Is That a Wombat on Your Belly, Or Are You Just Happy to See Me?

I attended a Ph.D. defense a few weeks ago on the effects of salmon lice (which are copepods, not insects) on their juvenile hosts. The student showed some gory photos and pointed out that for such a little fish, carrying a louse was like a human lugging around a raccoon on his back. Some mites can be just as burdensome, such as this Macrocheles muscaedomesticae (Scopoli) attached to the abdomen of an unfortunate Drosophila hydei Sturtevant.

Scanning electron micrograph of a Drosophila hydei carrying a female Macrocheles muscaedomesticae (image by HP)

Scanning electron micrograph of a Drosophila hydei carrying a female Macrocheles muscaedomesticae (image by HP)

Females of many species of Macrocheles (Mesostigmata: Macrochelidae) hitch rides on winged insects to move from a place to place, a phenomenon called phoresy. Strictly phoretic organisms do not feed on the host while attached. A great many mite taxa fall into this ‘purely phoretic’ category. Others may facultatively snack on the host while in transit. My colleague Lien Luong has investigated one such mite species, Macrocheles subbadius (Berlese), and its cactus-associated host Drosophila nigrospiracula Patterson & Wheeler. When Lien moved to the University of Alberta it proved difficult to replicate the system, in part because cacti are not common in this part of Alberta.  Compost bins are abundant, however, and Lien and her students are investigating the ecological relationship between two compost-associated species, Macrocheles muscaedomesticae and Drosophila hydei. Does M. muscaedomesticae feed on its host while attached, or is it just holding on? One way to test this is to determine whether the mite’s mouthparts pierce the fly’s integument. In this N = 1 sample, the mite just seems to be holding on firmly, probably uncomfortably so from the fly’s point of view.

mite biting medium close

Piercing or just pinching?


mite biting close

Looks like pinching, probably painfully.

But by definition, facultative parasites aren’t always parasitic. More mites must be examined, and other lines of evidence followed, such as presence of melanized wounds on hosts after the mites have dropped off, or presence of Drosophila DNA in the guts of the Macrocheles.


Brazilian Beauties

A couple of weeks ago my colleague Fabio Akashi Hernandes* from the Universidade Estadual Paulista sent me the file for a poster that I immediately printed on high-gloss paper and proudly affixed to the door of my office. The poster depicts some of the feather mites that Fabio has found on birds from Brazil and a few other tropical countries. Eye candy for acarologists! They are all scaled to the mm mark at bottom right, where you can see the gigantic Laminalloptes phaetontis (Fabricius) from tropicbirds. Among the selected mites are the hoatzin-dwelling Opisthocomacarus umbellifer (Trouessart) (mite #40) in which both sexes are adorned with feather-like setae of unknown function. Typically, though, male feather mites are more elaborate than females. The poster includes species whose males have vicious-looking hind legs (e.g., 1, 28), or are asymmetrical (e.g., 31, 32, 58), or are very well-endowed (20).

Fabio is doing some marvelous work on taxonomy and ecology of these mites, including the very recent discovery of a host-switch from wild cuckoos to domestic poultry. But even though he and his colleague Michel Valim have been working hard to describe new species, at least 80% of bird species in Brazil have yet to be investigated for their acarofauna. Many more wonders await.

Click on the poster image then mouse over and click to magnify.

Fabio's Feather mite poster 6 Oct 2015 sml


Smaller fleas

In his very long poem on the nature of poets, Jonathan Swift famously noted that parasites can themselves be parasitzed. A few weeks ago I came across an interesting case of hyperparasitism. I had washed a recently road-killed Yellow-bellied Sapsucker. It yielded many lovely mites and one feather louse. I slide-mounted the latter and representatives of the former.

Pteronyssus sphyrapicinus male and female ex YPSS HP0929 sml

Pteronyssus sphyrapicinus (Astigmata: Pteronyssidae) feather mites from a Yellow-bellied Sapsucker. Male on left, female on right.

When I looked at the louse under the compound scope I thought its Malpighian tubules had burst out of its abdomen. At higher magnification, the tubules turned out to be hyphae.

Penenirmus auritus with arrows

Fungally infected Penenirmus auritus (Phthiraptera: Philopteridae) from a Yellow-bellied Sapsucker.

I figured it must be a member of the Laboulbeniales, fascinating and highly modified ascomycotan fungi: look here and here! Almost all of the 2000 or so described species are ectoparasites – or perhaps in some cases harmless commensals – of living arthropods. One species has achieved recent notoriety due to its spreading from a native ladybird in the U.K. to an invasive one. I had seen them on various critters before, including beetles and mites, though never on a feather louse. But Googling revealed that in 1951, Wolfdietrich Eichler had published an interesting overview of the Laboulbeniales he’d seen on lice from birds*.Eichler figure

They were all from the genus Trenomyces. I asked my mycologist friend Randy Currah if he could tell whether the fungus on my louse was one that Eichler had identified. He referred me to Meredith Blackwell at Louisiana State University. She identified the images as a Trenomyces sp. (like Eickler’s) and then sent the images I emailed to her to Danny Haelewaters at Harvard University. I’m not sure whether Danny will be able to get it to species based on my bad photos, but if he does I will update. UPDATE (22 Aug 2015) – Danny has just identified the fungus as Trenomyces circinans Thaxter, a new record for Canada. Thanks, Danny!

Penenirmus auritus from YBSS trimmed

Closer view of the Trenomyces showing a big ascocarp, two ascospores (lower right) and juvenile multiseptate things that probably have proper names but I will just call ‘babies’.

*Eichler, W. 1951. Laboulbeniales bei Mallophagen und Läusen. Feddes Repertorium. 54(53):185-206.

What happens when you ask an undergrad to draw a spider?*

This summer the arthropodologists in my department are being moved from one building to another, as part of the mysterious game of reshuffling that university administrators so enjoy. As preparation for the move, I’m downsizing the contents of my filing cabinets. In a folder from 2004 I found this collection of drawings from the first time I taught Biology 108, Introduction to Biological Diversity. I had given two lectures on arthropods with a strong emphasis on differences in appendages and tagmata among the major groups. This is what I thought was an easy bonus question on the final exam: draw a spider and label the relevant parts. Here is a selection of drawings, from ‘quite respectable’ to ‘huh?’.



Based on the last image, some university students believe that spiders should be speared on toothpicks and served in martinis.

*apologies to Facebook friends who’ve already seen a version of this.

On the backs of wasps

In March, I was given two specimens of solitary wasps that were covered with mites. The first was one of several Crossocerus  (Crabronidae) that had overwintered in holes in a wooden chair left outside on the campus of the University of Alberta. I had expected the mites to be phoretic deutonymphal astigmatans, but they weren’t, they were adult female scutacarids (Prostigmata: Scutacaridae). Many scutacarid species have phoretic and non-phoretic morphs. The big anterior tarsal claws you can see (blurrily) on the photo below are typical for phoretomorphs. What wasn’t typical was a pair of strange internal structures that became apparent in well-cleared specimens.

scutacarid from Crossocerus April 2015 E

At first I thought the pair of round things near the female’s genital area were sperm-storage chambers. But when I Googled ‘Crossocerus’ and ‘Scutacaridae’, I found a paper that showed I was only half right – they were sporothecae*, not spermathecae!

scutacarid from Crossocerus April 2015 C

Two big spores tucked into the genital atrium of this female Imparipes.

scutacarid from Crossocerus April 2015 A

Ebermann & Hall (2004) described a new species of scutacarid, Imparipes haeseleri, from several species of wood-associated Hymenoptera. In the genital atrium of these mites, they observed two large round fungal spores, one on each side, looking remarkably similar to the ones in the mites from the rotting chair. I asked Evert Lindquist, an expert on the Heterostigmata (the larger group to which Scutacaridae belongs) if these mites were Imparipes. Yup, they were. Were they I. haeseleri? There is a closely related species known from North America, I. vulgaris, but several setal characters matched haeseleri rather than vulgaris so I decided to go with Imparipes cf. haeseleri.

Why are the female mites carrying spores? No doubt they and their offspring feed on the wood-digesting mycelium produced from the germinated spores. The mites that hop on wasps as they depart from their overwintering chambers take with them the starter culture for their future meals. Dr. Lindquist noted that the spores these mites were carrying looked very similar to the Nigrospora spores known to be carried by a different species of heterostigmatan, Siteroptes reniformis Krantz. In his 1984 paper, Lindquist notes that S. reniformis “not only serve to transport and place spores of Nigrospora in an environment favorable for germination and growth, they also stimulate mycelial growth, apparently by secreting a chemical substance when feeding on the fungus.”

The second wasp was collected from an overwintered artificial nesting block that was supposed to house solitary bees. It was an Ancistrocerus sp. (Vespidae: Eumeninae). Knowing this, it was easy to guess who the mites were, and slide-mounting confirmed it: deutonymphs of a Kennethiella sp. (Astigmata: Winterschmidtiidae).


Like almost all phoretic deutonymphs of Astigmata, these Kennethiella have a terminal sucker plate to adhere to hosts. Unusually, they also have anterior ocelli. Why ocelli are present in only a small number of Astigmata is unclear (at least, it’s unclear to me).


Sucker plate.

Winterschmidtiid ocelli

Pair of ocelli.

The reason I expected the mites to be Kennethiella is because the relationship between them and their host wasps is famous among acarologists. Cowan (1984) unraveled the interactions for one mite-wasp duo.  To quote the abstract: “The mite Kennethiella trisetosa is phoretic on adults of the wasp Ancistrocerus antilope and develops in the nest with immature wasps. Female mites and a large type of male develop oviparously, whereas a small male develops oviparously. Small males kill each other, but are ignored by large males. By mating with females before small males are mature, large males may monopolize fertilization. Larvae of female wasps usually destroy mites within their cells but, as adults, are reinfested when mated by mite-bearing males. Each time a male wasp mates, about half of its mites transfer to the female.”

It’s worth reading the original to appreciate the full intricacies of these intertwined life-cycles.

Ancistrocerus showing Kennethiella mites 16 Aug 2009

A home-grown Ancistrocerus with a load of Kennethiella, from my back yard in Edmonton a few years ago.

*according to Evert Lindquist, they aren’t sporothecae (which are spore-storage sacs) but simply the spores themselves, tucked into corners of the genital atrium. Thanks, Evert!

Painless mites

My freezers at work are getting rather full, so I’ve been washing birds and sending the clean bodies to the Royal Alberta Museum. Last week I washed a batch of white-throated sparrows (Zonotrichia albicollis) that had met a sad communal death by flying into a window in Edmonton. They were very mite-rich, providing dozens of specimens of Proctophyllodes (Proctophyllodidae), Mesalgoides (Psoroptoididae), and Analges (Analgidae).  All of these taxa belong to the feather mite superfamily Analgoidea. Analges means “without pain”, and the genus was called thusly by Nitzsch in 1818 because it seemed that even heavily laden birds showed no signs of distress. Almost two hundred years later, a huge comparative study by Ismael Galván and colleagues in 2012 compared feather mite load and host condition of 83 species of birds and found no evidence of a negative relationship. Feather mites in general appear to be harmless commensals of their hosts.

Analges species are interesting because of their striking male polymorphism. All males differ from females in having enlarged third legs with spear-like tarsal claws, but legs of some individuals are much more grotesquely hypertrophied than others. Such males are also larger overall.

White-throated Sparrow Analges compilation lightened

Analges sp. mites from white-throated sparrows from Edmonton, Alberta. From left to right: female, homeomorphic male, heteromorphic male (all to the same scale).

Male polymorphism is very common in feather mites and many other Astigmata. The less elaborated male forms are typically called ‘homeomorphs’ and the extravagant ones ‘heteromorphs’ (the reason for the terms being that the former are more similar to females than the latter).

But what are the modified third legs used for? Holding females? Stabbing rival males? I’m not sure that anyone knows.

White-throated Sparrow Analges male legs

Legs of homeomorphic (left) and heteromorphic (right) male Analges. The pointy tarsal claws look nasty.





Tasty Trivia from Almonds to Yeast

Lectures for this semester are done, exams have been endured, and all that’s left is grade assignment. That and a feeling of regret that much of the cool trivia I picked out from Harold McGee’s “On Food and Cooking” (2004) to incorporate in my intro biology lectures went unused.  So I thought, why not share them in a blog post? They are timely, given the seasonal focus on food. Here are some of my favourite biological revelations in order of their appearance in the book.

p. 505 – almonds are among the most oil-rich of nuts (54% oil, see Table on p. 502), and a faux ‘milk’ can be made by soaking the nuts in water and grinding to release tiny oil bodies, together with proteins and sugars. Almond milk is not a new creation, as it was known in Medieval Europe, and used in Arabian cooking before then.

p. 506 – Brazil nuts have nutrients stored in embryonic stems rather than in embryonic leaves. They are even oilier than almonds at 67% oil, and hence are very calorie-rich. They have the highest level of selenium of any food known and too many can be toxic (maximum recommended daily intake for adult humans = 14 g)

p. 507 – the cashew is a relative of poison ivy, hence we never see cashew nuts for sale in the shell.

p. 509 – ginkgo seeds are edible and mild in flavour even if the flesh of the ‘fruit’ is stinky.

p. 510 – there are two other nuts that beat out almond and Brazil nuts re. oil. Macadamias have 72% oil and nuts of some Asian pines have 78%.

p. 512 – pistachios are green because their cotyledons contain chlorophyll.

p. 513 – poppy seeds contain enough opium-associated alkaloids to make one’s urine test positive for drugs, even though they don’t cause other pharmacological effects. It takes 2-4 million poppy seeds to make a kilogram.

p. 517 – yeast causing dough-rising was initially ‘wild’ and accidental, but by 300 BC there is evidence of a special profession of yeast-making for bread in Egypt (probably as a by-product of beer making).

p. 519 – baking soda and baking powder weren’t invented until 1830 and 1850, respectively.

p. 545 – pumpernickel = ‘devil’s farts’. See also below.

p. 552 – the name of a type of puff pastry, pets de nonne, means ‘nun’s farts’.

p. 609 – Agar-agar is a Malay term. It refers to a mixture of carbohydrates from several genera of red algae. To make it, the algae is boiled and the liquid filtered and freeze-dried. Agar forms a gel at even lower concentrations than does gelatin (<1% by weight). Few bacteria can digest agar and it stays solid at room temperature, so it’s a good medium for growing microbes (which can be fed with nutrients added to the agar).

p. 610 – carageenan, used in ice cream and toothpaste among other things, comes from the red alga Chondrus crispus and a few other species.

p. 647 – the names Melissa and Deborah both mean ‘bee’.

p. 647 – a quote from Pliny indicates that he thought the source of honey to be ‘star saliva’.

p. 648 – sugar cane may have first been domesticated in New Guinea; however, the first people to refine sugar from cane were in India around 500-350 BC. The word ‘sugar’ comes to English from Arabic via Sanskrit.

p. 651 – discovery of how to extract sugar from beets (Beta vulgaris var. altissima) in 1747 was a major cause of the decline of slavery in the West Indies (an economic rather than a moral reason to stop using expensive human labour); however, beet sugar didn’t really take off until the 1810’s. Beet sugar currently = ~30% of world sucrose production (p. 652).

p. 663 – honey made from nectar of particular species of Rhododendron is ok for bees but affects lungs and hearts of humans.

p. 668 – maple syrup is usually made by boiling off water from sap, but can also be made (as done by some native North Americans) by allowing the water to freeze then removing the upper skim of ice repeatedly.

p. 669 – can also make a sweet syrup from birch sap, but it is a much more dilute sap than that from sugar maple (about 1/3 the concentration).

p. 670 – the Asian sugar palm (Borassus flabellifer) has much sweeter sap than sugar maple, up to 12% sucrose compared to maple’s 3%. Crystallized palm sugar is called jaggery in English, from Sanskrit sharkara.

p. 670 – ‘sugarloaf‘ as a term referring to, e.g., the shape of a mountain, comes from the use of a mould shaped like a truncated inverted cone with a hole in the bottom to drain molasses from cane sugar.

p. 677 – corn syrup is actually made from corn starch that is broken down into glucose using acids and/or enzymes. The most common enzymes today come from Aspergillus. High-fructose corn syrup is made by converting some of the glucose into fructose via other enzymes. Retention of some larger carbohydrate molecules makes corn syrup viscous.

Many things to think about when making or enjoying Christmas fruitcake (and yes, I do like fruitcake even though most of the world seems to disparage it).

fruitcake ribbon

Two Bad Mites

This August I met two of the most important mite pests in North America. The two-spotted spider mite, Tetranychus urticae Koch (Prostigmata: Tetranychidae) is particularly devastating in greenhouses. That’s where I encountered it – slaughtering my dill. The common name ‘spider mite’ refers to the vast quantities of webbing they produce.

spider mite webbing on dill from greenhouse Aug 2014

Tetranychus urticae and its webbing on my unfortunate dill plants.

spider mites on dill from greenhouse Aug 2014

Closer view of webbing, showing the mites themselves.

This spider mite has a huge host range, having been recorded from more than 1000 plant species. It feeds by piercing host tissues with its fine stylet-like mouthparts.

Tetranychus urticae from dill 22 Aug 2014 body

Tetranychus urticae from dill 22 Aug 2014 stylets

Tetranychus urticae female: above, whole body; below, gnathosoma showing stylet-like chelicerae.

The name ‘Tetranychus‘ means ‘four claws’ and presumably refers to the four nail shaped setae (tenent hairs) on the tarsi. Why ‘urticae‘? Because they are irritating, like nettles (Urtica spp.)? Or maybe they were first identified from urticaceous hosts?

Tetranychus urticae from dill 22 Aug 2014 tenent

Four nail-like tenent hairs can be seen at the tip of this mite’s tarsus.

Tetranychus urticae has made the big journals lately for having the smallest known genome of any arthropod, and for having likely picked up genes for producing carotenoid pigments by horizontal transfer from fungi. Until recently, it was thought that all animals acquired carotenoids from plants, bacteria or fungi in their diets rather than creating the pigments through their own metabolism. But pea aphids and T. urticae are able to make carotenoids themselves, thanks to these horizontally transferred genes.

The other bad mite I met in August has a much narrower host range – bees of the genus Apis, including the domesticated honeybee Apis mellifera Linnaeus.  This mite is the infamous Varroa destructor Anderson & Trueman (Mesostigmata: Varroidae). These parasites are huge relative to their hosts, being about the size of the bee’s eye. They feed on host haemolymph, thereby weakening the bee, and can transmit crippling viruses. Although I don’t have honeybee hives in my backyard, one of my previous graduate students is a member of YEG Bees and was taking part in the first trial of urban bee-keeping in Edmonton. He invited me to one of their hive checks. Part of the check involved looking at the sticky boards under the hives for Varroa that had been knocked off the bees. Sure enough, they were there. I collected a couple and managed to get an ok photograph of one of the vaseline-covered mites.

Varroa from Beeyonce's hive with pen for scale Aug 2014

A Varroa destructor from Beeyonce’s hive. The queen of the other hive I visited was named Justin Beeber. Beeber’s hive failed – prophetic?

Varroa from Beeyonce's hive A

A V. destructor, after having had vaseline removed via a fine probe and Photoshop.

Varroa can be treated with chemicals or through careful selection of mite-free brood starters. But it is getting harder to find the latter, as V. destructor is found in almost every Apis mellifera-producing country except Australia.  Researchers and apiarists are also trying to breed a more Varroa-resistant honeybee by selecting for intense grooming behaviour.

On the one hand, these two species tarnish the image of other mites through their economic nastiness. But on the other, their bad behaviour helps to pay the salaries of many acarologists.



Snipe hunt

This afternoon one of my colleagues passed on the good news that he had just put a roadkilled charadriiform in the Museum of Zoology’s freezer. I don’t have a lot of mites from Albertan charadriiforms, so I was eager to see get the bird and wash it. The body turned out to be that of a Wilson’s Snipe, currently Gallinago delicata Ord in most taxonomies, though not all feel that it deserved having been raised from its previous subspecies status (G. gallinago delicata).

It was a lovely specimen and I took it to show to people in the main office. “It’s pretty rare to come back from a snipe hunt with an actual snipe!” I said, attempting to be amusing. Two people laughed, and two just stared. “You know what a ‘snipe hunt‘ is, right?” I asked the latter. Nope. When I explained, they got the concept immediately, and came up with other examples (e.g., an apprentice carpenter being sent for a ‘board stretcher’). I wonder if there is an unrecognized linguistic divide in Canada, with snipe-hunting being common in only some regions.

A snipe in the hand.

A snipe in the hand. I washed it after taking the photo and was rewarded with a small number of feather mites and lice.

Cheese, soldiers, mites and mice

I’m reading “On Food and Cooking: the Science and Lore of the Kitchen“, a most absorbing book by Harold McGee. A while ago I finished the section on cheese. Among other fascinating tidbits, I learned that the crunchy crystals one sometimes encounters when eating cheese consist of calcium phosphate, calcium lactate, or the amino acid tyrosine. The Greek root ‘tyros’ means ‘cheese’, which suggests that tyrosine may first have been isolated from cheese (a hypothesis supported by Wikipedia). It also made me think of Tyrophagus putrescentiae (= rotting cheese-eater), a widely distributed mite pest of stored products and arthropod cultures that can rapidly go from a few individuals to a pulsing hairy carpet of thousands.

Tyrophagus on superworm container 27 Dec 2011 banner

A small subset of the hordes of Tyrophagus putrescentiae that overflowed from my tenebrionid culture.

A related ‘tyro’ mite is Tyrolichus casei, which is employed to make the unusual cheese Milbenkäse. But I also knew that ‘tyro’ referred to a raw novice, particularly a young soldier.  Did the ancient Greeks feed their new recruits on cheese? Off to the OED in search of an answer.  To my surprise, ‘tyro’ wasn’t defined under the common spelling, but rather under ‘tiro’, Latin for young soldier.  No mention of cheese, but also no etymology provided. Off to Google in search of a more complete answer. No agreement that I could find, but plenty of contention.

Even more recently, including yesterday, I employed cheese to capture some of the numerous mice (Mus musculus) that occupy the house, despite the presence of my cat Fred.  Or maybe because of my cat; I’ve seen mice march boldly up to to the catfood bowl and steal kibble from it as Fred watched complacently. Snap traps baited with Swiss cheese do a much better job of mouse control. As an acarologist interested in symbiotic mites, I of course have washed some of the mouse bodies. From the washings I picked out a few tiny fur mites.  They have impressively powerful claws on their first legs.

maybe Radfordia ensifera from HPs house mouse

One of the fur mites from my mouse washings.

My first assumption was that they were Myobia murismusculi (Prostigmata: Myobiidae). But this site says that M. murismusculi (a.k.a. M. muris) has only one claw on its second pair of legs. This individual clearly has two claws, which would make it a Radfordia. The claws seem to be equal in length, leading me to conclude that it is R. ensifera (illustrated here; unequal claws mean R. affinis). All three species are known from Mus musculus. It would be interesting to map the distribution and diversity of fur mites on house mice in Alberta, as one would predict that in longer-settled areas (e.g., old parts of Edmonton), the mice would have a greater number of mite species than in areas recently colonized by a potentially small number of founders.