Snap and Grab: One way to snare a springtail

One of the interesting things about the human mind is that although we tend to be fascinated by the diversity in Nature, we endlessly try to simplify what we see, to control Nature by reducing it into a smaller number of units. We value simple explanations over complex ones and even codify this preference in science with Occam’s Razor. This has various formulations, but Frustra fit per plura quod potest fieri per pauciora at least comes from Occam’s writings and fits this posting: ‘It is futile to do with more things that which can be done with fewer’.

Another long bite for a springtail

It is winter now, if a rather mild one so far, but still not the best time for observing living arthropods. However, a friend has posed a challenge – how many living arthropods can you find during winter in Alberta? So, I’ve been wandering around the house taking bad pictures of tiny insects and far too large spiders and trying to coerce my wife into taking better ones. However, exams and marking reign at the moment and she suggested: why not see what is living in the soil of our house plants? Brilliant idea! – at least 21 species in the first extraction, 2/3rds mites, but also 7 species of Collembola – springtails. As I was perusing said springtails I noticed that the large entomobryid and isotomids all were missing the distal segements of their antennae.

Entomobryid springtail with its antennae intact

Although Tennyson’s “Tho’ Nature, red in tooth and claw, With ravine, shriek’d against his creed [i.e  God's]” is most colourfully exemplified by vertebrate predators at their dinner, you can get an idea of what life in the soil is like for springtails by viewing Jeffrey Newton’s entertaining video. The spring in the springtail is one way these animals avoid being eaten, as are the slippery scales on some (as in the SEM above) and the chemical defenses of others. Apparently, shedding the ends of the antennae is another (good news is that they can grow back – as one victim with half-regrown antennae demonstrated).

Another snap & grab - but more shear-like than toothy

In my house plant ecosystem, the antenna-snapper seems to be a species of Holaspulus. These are rather large predatory mites (Mesostigmata, Parholaspididae) more typically found in tropical areas. But then, I guess the greenhouses these plants came from do all they can to mimic the tropics including, it seems, hosting tropical mites.

Long snapping chelicerae on a Holaspulus adult female

As you can see from the image above (this mite is from Queensland), Holaspulus  have very long chelicerae, almost half the length of their body. These chalicerae can be shot out to snap and grab prey, such as springtails. I know this is true through my own observations, but I also know this for the other chelicerae of the very different mites illustrated above and several other unrelated genera.  Just as springtails have a diversity of means of escaping becoming dinner, so do their predators of capturing them.

Diagram of Holaspulus chelicera deployed: snap and grab

And just to keep things clear as mud, I know of many mites with much less impressive chelicerae that also seem to have no problem catching springtails, e.g. the parasitid mites in Jeffrey’s video. Another example,  species of Podocinum have fairly typical chelicerae, not obviously enlarged at all, but are seemingly efficient predators of springtails.

Business end of a Podocinum: not at all springtail-challenged

Such cheliceral modesty is true of many mesostigmatans that prey on springtails – they lack the snap-trap type of chelicera. But  some such as Podocinum species do have extraordinarily attenuated legs.

Podocinum fishes for springtails with it elongate front legs

I’ve watched Podocinum fishing for springtails. They are slow-moving, stately mites, but as they wander the front legs dangle in front exploring their world. When a springtail is encountered by the light touch of the long distal setae, the mite pauses, and then quickly scopes their prey in towards their chelicerae: another springtail become mite fodder.

Epicriid mite with sticky setae to trap springtails

Epicriid mites carry this long-legged fishing one step further. The long ventral setae on the tips of the front legs have blobs of glue with which they capture their collembolan prey (see Alberti 2010*). So we have yet another way to scarf-up a springtail, but why such diversity in such a simple pursuit?

Another toothful springtail nemisis?

As far as I know, no one has studied the feeding behaviour of the mite above, but I suspect springtails are part of its diet. For those who like a challenge, try naming the unnamed cheliceral images. A genus would do and you have five such unlabelled images to guess upon.

I know of only one genus with multiple rows of retrorse teeth - care to guess?

*Alberti, Gerd. 2010. On predation in Epicriidae (Gamasida, Anactinotrichida) and fine-structural details of their forelegs.  Soil Organisms  Volume: 82  ( 2);  179-192.  (Open Access – search for the title and the pdf is yours)

Eustigmaeus frigida (Habeeb) - a mite that feeds on mosses

I find the Raphignathoidea (Acariformes, Prostigmata, Raphignathina) one of the more fascinating superfamilies of mites. Many of its members are bizarrely attractive, for example species of Xanthodasythyreus and Dasythyreus (Dasythyreidae) that look like an ambulatory pincushions.

The elongate setae probably act as a defence against predators and are produced in members of several other families. In other raphignathoid families increased degrees of sclerotization are the most obvious trend in predator defence.

A species of Stigmaeus, a typical predatory raphignathoid mite

Armour reaches it apogee in groups such as a the Homocaligidae or the Cryptognathidae. In the latter, the body is completely encased in a dorsal and a ventral shield that fit together rather like a tin and its lid, but with a tube at the anterior end into which the mouthparts can be withdrawn (and hence crypto = hidden, gnatho = jaws).

Gnathosomal capsule with elaborate peritreme in Xanthodasythyreus

Currently, 11 families of Raphignathoidea are recognized and they are highly variable in form from soft-bodied to fully armoured. They all share some characters in common, for example the chelicerae have a needle-like movable digit used to stab and a sheath-like fixed digit that protects the needle when not in use, the genital papillae are not expressed, an ovipositor is not present, prodorsal trichobothria are absent, and the pad between their claws bears tenent hairs. Seven families have stigmatal openings near the bases of their chelicerae and simple to elaborate peritremes, but four families do not, and in any case stigmata and peritremes occur in other superfamilies as do the other character states that have been mentioned. As a result, the superfamily is difficult to key – it shows up at two spots in the current edition of the Manual of Acarology and the second couplet is one of those messy, exception-filled, paragraph-long abominations that are embarrassing to write and a headache to use.

Needle-like stabing digits of a predatory stigmaeid mite (Agistemus sp.)

The 7 families with stigmata and peritremes mostly have fewer than 50 described species and are characteristic of dry habitats (grasslands, deserts) or dry microhabitats (tree trunks, logs) in moister places. In contrast, the four families without stigmata, including the obscurely named Stigmaeidae with well over 300 described species, are found from dry to wet habitats and all types in between. In fact, the largest genus in the family Eustigmaeus (eu = good) Berlese, 1910, repeats this act, being found from deserts to submerged lake margins. Most stigmaeids that have been studied are predators of small arthropods and some are important biocontrol agents. However, Uri Gerson of the Hebrew University of Jerusalem demonstrated that at least some Canadian species of Eustigmaeus feed on mosses.

Eustigmaeus frigida mouthparts, lateral view (arrow = cheliceral digit)

This seems to be true of the species that inhabits the mosses growing along the margin of the lake at my research site: E. frigida (Habeeb, 1958). The cheliceral digits are difficult to observe on a light microscope, even under oil immersion, so I thought I’d check them with the SEM, but this is one of those cases where more magnification is of no help. The mouthparts seem well along the road to becoming a gnathosomal capsule and only the tips of the cheliceral digits protrude from their wrapping. I wonder if the mite simply rasps the leaves of the mosses with the protruding tips of the chelicerae and sucks up the juices? Seems like that would work even under water.

E. frigida mouthparts ventral view (arrow = cheliceral rasp?)

Margarodidae cf Margarodes: male dorsal habitus

I guess no one wins a heap of points for this one, but Greg Z. comes the closest with “something in the Coccoidea”. On Alberta Bugs, where I posted the url, Felix, Chris, Amanda, and Sylvia all also came to Coccoidea. Congratulations to all of them and five points to each (one to Ted for Hexapoda and one to Adrian for his comment on the eyes). I did better with the specimen in hand and Borror, De Long & Triplehorn – Margarodidae. It helps that I recognized it as probably a scale insect male too, and so did not have to attempt the order key. After that the compound eyes (rare in scales), one-segmented tarsi with single claw, and 10-segmented antennae got me to one of the 11 families (~8000 known species) of Coccoidea – Margarodidae.

That id was one-step beyond my level of expertise, but the internet and the generosity of the small community of margarodid aficionados came to the rescue. Penny Gullan at the Australian National University was first back with the confirmation that the animal did resemble Margarodidae sensu stricto – a Ground Pearl – and apparently the first record of the family for Canada! Bob Foottit at Agriculture and Agri-Food Canada agreed and his colleagues at the USDA backed him up. Chris Hodgson at the National Museum of Wales also agreed, but couldn’t be sure of the genus. Chris also explained that from what little is known about flying male scale insects, the body tends to be held more or less vertically – so the ‘ventral’ compound eyes are probably more oriented frontally in flight. Imre Foldi at the Muséum national d’Histoire naturelle in Paris and Yair Ben-Dov at The Volcani Center in Israel also agreed on Margarodidae s.s. and tentatively suggested that this animal is may be the undescribed male of a species of Margarodes. So, starting from a small white dish of soapy water in southern Alberta, this luckless male (or at least its image) has journeyed around a good chunk of the World.

Ground Pearls are so called because the spherical cysts formed by the immature feeding stage(s) on the roots of their hosts may be pearl-like in appearance (and up to ~4 mm in diameter). Although many if not most margarodids may go about their business without us even knowing they are there, some species are economically important and damage sugar cane in Australia, grape vines in South Africa and South America, and turf grasses in the southern United States (Allsopp et al. 2000, Unruh & Gullan 2007). For example, the Centipede Ground Pearl Dimargarodes meridionalis (Morrison) feeds on the roots of grapes and grasses (especially Centipede Grass Eremochloa ophiuroides) in the southern United States (Camarino 2009, Unruh & Gullen 2007).

As is often the case, most of what is known about margarodids comes from the study of the pest species. Their life cycle (the following discussion is based mostly on Foldi 2005) is almost as strange as their morphology. Eggs laid in a waxy ovisac in soil near a host plant hatch into a crawler stage with functional legs, antennae, and piercing-sucking mouthparts. The crawler finds and attaches to a host plant (usually on a root). As they feed both waxy filaments and blobs of liquid excrement are produced and develop into a protective test. As feeding continues, the insect becomes globular, and with enough imagination, pearl-like. The first moult results in an apodous blob (legs and antennae reduced to vestiges) attached to the plant by its feeding tube. The cyst (the blob-like insect and its protective test) continues to grow. The feeding cyst is also the overwintering stage and apparently may last for many years if conditions are inappropriate for forming adults. Some margarodids are asexual (partheongenetic) and only produce females. At the adult moult the female regains short legs and antennae, but lacks mouthparts and cannot feed. Parthenogenetic females may remain within the test and produce eggs or look for a new host. In the bisexual species, the female digs her way to the surface using her hook-like fossorial front legs (and may climb up onto vegetation) to emit a pheromone plume. Males also develop from cysts (see Fig. 2 in Foldi 2005), but pass through a prepupal stage with legs and antennae, an exarate pupa, and finally moult into a winged male that digs to the surface and takes wing to find females. With no mouthparts in either sex, I guess the adults have but one thing on their minds: after mating, the female returns underground and produces a waxy ovisac to protect her body and eggs of which she may lay 100 or more.

Nine ground pearl species are known to occur in North America, mostly in the more southern states of the US from Florida to California. However, Eumargarodes laingi Jakubski, 1950 (=Margarodes dactyloides McDaniel, 1966), the pest of sugar cane in Queensland, also feeds on the roots of Buffalo Grass (Bouteloua dactyloides) at least as far north as Scotland, Texas (just south of Oklahoma) (Unruh & Gullen 2007). Buffalo Grass reaches its northernmost distribution in central Montana and western Saskatchewan – not far from the much collected from Onefour Heritage Rangeland Site, the mixed grass prairie from hence our wandering male – but Buffalo Grass is not reported in the Flora of Alberta. Also, males of Eumargarodes laingi (the only species in the genus) are unknown (Samson & Harris 1998) and at least the Australian populations are parthenogenetic. Another possible contender, Heteromargodes americanus Jakubski, is known from the roots of grasses in northern Wyoming and a male collected from a wind vane trap in Hansen, Idaho, has been doubtfully attributed to this species (Hodgson & Foldi 2006). However, this male has compound eyes that meet ventrally and differs in details of the sclerites and robustness of the legs, and so is not likely our species. Thus, we have Canada’s first known Margarodidae – possibly a species of Margarodes, but most likely not described, and host unknown. Something tells me I may be spending some time digging in the mixed grass prairie in southern Alberta next summer.

References

Allsopp PG, McGill NG, Stringer JK. 2000. Host-plant resistance in sugarcane to pink ground pearls, Eumargarodes laingi Jakubski (Hemiptera: Margarodidae): Confirmation and further screening of clones. Australian Journal of Entomology 39: 316-321.

Camarino A. 2009. Ground Pearls, Earth Pearls, Pearl Scale, Margarodes spp. (Insecta: Hemiptera: Margarodidae). http://edis.ifas.ufl.edu/in554

Foate KD. 2002. Entomologists swarm to Onefour.

Foldi I. 2005 . Ground pearls: a generic revision of the Margarodidae sensu stricto (Hemiptera: Sternorrhyncha: Coccoidea). Ann. Soc. entomol. Fr., 2005, 41 (1) : 81-125.

Hodgson C & I Foldi. 2006. A review of the Margarodidae sensu Morrison (Hemiptera: Coccoidea) and some related taxa based on the morphology of adult males. Zootaxa 1263: 1–250.

Samson PR & WJ Harris. 1998. Seasonal phenology and distribution in soil in sugarcane fields of the pink ground pearl, Eumargarodes laingi Jakubski, with notes on Promargarodes spp. (Hemiptera: Margarodidae). Australian Journal of Entomology 37: 130-136.

Unruh CM & PJ Gullan. 2007. Hypogeal margarodids of the genus Heteromargarodes Jakubski (Hemiptera: Margarodidae) from the western United States. Proc. Entomol. Soc. Wash. 109 (1): 166-181.

USDA Margarodidae 

You will obey. What is my name?

This 3 mm long monster landed on my desk last week. I was nonplussed, but not intimidated, and soon had made some sense of its secret name. Now it’s the turn of my devoted readers to show their skill. Unlike most bug blogs that post a challenge, macromite is usually willing to show you as much of the critter as can be seen, so below is the full ventral view and below that the collection data. Never let it be said that macromite doesn’t play fair.

There are more things in heaven and earth ...

AB: Onefour Heritage Rangeland Natural Area,
49°9.370’N 110°16.397’W, el. 900 m,
23 Jul 2010, white pan trap

Update – Like most of you, my first impression was Strepsiptera, but like Ted, a second’s thought said not really. So far Ted is the only one with any points here (but at Alberta Bugs things are heating up). Adrian’s point about the eyes is interesting, though, and deserves a point. Here are a couple more views of our new alien overlords:

Ventral view of gnathosoma of Antennolaelaps sp.

What do Antennolaelaps, Emmylou Harris, Catherine Deneuve, FDR, The BVM, and assorted ladies with musical instruments, ladies in informal attire (or not attired), and a couple of strange dudes have in common?

Results of a Google Image Search

It must be the colour scheme, but at least no algorithm has confused this attractive member of the Mesostigmata with Darth Vadar. That would only be appropriate for members of the genus Darthvaderum Hunt, 1996, a member of the Oribatida.

Hat tip to Myrmecos.

Putative Mycetophagus prepupa with Paracarophenax

Well, Ted gets a point for the adult beetles – they are Mycetophagidae – and a species of Mycetophagus according to Arnett, although if the adult male beetle didn’t have a distinctive tarsal formula, I’m not sure I would have ever keyed it out. A coleopterist now has the specimens and a species identification may be forthcoming. The associated larva is not a Ciidae – I think these are restricted to polypore mushrooms and the habitat was a fleshy gilled mushroom, Pleurotus ostreatus.  My inference that the larvae associated with these adult beetles is the same species is based on co-occurance, appropriate size, and lack of any alternative. I’ll see if I can get a specialist to agree, but larvae don’t seem to be especially well known.

I think I’ll have to give Kaitlin the win here, though, with three points: one for recognising the mite as a member of the Heterostigmatina (aka Heterostigmata), one for a creative (if wrong) story about the life history, and one for boldly guessing where no other acarologist dared.

The mite is, in fact, an undescribed species of Paracarophenax Cross, 1965 (Acariformes: Heterostigmatina: Acarophenacidae). Of the five described species in the genus (Magowski 1994), Paracarophenax dermestidarum (Rack, 1959) seems to be the only species that has been studied in any detail – it is a parasitoid of the eggs of a dermestid beetle. However members of other genera in the family are of considerable interest as biocontrol agents of stored product beetles.

For example, Acarophenax lacunatus (Cross & Krantz, 1964) is an egg parasitoid of a number or grain-infesting beetles (Oliveira et al. 2003a,b) including the Lesser Grain Borer Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). Adult female mites are phoretic on adult beetles. The mites detach from the beetle as eggs are laid. A mite attaches to the egg, swells up (physogastry), and as it kills the egg up to two dozen offspring develop inside the body of the mother mite (Faroni et al. 2000). One or two of these internal young are males and they mate their sisters before they pop open the mother and start looking for new eggs or new beetles to hitch rides on.

This seems to be the general life style of these mites, including those in the genus Adactylidium Cross, 1965 on thrips eggs and Aeithiophenax Mahunka, 1981 on the eggs of scolytine bark beetles. So, we may assume that our Paracarophenax does something similar. I’m not aware of reports of these mites attaching to larvae, but the three ‘Mycetophagus‘ larvae with mites were all large, plump, and probably prepupae (smaller larvae did not harbour mites). In the swampy morass of a decomposing oyster mushroom, I think it makes sense that the mites hang on (they were not feeding) to the late stage larva. One wonders where pupation takes place, but for the mites to have another generation, they need to hitch a ride on an appropriate insect.

Further reading:

Cross EA, Krantz, GW. (1964) Two new species of the genus Acarophenax Newstead and Duvall 1918
(Acarina:Pyemotidae). Acarologia, 6, 287-295.

Faroni LRD’A, Guedes RNC & Mathioli AL. (2000) Potential of Acarophenax lacunatus (Prostigmata:Acarophenacidae) as a biological control agent of Rhyzopertha dominica (Coleoptera: Bostrichidae). Journal of Stored Products Research, 36,  55-63.

Magowski WL. (1994) Discovery of the first representative of the mite subcohort Heterostigmata (Arachnidae:
Acari) in the Mesozoic Siberian amber. Acarologia, 35, 229±241.

Oliveira CRF, Faroni LRD’A, Guedes RNC. (2003a) Host egg preference by the parasitic mite Acarophenax lacunatus (Prostigmata: Acarophenacidae). Journal of Stored Products Research, 39, 571–575.

Oliveira CRF, Faroni LRD’A, Guedes RNC, Pallini A. (2003b) Parasitism by the mite Acarophenax lacunatus on beetle pests of stored products. BioControl, 48, 503–513.

Rack G. (1959.) Acarophenax dermestidarum sp.n. (Acarina, Pyemotidae), ein eiparasitic yon Dermestes arten. Z.  Parasitenkunde, 19, 411-431.

Acroseius - undescribed species from Queensland - venter

I recently had a request for an image of Polyaspinus tuberculatus Womersley, 1961 and I realised that my Polyaspididae, I mean Trachytidae (current usage), were not in very good nick. Actually, the mite in question is now Acroseius tuberculatus (Womersley, 1961) too.

Polyaspinus sp. (probably undescribed) from Queensland - venter

The short answer is that I do have images of what appears to be an undescribed species of Acroseius and also a probably undescribed species of Polyaspinus from Queensland. I also have an undescribed Polyaspinus from Alberta (no image yet) and a species of Trachytes  that is probably described from Oregon.

Trachytes sp. from Oregon - dorsum

All of these mites are interesting for several reasons, but I will have to wait to post on that – I’m being dragged off on family duties.

Ex Ips pini and once the same genus as the Challenge

Ted MacRae at Beetles in the Bush once complained that my Challenges are too tough, but his Close Crop Challenges are even worse, IMEO (in my exalted opinion). Well, I just took the plunge at his latest Challenge, so anyone misguessing here can laugh at my answer there. It’s all part of the learning process and the more we learn, the less mistakes we will make in the future (or at least this is the theory).

Hi, I'm back and bode ill for beetles

So far, the fearless Kaitlin has been the only one to venture a guess. Her logic is impeccable, but the premise is false. Given the miserably blurry picture of the larva, that isn’t too surprising. I think I will give this one away and show the adults associated with the mitey larva. I may be making a false assumption here too – the larvae and adults occurred together in the rotting mushroom, but that is only weak inference.

What are we?

Pygmephoridae is a good guess for the mite, this is a member of the Heterostigmatina, so one point for Kaitlin, but not of the Pygmephoroidea. All the pygmephoroids that I am familiar with have a more or less distinct gnathosoma, but this mite seems very withdrawn. Here’s a hint – these mites will not harm the larva, but bode ill for its future fitness. At the head of the post is a mite related to the Challenge mite, once it belonged to the same genus, but now it does not. Below is the actual mite itself.

Lightmicrograph of mystery mite

What is my secret name and what do I want from life?

‘To-morrow, and to-morrow, and to-morrow, Creeps in this petty pace from day to day’, but at last the the tomorrow promised in the last post (in March no less) has finally arrived. I plead overwork – I’ve had two massive taxonomic projects to complete including a listing of all of the species of mites known from Alberta – before the new field season commences.  Above is one of these little monsters saying high and below are a number of them clinging to an insect collected from a rotting oyster mushroom (Pleurotus ostreatus). Any guesses to the mite, insect, spores, ecological interactions?

Mites & insect - name them both and what is happening.

ANSWER TO PHOTON CHALLENGE

I’m fairly pleased in how well everyone did in the first Photon Challenge, especially considering the quality of the pictures.  Ray even got the fly to genus and Kaitlin got pretty close to the family of the mesostigmatan – at least according to the Manual of Acarology 3rd Edition the Halolaelapidae belongs in the Rhodacaroidea and they certainly are phoretic as deutonymphs, as one would expect in that superfamily. So Kaitlin gets points for that. Bruce got the family, and, I believe, the genus correct, at least in the broad sense: Halolaelaps s.l.  Bruce has the advantage of having described the only known Australia species of the group and to have pointed out how messy the generic concepts are (see Halliday 2008 Systematic & Applied Acarology 13, 214–230). I am neutral on what superfamily Halolaelapidae belongs to – Rhodacaroidea is unlikely to be monophyletic and deutonymphal phoresy is probably a ‘primitive’ behaviour in Mesostigmata.

Deutonymph of Myianoetus - note bifurcate claws

Alas, no one guessed the genus of the histiostomatid – Myianoetus! All acarologists should know this genus if only because it contains one of the few mites to lurk among the pages (as an anoetid) of  a large circulation, general science magazine – Science itself – and the interesting concept of ‘fly factors’:

Greenberg & Carpenter (1960) Factors in Phoretic Association of a Mite and Fly. Science 132: 738-739.

“Abstract: Combined rearing of the mite Myianoetus muscarum (L.), and the fly Muscina stabulans (Fall.) has revealed adaptations of the hypopus to a series of fly factors. These adaptations favor the mite’s dispersal. Hypopi are attracted to the pupa by a volatile substance and cluster on the anterior end, from which the fly emerges.”

Read the whole thing, as they say, but, although published over 50 years ago, you will still need access to Science to do so (and to read the next paper entitled  ‘Licking Rates of Albino Rats’). Rat licking trailer aside, I think the most interesting thing about the Myianoetus paper is that I can’t remember any follow-ups that explain ‘fly factor’ or ‘beetle factor’ or ‘ant factor’. Most of the chemical clues used to induce or terminate phoretic behaviour in mites remain unknown. Only skatoles and dung beetles come to mind. If someone out there in the ether knows of other studies, please let me know – I can use the information to help a student.

Business end of Antennolaelaps

Well, this Photon Challenge has gone on long enough: last chance for demonstrating your acarological expertise. Tomorrow I will reveal all.

Kaitlin and Ray have done well to the family level of the histiostomatid, but I don’t think a leap to the genus is impossible. After all, just how many mite genera have made it into the pages of Science magazine?

Ray has an embarrassingly detailed grasp of the anthomyiids breeding in indelicate accumulations of organic matter. But no one seems to be willing to stick their neck out on the phoretic mesostigmatan deutonymphs with two dorsal shields that have a death grip at the base of the abdomen of the Eutrichota. Last hint: the family of the phoretic mesostigmatan is currently placed in the same superfamily as the Antennolaelaps featured above.