Pogonomyrmex

Taxobox
name = "Pogonomyrmex"


image_caption = "P. barbatus"
image_width = 250px
regnum = Animalia
phylum = Arthropoda
classis = Insecta
ordo = Hymenoptera
familia = Formicidae
subfamilia = Myrmicinae
tribus = Myrmicini
genus = "Pogonomyrmex"
genus_authority = Mayr, 1868
diversity_link = Pogonomyrmex
diversity = c. 71 species + subspecies
range_

range_map_width =
subdivision_ranks = Species
subdivision = "P. barbatus"
"P. californicus"
"P. maricopa"
"P. occidentalis"
"P. rugosus"
many more, see text.

"Pogonomyrmex" is a genus of harvester ants, occurring primarily in the deserts of North and South America. The genus name originated from the Greek language and refers to a beard-like structure, the psammophore, below the head (gr. pogon = beard), which can be found in most species of the subgenus "sensu stricto". The psammophore are used for gathering small seeds, helping to increase the efficiency of transportation of fine sand and pebbles during nest construction, or to carry eggs. However, this structure is missing in species of the subgenus "Ephebomyrmex" (gr. ephebos = beardless lad): these species generally have smaller individuals and colonies.

"Pogonomyrmex (sensu stricto)" workers have the most toxic venom documented in any insects, with "Pogonomyrmex maricopa" being the most toxic tested thus far. [cite web
title=Chapter 23 — Most Toxic Insect Venom
url=http://ufbir.ifas.ufl.edu/chap23.htm
author=W. L. Meyer
publisher=University of Florida
date=1996-05-01
work=Book of Insect Records] It has an LD50 of only 0.12 mg/kg, compared to Western honey bee venom, at 2.8 mg/kg, and comparable to cobra venom (there are, in fact, only about a dozen recorded LD50 values for snakes which are lower than 0.12, mostly seasnakes). This venom is presumed to be an anti-vertebrate defense, specifically against predators that have evolved to selectively feed on them, most notably horned lizards. Note, however, that the actual amount injected by a single ant is incredibly small, and they pose no actual threat to humans or other animals. Also note that very few insects have had the toxicity of their venoms formally tested, and it is likely that other insects have more potent venoms (e.g., the venom of "Lonomia", which can kill humans).

These ants dig very deep nests with many underground chambers in which they keep seeds, from which they derive food for their larvae. The areas around most "Pogonomyrmex (sensu stricto)" nests tend to be utterly devoid of vegetation, and are easily seen from a distance. In addition to horned lizards, there are predatory wasps in the genus "Clypeadon" which feed only on "Pogonomyrmex" workers, paralyzing them with their venom, and then carrying them back to a burrow where they will serve as food for the wasp's larva.

References

External links

* myrmecos.net: [http://myrmecos.net/myrmicinae/pogonomyrmex.html Photographs of many "Pogonomyrmex" species]
* [http://cals.arizona.edu/urbanipm/insects/ants/harvesterants.html Harvester Ants (Pogonomyrmex spp.)] — Urban Integrated Pest Management
* [http://creatures.ifas.ufl.edu/urban/ants/harvester_ant.htm "Pogonomyrmex badius", Florida harvester ant] on the UF / IFAS Featured Creatures Web site