Monday, September 20, 2010

Aculeata Agonistes: Vespula alascensis, vulgar no longer

Ever wish you knew what that bee buzzing your flower was properly called? Or that hornet that won’t let you relax in the garden? Or that sleek black and yellow waspy thing on the goldenrod? Does it needle you when an aculeate hymenopter zips through your garden leaving you none the wiser? Of course, as Lewis Carroll’s Gnat sagely noted, knowing the names of insects is little use if they won’t answer to them. But that is so very B.G.: if we know a name, we can make Google talk for them.

So herein I begin a new series of posts wherein I will struggle to learn the names and natural histories of the stinging wasps, bees, and ants (Aculeata) that may frequent the Home Bug Garden. I think I’ve learned my lesson from alliterative day-of-the-week ‘regular’ posts. Rarely do Wildflower Wednesdays occur even near mid-week nor Sawfly Sundays on the Sabbath. Starting these series, however, has forced me to do lots of rewarding research that I would otherwise have put off for that mythical day when I have some free time. So this new struggle, Aculeata Agonistes, initiated on a Wildflower Wednesday a Sawfly Sunday another dreary Monday, will appear when the Muses and Chronos are in agreement.
 And what better way to start such a series than with a wasp where no one knew its proper name? That is the case with what was until recently the Common Yellow Jacket, Vespula vulgaris, described by Linnaeus from Europe in 1758 and reported from North America 79 years later. Or so most everyone thought until James Carpenter at the American Museum of Natural History in New York and Travis Glare from Lincoln University in New Zealand unraveled the true relationships – and more importantly to us - the true name. As taxonomic stories go, this one is pretty exciting: full of names, invasive species, and even consequences of Mrs O’Leary’s famous cow. All of this is available free on-line from Carpenter & Glare’s paper (see below), but I will quote a few sentences that gives the species name to which our not so common yellowjacket should answer: “Bequaert (1932) also listed Vespa alascensis Packard, 1870, described from ‘‘Lower Yukon,’’ as a synonym of Vespula vulgaris. Packard (1870) is an obscure publication indeed, because most of the copies of the publication were destroyed in the Great Chicago Fire of 1871.”

You may have noted that my picture of Vespula (now the correct genus) alascensis is a bit blurry. That is because it was taken with my point-and-shoot not long after I got it and before I had any idea what I was doing (the wasp, however, is licking honeydew). All of the decent pictures that my wife or I had managed to capture of what we thought was Vespula vulgaris, for example, the picture at the head of this post, turned out on closer inspection to be the Common Aerial Yellowjacket Dolichovespula arenaria. The break in the middle of the yellow band on the first abdominal tergite is a good character for this species in dorsal view. And so the struggle with the Aculeata begins with a repeat of the lesson from the last post: it helps to know what characters are important before you start taking pictures.

Carpenter & Glare 2010 Misidentification of Vespula alascensis as V. vulgaris
in North America (Hymenoptera: Vespidae; Vespinae). AMERICAN MUSEUM NOVITATES 3690

Sunday, September 19, 2010

Sawfly Sunday: On the Importance of Prolegs

As well as the three pairs of jointed legs on their thoraces, some immature insects have additional grasping/ambulatory organs on their abdomens called prolegs. In this case ‘pro-‘ seems to be used in its ‘before in time’ mode. Perhaps whoever coined this term in the early 1800s thought these fleshy lobes were the precursors of true legs, as some think of the lobopods in modern velvet worms. On the other hand, the OED states ‘prop-leg’ as an alternative, so perhaps proleg results from an elision. In any case, the number of pairs of fleshy abdominal prolegs is a good character for distinguishing those butterfly and moth caterpillars that feed on the surfaces of plants from those of sawflies.
There are exceptions, but a good general rule is that the caterpillars of butterflies, skippers, and moths (Lepidoptera) usually have 2- 5 pairs of prolegs. A typical arrangement is on abdominal segments 3, 4, 5, 6, and then at the end (anal proleg). Inchworms (Geometridae) are, perhaps, the most commonly noticed variant – all but the last two pairs of prolegs are absent, possibly atrophied after an ancestor took up measuring its stride. 
Then there are the strange Prominents (Notodontidae) where the anal claspers have become a kind of tail. And then the miners and burrowers that may loose all trace of prolegs.
 In contrast, most sawfly caterpillars with prolegs have them on abdominal segments 2-7 or 8 and retain the anal claspers. The rarely seen larvae of Mecoptera, the scorpionflies, may have prolegs on segments 1-8. Thus, if one can count and has a reasonable guess as to which folds of abdominal skin makes a segment, then one can usually tell an eruciform (eruca is Latin for caterpillar) larval lepidopteron or mecopteron from a sawfly without any special entomological experience.
Of course, to count the number of prolegs it helps to see them. This is a special problem in a picture and a good example of why it helps to have an idea of what the important identification characters are before one takes a picture. If you have the disk space, it is also an excuse to hold on to those poorly framed or out-of-focus shots that may have useful information for identification.
 The picture above is of a sawfly caterpillar – I know it from the shape of the head capsule and the general Gestalt (I was an entomologist for many years and some of it still sticks with me) - but how many prolegs does it have? At BugGuide, Dave Smith points out that most of the grass-feeding sawflies in North America belong to one of two genera: Dolerus and Pachynematus. Larvae of the former have an asymmetrical labrum and prolegs on segment-8; the latter have a symmetrical labrum and no prolegs on segment-8. Alas, neither the labrum nor the prolegs are visible and this id is stuck at my doleful level of Gestalt.

Sunday, September 12, 2010

Wildflower Wednesday: Nodding Onion

With Autumn bearing down upon us and two near frosts (0.5 C or 33 F) in the Home Bug Garden already, the thoughts of all optimistic Zone 3 gardeners turn to Spring. Well, really, one should be filling one’s basement with the famous Alberta green tomatoes first, but it is best to have one’s bulbs in the ground here as soon as possible and before the end of September for sure. Thus, another tardy Wildflower Wednesday is given impetus as I watch the frost on the garage roof dissipate in the weak Sunday sun.
 Although Alberta's current native flora can boast of about a dozen species that form true bulbs (essentially a buried bud composed of thick leaf and stem tissue), many of these are restricted to the extreme southwestern part of the Province. Most Albertan orchids, irises, and members of the Lily family (in the old sense) tend to overwinter as fat roots or rhizomes. The most spectacular exception is the Western Wood Lily (Lilium philadelphicum) that seems to do well everywhere except the prairie and the far north. One would think from the name that the Venus’ Slipper Orchid (Calypso bulbosa), a circumboreal inhabitant of coniferous forests, would also qualify, but leaf tissues seem to be missing from the ‘bulb’, so it is more likely a corm. Perhaps less spectacular are two species of Death Camas (Zigadenus elegans, venenosus) that cast their pallid pall across southern Alberta and three of the four species of Albertan wild onions (Allium).
 More than one hundred species of wild onions currently make their homes in America north of Mexico, although several of these are recent colonists and even weeds, e.g. the invasive Eurasian Wild Garlic (Allium vineale). Alberta has only four species, all considered native: Geyer’s Onion (A. geyeri), restricted to the SW mountains, and the more widely distributed Wild Chives (A. schoenoprasum), Prairie Onion (A. textile), and Nodding Onion (A. cernuum). The Home Bug Garden can boast two of these species: Nodding Onion and Chives. Native plant purists might challenge us on the Chives – var. sibiricum being considered native and var. schoenoprasum the introduced culinary Eurasian variant. However, since some chives came with the house, we may have both. Actually, a purist might even challenge us on the Nodding Onion. Our plants came from a sunny south slope of a glacial knob on our Moose Pasture 75 km to the east. It is quite likely that a century ago pondweeds, sedges, and cattails were the HBG native flora.
 As wildflowers go, though, Nodding Onion (Zone 2, sun to part sun, average to dry soil) is quite an attractive and interesting one and fits in well with other garden plants, at least on the border. The plants produce a tuft of strap-like leaves (~2-3 dm [8-12”] long) with an oniony taste and smell in May and the leaves persist all summer. The umbels of pink flowers are unlike most onions in that they dangle – the flowers are all upside down – seemingly making things a bit more difficult for pollinators. 
Interestingly, a study of Nodding Onion pollination on the coast of British Columbia, Schuett & Vamosi (2010, Evol Biol 37: 19-28) found that flowering at the same time as another wild onion or another Alliaceae, a starflower (Brodiaea), resulted in a decrease in the “quantity and proportion of conspecific pollen” being delivered by pollinators to the stigmas of Nodding Onion. That suggests to me that Nodding Onion may be being different on purpose, perhaps to keep the attention of bees that can learn how to pollinate difficult flowers. Schuett & Vamosi were more interested in theory than the natural history of Nodding Onion, but do mention that species of Andrena and Bombus were seen visiting the flowers. Bumblebees are known to be able to learn pollination tricks, so that is consistent with my hypothesis. Verbeek & Boasson (1995, Can J Bot 73: 723-727), however, have another hypothesis: nodding flowers are dodging the rain. They note that nodders (shooting star, some lilies, trout lilies, fritillarias, and Nodding Onion) in coastal British Columbia tend to bloom early when there is more rain. This would not seem to hold in Alberta (especially not this year – with the wet and cool weather continuing throughout the summer and into today). The central Asian Honey Lilies (once Allium, then Nectaroscordum, but now back in Allium) also dangle and some research (e.g. Dubouzet & Shinoda 1998. Theor Appl Genet 97: 541-549) supports a close relationship to Nodding Onion, so perhaps they may one day shine some light on the cause(s) of nodding (other than overly long blog posts).
 Nodding one’s umbels of flowers is an interesting behaviour, but what happens after pollination is even more interesting: the umbels become erect, assume a typical Allium exploding firework pattern, and seem to grow a bit larger too. Verbeek & Boasson report post pollination stem elongation as a general pattern in their meadow plants and explain it as facilitating seed dispersal. This seems to make sense to me and the addition of an attractive seed head is always welcome in a garden plant. Another advantage of Nodding Onion is that takes well to Green Roofs. One can find Green Roofs in British Columbia – the one on Vancouver Island with the goats is one of my favourites – but what with the extremely steep pitch to the typical Alberta home roof, weight of snow, and the intense winter cold - I can’t see them in my future. In Michigan, however, Getter et al. (2009, Urban Forestry & Urban Greening 8:269–281) found that Nodding Onion does very well on green roof plots with shallow soils (8-12 cm) and in sun or shade. So, perhaps some day I’ll get out the harness, ropes, and carabineers and start planting Nodding Onions on the roof. Not in the rain though. No matter how nice rain is for transplanting, this interminable rain of 2010 makes me want to stay indoors and away from slippery slopes and slugs.

Wednesday, September 1, 2010

Sunday Sawfly: A Dolerus deceptively not interested in a Mayday

The middle of the week is about as far from Sunday as one can get, but last Sunday I was overworked and this Sunday I’m on holiday, so I’m serving two Sundays with one small black sawfly. Dave Smith has identified this as a species of Dolerus (a genus with almost 200 described species, including about 75 in the Nearctic) and possibly the introduced European species D. nitens Zaddach. Dave doesn’t have records of this sawfly from Alberta, but it is sawing its way across North America, so was bound to get here sooner or later. This picture was taken on a Mayday bud in the process of opening in early May – what passes for early spring most years in Alberta. Dolerus nitens is known to be one of the very early emerging sawflies, but it does not feed on Mayday (Prunus padus) or other cherries or plums.

With its somber black colour, it is tempting to think that Dolerus comes from the Latin for sorrows (dolor), but ‘doler’ is Greek for ‘deceptive’. The genus was named by Panzer, presumably the famous German botanist and entomologist Georg Wolfgang Franz Panzer who died in 1829. Perhaps he was referring to something deceptive about the larvae. The caterpillar-like larvae of D. nitens graze on grasses (Poaceae) and sedges and their relatives (Cyperaceae) and are considered pests in grains. The Home Bug Garden has a few clumps of ornamental reed grasses (Calamagrostis), one clump of a native needle-grass (formerly in Stipa), and a pond-full of spike-rush (Eleocharis) and sedge (Carex). Species of all of these genera are suitable hosts for D. nitens, so we may one day be able to be decode the deceptive name.

I’ll end this short post with an even shorter digression, stumbled upon while searching (with little success) for some biological information on D. nitens. It seems that sawflies are one of those interesting entomological groups that are more diverse in the cooler parts of the World (or at least of its northern half) and become less diverse as one moves towards the tropics*, reversing what one normally expects of insect diversity. I suppose that helps to explain why the Home Bug Garden seems so blest with sawflies, while in Queensland I can't even remember seeing one.
*Kouki et al. 1994. Reversed latitudinal gradient in species richness of sawflies. Ann. Zool. Fenn. 31: 83-88.

Wildflower Wednesday: Tickseeds & Beggarticks

'Wildflower’ is an interesting concept. One might think that it refers to a plant version of ‘wild beast’, but the connotations barely overlap. If a wildflower really did go wild, then I would soon weed it out. Thus, cultivating ‘wildflowers’ in a garden creates a certain level of cognitive dissonance. The pedant in me wonders if I should look for another name for this series of posts? But I think not, for as William Cullina states in his book Wildflowers (see sidebar) about this week’s offering: “Tickseeds are indispensible wildflowers for the sunny garden.”
Only one of the 33 species of North American tickseeds (Asteraceae: Coreopsis) is currently found growing wild in Alberta: Golden Tickseed – Coreopsis tinctoria. I don’t grow it in my garden because I’ve never come across it. I’ve tried a related native annual, Nodding Beggartick Bidens cernua, but it didn’t establish, and besides, the local wild beggarticks support large populations of the chyromelid beetle Calligrapha californica corepsivora. As pretty as the beetle is, I’d prefer that this beast stay in the wild.
The Home Bug Garden does have tickseeds, but only those that are perennial, not quite native, and dubiously wild. Given a few more millennia of postglacial thaw, several of these North American plants may have gotten to Alberta on their own, but for now they need to be transplanted or seeded. Flying Saucers - Coreopsis grandiflora ‘Walcorep’ - was my first tickseed. Although it ‘naturally’ occurs as far north as Maine and Wisconsin, my plant failed to survive its first Alberta winter. Sad, because the flowers could be envisioned as giant yellow flying saucers and made a spectacular display.
In contrast, and although only rated to Zone 4, Threadleaf Tickseed Coreopsis verticillata has done well in my Zone 3 garden. The wildflower is found in dry woods and clearings in the southeastern US (perhaps driven there by the glaciers). ‘Golden Showers’ is tallish (1 m) variety with bright golden ray flowers and has survived three years of part-sun and cold, cold winters, blooming from mid-summer to frost. ‘Moonbeam’ is a dwarfish variety (1-2 ft.) with pale lemon ray flowers. It is nearing the end of its second summer in the HBG and it is a delightful flower. The Perennial Plant Association named Moonbean 'Plant of the Year' in 1992, but I don’t think I can call this a sterile hybrid a wildflower. Treating a horticultural variety as a ‘wildflower’ stretches the concept to the breaking point, so lets not.
But all is not lost - my final tickseed should more or less count as a wildflower: Lance-leaved or Sand Tickseed - Coreopsis lanceolata. It is native to Canada, or at least Ontario and British Columbia, and my plants derive from seeds from open-pollinated plants at the nearby Devonian Botanical Garden. The seeds germinated readily last year, but all I got was a basal clump of leaves. The leaves are evergreen even in this climate and so added a little colour to the early spring. This year the flowering stalks went a metre and a half (~5 feet) and added to a nice composition of native (e.g. Helianthus maxmilliani, Rudbeckia hirta) and near native composite ‘wildflowers’ (Echinacea purpurea, Heliopsis helianthoides, Liatris spicata) in the front woodland garden.
Although bees and other pollinators come to Lance-leaved Tickseed flowers, some recent research has called attention to the plant’s usefulness in attracting insect natural enemies*. ‘Natural enemies’ in this case was rather loosely defined as any arthropod that eats or parasitizes another arthropod, so predators and parasites of pollinators counted as much as those that eat crop pests. Still, planting strips of native ‘wildflowers’ around your crops probably would contribute towards maintaining arthropod biodiversity. Companion planting of ‘wildflowers’, however, continues to erode away at the concept.
Coreopsis comes from the Greek for ‘like a bedbug’. Presumably Linnaeus thought the seeds looked like some bugs with which he was familiar, but when I was collecting tickseed seeds earlier, a Minute Pirate Bug tumbled out of the seedhead. According to Fiedler & Landis (2007) Lance-leaved Tickseed seems especially attractive to Minute Pirate Bugs (Anthocoridae: Orius) which tend to feed on small pests such as aphids, thrips, and spider mites. Anthocoridae (‘flower bugs’) also have a habit of biting people and are thought to have shared a common ancestor with bedbugs, so perhaps Linnaeus was having another of his amazing insights. Personally, I can’t see the similarity of tick-seed (both Old English words) to either bedbugs or ticks, but perhaps I’m looking at the wrong species.

*A. K. Fiedler and D. A. Landis 2007. Attractiveness of Michigan Native Plants to Arthropod Natural Enemies and Herbivores. Environ. Entomol. 36(4): 751-765.