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.

A(i)nt and gast(e)ropost

While at the Los Tuxtlas field station I had the opportunity to be attacked by numerous arthropods, including trombiculid mites (chiggers), numerous species of ants, and an urticating caterpillar. Don’t laugh about the caterpillar!  They can kill you. But the one that got me only left a caterpillar-shaped welt on my shoulder. I’ll describe two ant attacks of note. One involved an invasion of sleeping quarters by male and female ants after a hot day and heavy rainstorm induced a flight of reproductives. The bedroom walls and ceiling were covered in winged ants, which proceeded to fall down on the bed at night. One added both injury and insult by biting my bottom.

winged ant queen like the one that bit me in bed Los Tuxtlas 18 July 2014 sml

One of many reproductive female ants that swarmed the bedroom in Los Tuxtlas. Unfortunately, I don’t know the genus.

The next morning I took some photos of the remaining reproductives, which revealed that the males have grotesquely enlarged and protuberant ocelli.  A cursory Googling revealed that ocelli tend to be larger in reproductives of night-flying ant species, but I couldn’t find a good explanation for the sexual difference. This paper suggests that males of Myrmecia (a genus different from the that of the ants that fell on me) may have to engage in more intense visual tracking to find the females for mating.

ocelli of female vs male reproductive ants Los Tuxtlas 18 July 2014 sml

Heads of female (left) and male (right) reproductive ants showing the difference between the sexes in relative size and sphericality of the three ocelli.

The second ant attack occurred when I was peaceably watching a lecture on salticid taxonomy in the lab. Suddenly I felt a burning pain on my throat. Remnants of the crushed body of the perpetrator revealed that it was a Pseudomyrmex, probably P. salvini.  This ant was many times larger than the other species of Pseudomyrmex that had attacked my hand near Chamela, and it produced a goiter-like swelling commensurate with its size. I don’t know what induced it to stab me in the neck – sheer viciousness, perhaps. But on the bright side, the nasty nature of the Pseudomyrmex is probably why a particularly striking species of jumping spider mimics it. The a(i)nt pictured below with its model is a species of Synemosyna. They were common on the station walls and foliage.

Pseudomyrmex most likely salvini and Synemosyna mimic Los Tuxtlas 14 July 2014

Pseudomyrmex ant on left and a mimicking Synemosyna salticid on the right.

 So there is the gasteropost – on to the gastropost.  In Morelia we had much enjoyable food and drink, including a surprisingly good Mexican IPA, but there was also some awful stuff. One meal resulted in a three day trial of having my Edmontonian gut flora violently replaced with a Morelian community. After that had settled down, I decided I was digestively robust enough to sample a mysterious drink called a ‘Michelada’, which was advertised everywhere, but I had no idea what it might be. When the beverage arrived, this is what it turned out to be:

Michelada trimmed

Creating the Michelada – beer plus Clamato juice. Urgh. (photo by Wayne Maddison)

I managed to drink about a fifth of the concoction before the guts said ‘no’! Tastebuds concurred. But as odd as this beer+Clamato sounds, there is an equivalent in Alberta: the Red Eye. Why someone decided to replace the vodka in a Caesar with beer is unclear to me.

A more pleasant food experience took place in Mexico City after I had given my talk at UNAM. My host, Dr. Tila Pérez, took me and some other arachnologists to a traditional restaurant for lunch. There in addition to delicious moles (poblano, negro, verde and rojo), we sampled some unusual appetizers. My favourite was escamoles – fried ant juveniles (maybe a mixture of larvae and pupae) served with guacamole and eaten with tortillas. They tasted like buttery fried things, and I enjoyed them maliciously.

escamoles - fried ant pupae raised on agave roots Mexico City 28 July 2014

Fried baby ants – delicious revenge! (photo by Grislda Montiel)

Arachnids at Los Tuxtlas


students collecting Los Tuxtlas 14 July 2014 B sml

Students collecting around the field station.

I spent an enjoyable week of this July at the UNAM Los Tuxtlas field station in Vera Cruz, Mexico, sitting in on a field course and taking a macrophotography holiday. The course was on the taxonomy and biology of Salticidae jumping spiders, and was run by Wayne Maddison from the University of British Columbia (Canada) and Gustavo Ruiz from the Universidade Federal do Pará (Brazil).


Seventeen undergraduate and graduate students from Mexico, Central America, and South America were eager vessels for the instructors’ salticidological wisdom.

classroom Los Tuxtlas 16 July 2014

Classroom at Los Tuxtlas.

Jumping spiders were abundant and conspicuous at Los Tuxtlas.  Quite a contrast from the situation in Alberta, where hunting salticids requires a vast amount of patience and belief in divine intervention. Here is a small selection of the beautiful jumping spiders we saw.

big male Freya regia on leaf Los Tuxtlas 14 July 2014 sml

Despite being named for the Norse goddess of love, this Freya is all man.

Corythalia on wall Los Tuxtlas 16 July 2014 sml

One of about a dozen species of Corythalia from Los Tuxtlas.

Lyssomanes male Los Tuxtlas 17 July 2014 sml

Male Lyssomanes maddisoni court via semaphore.

There was a great diversity of other families of spiders at Los Tuxtlas. Large wandering spiders of the genus Cupiennius (Ctenidae) were everywhere. Less common, but a great treat for me as I hadn’t seen them since I lived in Australia more than a decade ago, were two-tailed spiders (Hersiliidae). Neither is as flashy as most salticids, but they have a subtle beauty of their own.

ctenid Cupiennius on wall UNAM Los Tuxtlas 14 July 2014 trimmed sml

Cupiennius on retaining wall.

two-tailed spider Hersiliidae Los Tuxtlas 17 July 2014 sml

Two-tailed spider (Hersiliidae)

In addition to Araneae, I saw many other orders/superorders of arachnids at the field station including Acariformes, Opiliones, Palpigradi, Parasitiformes, Pseudoscorpiones, Ricinuleida, Schizomida and Scorpiones. The only terrestrial ones I didn’t see were Solfugida, Amblypygi and Uropygi, though the latter two were no doubt there. I was particularly excited to photograph live ricinuleids. At one point they were thought to be the sister group to mites because they shared with the Acari a 6-legged larval stage, among other things. Molecules say otherwise, though, both with regard to the relationship between mites and ricinuleids and the monophyly of mites themselves. Unfortunately, the post-larval ricinuleid got tangled up in residual spider webbing from the vial it was held in, and was too hobbled to walk naturally.

trombidioid Los Tuxtlas 15 July 2014passalid venter with mites Los Tuxtlas 15 July 2014 sml

gonyleptid sl opilionid Los Tuxtlas 14 July 2014scorpion prob Chactidae 16 July 2014 sml

ricinuleid larva and HPs pinkie finger Los Tuxtlas 16 July 2014 smlricinuleid adult unfortunately webbed up Los Tuxtlas 16 July 2014 A

Non-spider arachnids, starting at top left: acariform mite, parasitiform and possibly also acariform mites on the venter of a passalid beetle, opilionid, scorpion, 6-legged larval ricinuleid and my pinkie finger, post-larval ricinuleid.

There and back again

Two days ago I got back from another trip to Mexico!  The first destination was Los Tuxtlas, one of the two large UNAM field stations (Chamela being the second of the pair). This station is located in rainforest in Vera Cruz on the Atlantic side of the country. After a week there it was off to the old city of Morelia in Michoacan to attend an arachnological conference. Morelia’s history and amazing architecture definitely justify its being a World Heritage Site. The trip ended with my giving a talk at UNAM in Mexico City. But despite the many wonderful opportunities for photography of landscape, buildings and people, most of my tourist shots were taken with a cell phone from the vans and buses in which we traveled. A compilation of such images arranged in rough temporal order is below. Posts on arthropods will follow.

collage of on-the-road travel pix Mexico July 2014 reduced

Diamond Life

In mid-June I spent a week working a at a location farther north than I had ever been – Lac de Gras, 220 km south of the Arctic Circle in the Northwest Territories. On an island in Lac de Gras is Diavik Diamond Mine. Diavik employs about 1000 people to mine and process diamonds and to support the mining operations. The cafeteria is stupendous but the sleeping quarters are not particularly salubrious. It is a dangerous place due to gigantic vehicles, rockfalls, extreme weather and large mammals including caribou and grizzly bears. At Diavik, people are very very safety-conscious.

bad things can happen Diavik trip 12 June 2014 C

Diavik cautionary tale – me beside two heavy equipment tires and the pickup truck they crushed (photo by C. Uherek)

They have made some rather large holes in this island.

Diavik mining pits as seen from helicopter 17 June 2014

Diavik mining pits as seen from helicopter.

To compensate, in part, for their impact on the local environment, Diavik is supporting a number of research and remediation projects on and near the mine, including studies on soil and plants, and on stream fauna. I am involved in the latter via my M.Sc. student Christiane Uherek, whom I cosupervise with Bill Tonn, a fish ecologist in my department. Bill and a half dozen of his students have worked hard over the past several years to create and monitor an artificial stream connecting a previously isolated lake on an island near the mine site with Lac de Gras. The hope is that grayling and other fishes will use this stream to access the lake for breeding.  Christiane isn’t working on the fish directly, but rather on the artificial stream’s physical and biological characteristics. She will compare these features with those of nearby natural streams (references) to determine whether flow, woody debris and invertebrate assemblages of the artificial one fall within the range of variation of natural ones. It’s the macroinvertebrates that connect me to this project.

Reference 6 lake 16 June 2014 sml

Reference 6 Lake, from which Ref 6 Stream 1 flows.

To measure retention of organic matter we tossed artificial sticks and paper ‘leaves’ into streams and measured how far they went downstream before they got stuck.

HP dropping artificial sticks into stream with Chrisitane recording13 June 2014

Me dropping artificial sticks into an artificial stream, with Christiane recording data.

Terrestrial vertebrates (in addition to humans) are surprisingly common at Lac de Gras. Voles, ground squirrels and willow ptarmigan regularly dropped by to check out what we were doing.

male willow ptarmigan West Island stream 15 June 2014 C sml

Male willow ptarmigan wondering why we are measuring sticks.

According to the New Shorter Oxford, ‘ptarmigan’ is a falsely Greekified modification of the original Gaelic name ‘tarmachan’, which means ‘grumbling or croaking'; apt if you listen to the bird’s rather frog-like calls.

During my week there I came to understand why Diavik emphasizes safety with such religious fervour. We experienced lightning storms, rockfall alerts, a vehicle that burst into flames in front of our truck, and a couple of grizzly bears, one of which we escorted with the help of a helicopter from the mine site, across frozen Lac de Gras, to the mainland.

chasing grizzly bear across Lac de Gras with a helicopter 16 June 2014 A

Note to self: grizzly bears can run very fast for a very long time. Fear them.






The truth about velvet mites

A few days ago, three of my colleagues independently sent me a link to The Oatmeal’s cartoon “This is a Red Velvet Mite and He is Here to Teach You About Love“. Like many of The Oatmeal’s cartoons, this is about sex and is unabashedly rude. But unlike most of his comics, the topic in this case was one on which consider myself to be somewhat expert: indirect transfer of sperm via spermatophores.

Proctor 1998 Ann Rev Ent

I hope this isn’t a copyright violation.

‘Indirect’ refers to the placement of sperm packets (typically on or in stalks of hardened exudate) on a substrate by the male, with the female then picking up the sperm herself. This can be done in a paired fashion in which the male directs his deposition to a particular female, often physically contacting the female at some point (e.g., scorpions), or it can be dissociated, in which the male and female don’t interact at all (many springtails and mites).  In addition to the taxa just mentioned, many other animals transfer sperm via substrate-associated spermatophores, including centipedes, pseudoscorpions, vinegaroons and even salamanders.

Velvet mites are members of the large acariform mite taxon Parasitengona, and can be roughly divided into the short-legged velvet mites (Trombidiina) and the long-legged ones (Erythraeina).  Many but not all have a sparse to plush coat of setae covering their red or orange bodies.  Based on the relatively little we know about sperm transfer in velvet mites, The Oatmeal got a lot of things right in his cartoon. Sperm transfer is indirect, males often lay down trails of exudates leading up to the spermatophores, females fertilize themselves, larval velvet mites are parasites, cannibalism is not uncommon (especially consumption of smaller males by larger females), and males do indeed trash the spermatophores of their competitors.  But sperm blobs are small, tidy and on stalks, not giant dripping beachballs as in the cartoon. Male dancing, if it occurs, is not particularly elaborate. And what’s this about building castles out of sticks and leaves? I’ve never read anything about that.  The author wasn’t forthcoming on the scientific source of the love-shack info. I searched Google Scholar for various combinations of “velvet mite*”, “Dinothrombium” (the velvet mite genus shown in the associated video), “mating” and “spermatophore*”. Nothing about castles. Perhaps the relevant publication isn’t in English? Or…could it be that The Oatmeal sometimes just MAKES THINGS UP?!?

wrestling Eutrombidium Microtrombidiidae Gull Lake AB 26 June 2013 A

Two Eutrombidium (Trombidiina: Microtrombidiidae) fighting for access to a grasshopper oviposition hole. Or maybe I’m just making that up.

Inquisitive and very very fast

Speedy anystids are in the media this week because of a recent presentation at the Experimental Biology meeting in San Diego. The now famous whirligig mite is Paratarsotomus macropalpis (Banks), a member of the anystid subfamily Erythracarinae. Erythracarines have a more elongate body than species in the Anystinae (one of which is by the ‘The” in this blog’s title) and often have very attractive striped legs, such as this individual from New Zealand (photo by S.E. Thorpe from Wikimedia Commons). Erythracarine from Wikimedia Commons by SE Thorpe Rubin et al., the authors of the abstract, clocked Paratarsotomus macropalpis running on hot pavement at 0.8 km/h, which doesn’t sound impressive until this is converted into body lengths: 322 body lengths/second. As National Geographic reports, this is much greater than a cheetah can achieve (16 body lengths/s), and faster than what they state is the previous record holder, a tiger beetle (171 b.l./s).  But what about the copepods that were celebrated only as few years ago as being able to leap through water (!) at 500 body lengths/s? Maybe it doesn’t count because it isn’t sustained running? Or do aquatic animals keep their own statistics? Irrespective of such semantic quibbles, it’s wonderful to see anystids getting press for their athletic achievements.

The Accidental Taxonomist

Accidental Taxonomist title image sml

Dr. Thelma Finlayson, an emeritus professor at Simon Fraser University, will soon be celebrating her 100th birthday. In honour of this event, a half-day symposium was held at FSU a couple of weeks ago. The themes reflected Finlayson’s own research: insect biocontrol and taxonomy. I had been asked by the coordinator of the event, Dr. Elizabeth Elle, to give the final lecture in the symposium with a focus on biodiversity and systematics.  An honour, but also daunting! According to Elle, Finlayson became a parasitoid taxonomist by necessity rather than by original intent. Her main interest was biocontrol but in order to do that she had to become an expert in the taxonomy of tiny wasps. That story made me reflect on my own path to becoming a mite taxonomist.  I, too, had followed an accidental route, with my original interests being ecology and behaviour. Then I wondered how many of my colleagues were also Accidental Taxonomists.

About a month before the symposium I sent a request to three arthropod oriented listservs with different audiences: mite biologists, arachnologists working on taxa other than mites, and parasitoid hymenopterists.  This is the content of that request:

Dear XXX people: I will be giving a presentation on taxonomy at Simon Fraser University at the end of March, and as part of my seminar I would like to discuss how people end up being taxonomists.  In some cases, becoming an expert on the taxonomy of a group may have been a deliberate choice, e.g., as your M.Sc. project you may have chosen to revise a particular genus of XXX.  But in other cases one may have planned to do a project on behaviour or ecology, and discovered that you couldn’t complete the project without first learning the taxonomy of the group.   So, I would greatly appreciate hearing from those of you who have become local (or international!) experts in taxonomy of particular groups of XXX.  Here are my two questions: (1) for what xxx group(s) have you become a taxonomic expert? By ‘expert’, I mean expert at identification, not necessarily someone who also describes new taxa. (2) how did you happen to become an expert? Was that your first choice, or had you originally planned to work on some other aspect of that group’s biology? Many thanks! Heather Here are the results that I presented to a wonderful audience of Finlayson fans on 25 March. (1) Geographical distribution of respondents: 64 people from 23 countries, top five being U.S.A., United Kingdom, Australia, Canada and the Netherlands (see map below). map of Accidental Taxonomist replies (2) Here are the taxonomic orientations of those respondents:Accidental Taxonomist - replies broken down by taxon   (3) Out of curiosity, I checked the sex-ratio of the respondents. Strongly male-biased – but note the caveat (which is relevant to ALL of the responses, not just this one).Accidental Taxonomist - replies broken down by taxon and sex (4) And then the main question: how many respondents became taxonomists deliberately, as their first choice, or by accident or necessity? A few people didn’t answer this question directly, so I made an educated guess based on the stories associated with their responses. The answer is that about half of them were Accidental Taxonomists. Accidental Taxonomist - replies broken down by deliberate or accidental (5) My gut feeling after reading the responses was that non-mite arachnologists were much more likely to have chosen taxonomy as a career than were acarologists.  Araneologists seem to be born rather than made.  My guts were correct! One could also hypothesize, conversely, that mite biologists tend to be forced into taxonomy out of necessity, given the vast unknown that is acarine biodiversity. Accidental Taxonomist - replies broken down by deliberate or accidental and by taxon Although some taxonomists responded in a brief and businesslike manner, others provided long and delightful (or sometimes sad) stories of how their scientific careers had evolved.  After the symposium, a few people asked me whether I planned to publish the results.  Nope – can’t.  Didn’t have Human Ethics clearance to do this survey. It is totally illegal, contraband data.  Plus, the survey was not at all scientifically designed. So please take these results cum grano salis.