Pogonomyrmex occidentalis
Encyclopedia
Pogonomyrmex occidentalis is an ant
species.
consists of 16 species (salinus, P. owyheei, P. occidentalis, P. subnitidus, P. subdentatus, P. brevispinosus, P. maricopa
, P. californicus
, P. comanche, P. badius, P. apache, P. desertorum, P. rugosus
, P. barbatus, P. anergismus
and P. colei
) subdivided into five species complex
es (occidentalis, subdentatus, californicus, desertorum and barbatus). Pogonomyrmex individuals are colloquially known as harvester ant
s. Pogonomyrmex occidentalis individuals are colloquially known as western harvester ants.
consist of up to 20,000 workers and one queen
. A queen can live up to 40 years, and many colonies survive for 20 years. Colonies of the close relative, P. owyheei, contain 1000–3000 brood items and can produce 1000 reproductives, or alate
s, in a year.
s and pollen
directly from plants and gather fallen seeds. Some seeds are sometimes stored in chambers within the nest and are depleted during winter. Workers also gather newly-dead insects. Workers generally forage April–September. Workers generally forage throughout the day during cooler months and only 5–11am and 3–9pm during summer. Genetically diverse colonies forage for more hours daily. Foraging times within a day and foraging temperature range vary consistently among colonies. Given a choice, workers select seeds containing more energy. Given a choice, workers select a diversity of seeds or seeds that are new to the colony. Workers usually forage one kind of item each day, but change their specialty daily. Workers usually forage in one direction over and over, even across days. Colonies recruit more workers (from the total worker pool) to forage at a good food source. Colonies lose foragers in encounters with neighboring colonies. Workers defend foraging territories against neighboring colonies (personal observation). Different plant environments support different densities of colonies. Foragers produce more period mRNA during darkness, the timing of which varies seasonally.
ingest solids, while adults ingest liquids, including larval excretions (The Ants). Immature individuals cannot pass from one larval stage to another or to adulthood without the help of adults; adults help immature individuals remove their old larval and/or pupa
l skins during ecdysis
(molting). As larvae are relatively immobile, they only interact with nutrients as adults bring the nutrients to the larvae or the larvae to the nutrients. Bigger colonies do not necessarily produce a greater total reproductive biomass. Colonies stop producing brood before they overwinter.
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
species.
Phylogeny
The ant genus PogonomyrmexPogonomyrmex
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 , which can be found in most species of the subgenus sensu stricto...
consists of 16 species (salinus, P. owyheei, P. occidentalis, P. subnitidus, P. subdentatus, P. brevispinosus, P. maricopa
Pogonomyrmex maricopa
The Maricopa harvester ant, Pogonomyrmex maricopa, is one of the most common species of harvester ant species found in Arizona, USA. Its venom is believed to be the most toxic insect venom in the world....
, P. californicus
Pogonomyrmex californicus
Pogonomyrmex californicus is a species of insect in family Formicidae. It is endemic to the southwestern United States. It is best known as the ant that is sent out for Uncle Milton's Ant Farm.-Biology:...
, P. comanche, P. badius, P. apache, P. desertorum, P. rugosus
Pogonomyrmex rugosus
Pogonomyrmex rugosus is a species of ant in family Formicidae which is endemic to the southwestern United States....
, P. barbatus, P. anergismus
Pogonomyrmex anergismus
Pogonomyrmex anergismus is a species of ant in the family Formicidae. It is endemic to the United States.-Source:* Social Insects Specialist Group 1996. . Downloaded on 10 August 2007....
and P. colei
Pogonomyrmex colei
Pogonomyrmex colei is a species of insect in family Formicidae. It is endemic to the United States.-Source:* Social Insects Specialist Group 1996. . Downloaded on 10 August 2007....
) subdivided into five species complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...
es (occidentalis, subdentatus, californicus, desertorum and barbatus). Pogonomyrmex individuals are colloquially known as harvester ant
Harvester ant
Ants known as Harvester ants include:species*Red harvester ant *Florida harvester ant *Maricopa harvester ant , the most venomous insect in the world....
s. Pogonomyrmex occidentalis individuals are colloquially known as western harvester ants.
Colonies
Mature coloniesAnt colony
An ant colony is an underground lair where ants live, eat and mate. Colonies consist of a series of underground chambers, connected to each other and the surface of the earth by small tunnels. There are rooms for nurseries, food storage, and mating...
consist of up to 20,000 workers and one queen
Queen ant
A queen ant is an adult, reproducing female ant in an ant colony; generally she will be the mother of all the other ants in that colony. Some female ants do not need to mate to produce offspring, reproducing through asexual parthenogenesis or cloning and all of those offspring will be female.Ant...
. A queen can live up to 40 years, and many colonies survive for 20 years. Colonies of the close relative, P. owyheei, contain 1000–3000 brood items and can produce 1000 reproductives, or alate
Alate
An alate is a winged reproductive of a social insect . Alate females are typically those destined to become queens , whereas alate males are occasionally referred to as "drones"...
s, in a year.
Individual workers
Workers' bodies are usually dark red and those in a mature colony are on average 6 mm long. Workers vary in size, but are not subdivided into groups of differently-sized individuals with special roles. A worker lives for an average of 6 months, and as it ages, it usually progresses through different roles within the colony. For example, workers forage towards the ends of their lives. In the field, workers are active when the temperature at the surface of the colony's mound is 25–53 °C (77–127.4 F).Ecosystem
P. occidentalis inhabits the deserts and arid grasslands of the North American west at or below 6300 feet (1,920.2 m).Nest architecture
A colony inhabits a nest that is up to 5 metres (16.4 ft) deep. The queen stays at the bottom of the nest, and workers usually relocate themselves and brood within the nest, capturing safe levels of heat. A colony's nest is topped by an irregularly conical nest mound that can be more than 89 centimetres (35 in) in diameter. The composition, shape, and size of the mound differ across plant environments. The mounds of most colonies are surrounded by an area devoid of vegetation, and so do not burn during fires. The soil in the mound is drier than that in the surrounding denuded area. Bigger P. occidentalis colonies (in number of workers) have bigger mounds.Nutrition
Workers harvest seedSeed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s and pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
directly from plants and gather fallen seeds. Some seeds are sometimes stored in chambers within the nest and are depleted during winter. Workers also gather newly-dead insects. Workers generally forage April–September. Workers generally forage throughout the day during cooler months and only 5–11am and 3–9pm during summer. Genetically diverse colonies forage for more hours daily. Foraging times within a day and foraging temperature range vary consistently among colonies. Given a choice, workers select seeds containing more energy. Given a choice, workers select a diversity of seeds or seeds that are new to the colony. Workers usually forage one kind of item each day, but change their specialty daily. Workers usually forage in one direction over and over, even across days. Colonies recruit more workers (from the total worker pool) to forage at a good food source. Colonies lose foragers in encounters with neighboring colonies. Workers defend foraging territories against neighboring colonies (personal observation). Different plant environments support different densities of colonies. Foragers produce more period mRNA during darkness, the timing of which varies seasonally.
Biomass and brood production
Different developmental stages of ants within a colony process different kinds of food; larvaeLarvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
ingest solids, while adults ingest liquids, including larval excretions (The Ants). Immature individuals cannot pass from one larval stage to another or to adulthood without the help of adults; adults help immature individuals remove their old larval and/or pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
l skins during ecdysis
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
(molting). As larvae are relatively immobile, they only interact with nutrients as adults bring the nutrients to the larvae or the larvae to the nutrients. Bigger colonies do not necessarily produce a greater total reproductive biomass. Colonies stop producing brood before they overwinter.
Mating
Colonies release alates synchronously. Alates mate in hilltop leks in swarms. Major mating swarms are about 1.4 kilometre (0.869921831309729 mi) apart, and queens can fly no more than 800 metres (2,624.7 ft). Gynes mate with 2–11 (an average of 6.3) genetically distinct males. Females always mate multiply. Queens that mate only a few times are less successful. The colonies of queens that mate with more males grow faster. Males sometimes mate multiply. Females mate nonrandomly. Larger males are more successful at mating (i.e. they are overrepresented among collected maters), but small males can still mate. Certain shape characteristics improve male chances of mating success. P. occidentalis populations are effectively small and inbred. Queens pick bare and bright areas to land and then dig where they land.Colony founding
Individual queens found colonies on their own, without workers or other queens. Survivorship of colonies in the first year is negatively correlated with increasing density of foundresses. Foraging workers kill queens that they encounter aboveground and occasionally excavate queens. Factors independent of colony density are responsible for >90% of foundress mortality. Queens in some populations found colonies claustrally and in others, semi-claustrally. Many of the eggs laid in the first batch die or are unembryonated eggs. During colony founding, larvae may eat eggs. The first workers produced, nanitics, are 2 mm (33% shorter than typical worker). 2/188 founding queens survived from July to March.Population ecology
Mating swarms that are consistently present and large determine much of the spatial variability in colony density and emerge over the long term. New colonies are founded in a clumped pattern, around the mating sites. The population may self-thin through direct interference competition resulting in a uniformly overdispersed distribution pattern. Long-term colony survival is mediated by proximity to older colonies. Smaller colonies have closer nearest neighbors. Smaller nests are more likely to die. The further a colony is from its nearest neighbor (especially for small colonies), the higher the colony's survival probability. Colony age and size are correlated, especially in young colonies.External links
- http://www.tightloop.com/ants/showspecies.php?species_id=18
- http://navajonature.org/ants/myrmicinae/pogonomyrmex-occidentalis.html
- http://hol.osu.edu/index.html?id=34368
- http://nap.entclub.org/NewFiles/Pogonmyrmex%20occidentalis.html
- http://www.antweb.org/description.do?rank=species&name=occidentalis&genus=pogonomyrmex&project=arizonaants
- http://www.discoverlife.org/mp/20q?search=Pogonomyrmex+occidentalis
- http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm
- http://www.alexanderwild.com/Ants/Natural-History/Ant-Nests/9403626_3gWsi/4/577992308_Rs2g7
- http://www.eol.org/pages/599427
- http://www.insectimages.org/browse/subthumb.cfm?sub=8478
- http://www.myrmecos.net/myrmicinae/PogBall4.html