Acari

Who likes shrews? These mites do!

My friend Allan Lindoe, fossil preparator extraordinaire, lives on an acreage near Athabasca and makes the journey south to Edmonton about once a week to carefully remove rocky matrix from around the skeletons of long-dead fishes, mosasaurs, and dinosaurs. Two cats share his home and frequently bring him presents of wild game. A few weeks ago I washed a mixed bag (literally) of a dozen shrews he had accumulated over the summer and fall of 2015. Chewed-on shrews are not easy to identify unless you know a lot about insectivore teeth, but based on tail length and known distributions of shrew species in Alberta, they were one or more of the masked shrew (Sorex cinereus), Arctic shrew (S. arcticus), pygmy shrew (S. hoyi) and/or dusky shrew (S. monticolus)*. Some of the shrews were rather decomposed, so I wasn’t expecting much from the washings, but I was pleasantly surprised: 6 species of mites! Members of both major lineages were present. From the Acariformes were Prostigmata (Myobiidae, Pygmephoridae and Trombiculidae) and Sarcoptiformes (Glycyphagidae). From the Parasitiformes there were larval hard ticks (Ixodida: Ixodidae) and what look like Melicharidae (Mesostigmata).  Myobiids, trombiculids, and ixodids are parasitic, and the others are all likely just phoretic. Who knew the zoo on shrews? Now you do.

Protomyobia female ex shrew

Protomyobia nr. claparedei female (note egg).

 

Protomyobia ex shrew

Protomyobia nr. claparedei male (note well-sclerotized aedeagus).

 

Protomyobia lv I think A

Larval Protomyobia nr. claparedei (note styletiform chelicerae).

 

pygmephorid ex shrew

Ventral view of one of the many pygmephorids from the shrew washings.

 

pygmephorid ex shrew legs I

Pygmephorid showing modified legs I.

 

chigger ex shrew A

Dorsal view of a shrew chigger (Trombiculidae).

 

chigger ex shrew B

Prodorsal shield of a shrew chigger, showing the posterior pair of trichobothria and single anterior median seta (just the base can be seen here) indicative of the family Trombiculidae, as opposed to members of the Leeuwenhoekiidae, which have two anterior median setae.

 

prob Oryctoxenus A

An Oryctoxenus sp. deutonymph (Glycyphagidae). Anterior is pointing up, and yes, it doesn’t have mouthparts.

 

prob Oryctoxenus B

Posterior hair-clasping structures of an Oryctoxenus deutonymph.

 

ixodid larva ex shrew A

A larval hard tick (Ixodidae).

 

ixodid larva ex shrew B

Retrorse spines on the tick’s hypostome help keep it attached to the host.

 

maybe Proctolaeleps A

Maybe a female Proctolaelaps sp.(Melicharidae). Not in great shape.

 

maybe Proctolaeleps B

The ‘procto’ part of Proctolaelaps refers to the large anal opening, or so the etymological legend goes.

*Smith, H.C. 1993. Alberta Mammals: an Atlas and Guide. The Provincial Museum of Alberta, Edmonton, Alberta.

 

 

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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

*abakashi@gmail.com

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).

Winterschmidtiid_001

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).

Winterschmidtiid_003

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.

 

 

 

 

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.

 

 

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.

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.

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.