Ant Research Roundup (5.ii.08)

A trail of Atta leafcutting ants in Gamboa, Panama.

From the recent literature:

The Journal of Experimental Biology has a lab study by Dussutour et al documenting how leafcutter ants avoid traffic jams under crowded trail conditions.  Apparently, unladen ants increase a narrow trail’s efficiency by following the leaf-carrying ants instead of trying to pass their slower sisters. See also commentary by JEB and Wired.

source: Dussutour, A., Beshers, S., Deneubourg, J. L., Fourcassie, V. 2009. Priority rules govern the organization of traffic on foraging trails under crowding conditions in the leaf-cutting ant Atta colombica. J Exp Biol 2009 212: 499-505.

In the journal PLoS One, Youngsteadt et al document that the seeds of the neotropical ant plant Peperomia macrostachya are dispersed by just a single species of Camponotus in spite of a high ant diversity at the study site.

source: Youngsteadt E, Baca JA, Osborne J, Schal C, 2009. Species-Specific Seed Dispersal in an Obligate Ant-Plant Mutualism. PLoS ONE 4(2): e4335. doi:10.1371/journal.pone.0004335

A smattering of ant taxonomic papers in the online journal Zootaxa includes work on Lordomyrma by Bob Taylor, Pheidole by Jack Longino, and the Egyptian Solenopsis by Mostafa Sharaf et al.

source: Zootaxa Hymenoptera

Friday Beetle Blogging: Spider Beetle

Gibbium sp. Spider Beetle, Arizona
Gibbium sp. Spider Beetle, Arizona

Spider beetles are not predators like their namesakes but are instead pests of stored grain.  I was surprised at how difficult they were to photograph.  Their round bodies were hard to fit into a single focal plane, while their reflective elytra were prone to harsh glare.  I could not do much about the first problem, but the lighting was solved by placing the beetle inside a white box and firing an off-camera strobe into the box but away from the beetle.

Gibbium sp., Arizona
Gibbium sp., Arizona

photo details (both images): Canon MP-E 65mm 1-5x macro lens on a Canon EOS 20D
ISO 100, 1/250 sec, f/13, indirect strobe fired into white box

On gossamer wings

Acromyrmex versicolor, mating swarm, Arizona
leafcutter ant mating swarm, Arizona

The sparkle of these insects’ wings was captured by pointing the camera at the sun while standing behind the mating swarm.  I find backlighting to be one of the most pleasing effects for translucent wings.

photo details: Canon 100mm f2.8  macro lens on a Canon EOS 20D
ISO 100, f/11, 1/500 sec


A long-tongued horse fly drinks from a flower in Arizona's Chiricahua mountains
A long-tongued horse fly takes a sip of nectar in Arizona's Chiricahua mountains.
100% crop of the same image.
100% crop of the same image.

photo details: Canon 65mm MP-E 1-5x  macro lens on a Canon EOS 20D
ISO 100, f/13, 1/250 sec, flash diffused through tracing paper

Friday Beetle Blogging: Beyer’s Scarab

Chrysina beyeri - Beyer's Scarab - Arizona

Arizona’s Jewel Scarabs emerge after the onset of summer rains. These large insects have something of a cult following among collectors, and enthusiasts from around the world descend on the Sonoran desert every monsoon season with their mercury vapor lamps and blacklights to entice the lumbering beetles into their traps.  The effects of this mass harvesting on Chrysina populations have not been studied, but they should be.  I’d hate to lose such an attractive species.

Beyer’s scarab, the largest Chrysina in the United States, feeds on oak foliage.


photo details (both images): Canon 100mm f2.8 macro lens on a Canon EOS 20D
ISO 100, f/18, 1/250 sec, indirect strobe in white box

Question: Ritualized Fighting in Harvester Ants?

Here’s a question for my myrmecologist readers.  Has anyone published observations of ritualized fighting among colonies of Pogonomyrmex harvester ants?  I know such behavior was famously studied by Bert Hoelldobler in Myrmecocystus, and that ritual combat has been noted in Camponotus and Iridomyrmex.  The reason I ask is that the pogos in my front yard back in Tucson would engage in what looks like the same sort of behavior.  Ants from opposing colonies stand up on little stilt-legs and push each other about without anyone getting hurt.

I suspect these non-lethal ways of establishing territorial boundaries may be more common among ants than we’d thought, and if no one has recorded ritual combat in Pogonomyrmex it should be worth publishing a note somewhere.  More photos below the fold. (more…)

Friday Beetle Blogging: Strategus Ox Beetle

Strategus aloeus – Ox Beetles, female (left) and male
Arizona, USA

Impressive pronotal horns mark the male in these sexually dimorphic scarabs. Strategus aloeus is found in the southern United States from Florida to Arizona.

photo details, top photo: Canon 100mm f2.8 macro lens on a Canon 20D
f/9, 1/200sec, ISO 100, indirect strobe in a white box
bottom photo:
Canon 100mm f2.8 macro lens on a Canon 20D
f/14, 1/200sec, ISO 200, indirect strobe in a white box

Moving to Illinois

The more avid readers (that’s you, mom!) may have noticed a lack of activity on the blog of late.  Life has intruded.  Next week I will be leaving my job at the University of Arizona and taking a new one in Illinois.  This means tying up loose ends on the beetle project, saying goodbye to friends, and moving a house.   Full-on blogging will resume by mid-August, I presume, once the dust has settled.

There is much I will miss about Tucson, but on the other hand I’ll be joining the Entomology Department at Champaign-Urbana, one of the world’s finest centers of insect research.