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
● Boardman [Morrow Co], OR USA [el. 91m/298 ft] view location in Google Maps » ● 7/22/09 8:30PM sunny, windy, air temp: 29°C / 84°F
[IMAGE 3 of 4] Ants of the genus Tetramorium, attacking and killing Pogonomyrmex salinus workers, in central Oregon. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
These Pogonomyrmex salinus workers, with their powerful mandibles and formidable stings, appeared to be defenseless against dozens of attacking Tetramorium ants (workers of Tetramorium species 'E', also known as pavement ants).
On a very warm July evening, we came upon this melee in progress. The westernmost entrance of a P. salinus nest (with at least three entrances total) was located approx. 20 cm / 8 in from a cryptic (difficult to see) Tetramorium nest entrance.
The pavement ants were attacking any Pogo that emerged from the above-mentioned entrance. They ran at, and stung the much larger Pogos, with incredibly quick movements (so quick, that we couldn't see exactly where they were delivering the sting).
The attacked Pogos twitched and writhed for a few moments, and then, without exception, clamped tightly onto a grass or other plant stem with their mandibles. A group of four to six Tetramorium workers surrounded each one of these afflicted Pogos, pulling on their legs and antennae (and in some cases removing these appendages, or parts of them) - or simply menacing them with open jaws. This looked a lot like the 'pinning down' behavior used by many ants to immobilize an intruder - but since the Pogos were already held fast, this seemed more like an attempt to kill, and dismember them. Tetramorium ants are well-known scavengers, so even if this began as a territorial war, it is likely they would take advantage of the killed Pogos, as a food source.
We saw two instances where a dying Pogo made a feeble attempt to defend herself with her mandibles - but we didn't see any Pogos actually inflict any damage on their assailants.
During the 'battle', a P. salinus head capsule with no antennae (or body), was observed still clinging to a grass stem, and a Tetramorium carrying the gaster (part of the abdomen) of a Pogo, was seen.
The next morning, we also saw pavement ants transporting detached P. salinus head capsules. Many Pogos still could be seen clinging to grass stems, some obviously dead, others moving slightly. The Pogo entrance at the center of all of this was blocked with debris at some point - probably by the Pogos themselves.
Curiously, during the height of the confrontation - foraging, and nest maintenance continued pretty much as usual at the main entrance to the Pogo nest, just .45 m / 1.5 ft away. No defense force was raised to come to the aid of those nestmates being attacked by the pavement ants. There was a strong wind blowing (from the main entrance, toward the site of the battle), and this may have prevented alarm pheromones from reaching the ants at the main entrance.
pogopogonomyrmexpogonomyrmex salinusantspreydefensemacroharvester ants
