Defense, Aggression, and Pogos as Prey
Wrestling and stinging
ants, lunch for spiders, and territorial wars. Pogonomyrmex spp.
ants at various locations in North America.
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Pogonomyrmex salinus
● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps » ● 9/16/10 10:57AM 50% cloud, air temp: 26°C / 78°F
[IMAGE 4 of 4 - see preceding 3 images] As mentioned in the notes below, these wasps often abandon an ant after stinging it, and capture a different one. Evidence suggests that the predators may prefer larger individual ants (there is considerable size variation among workers in a Pogo colony). This image shows a callow P. salinus worker that has apparently been stung and abandoned by the Clypeadon wasp. Pogos are known to cling to grass stems or twigs after being envenomated by other insects - you can see other examples of this elsewhere in the 'Defense, Aggression, and Pogos as Prey ' gallery. We also observed the wasp to sting and abandon a different worker at this nest; the partially paralyzed ant then staggered to the mostly-blocked nest entrance and disappeared inside. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
Female digger wasps of the genus Clypeadon are known predators of Pogonomyrmex harvester ants. Predation on Pogonomyrmex occidentalis workers by Clypeadon laticinctus wasps has been studied and documented in detail.
In the case of C. laticinctus, wasps typically land at an ant nest site, run up to an ant, grab it, then sting it. The paralyzed ant is then grasped by a special 'ant clamp' (modified pygidial plate and hypopigium) on the wasp's abdomen, and transported to the wasp's nest to be used as food for the developing larvae. The wasps' nests are in the form of burrows, excavated to depths of up to 25cm/10in, in sandy soils. There may be several brood chambers, each one packed with up to 26 ants. An egg is laid on the last ant put into the brood cell, then the cell is sealed up. The wasp larva will then consume the ants as it develops.
The hunting wasps will actually enter ant mounds to capture prey if ants are not present on the surface.
Ants will often turn to face the attacking wasp, and/or lunge at it. These tactics, along with the simple defense of running away, often result in an individual ant escaping capture. A 1984 study in Colorado showed that "approximately 63% of visits by wasps to ant mounds resulted in a successful prey capture." Despite their powerful mandibles and stings, Pogos have never been observed to injure or kill an attacking wasp.
Sometimes a wasp will sting a worker, then discard it before attacking and carrying away another ant. The reasons for this are not well understood, but there is some evidence that the wasps are selective, with larger individual ants being preferred.
Clypeadon wasps are members of the family Crabronidae, subfamily Philanthinae, and the tribe Aphilanthopini.
·Alexander, B. 1985. Predator-prey Interactions between the Digger Wasp Clypeadon laticinctus and the Harvester Ant Pogonomyrmex occidentalis. Journal of Natural History, 1985, 19:1139-1154
·Bohart, R.M. & A.S. Menke. 1976. Sphecid Wasps of the World: A Generic Revision. University of California Press, pp. 570-571
·Taber, S.W. 1998. The World of the Harvester Ants. College Station, TX, Texas A&M University Press
·Bohart, R.M. & A.S. Menke. 1976. Sphecid Wasps of the World: A Generic Revision. University of California Press, pp. 570-571
·Taber, S.W. 1998. The World of the Harvester Ants. College Station, TX, Texas A&M University Press
