathe to collect and kill. Instead, we flutter around flowers with our cameras capturing many a mysterious mugshot. I’ve spent much of my spare time the last few weeks perusing BugGuide for matches, but I’ll be buggered if I can identify many pictures with any certainty. That leaves the Laverty & Harder, Discover Life, and BMNH keys (see previous post for links). The authors of these keys, however, expect you to know all the characters they think important, not just those you happen to have photographed clearly.
The keys also are written with the expectation that you to have a bumble bee in hand, and not some faker. Discover Life does have a Bumblebees & Mimics Key with some of the likely mistakes. Robber flies (Diptera, Asilidae, Laphria spp.) and hover flies (Syrphidae) such as Volucella bombylans are the mimics with the mostest – but as with the drone flies discussed in the previous post, the wings, head, and antennae give away their true fly identity. Also, any ‘bumblebee’ eating another insect is not a Bombus. If you live further south, you could be fooled by large carpenter bees in the genus Xylocopa especially the Eastern Carpenter Bee X. virginica, but they do not make their homes in Alberta. We do, however, have several bumblebeeish solitary bees, e.g. some digger bees (Andrena) and mason bees (Osmia). All I can say is that most bees do not resemble Bombus except in the most bee-general way, and those that do are only as large as the smallest bumble bee workers, their fur isn’t as brightly coloured, and they never have orange bands (but a red thorax is possible).
Bumble bees themselves indulge in mimicking each other which leads to convergence in colour patterns between species: mimicry complexes that emphasize the “don’t mess with me” message of the boldly contrasting bands of black and brightly coloured hairs (the skin itself is invariably black). Self-mimicry is probably the primary non-taxonomic impediment to bumble bee identification. So, if one wants to pursue the species identity of the local Bombus, you need to take one of two routes: (1) collect, kill, and pin a good selection or (2) take lots of photographs of individuals from every angle. If one really wants to get serious about Bombus identity, then you need to consider being even more intrusive than the TSA and pulling out the genitalia of the males for inspection. Male claspers are a useful guide to Bombus subgenera and probably to species. Williams at the BMNH provides a rather Andy Warholish gallery of dissected male claspers. I’m sure this is a worthy project, but at my level of understanding, I can’t say that the images are of much help. However, the Home Bug Garden has now become a dangerous place for lazy, shiftless drone bumble bees (the corpses of whom are destined to repose in the Royal Alberta Museum – where irrespective any names I rightly or wrongly put on them, they will contribute to a record of what lived here at this time).
So on to our first subgenus Bombus (Bombus) – a mere 11 species worldwide and only 4 in the Nearctic. Range and unique colour patterns can be used to eliminate three of the four species from my female Bombus. That leaves Bombus (Bombus) terricola looking like some of my bees. A good colour pattern character is that the upper side (tergum) of first and fourth segments (T1 and T4) of the ‘abdomen*’ are covered in black hairs and the second and third (T2, 3) with yellow hairs (remember the skin underneath is black). This contrasting yellow-black pattern, I suppose, accounts for the common name Yellow-banded Bumble Bee. No other local Bombus have this specific pattern, although many are black and yellow. The only local Bombus with the first abdominal segment black belong to the subgenus Psithyrus – cuckoo bees that usurp young colonies of species in other subgenera of Bombus – and these kleptoparasites also have black-haired second abdominal terga.
Among those bees pinned and pictured are a few with a black-yellow-yellow-black abdominal pattern and also a yellow-black thorax and other characters consistent in all three keys = Yellow-banded Bumble Bee Bombus terricola. One of my pinned specimens is a TSA’d male and the genitalia match the BMNH picture. However, on double checking for somewhere I may have gone wrong, I found a species on BugGuide - Bombus occidentalis – that is not present in the Williams’ key. A little searching on other pages of the website discloses that current research suggests that occidentalis and terricola may be one highly variable species, which helps explain the 13 different colour form pictures in the Williams’ key for terricola. This would be a bit annoying if I had colour morphs attributable to occidentalis (especially since Bertsch et al. 2010 think they are both good species) but I don’t. The reason that I don’t is probably because (a) occidentalis was restricted to southern Alberta (Hobbs 1968) and (b) this once common species has essentially disappeared in the last two decades (Evans et al. 2008).
Now that we have an id, what can we say about our bee? Well, Laverty & Harder (1988) list it as an underground nester (places like rodent burrows are good) and with early spring emerging queens. Like all bumble bees, Bombus (Bombus) terricola is considered a long-tongued bee, but all is relative: our humble bee is rather short-tongued. This means that terricola can pollinate only relatively shallow flowers or those that require buzz pollination. But as Laverty & Harder point out “queens and workers commonly bite holes in flowers with long corolla tubes”. Technically, this makes terricola a nectar robber and not necessarily the best pollinator in an ecosystem. Also, terricola seems to be a bit lazy when it comes to foraging from shallow flowers – it prefers to walk when it can, rather than fly.
Plowright & Plowright (1998) noticed that at a site in Ontario where B. terricola and B. ternarius (one of the orange banded bees in the subgenus Pyrobombus) were foraging at the same time, terricola was confined to the milkweed Asclepias syriaca L. – a plant with a dense cluster of upright flowers – and ternarius to the dogbane Apocynum androsaemifoliurn L. – a plant with loose clusters of pendulant flowers. At another site without milkweed, however, both species foraged together in dense patches of dogbane. Their observations and experiments demonstrated that B. terricola is relatively inefficient at flying between flowers, and so tends to visit dogbane only in areas where the plants are dense and closely spaced. Also, Williams et al. (2008) note that Pyrobombus species are noted for their ability to forage from hanging flowers, no doubt giving them an advantage when there is no easier alternative.
All this is interesting, but the place that B. terricola most often shows up in studies is where it isn’t showing up at all – this is one of the species that appears to be disappearing. What could account for the decline? Perhaps as a consequence of emerging early in the spring, Franklin & Sampson (1992) report that the cuckoo bee Bombus (Psithyrus) ashtoni will usurp terricola nests. Cuckoo bees enter a young nest, usually kill the resident queen, and then take over the workers to raise new queen and drone cuckoos. B. (P.) ashtoni, however, is also in decline and may be on the edge of extinction (Evans et al. 2008), presumably because of the decline of its hosts B. (B.) terricola and the related B. (B.) affinis.
Well, if not a cuckoo, then perhaps a predator is knocking off our B. terricola. There are lots of predators and parasites of bumble bees and Morse & Myles (2005) found that B. terricola workers showed no tendency to avoid patches of milkweed with predatory crab spiders. However, mice, shrews, ants, parasitic conopid and syrphid flies, crab spiders, and ambush bugs seem to be problems with which all Bombus must deal, so too the habitat destruction and pesticide encounters that are the suspected causes of much native bee decline. A more insidious cause, and one that seems a likely explanation for the rapid decline of the species in the subgenus Bombus is pathogen spillover (Colla et al. 2006, Rao & Stephen 2007, Otterstatter & Thomson. 2008).
Members of the subgenus Bombus are good pollinators, including of plants that require buzz pollination, and these bees are easy to rear and handle. As a result, Bombus (Bombus) species such as the European terrestris and the North American occidentalis have been mass reared and shipped around the World. As part of these commercial operations, New World bees have been exposed to Old World pathogens and then shipped back to North America for use in greenhouses. Invariably, some escape and intermingle with native bees foraging at flowers around greenhouse facilities. The result is the spread of Old World diseases for which our New World bees have little or no resistance. What a bummer: the first bumble bee that I feel comfortable identifying is now on its way to the Red List of Threatened Species (Mann 2010). I guess I can take some comfort in knowing that, although rare, they are still here around Edmonton. Perhaps some of these survivors are resistant to the introduced diseases and with luck the populations will eventually recover.

*All aculeate Hymenoptera have a ‘wasp-waist’ or petiole that divides the first segment of the abdomen from the remainder. Although there are technical terms for this reorganization of the abdomen, aculeate workers seem happy to use abdomen for the rump and start numbering with the first apparent segment, and so shall I.

Literature Cited

Bertsch A, de Angelis MH & Przemeck GKH. 2010. A phylogenetic framework for the North American bumblebee species of the subgenus Bombus sensu stricto (Bombus affinis, B. franklini, B. moderatus, B. occidentalis & B. terricola) based on mitochondrial DNA markers (Hymenoptera: Apidae: Bombus). Beitraege zur Entomologie 60: 229-242.

Colla SR & Packer L. 2008. Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379-1391.

Colla SR, Otterstatter MC, Gegear RJ & Thomson JD. 2006. Plight of the bumble bee: Pathogen spillover from commercial to wild populations. Biological Conservation 129: 461-7.

Donovall LR & van Engelsdorp D. 2010. A Checklist of the Bees (Hymenoptera: Apoidea) of Pennsylvania. J Kansas Ent Soc 83: 7–24.

Evans E, Thorp R, Jepsen S & S. Black H. 2008. Status Review of Three Formerly Common Species of Bumble Bee in the Subgenus Bombus. Prepared for the Xerces Society of Invertebrate Conservation [Online]:

Grixti J C, Wonga LT, Cameron SA, & Favret C. 2009. Decline of bumble bees (Bombus) in the North American Midwest. Biol Conserv 142: 75-84)

Fisher RM & Sampson BJ. 1992. Morphological specializations of the bumble bee social parasite Psithyrus ashtoni (Cresson) (Hymenoptera: Apidae). Can. Ent. 124: 69-77.

Hobbs GA. 1968. Ecology of species of Bombus Latr. (Hymenoptera: Apidae) in southern Alberta. VI. Subgenus Bombus, Canadian Entomologist 100: 156-164.

Laverty TM. & LD Harder. 1988. The bumble bees of eastern Canada. The Canadian Entomologist 120: 965-987.

Mann A. 2010. Plight of the bumblebee. Nature News.

Otterstatter M C & J D Thomson. 2008. Does pathogen spillover from commercially reared bumble bees threaten wild pollinators? PLoS ONE 3(7):e2771.

Plowright, CMS & Plowright, R.C. 1998. Floral use by two sympatric bumble bee species (Bombus terricola and Bombus ternarius): efficiency considerations. Canadian Entomologist 130: 595 – 601.

Richards KW. 1978. Nest site selection by bumble bees (Hymenoptera: Apidae)in southern Alberta. Can. Ent. 110: 301-318.

Rao S & Stephen WP. 2007. Bombus (Bombus) occidentalis (Hymenoptera: Apiformes): In decline or recovery? The Pan-Pacific Entomologist 83:360–362.

Williams PH, Cameron SA, Hines HM, Cederberg B & Rasmont P. 2008. A simplified subgeneric classification of the bumblebees (sic) (genus Bombus). Apidologies 39: 1-29.

Sunday, November 14, 2010

Aculeata Agonistes: Bumbling among the Bombus

 Although a few flowers are still defrosting on sunny days, it has been several weeks since the last greedily feeding queen bumblebee has been active. Or rather, I should say ‘bumble bee’ not ‘bumblebee’, because I don’t want to upset any entomologists. Bug people have a simple rule about names with a bug in them: if the common name is technically correct, then keep them separate; if not, merge them. Hence the dragonflies and damselflies in the last post are merged. They are not true flies (= Diptera), but bumble bees and honey bees are true bees (= Apoidea), so keep them separate.
 I admit that I’m not always properly pedantic about bees (bumblebee has ruled on this blog) and sometimes it can get perplexing. For example, what to do about a ‘bee fly’: a fly true, but a bee not. I guess the noun used as a noun trumps the noun used as an adjective, so bee fly it is. Then there is the ‘fly bee’ that adorns Small Farm Canadas otherwise exemplary editorial “Bee-ware” (Nov-Dec 2010, p. 13 in hard copy) about the importance of bees as pollinators and their apparent decline in abundance. Unfortunately, the picture of a bee in a pasture is actually a hover fly, probably the Drone Fly (Eristalis tenax), a mimic of honey bees. A mistake like this really bugs entomologists, but probably makes life easier for the fly.

 Technically, calling a fly a bee is a big time taxonomic failure that you can quantify if you’d like using the Myrmecos Taxonomy Fail Index. Perhaps more importantly, if you can’t tell a hover fly from a bee, then you may not notice if your bees start disappearing. Many flies are pollinators, especially of easily accessed flowers like daisies or apples, but in general bees are what you want to see visiting flowers, at least if you want to maximize your production. Also, many structurally complex flowers require bees for pollination. For example those interesting pea-like flowers that adorn legumes (e.g. alfalfa, clover, peas, beans, lentils, peanuts) usually need a bee that knows how to pry apart the petals to get at the goodies. Then there are those crops with specialized anthers that require buzz-pollination (e.g. tomato, egg plant, blueberries). Nature is full of strange pollination syndromes and bees are integral to many. Even seemingly simple flowers, e.g. those of squash, have bees that specialize on them.
 There are lots of different kinds of bees – perhaps 25,000 different species sharing the Earth with us at this very moment. That seems like a lot to keep track of and, in fact, fewer than 20 thousand have been given names and we know little about more than a few species. Foremost among these favoured few are the members of the genus Apis – barely more than a half dozen species. In much of the World it is one species, the honey bee (Apis mellifera), that we depend on for honey and pollination. Here and there in far parts of the World or here in specialized jobs (e.g. alfalfa bees) people have developed mutually beneficial relationships with other kinds of bees, but for the most part bees go about their business with more hindrance than help from us.
 How much we may be hindering wild bees is a question now being asked, but one that is difficult to answer. A recent study using museum specimens (Grixta et al. 2009. Biological Conservation 142: 75-84) came to the conclusion that half of the bumble bee (Bombus) species historically present in the state of Illinois had become locally extinct or highly reduced. Colla & Harder (2008, Biodivers Conserv 17:1379–1391) also found an apparent general decline in bumble bees in southern Ontario. These results would seem to mirror the declines and local extinctions of bumble bees that have been reported in Europe.
 So what is happening in the Edmonton area? To know whether a bee is doing well or is in decline, one must first be able to put a name on it. In my experience, most entomologists can tell a bee from a fly, and many can make a good guess at family or genus, but usually only those that have specialized on bees can make a good guess at the species identity. This is true even of large, colourful, and noisy bees like bumble bees. A bumble bee proclaims its genus to anyone who cares to look, but keeps its species identity closely guarded.
 So is it possible to identify the Home Bug Garden bumble bees to species – especially without killing them? Well there is a key, Laverty & Harder (1988)*, and it is worth quoting what they think: “The single most useful character for species identification is colour pattern.” (Can. Ent. 120: 966). Sounds like bumble bees and birds may have something in common. However, there is a caveat: “It should be noted that although colour pattern is usually a reliable guide to species, colour variants do occur and misidentification of some specimens is inevitable. We estimate that about 5% of specimens identified by the key will be incorrect... (p. 967).” Also, alas, the key is to the bumble bees of eastern Canada and does not include some of the most common ones in the Edmonton area. However, it does have black & white cartoon-like images of the colour patterns in the 26 species of Bombus covered in the key.

Discover Life also has a key to North American bumble bees. I’ve found this key to be a bit difficult to use and the answers I get don’t always match up to pictures (mostly really sad looking pinned specimens) or distributions (which seem to be more museum collection records than actual distributions). My getting a wrong answer may say more about me than the key, but I’m willing to share the blame. Also, the Discover Life key is clearly under construction and it seems to be improving all the time. For example, it now has Canadian Provinces as one of the characters that can be used to reduce the number of taxa.
Continuing with the Worldwide Web, perhaps the most definitive of all bumble bee keys is the British Museum of Natural History’s Paul Williams’ Lucid interactive key to queens and workers (males are not included) of the World. As with any image-rich interactive key, this requires a fast internet connection and a reasonably powerful computer to avoid giving up in frustration. The complete key contains 1070 diagrammatic images of various colour patterns, but one can select only those in the Nearctic Region – only 220 colour patterns! After that one must have some idea of the subgenus to have much hope of making progress. Subgenera should provide some grist for the Aculeate Agonistes mill and I think Bombus (Bombus) will be the first up – a nice simple, small subgenus. The colour pattern diagrams in Williams’ key and the early, black & white examples in Laverty & Harder seem pretty useful. I’m not much of an artist, but I can handle computer drawing programs and will try work up a key using cartoons and pictures to the Edmonton bumble bee fauna. Here’s a first start comparing two common black & yellow local bumble bees. Any not too caustic suggestions for improvement appreciated.

I'm sure I will be making lots of errors as I bumble through the Bombus. Corrections are always appreciated, but I hope I don't end up on Arthropoda Blog's Friday Fail!

*Laverty TM. & LD Harder. 1988. The bumble bees of eastern Canada. The Canadian Entomologist 120: 965-987.

Saturday, October 30, 2010

Dragons & Damsels: Odonate Overlap

Although killing frosts struck on 17 September, a week before schedule, after this Summer, September was quite a pleasant month. October has been up and down, and not much greenery or insects are in evidence, but the pond bubbler is still on. I usually chicken out in the first or second week of October, but the pump has persevered for 5 summers and probably won’t last that much longer anyway. So, for the benefit of the resident ‘native’ birds (chickadees, red and white breasted nuthatches, house finches, blue jays, and magpies), I’ve kept it going. Soon, though, I will have to give in to the ice gods.
So, what better excuse on a cool, but sunny Saturday, to post about some aquatic insects – and also, to start answering a question that Middle Earth Garden asked back in March – just how similar is the Home Bug Garden fauna to other more natural systems in Alberta? Her question is actually far more interesting than I can attempt to answer. I’d love to spend my summers wandering Alberta and documenting the various insect faunas, but so far no one has offered me a job doing so. However, I do spend many of my weekends at our Moose Pasture and at least for certain groups, I can now make reasonable comparisons between the HBG and the MP. (NB – pictures with blue borders are from the Moose Pasture, no colour borders from the Home Bug Garden.)
 First up is the Odonata. Even the smallest adult odonates are relatively large (or at least long) insects, often very abundant, and not as leery of people as many others. Thus they are more obliging to the photographer and especially friendly for close-focusing binoculars (I like my Pentax UCF XII). BugGuide has many good pictures and even better, for Christmas I got an excellent guide: Dennis Paulson’s Dragonflies and Damselflies of the West (2009, Princeton University Press).
Paulson’s field guide has a distribution map for each species with the species descriptions and pictures – so likely from unlikely species are easily separated. As well as color pictures of mature males and females, plates with line drawings showing male genitalia (claspers) and critical female characters are presented for easy of comparison. Each species has paragraphs with a description and a review of key characters in comparison to similar species. Also, the natural history, habitat, flight season, and a comment on distribution are given. The only complaint I have is that he relies too much on the common, rather than the scientific names – but this complaint may be restricted to entomologists.
Odonate Family Genus species   Moose Pasture  Home Bug Garden
Aeschnidae Aeschna interrupta                +                +
Aeschnidae Aeschna eremita                      +                 -
Corduliidae Epitheca spinigera                   +                -
Libellulidae Leucorrhinia cf hudsonica        +                 -
Libellulidae Leuchorrhinia intactor             +                -
Libellulidae Libellula quadrimaculata       +                +
Libellulidae Sympetrum internum             +                +
Libellulidae Sympetrum danae                  +                +
Coenagrionidae Coenagrion resolutum     +                 +
Coenagrionidae Enallagma cyathicerum      +                -
Coenagrionidae Enallagma ebrium              +                -
Coenagrionidae Nehallenia irene                  +                -
Lestidae Lestes congener                             +                -
Lestidae Lestes disjunctus                          +                 +
Lestidae Lestes dryas                                  -                 +
(excuse the drunken columns - Blogger seems to have trouble with tables. Bold = shared species. Red = HBG only)
As usual, you should take all my identifications with a grain of salt, but in this case if there are any errors, they are probably applicable to both sites. Also, we have many unidentifiable pictures of damselflies, so their actual diversity is probably higher. With damselflies, and I suppose this is ironic, dead males on a pin are the best route to a solid identification.
 So, of the 15 species identified to date, 6 occur both at the Moose Pasture and in our backyard, and only one, the Emerald Spreadwing (Lestes dryas) has yet to be identified at the Moose Pasture. A quick reading of Paulson suggests two reasons for this apparent difference. The Emerald Spreadwing favours shallow densely vegetated ponds (sounds like our backyard pond) and oviposits in live sedges, grasses, and horsetails (the pond is full of sedges). Permanent water bodies are not favourable breeding sites for this species.
Although our backyard pond has only about 2 m square of surface area, it does have lots of emergent vegetation and the bubbler to keep it aerated. At the Moose Pasture, Dancing Elephant Lake (DEL) and its attendant marsh and pond cover about 28 acres. The topography results from stagnant chunks of glacier that were left behind the main retreating mass and formed kettles surrounded by knobs (now covered with aspen) There is much emergent vegetation, and also lots of aquatic marcophytes and some deep areas without vegetation.

The difference between a lake and a pond isn’t well agreed, but usually lakes are expected to be larger and have some area too deep for rooted plants, and DEL seems to just qualify. One of the neighbours calls it a slough, but ‘slough’ is as loosely used as ‘lake’ for everything from an alkaline prairie pothole, to a treed swamp, to a marsh. The only trees in DEL are the skeletons of the willows drowned when the beaver flooded out the meadows that we now call marsh, which to us means it is weedy and shallow enough that getting the canoe through is difficult (The Trunk and Lower Legs). But whatever you want to call it, a host of odonates emerge every year.
The same is true for our backyard pond. Well, maybe ‘host’ is an exaggeration. However, we do have yearly emergences of many damselflies and some dragonflies. It is a rare summer day that one or more of these attractive and useful insects isn't around. They eat other insects, and so we can think of them as good ‘natural enemies” – and if they take any bees, it is only the tiny ones.
And what can we conclude, if anything, from this data? I’ll argue that even a small backyard pond can act as an urban refuge for a subset of the local odonates. This exaggerates the usefulness of the pond for dragonflies – the 4-spotted Skimmer was a one-off (possibly brought in with a plant) and the Variable Darner (Aeshna interrupta) may cruise through your yard even if you don’t have a pond.
 The Cherry-faced and Black (S. danae) Meadowhawks, however, breed in the pond as do several of the bluet damselflies. The Emerald Spreadwing finds a small pond a perfect habitat. In Edmonton, where synanthropic mosquitoes that breed in small accumulations of water are absent, there is no real downside to a backyard pond – the birds love it, the bubbler adds some relaxing white noise, water plants are interesting, and a host of aquatic insects, snails, and other even smaller invertebrates can make a living where dandelions and grass once dwelled.