EPOW - Ecology Picture of the Week

Each week a different image of our fascinating environment is featured, along with a brief explanation written by a professional ecologist.

11-17 August 2003

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Matabele Ant Swarm


Matabele Ants (see below for identification discussion)
South Luangwa National Park, Zambia, Africa

Credit & Copyright: Dr. Bruce G. Marcot

Explanation:   Do not  step here!  This is an advancing column of matabele ants in an open plain of South Luangwa National Park of eastern Zambia, Africa.  Matabele ants form tightly structured armies and amass by the thousands to raid termitaria (termite nests).  

Ant swarming into a ground termite nest

The ants organize their raids by stationing large soldiers with powerful jaws, on the flanks of the column.  

Large soldier guarding the flanks

The column moves as a unit, all in one direction, out from their mounds, following the ant trail pheromone N,N-dimethyluracil laid by the scout worker ants.  

Matabele ants sound stridulations as they move (as do some other swarming, predatory ants).  Perhaps that was the inspiration for South African master steel-string acoustic guitarist Tony Cox to compose his popular album "Matabele Ants."  

Matabele ants are named after the Matabele Warriors who advanced through south and central Africa in the 1850s, wiping out villages as they went.  Matabele ants are likewise most dangerous; 10 bites can paralyze your arm.  

Taxa such as Megaponera foetens have a kind of swarming "army ant behavior" or "Matabele ant behavior" (which means behavior of warriors).  

     Crewe, R. M., C. P. Peeters, and M. Villet.  1984.  Frequency distribution of worker sizes in Megaponera foetens (Fabricius).  South African Journal of Zoology 19(1):247-248.
     Villet, M. H.  1990.  Division of labour in the Matabele ant, Megaponera foetens (Fabr) (Hymenoptera: Formicidae).  Ethology, Ecology and Evolution 2: 397-417.

Updates on Species Identification
EPOW reader Marcus Stüben, Ph.D. biology student at Theodor-Boveri-Institut für Biowissenschaften der Universität Würzburg (Biozentrum) in Würzburg, Germany, suggests that the species shown on this page might not be "Megaponera foetens" (which is a synonym of the valid name Pachycondyla analis, Ponerinae, Ponerini), but rather army ants, Dorylus species (Dorylinae), on a swarm raid.  Stüben wrote that Pachycondyla analis is a blackish species and has normally less numerous raiding parties.  

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However, another EPOW reader, Simon Williams of the BBC Natural History Unit in Bristol U.K., has written that the species shown likely is Megaponera foetens.  

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Further, Dr. James C. Trager, Restoration Biologist and Ant Taxonomist with Shaw Nature Reserve, Gray Summit, MO, wrote that the species shown is "one of the African driver ants, probably Dorylus wilverthi.  He wrote, "Note the polymorphic workers, with large-headed majors guarding the flanks of the column" and that "Pachycondyla spp. by contrast have monomorphic workers, for example, this South American termite raiding species.  
     Dr. Trager also wrote:
     From http://antbase.org/ants/africa/pachycondyla_1.htm comes the following information on Megaponera foetens, a.k.a. Pachydondyla analis:
     "In Nigeria, studied at Mokwa, in the southern Guinea savannah, ... Longhurst & Howse .... described its predation on termites, and the biology of males. Almost half of the 73 nests which they examined were in deserted nests of the termite Macrotermes bellicosus (Smith), most of the rest were in the ground under bushes. Activity was either early morning (0700-0930 h) or late afternoon (1630-1830h). Major 'scout ants' locate foraging termites, by detecting chemicals in the soil sheeting built by the termites. The scouts then recruit other workers, scent trails being used once the route is established. Only the minor workers enter the ... [termite nest] and bring out captured termites, stacking the prey around the entry points. At the end of the raid the termites are carried back to the P. analis nests, mainly by the majors."
     This site includes dimensions and pictures of the dull-headed majors and shiny-headed minors and a discussion of the taxonomic confusion caused by these different-looking castes. Still, most if not all other Pachycondyla species have monomorphic workers, and the picture is indeed of Dorylus. The raiding columns of P. apicalis have all workers going either to or fro, and lack the flanking ranks of much larger, outward-facing soldiers typical of Dorylus.
     Later, Dr. Trager also wrote that the photos on this page are not of Pachycondyla analis (formerly called Megaponera foetens), but rather one of the African driver ants, probably Dorylus wilverthi.  He pointed out the polymorphic workers with large-headed majors guarding the flanks of the column.  These occur with Dorylus but not Pachycondyla spp. which by contrast have monomorphic workers, such as this South American termite raiding species (http://www.myrmecos.net/ants/PacMar1.html).
     Dr. Trager also said that he cannot confirm if the term matabele is used for both Pachycondyla analis (which he says it is for sure) and for swarm-raiding driver ants, and suggests that perhaps the term matabele ant not be used at all because the photos posted on this page are not
Pachycondyla.  Dr. Trager also wrote:

     Dorylus spp. are mass-foraging, swarm-raiding army ants which have highly varied prey, and only opportunistically feed on termites or take up residence in their abandoned nests. They search for AND attack prey en mass, as is typical of all true army ants. I am not familiar with the chemistry of their trail and recruitment pheromones, and indeed, I don't think Dorylus trail pheromones have been chemically characterized.
     P. analis, on the other hand, searches for prey singly, by means of individual scouts that go out looking for potential termite prey. Their raids are columnar rather than broad-fronted swarms, and are a separate event from the scouting expeditions, resulting from recruitment by successful scouts. A major component of their trail pheromone is N,N-dimethyluracil, and this compound appears to be unique to P. analis in this role. Finally, and in stark contrast to Dorylus, P. analis is a specialist predator on termites, never hunting other fare.
     It is because of the deeply rooted phylogenetic, ecological and ethological differences between these two ants that I have been trying to make the distinction to the viewers of your page. I would make the radical suggestion that since the actual image is of a Dorylus species, that it would be best to confine the commentary to them, and not confuse the issue by bringing in the biology of another unrelated species.

Apparently, the name "Matabele ant" is used by some authors for both Dorylus and Megaponera species, although Dorylus is actually a real army ant.  

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Some time later, EPOW reader Doug Grewar (resident of Zululand, South Africa, and who grew up in Zambia), conveyed that he too is trying to sort out the confusing names of Red or Driver or Siafu ants and to determine their correct Latin names.  He suggests that the EPOW photos on this page are Siafu ants, and provided some of his own photos and stories of such.  He also suggests that both red Siafu and black Matabele ants seem to be referred to as "Safari ants," and "I have now found the chiBemba names for red driver ants is impashi and the larger black Matabele ants is iminangu. Bemba is the major language in Zambia although in the Luangwa valley area, where you visited, chiNyanja would be common."  My thanks to Doug for also sending extensive stories, photos, links, and descriptions of various of these ant types.   

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My sincere appreciation to all the EPOW readers and ant experts who contributed their knowledge and perspectives.

Next week's picture:  Vaux's Swifts

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