Archive for the ‘Photon Challenge’ Category

And the answer is: Margarodidae

August 26, 2011

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.


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).

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 


Meet your Martian Overlord: Photon Challenge #4 – Updated

August 17, 2011

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:

New Photo-Electron Challenge & Old Answers

May 14, 2011

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.


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.

Photon Challenge: Last Chance

March 19, 2011

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.

Photon Challenge: New Hints

March 5, 2011

A closer view of a mitey fly

Kaitlin and Ray have both demonstrated that even the smaller of the two mites hitching a ride on our fly can be identified to family from a not so great photo: heteromorphic deutonymphs (aka hypopi) of a member of the Histiostomatidae. They also correctly placed the larger mite to order: Mesostigmata. Not much luck on the fly, though, so I guess that means mites are easier to identify than flies? Anyone who has struggled with the generic key for this family in Nearctic Diptera might very well say yes. However, the family of the fly should be an easy guess for a dipterist.

Genus anyone?

Here’s a light microscope view (this is a Photon Challenge) of the venter of one of the histiostomatid hypopodes (yet another name for these deutonymphs) and a closeup of one of the pretarsal claws. The ventral shot is layered from three images in the wonderful CombineZP and the claw from two shots. The host association and characters visible in this image should give the discerning astigmatologist a good guess at the genus (I have checked with the North American authority on this one and he had no problem).

I’ll give one more hint on the mesostigmatans too – they also are deutonymphs.