Monthly Archives: April 2013

Soil washing and Mayetia

Our collection manager Zack and I have been talking about soil washing in Kansas for some time now. Soil washing, for those of you who don’t know, is a technique used to collect insects (in my case) that are subterranean.

In staphylinids, two lineages, Leptotyphlinae and Mayetiini (Pselaphinae) are exceptional in having taken this lifestyle to its extreme and have appreciably diversified in doing so. The two are surprisingly convergent in morphology, although they occupy disparate regions of the rove beetle tree of life.

Zack had heard a rumor that a leptotyphline, one of these subterranean staphylinids, had been collected from a root-ball in a Kansas prairie. Rumor passes down to me, and this rumor was what fueled our motivation to put into action, what is arguably the most tedious method of collecting.

Step 1. You dig. I don’t know, pick a spot, any spot. We chose a variety.

Me, digging for, well… soil, out in Kansas prairie. Photo courtesy of Zack.

Step 2. For this step, you literally wash the soil. I dumped the soil etc. into trash bin and added water with a hose. After a reasonable amount of water had covered the soil underneath, I sloshed the soil around and skimmed off anything that floated to the surface (this is all organic material, including bugs).

Wash'n some soil.

Washing some soil.

Step 3. I then wrapped any organic material I skimmed from the surface of the water into a bundle, using cheesecloth. I then wrung out this organic bundle of any excess water, wrapped it again, this time in paper towels to further dehydrate, and stored them in labeled baggies until Berlese time.

A bundle of organic stuff. The samples can be stored like this for about a week. So you can transport them back from the field if you're far from home.

A bundle of organic stuff. The samples can be stored like this for about a week, so you can transport them back from the field if you’re far from home.

Step 4. Berlese time. It only took about a day, the stuff wasn’t very dense.

Berlese!

Berlese! A little makeshift spot for this particular project.

Step 5. Sort.

Mayetia peasei are easily packed into a 1 cm square.

Mayetia peasei are easily packed into a 1 cm square.

To some extent, I think I speak for both Zack and I when I say we had low expectations. This added to our surprise when we found close to 20 individuals of a teeny-teeny staphylinid. We go back and forth for some time about whether it was a leptotyphline or Mayetia, finally settling on the later – I mean they’re so damn convergent-looking!

A little more digging around lead to a species identification, Mayetia pearsei. This species is presumably parthenogenic, argued from the fact that not a single male has been discovered, despite some serious effort. Other species in the genus are known to demonstrate extremely female-biased sex ratios.

Mayetia populations aren’t very dense and individuals are poor dispersers. If chances of meeting a mate are unlikely, this can fuel the establishment of parthenogenesis in a population. In some species where males are present in low frequency, they may play a dwindling role as a population marches on towards purely parthenogenic reproduction. Also possible, males are retained for periodic out-crossing, which theoretically can help avoid pitfalls like Muller’s ratchet and environmental instability. Whatever the case, it seems clear to me that this is an interesting system that deserves more attention; several obvious questions and solutions immediately pop in mind.

I heard some pleasing news today and it made my day.

This photo’s from Costa Rica. I think it’s a Microdon sp., checking out the nest entrance. Honestly, I know they’re myrmecophilous so I should be able to identify the genus from other hover flies, but the characters that define them are found in the wing venation, so kinda hard to check out in the wild.

Thanks to a comment by Martin, this fly was identified as a species of Lepidomyia. Martin also informed me that the larvae are unknown, but those of a related genus develops in decaying wood. Makes sense, this individual was scouting a tree hole opening, which was coincidentally occupied by an ant colony.

Whatever, gestalt is a taxonomist’s best friend anyways.

Gestalt betrayed me…

Microdon checks out an ant nest entrance.

Lepidomyia checks out a tree hole opening.

And, some more myrmecophiles from Sat.

Camponotus were preparing for colonial proliferation.

Reproductives patiently wait for the right moment.

Reproductives patiently wait for the right moment.

Some case-bearing leaf beetles can be found with ants, where they feed on nest refuse. I’ve previously collected adults and larvae from Arizona, Arkansas and Oregon. The ones from Arizona and Oregon were in the genus Saxinis.

I kept them alive. We'll have wait and see what the adults look like.

I kept them alive. We’ll have wait and see what the adults look like.

Poster child myrmecophile, Myrmecophilus, hey it’s right in the name!

An immature female, you can see her still-developing ovipositor.

An immature female, you can see her still-developing ovipositor.

The current revision that treats North American taxa, in my opinion, is not that reliable. I don’t think hind leg spine number is a stable enough character to be used in identification. I have seen taxa with unequal numbers between their hind legs. I think molecular data will give us an entirely new perspective, just as the research in Japan has. I suspect this is what people call Myrmecophilus pergandei.

There is some evidence to suggest that individuals develop according to the size of their hosts. Therefore, some species are known to demonstrate extreme size polymorphism. Could this really be the reason behind these observations?

There is some evidence to suggest that individuals develop according to the size of their hosts. Therefore, some species are known to demonstrate extreme size polymorphism. Could this really be the reason behind these observations?

First termitophile of 2013

I checked out the weather Friday evening and Saturday was forecast to be excellent weather, in the high 70s. Couldn’t resist, I woke up at 5 AM on Saturday and headed 2 hours south of Lawrence to a favorite inquiline spot.

I’ve introduced some collecting from here previously.

It was a little early still in the season, but the social insects were out and so were their guests. This time I brought home the Philotermes species that occurs here along with its hosts and observed its behavior. Conclusion, a damn lot of grooming.

Philotermes sp. in typical abdomen-over-body look.

Philotermes sp. in typical abdomen-over-body look.

A worker termite checks out Philotermes.

A worker termite checks out Philotermes.

More Masoncus!

The female yesterday was a little teneral. The ones today are fully pigmented, and look, an immature!

Masoncus_sp_blog4

Masoncus-season #2 begins

About a year ago I blogged about how I had started collecting a species of linyphiid spider with Formica ants that nest in my front yard. I left the post open ended, hoping that someone would have an idea of what the spider species might have been. I was picking up multiple life stages, both sexes and had accumulated over 40 specimens over the course of the field season. Given these statistics, it was hard for me to believe that these spiders were accidentally occurring with ants and became convinced these spiders were myrmecophilous.

A mature female Masoncus sp. wanders among its hosts.

At the time little did I know that I was to receive an email informing me that the spider may belong to the genus Masoncus and was directed to the research of Paula Cushing. She worked with a, at the time, new species of Masoncus that occurred with Pogonomyrmex in southeastern USA. Observations revealed that these spiders follow host trail pheromones to accompany host nest site switches. I contacted Paula and we believe that the species in my yard might be a new species, which had also been collected recently in Wisconsin.

Masoncus sp.

A mature female Masoncus sp.

Masoncus sp.

A mature female Masoncus sp.

Several of us are now working together to further understand the biology of Masoncus in relation to its hosts. As a part of this objective, we are currently accumulating material for gas chromatography-mass spectrometry (GC-MS) to compare guest and host cuticular hydrocarbon profiles (CHC). These spiders wander the nests freely, undetected, and may be acquiring CHCs from their hosts either passively or actively, essentially camouflaging themselves among the ants. On the flip side, these spiders may just “have no smell.” These are both commonly employed strategies to infiltrate ant colonies among arthropods. Either way, the GC-MS should tell us more.

Snail eater

When Patrick and I were out collecting in Massachusetts for Gymnusa, we found a spot with Scaphinotus scrambling up and down tree trunks in search of snails. Typical behavior for the snail-eat’n Scaphinotus. These large and beautiful beetles are a sign of a healthy forests. They seem to be associated with relatively old and undisturbed forests.

Scaphinotus sp., they like snails.

Scaphinotus sp., they like snails.

I remember Jim telling me at Cornell that our local collecting spot, Six Mile Creek, sported historical records from the mid 1900’s, but has never produced an individual since, despite the location being a relatively active site for entomological collecting. This charismatic beetle is presumably extinct in Ithaca, NY.

I heard a Celtic band do a rendition of this song and reminded me that I was really into it in high school. Come on, we’ve all ransacked our parents’ music.