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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<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 9/16/10 11:25AM 50% cloud, air temp: 26°C / 78°F</span>

<div class="captionImageMain">[IMAGE 1 of 4] When we arrived at this <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> nest in central Washington state, we immediately noticed several frantic <a href="http://www.davidlouisquinn.com/pogolumina_pheidoleWorkerInfo.htm"><span class="glossLinkSm">workers</span></a> using pebbles to block the nest entrance. It wasn't long before we saw the source of their distress; a <em>Clypeadon</em> digger wasp was preying upon these ants. In this image we see the predator on one of her visits to the <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogo</span></a> nest in search of prey. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
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<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:

<em>Female digger wasps of the genus Clypeadon are known predators of <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogonomyrmex harvester ants</span></a>. Predation on <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a> 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<br>·Bohart, R.M. & A.S. Menke. 1976. Sphecid Wasps of the World: A Generic Revision. University of California Press, pp. 570-571<br>·Taber, S.W. 1998. The World of the Harvester Ants. College Station, TX, Texas A&M University Press
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● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps » ● 9/16/10 11:25AM 50% cloud, air temp: 26°C / 78°F

[IMAGE 1 of 4] When we arrived at this Pogonomyrmex salinus nest in central Washington state, we immediately noticed several frantic workers using pebbles to block the nest entrance. It wasn't long before we saw the source of their distress; a Clypeadon digger wasp was preying upon these ants. In this image we see the predator on one of her visits to the Pogo nest in search of prey. [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