Ant Introduction

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The Main Ant Pages On Wayne's Word: Images Taken With Nikon & Sony Cameras
  Ant Genera Index        Introduction        Ant Page 1        Ant Page 2        Ant Page 3        Nikon        Sony  
San Diego County Ants:
  Owens Peak  
 
  Merriam Mtns  
 
  Palomar Mtn  
   
  Daley Ranch  
A Brief Introduction To Ants: Some Interesting Facts & Images
© W.P. Armstrong 05 June 2017
      Index Of Ant Genera On Wayne's Word       Ant Genera Photographed By Alex Wild  
     

Pseudomyrmex apache From Owens Peak
  1. Ant Species On Owens Pk
  2. Some Facts About Ants
  3. What Good Are Ants?
  4. General Ant Anatomy
      2a. Wingless Wasp That Resembles An Ant
      2b. Winged Male Ant That Resembles A Small Wasp
      2c. Ant & Termite Comparison: Two Insect Orders
  5. Ant Diet & Food Digestion
  6. The Worst Enemy Of Ants Is Other Ants
  7. Five Of The Worst Tramp Ant Species
  8. The Southern Fire Ant: A Native Species
  9. South American Fire Ant In San Diego County
  10. Fungus Gardens Of Leaf-Cutter Ants
  11. The Acacia Tree & Its Symbiotic Acacia Ant
  12. The Honeypot Ant & Its Food Storage Repletes
  13. The Trapjaw Ant: Fastest Moving Appendage
  14. Bullet Ant: Most Painful Ant Sting
  15. Stinging Arizona Harvester Ant Hybrids
  16. Harvester Ants In Anza-Borrego Desert
  17. Argentine Ant Problem In San Diego County
  18. Winter Ants Can Defend Against Argentines
  19. Long-Horned Crazy Ant Invaded Biosphere2
  20. Army Ants (Neivamyrmex) In The Superstitions
  21. How To Exterminate Argentine Ants

Some On-Line Ant Resources

  Disclaimer: I am reasonably certain about most of the identifications, especially those verified by James Trager & Alex Wild. For some of the names I used cf. (compare with) because of the difficulty in separating very similar species. On others I simply placed the ants in their respective subgroups of closely-related species. Large, difficult genera often require a specialist for precise species verification. Although identifications from my photo images may be impossible without voucher specimens to examine, comments and/or suggestions about my identifications are welcome.
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Owens Peak North Of Palomar College, San Marcos, CA

This is where I take daily exercise hikes. I have identified 15 species of ants on this peak, more than any other place I have visited. The reason I find so many ant species is that I go here often and I am always staring at the ground. I even found the beautiful Pseudomyrmex apache (scroll up to image in ant table of contents) on this hillside.

Some of the small black ants on Owens Peak superficially resemble each other. You must look very carefully to distinguish between different species. In fact, these two species even belong to different subfamilies, the Formicinae and Dolichoderinae.

16 Ant Species Found On Owens Peak
Click On Images To See Larger Images & Captions


1. Pheidole vistana

2. Pseudomyrmex apache

3. Prenolepis imparis

4. Messor andrei

5. Pogonomyrmex californicus

6. Solenopsis xyloni

7. Forelius pruinosus

8. Dorymyrmex bicolor

9. Linepithema humile

10. Tapinoma sessile

11. Crematogaster sp.

12. Formica moki

13. Camponotus dumetorum

14. Camponotus fragilis

15. Dorymyrmex insanus

16. Myrmecocystus testaceus
Note: #5 may be Pogonomyrmex subnitidus; Myrmecocystus wheeleri occurs in the Merriam Mtns a few miles away.
Comparative Ant Sizes on Owens Peak:
Camponotus dumetorum is the Largest.
(Click On Image To View This Species)

I recently found another ant species in my traps on Owens Peak. I am reasonably certain it is a large-eyed, nocturnal species of honeypot ant (Myrmecocystus testaceus). It clearly belongs to the subfamily Formicidae with one petiole node and an acidopore. In addition, it has long maxillary palps typical of Myrmecocystus. I also collected this species in a trap at Daley Ranch. This makes a grand total of 16 species for Owens Peak!

  Myrmecocystus testaceus At Daley Ranch  

Trail up Owens Peak from Twin Oaks Valley.

Additional Species In The Merriam Mtns Just N. Of Owens Peak

Honey Pot Ant (Probably Myrmecocystus wheeleri)

  More Images Of Myrmecocystus In The Merriam Mtns
Myrmecocystus mexicanus (or M. navajo) near Holbrook, Arizona
  

Black pyramid Ant (Probably Dorymyrmex insanus)


1. Some Gee-Whiz Facts About Ants

Ants are social insects in the family Formicidae (Order Hymenoptera), with over 300 genera in 20+ subfamilies. They evolved from wasp-like ancestors during the early Cretaceous period (130 million years ago) and diversified with the rise of flowering plants. They survived the Cretaceous-Tertiary (Cretaceous-Paleogene) extinction 65 million years ago when a giant asteroid collided with the planet Earth. More than 12,500 species out of an estimated 22,000 species have been classified. The earliest ants were predators with stingers, a characteristic still shared by some of today's ants, particularly solitary hunters and species that interact with mammals. The majority of species have evolved sophisticated chemical defense systems that are more effective against rival ant colonies. In fact, some modern ants with stingers use them to excrete or spray toxins rather than inject them into rival ants.

This bullet ant from Costal Rica resembles a giant wingless wasp. The only wasp that even comes close to its excruciating sting is the tarantula hawk wasp!

  Go To The Schmidt Sting Pain Index  
See The Tarantula Hawk Wasp

Ants range in size (length) from less than one millimeter to 50 millimeters, an increase of more than 4,000 percent. In terms of total numbers, there are an estimated 1 million ants for every person on earth! With a current world population of 7 billion people, that's an enormous number of ants: 7 quadrillion or 7,000,000,000,000,000. I have also seen estimates of one quadrillion ants, but this number seems too low. According to Mark Moffett (Scientific American January 2011), an Argentine ant supercolony extends from San Francisco to the Mexican border and may contain a trillion individuals (1,000,000,000,000), and this is only one enormous colony! Ant authorities Bert Hölldobler and Edward O. Wilson (The Ants, 1990) estimate that there are upwards of 10 quadrillion ants (10,000,000,000,000,000) alive on Earth at any given time.

Pheidole in the New World: A Dominant, Hyperdiverse Ant Genus by Edward O. Wilson. The book includes 624 species just in the genus Pheidole, with an estimated 1500 species worldwide! This is the largest genus of ants.


Ants In 25 Million-Year-Old Dominican Republic Amber

These ants became entombed in the sticky resin of the extinct Hymenaea protera about 25 million years ago. The latter resinous tree was the ancestor of modern-day West Indian locusts (H. courbaril). Although a Dominicam Republic amber mine was depicted in the movie Jurassic Park, all the dinosaurs were extinct by 60 million years ago.

  Cretaceous-Tertiary Boundary When Dinosaurs Became Extinct  

According to the website OMG Facts, "the total weight of all the ants on Earth is about the same as the weight of all humans on Earth." I would tend to question this record based on the average weight of a typical ant which is 3-5 milligrams. Using 5 milligrams or 0.00017637 ounces, the weight of a million ants is about 11 pounds, considerably less than the weight of an average adult human! 10 quadrillion ants divided by 7 billion people is 1,428,471 ants per person weighing about 16 pounds. Of course, the total weight of ants depends on the species. The giant Asian carpenter ant (Camponotus gigas) weighs much more than 5 milligrams. Another gee-whiz estimation: the weight of all the ants in Africa exceeds the weight of all the elephants!

Ant colonies may contain millions of individuals, mostly sterile wingless females forming castes of workers, soldiers and other specialized groups. They also contain one or more fertile queens and haploid males called drones. Ant colonies are sometimes described as "superorganisms" because the ants appear to operate as a unified entity, collectively working to support the colony. I previously compared ants with the "Borg" of Star Trek, a fictional cybernetic race. This is probably not an accurate comparison because the Borg apparently have centralized control by the "Borg Queen." Ant colonies exhibit "swarm intelligence" with the collective behavior of a decentralized system. The individual units (workers & soldiers) are sterile females that operate without a power hierarchy or permanent leader. The queen's role is basically an egg machine to reproduce and perpetuate the colony. The individual worker ants are like cells of an organism, and they are able to communicate with each other by the release of pheromones. This social unity is evident in extreme warfare between different colonies, and explains how colonies recognize "self" from "alien" ants. Recognition between cells of an organism is also controlled by chemicals. The recognition cues are genetically based odors on the surface of the ant called "cuticular hydrocarbons." These contain up to 100 compounds, including n-alkanes, alkenes and methyl branched hydrocarbons. As long as the ants have the same chemical odor they will not fight. Apparently, Argentine ants between San Diego and San Franciso "smell alike" because they do not fight.

  What Causes Army Ants To Run In Suicidal Circles?  
Why Do Army Ants Follow Each Other So Closely?

The role of workers may change with age. In honeypot ants (Myrmecocystus) young workers are fed liquid food until their abdomens (gasters) are distended. These ants with swollen gasters (called repletes) serve as living food storage vessels. In harvester ants (Pogonomyrmex), the young workers have sharp mandibles that can cut open tough seed husks, thus they serve as seed crackers in the nest. Eventually the mandibles become dulled from this work and the aging ants graduate to outside foraging duties. Female ants are typically diploid with 2 sets of chromosomes. Males are haploid and develop from unfertilized eggs. The Australian jack jumper worker ant (Myrmecia pilosula) has only a single pair of chromosomes. Male jack jumpers have only one chromosome, the lowest number known for any animal.

Jack Jumper (Myrmecia pilosula) Courtesy of Shannon Hartman / © Ant Web.org
Large, aggressive Australian ants of the genus Myrmecia (subfamily Myrmeciinae) can reach 40 mm in length. They are called bulldog ants or "jack jumpers." Their painful stings are dangerous because they may induce anaphylactic shock in allergic victims. Like honey bees and other hymenopterans, female ants are typically diploid with 2 sets of chromosomes. Males are haploid and develop from unfertilized eggs. The Australian jack jumper worker ant (Myrmecia pilosula) has only a single pair of chromosomes. Male jack jumpers have only one chromosome, the lowest number known for any animal!

Left: Jack jumper worker (Myrmecia pilosula) from southern Australia. Courtesy of Shannon Hartman 2011 www.antweb.org. Retrieved 24 May 2013.

Animal
Male
Female
Human
44 autosomes +
    X & Y chromosomes    
44 autosomes +
    two X chromosomes    
  Domestic Fowl  
16 autosomes +
two X chromosomes
16 autosomes +
X & Y chromosomes
Grasshopper
22 autosomes +
one X chromosome
22 autosomes +
two X chromosomes
Honey Bee
Drone (n=16)
Worker (2n=32)

Four methods of sex determination in animals.

The wax honeycomb of the honeybee (Apis mellifera) is composed of two layers of hexagonal cells. One layer of cells can be accessed from the front side, and another layer can be accessed from the back side. This ingenious construction of the two layers of cells utilizes the maximum utilization of space. The cells are used to store honey and larvae. Larger cells are constructed by the worker bees to accommodate the male drones which develop from unfertilized eggs. Extra large cells are used for larvae of fertilized eggs which are fed "royal jelly." These special females develop into sexually mature queens.

I once thought that the queen honeybee could determine the sex of her offspring. I was stating this when an elderly gentleman entered the rear of the lecture room. When the class was over he came down to my table and very diplomatically said that queen honeybees do not have this power. I later discovered that this man, Dr. Stanley Flanders, was a professor from UC Riverside and a world authority on honeybees with hundreds of scientific publications. As a biology professor in a very complex field I must say that it pays to be humble and always keep an open mind!

One of the most common questions I receive is "how long do ants live?" The life span of an ant depends on the caste member of a particular species. It also depends on optimal environmental conditions and available food supply. Workers generally live for a few months to a year. Queens of some species can live for more than 20 years. Some references say up to 30 years.

Ants have colonized almost every landmass on Earth. They thrive in most ecosystems and may form 15-20% of the terrestrial animal biomass. As I stated above, it has been estimated that the weight of all the ants in Africa exceeds the weight of all the elephants! Their coevolution with flowering plants has resulted in some fascinating symbiotic relationships, such as Acacia ants and leafcutter ants.


Unusual Place To Discover A New Species Of Ant!

A new tropical ant was recently discovered in the stomach of a poison dart frog in Ecuador. See article by C. Rabeling, J. Sosa-Calvo, L. A. O'Connell, L. A. Coloma, and F. Fernandez: Lenomyrmex hoelldobleri: A New Ant Species Discovered In The Stomach Of The Dendrobatid Poison Frog, Oophaga sylvatica (Funkhouser), Zookeys 618: 79-95 (19 September 2016). [doi: 10.3897/zookeys.618.9692].


Unusual Name For Another Recently Discovered Ant!

Tyrannomyrmex rex (T. rex for short) had eluded scientists since 2003, when entomologist Fernando FernŠndez revealed that a single dead ant from Malaysia represented a never-before-seen ant genus. The antís tiny mandibles reminded FernŠndez of the stubby arms of Tyrannosaurus rex and other carnivorous dinosaurs. In the years since, only a handful of Tyrannomyrmex ants have been found in India, Singapore, Sri Lanka, and probably the Philippines, all of them deceased and incidentally collected from leaf litter. But after digging in the dirt in a Singapore forest, National Geographic Young Explorer and entomologist Mark Wong has found the first recorded live colony of T. rex ants, revealing crucial details about the species, as well as additional mysteries.


2. What Good Are Ants?
While searching for ants in Daley Ranch (November 2015), an inquisitive gentleman asked me "What good are ants?" In their natural habitats, most of the world's 12,000+ ant species are living in their complex societies without bothering people unless, of course, you happen to disturb their nests or get too close to their migratory or swarming paths. When they get introduced to places where they don't belong, serious ecological problems often arise. Cases in point are the ubiquitous Argentine ants in California, the numerous alien ant species in the Hawaiin Islands, and South American fire ants in the southern U.S. Ants are ecologically diverse and constitute a large portion of the total animal biomass of their natural habitats. In fact, it has been estimated that the weight of all the ants in Africa exceeds the weight of all the elephants! Ants fill various important ecological roles, such as herbivores, predators, seed dispersers, and pollinators. They are also important scavengers & decomposers, recycling the nutrients in dead animal & plant matter back to the ecosystem. Like earthworms, they help improve soil quality. By digging tunnels, ants aerate and turn over the soil, bringing nutrients closer to the surface and allowing rainwater to percolate more readily through the soil. Some ant species form important symbiotic relationships with plants, such as acacia ants and swollen thorn acacias of Central America, and the remarkable epiphytic "ant plants" of tropical Asia & Australia. In southern California, native ants constitute the diet of several endangered animals, including the coastal horned lizard (Phrynosoma coronatum), granite night lizard (Xantusia henshawii), and the arroyo toad (Anaxyrus californicus). Coastal horned lizards feed exclusively on harvester ants (Messor & Pogonomyrmex) and the destruction of these native ants by Argentine ants in urbanized areas has eliminated this unique lizard in some areas of San Diego County. Ants are also valuable research organisms in several disciplines, including social behavior, communication, genetics of caste determination, and robotics studies. Because they are sensitive to microclimate change and are ideal functional measures of ecosystem disturbance, ants have been studied by The U.S. Geological Survey to show the effects of large California wildfires in San Diego and Orange Counties.

Epigenetics: The Making of Ant Castes

New research on ants and honeybees points to DNA methylation as a crucial factor in determining the caste of a developing individual. Epigenetics refers to developmental changes in gene expression or phenotype without changing the original DNA sequence. Epigenetic traits are caused by methylation of certain DNA bases, thus affecting the development of the larva. It is a mechanism that occurs by the addition of a methyl (CH3) group to DNA, thereby often modifying the function of the genes.

Exons In Epigenetic Ant Research

In eukaryotic cells, the initial messenger RNA (M-RNA) transcribed from the DNA (gene) is modified (shortened) before it leaves the nucleus. Sections of the M-RNA strand called introns are removed, and the remaining portions called exons are spliced together to form a shortened (edited) strand of mature M-RNA that leaves the nucleus and travels to the ribosome for translation into protein. Perhaps the deleted sections (introns) were needed by our ancestors, but are no longer necessary. In fact, this hypothesis was actually utilized in an episode of Star Trek: The Next Generation. In this episode the crew was reverting back to their ancestral state because their introns were reactivated.

According to A. Chittka, Y. Wurm and L. Chittka (2012): "As in honeybees, the bulk of DNA methylation in these ants was in the exons of transcribed genes, with the levels of methylation correlating positively with gene expression."

    Epigenetics: The Making of Ant Castes by Alexandra Chittka, Yannick Wurm, Lars Chittka. Current Biology Volume 22, Issue 19, pR835-R838, 9 October 2012.   Full Text Version   PDF Version

  Misrepresentations Of Science: Epigenetics & Power Of The Mind  

DNA is the master molecule of life that contains in coded form all of our genetic characteristics. In fact, the remarkable diversity of life is based on the "infinite" arrangements of DNA molecules. Mutations (stable hereditary changes in DNA) may lead to the evolution of new species. Although DNA sequences (genes) may remain stable for many generations, they may be turned on or off by regulator proteins. In the following simplified illustration of a small section of DNA with 68 base pairs (rungs), the molecule has 4^68 possible arrangements or 87 duodecillion (87 followed by 39 zeros)! [The previous statement assumes an unlimited number of A's, T's, C's and G's.] In epigenetic traits, like the castes of ants, the DNA is methylated but the original base sequence is not altered.

Some species of Pheidole have a supermajor (supersoldier) that is larger than regular majors. It has a strikingly massive head compared with its body. These species have 3 castes: minors, majors and supermajors. Most of the 1000+ species of Pheidole have only 2 castes, but apparently have the genetic potential (ancestral DNA) to produce supersoldiers. Biology professor Ehab Abouheif at McGill University in Montreal discovered that dabbing larvae with methoprene, a chemical that mimics juvenile hormone, will induce the development of supersoldiers. These large biting ants are presumably better able to defend the colony against invasions of aggressive army ants.

Telomeres In Epigenetic Ant Research

Telomeres are repetitive strands of DNA (sequences of repetitive bases) at the terminal ends of linear chromosomes. They play an essential role in maintaining the integrity of the chromosome by protecting it from degradation and from end-to-end fusion with other chromosomes. Telomeres are essentially protective "end caps" of non-coding DNA at the extreme ends of chromosomes. Telomeres have been metaphorically compared with the tips of shoelaces that keep the laces from unraveling. Each time a cell divides, the telomeres lose a small amount of DNA. Eventually, when all of the telomere DNA is gone, the cell can no longer divide and dies. End replication problem is not an issue in prokaryotic cells because they have circular DNA molecules without ends.

  Evolution Page: Telomeres & Aging Process  

Another interesting area of ant research concerns the biology of aging: "The link between caste-specific differential methylation and maintenance of telomeres (chromosome ends) is intriguing because of its potential links to the biology of ageing." Queens and worker ants are diploid with 2 sets of chromosomes and males are haploid with only one set. Queens may live more than 20 years while workers may only live a few months, even though they have the same DNA. How is this possible? Does it involve telomeres?

In the Indian jumping ant (Harpegnathos saltator), special egg-laying workers capable of mating (called gamergates) can replace an aging queen. A study of the genome and expressed genes of gamergates found that the production of enzymes that slow aging (telomerase and sirtuin deacetylases) are increased when workers turn into queens, thus increasing their longevity like queens.


3. General Ant Anatomy

Above Illustration From Wikimedia Commons

Dorymyrmex bicolor along dirt road north of Owens Peak. Note the prominent conical protuberance on propodeum. The propodeum is the first segment of the abdomen. It is fused with the posterior end of thorax.

  See Probable Dorymyrmex insanus from Portal, Arizona  

These are the 5 major characteristics to distinguish honeypot ants (genus Myrmecocystus) from other ants in southern California. Note that this ant has an acidopore instead of a stinger at the tip of its gaster.

Ant Compared With Wingless Wasp


Termite, Winged Ant, Small Wasp or Gnat?

The elbowed antennae and petiole node rules out a small wasp, gnat and termite. The pair of claspers at end of gaster indicate that this is a male ant.

A Swarm Of Small Winged Ants On Owens Peak (8 January 2013)

Left: Swarm of flying ants ("nuptial flight") over Owens Peak (18 January 2013). Right: Close-up view compared with U.S. Penny (19 mm in diameter). Individual ants are about 4 mm long with a brown spot on forewings. These are males because of the small heads and pair of claspers at posterior end of gaster. The species is undetermined; however, the most active ant I observed on Owens Peak at this time of the year was the winter ant (Prenolepis imparis). Dorymyrmex bicolor was active later in January, but the males of that species are smaller. The 2 petiolar nodes resemble workers of the southern fire ant (Solenopsis xyloni), another native species in the area. On January 19, I followed a large swarm of flying ants to its souce in a saddle north of Owens Peak. Winged ants were climbing the blades of grasses and workers of Tapinoma sessile were abundant among the adjacent rocks. This species has a single, flattened petiolar node and the antennal scape is longer than the next 4 segments combined. Its thorax does not have the shape of an hourglass as in Prenolepis imparis. It is clearly distinguished from the winter ant. There are undoubtedly more than one species of winged ants in the swarms observed over Owens Peak.

Small winged male ants compared with a U.S. penny.


Ants Compared With Termites

Termites belong to the insect order Isoptera. They are social insects with a well-developed caste system consisting of the fertile queen (original female of royal pair), king (original male of royal pair), workers (nymphs), and soldiers (modified workers with massive heads and enlarged mandibles). The name "Isoptera" is derived from "iso" (equal) and "ptera" (wing). Insects of this order have winged sexual adults with four membranous wings of the same approximate length. The immature nymphs feed on wood, much to the chagrin of home owners with wood frame houses. Termite guts contain flagellated protists that contain wood-digesting bacteria, which in turn contain cellulose-digesting enzymes. Termites are often confused with ants; however, the abdomen of termites is broadly joined to the thorax, whereas in ants it is constricted at the base and connected to the thorax by a narrow petiole. The antennae of termites are moniliform with segments resembling a minute string of beads. Antennae of ants are elbowed with a distinct bend. Ants and termites can readily be distinguished, even in 25 million-year-old amber from the Dominican Republic. Although they both have well-developed caste systems, termite workers and soldiers consist of individuals of both sexes, with all nymphs serving as workers. With the exception of haploid males (drones) in ants, the individuals of these castes in ant colonies are all females.

The massive head and mandibles of this rottenwood soldier are used to defend the colony against invading ants.

  See The Wayne's Word Termite Page  


4. Diet & Food Digestion

Adult ants cannot eat solid foods. Their mandibles are not adapted for chewing food into small pieces. Solid particles much larger than pollen grains will not pass through the narrow constrictions at the neck and waist. Adults bring solids back to the nest where their larvae (digestive caste) eat and regurgitate it back into mounths of adults. Leaf-cutter ants actually have two "digestive castes": The fungal gardens, which digest leaves and other cellulose matter, and their larvae, which chew, swallow, and regurgitate the fungus.

This queen survived in captivity for 4 months on a liquid honey diet. Adult ants cannot eat solid foods. Their mandibles are not adapted for chewing, and solid particles much larger than pollen grains will not pass through the narrow constrictions at the neck and waist. Adults bring solids back to nest where their larvae (digestive caste) eat and regurgitate it back to adults.

Although typical harvester ants appear to like Nature Valley Granola, they cannot digest solid food. The morsels are carried back to the nest and fed to larvae. Only the last (4th) larval stage can digest solid food. This liquified food is fed to workers who feed it to other workers and larvae. Trophallaxis is the transfer of food or other fluids among members of a community through mouth-to-mouth (stomodeal) feeding. It is most highly developed in social insects such as ants, termites, wasps and bees.

Carpenter ants (Camponotus fragilis) on Owens Peak: The smaller, minor worker placed its mandibles in the open jaws of the larger major worker, presumably sharing food (trophallaxis). In my container they repeatedly assumed this position. Wikipedia shows another species of Camponotus exhibiting this behavior.

The following abstract is from PubMed (The National Center for Biotechnology Information): "Trophallaxis and Prophylaxis: Social Immunity in the Carpenter Ant Camponotus pennsylvanicus" by C. Hamilton, B.T Lejeune, and R.B. Rosengaus (23 February, 2011).

In social insects, group behaviour can increase disease resistance among nest-mates and generate social prophylaxis. Stomodeal trophallaxis, or mutual feeding through regurgitation, may boost colony-level immunocompetence. We provide evidence for increased trophallactic behaviour among immunized workers of the carpenter ant Camponotus pennsylvanicus, which, together with increased antimicrobial activity of the regurgitate droplet, help explain the improved survival of droplet recipient ants relative to controls following an immune challenge. We have identified a protein related to cathepsin D, a lysosomal protease, as a potential contributor to the antimicrobial activity. The combined behavioural and immunological responses to infection in these ants probably represent an effective mechanism underlying the social facilitation of disease resistance, which could potentially produce socially mediated colony-wide prophylaxis. The externalization and sharing of an individual's immune responses via trophallaxis could be an important component of social immunity, allowing insect colonies to thrive under high pathogenic pressures.


5. The Worst Enemies Of Ants Are Other Ants

Close-up view of Pheidole vistana major worker.

The worst enemies of ants are other ants! Above image shows a sample of ant body parts collected near a Pheidole vistana nest on Owens Peak. There was apparently a battle with nearby field ants (Formica moki). Some Pheidole lost their heads, but based on the ratio of body parts, presumably the Pheidole colony was victorious. Undoubtedly, the big-headed major workers (soldiers) played a valuable role in this victory!

Both Ant Web & Ant Wiki state that Pheidole vistana feeds exclusively on insects. I always see minor workers running away from a boulder on Owens Peak with a piece of my Nature Valley granola bar in the mandibles. At 5:00 P.M. 21 Jan. 2015 I followed a procession of them to their nest. The following image shows a major & minor carrying a piece into their nest entrance!

Another Big-Headed Ant (Pheidole megacephala) On Maui

Big-headed ant major & minor workers coming out of a corrugation.

Close-up view of big-headed ant major (soldier).

  A Minute Big-Headed Ant North Of The Salton Sea  

Another Ant Encounter On Owens Peak Near Palomar College

Honeypot ants (Myrmecocystus) and a solpugid in a fight to the finish. I found them in this position in southern Arizona. This battle was not staged!


6. Five Of The Worst Tramp Ant Species

Tramp ants have spread from their native countries to other continents where they attack and kill native insects, birds, reptiles, and mammals. They also kill pollinators of native plant species and destroy agricultural crops resulting in enormous loses. In some cases they have invaded islands with no native ants, including the Hawaiian Islands, Galapagos Islands, and Christmas Island in the Indian Ocean.

The five species and their places of origin are: (1) Argentine Ant (Linepithema humile) from Paraná River in South America; (2) Yellow Crazy Ant (Anoplolepis gracilipes) from West Africa; (3) Red Imported Fire Ant (Solenopsis invicta) from South America; (4) Big-Headed Ant (Pheidole megacephala) from southern Africa; and (5) Little Fire Ant (Wasmannia auropunctata) from Central and South America. I have images of these ants in the following pages.

The little fire ant (Wasmannia auropunctata) has been introduced to Maui (and other Hawaiian Islands) through the nursery trade and other ways. Although it is tiny, it packs a potent sting and is a potentially disastrous alien introduction. It has the nasty habit of stinging native animals in the eyes and can cause blindness. In the Galapagos Islands, it kills tortoise hatchlings and targets the eyes of adults. www.lfa-hawaii.org


7. Southern Fire Ant (Solenopsis xyloni): A Native Fire Ant

Note: Many of these native ant species have been completely eliminated from urbanized areas of southern California by the Argentine ant (Linepithema humile). This is particularly true in areas that are regularly watered, providing damp, cool habitats for Linepithema. Even larger, more powerful harvester ants are no match for the sheer numbers of aggressive Argentine ants. The imported fire ant (Solenopsis invicta) is another prolific invasive species from South America that might even outcompete the Argentine ant.

Southern fire ant (Solenopsis xyloni), native to arid regions of the southern and western United States, and close relative of the infamous imported fire ant (S. invicta) of the eastern U.S. The latter species is native to South America and is a serious insect pest in many tropical and temperate countries of the world. This is a polymorphic species with two sizes of workers called majors and minors. The minor workers are only about 3.0 mm long (slightly over 1/8 inch). Major workers are twice as large. Although they are small they have a potent sting, especially if they get you between the fingers. When disturbed the workers exhibit a phenomenon known as "gaster wagging" where they raise and vibrate their abdomen. They are aggressive little ants, but have been annihilated in many urbanized areas of southern California by the Argentine ant (Linepithema humile). It will be interesting to see what happens when invasive Argentine ants clash with the equally invasive South American fire ant. According to "Controlling Fire Ants Takes a Group Effort" published in the July 2009 issue of Agricultural Research Magazine: "In a battle with the Argentine ant, Linepithema humile, the fire ant won 80 percent of the time."

The venom in the sting is mostly piperidine alkaloids including isosolenopsin. These are single nitrogenous rings found in black pepper (Piper nigrum), wild tobaccos (Nicotiana) and poison hemlock (Conium maculatum).

A clash between southern fire ants (Solenopsis xyloni) and orange desert ants (Forelius pruinosus) at the summit of Owens Peak (3 Aug 2013). The ants were attracted to my Nature Valley granola bar that I pulverized and placed on a metavolcanic boulder. Some of the fire ants have their gasters raised and stingers exerted with a drop of venom at the tip. Vibrating (flagging) their gasters (gaster wagging) releases venom into the air like an aerosol mist and repels other ants, in this case the orange (Forelius) ants. I watched the fire ants slowly force the Forelius ants away from the food source. The Forelius quickly backed away from the fire ants and retreated to another area of the boulder. See following video: Please wait about 6-7 seconds for video file to load, the wait is worth it!

  Solenopsis xyloni gaster wagging: Uploaded To YouTube (22 MB)  

Note: On 6 August 2013 shortly after the above video was taken, the smaller, orange Forelius ants came in droves to the boulder and eventually overwhelmed the fire ants, forcing them to retreat into their crevice entrance. Apparently gaster wagging on this day just wasn't enough to repel the foraging Forelius. I did not observe any ants making physical contact or biting each other. The fire ants simply retreated from the large numbers of faster moving Forelius.

Close-up view of orange desert ants (Forelius pruinosus). Each ant is about 2 mm long.

Unusual Color Variation In Forelius & Solenopsis

  Red & Black Forelius pruinosus In New Mexico  
Black Fire Ants (S. xyloni) In The Superstitions
Unusual Red Fire Ants North Of The Salton Sea


8. S. American Fire Ants (Solenopsis invicta ) In San Diego County

      Click Here To See Page About Fire Ants In Mira Mesa  

  South American Fire Ant Invasion Of Indio  


9. Fungus Gardens Of Leaf-Cutter Ants

Leaf-cutter ants (Atta and Acromyrmex) feed exclusively on a fungus that grows only within their colonies. They continually collect leaves which are taken to the colony, cut into tiny pieces and placed in fungal gardens. Workers specialize in related tasks according to their sizes. The largest ants cut stalks, smaller workers chew the leaves and the smallest tend the fungus. Hyphal swellings of the fungus called gongylidia are fed to the developing larvae and distributed throughout the colony to feed workers, soldiers, and the queen. The ellipsoid gongylidia are about 30-50 micrometers in diameter and are rich in lipids and carbohydtrates. [Some references say that the ant larvae feed on the fungus and adults feed on leaf sap].

The symbiotic basidiomycete fungus living inside colonies of Atta cephalotes and Atta sexdens has been identified as Leucoagaricus gongylophorus = Leucocoprinus gongylophorus. Interestingly enough, fruiting bodies (basiocarps) of Leucoagaricus species can be found in urbanized areas of North America, including L. americanus and L. naucinus. The two latter fungi have also been listed in the genus Lepiota.

The tropical leaf-cutter colony (Atta cephalotes is composed of several castes, including the queen, workers and large soldiers who often stand guard at the entrance of the nest, or even go on scouting missions to protect the colony from predators. Like the queen, the males are winged, and their only role is to inseminate the virgin queen. Workers include larger "media workers" who cut and carry leaf sections back to the nest, and "minima workers" who cut the leaves into minute pieces for the fungus garden. They also cover the leaf fragments with their antibacterial saliva which retards the growth of competing fungi, thus protecting their symbiotic fungus that is vital for their survival. They also feed the entire colony of ants.

A nest of leaf-cutter ants (Atta cephalotes). The white area at the right side of image is a colony of fungal mycelia. Note the smaller worker ants and the large soldier (white arrow).

Arizona leaf-cutter ant (Acromyrmex versicolor) carrying a pinnate leaf of palo verde (Cercidium microphyllum = Parkinsonia microphylla), the state tree of Arizona.

From Wikipedia (5 February 2017). Of all the ant species, the leaf-cutter ants have the most complex caste system. Next to humans, leafcutter ants form the largest and most complex societies on Earth. Each queen mates with multiple males and stores sperm to start her colony. She carries bits of the fungus garden mycelium in her oral cavity (infrabuccal pocket).

    There are 4 main castes:

    1. Minims: The smallest workers that tend the brood and care for the fungus gardens. Their head width is less than one millimeter.

    2. Minors: Present in large numbers around foraging columns and are the first line of defense.

    3. Mediae: Generalized foragers that cut leaves and bring leaf fragments back to the nest.

    4. Majors (Soldiers): Largest ants that defend nest from intruders.

Another symbiotic partner, the actinobacterium Pseudonocardia, grows on the ants and secretes antibiotic chemicals. Actinobacteria are responsible for producing the majority of the world's antibiotics.

Distinctive nests of leaf-cutter ants (Acromyrmex versicolor). The right image (red arrow) shows numerous smaller craters made by antlion larvae, remarkable ant predators.

Close-up view of an antlion larva showing its peculiar (grotesque) fusiform body and enormous, toothed jaws (mandibles). It waits at the bottom of its crater to grab an unfotumate passer-by who happens to fall in.

Cave Creek Canyon, Chiricahua Mtns

Trachymyrmex sp. (Probably T. arizonensis), a spiny fungus-farming ant in Cave Creek Canyon, southeastern Arizona. This species is smaller than Acromyrmex versicolor that is found in Arizona and in California north of Blythe.

See Tropical Leafcutter Ant (Atta cephalotes)
  Arizona Leafcutter Ant (Acromyrmex versicolor)  
Arizona Leafcutter Ant (Acromyrmex versicolor)


10. Coevolution Between Swollen Thorn Acacia & Acacia Ant

Several species of tropical American Acacia trees have swollen stipular spines that are hollowed out and occupied by symbiotic ants. The ants defend the tree against ravaging insects, browsing mammals and epiphytic vines. In return, the acacia supplies its little guardian ants with protein-lipid Beltian bodies from its leaflet tips and carbohydrate-rich nectar from glands on its petiole.

Another remarkable example of coevolution between a tree and an insect is the acacia and its symbiotic ant. Some species of Central American swollen-thorn acacias lack the chemical defenses of most other acacias to deal with their predators and competition. Without bitter alkaloids, ravaging insects and browsing mammals eat the leaves and branches, slowing the growth of the acacias and allowing fast-growing, competing vegetation to shade them out. Symbiotic stinging ants have taken over this vital defense role, protecting the acacia from hungry herbivores and pruning away competing plants. The ants live inside inflated thorns (stipular spines) at the base of the leaves. The ants will even clear away seedlings of fast-growing competing plants around the base of the acacia. The acacia tree provides housing for the ants in the form of hollowed-out thorns. It provides nourishment in the form of carbohydrate-rich nectar from glands on the leaf stalks (petioles). It also provides protein-lipid Beltian bodies from its leaflet tips. There is no other known function for these tiny, yellowish morsels other than to provide food for its ants. Swollen thorn acacias of lowland Central America include Acacia cornigera, A. collinsii, A. hindsii, A. sphaerocephala, and A. cookii. The ant colonies inhabiting these trees typically belong to the genus Pseudomyrmex.

Three species of Acacia with swollen stipular spines that are hollowed out and occupied by symbiotic ants. Left: The bullhorn acacia (Acacia cornigera), a swollen-thorn acacia native to Mexico and Central America. In its native habitat, colonies of stinging ants (Pseudomyrmex ferruginea) occupy the hollowed-out thorns and fiercely defend the tree against ravaging insects, browsing mammals and epiphytic vines. In return, the host supplies its little guardian ants with protein-lipid Beltian bodies from its leaflet tips (yellowish granules in photo) and carbohydrate-rich nectar from a gland on its petiole just above the pair of spines (white arrow). Center: Another Central American swollen thorn acacia (A. collinsii) with an acacia ant (P. ferruginea) sipping nectar from the petiolar nectary. Right: The African whistling thorn acacia (A. drepanolobium). The common name comes from the whistling sound that is produced when wind blows across the large hollowed-out thorns. Since the "thorns" on these trees are technically pairs of modified stipules, they are more correctly referred to as stipular spines. In order to have consistent monophyleic cladograms based on chloroplast DNA, these three Acacia species of have been moved to the genus Vachellia (See section 12).

Nests of at least a dozen bird species have been reported in swollen thorn acacia trees that contain Pseudomyrmex ants (Janzen, 1969). The relationship between birds nesting in acacias inhabited by ants appears to be commensal, because ants that protect acacias against herbivores also offer protection against avian nest predators (Janzen, 1969, 1983). On the other hand, the birds do not seem to provide any benefit to the acacias or ants. A symbiotic relationship in which one organism is benefited while the other is neither benefited nor harmed is called commensalism. Unlike the relationship between the fig and fig wasp, the acacia and acacia ant is probably not a good example of mutualism. Daniel Janzen also reported predation on the ants by certain birds, primarily by splitting open the thorns to access larvae and workers. In the latter case, the relationship between the acacia ant and bird could be considered parasitism (at least in part), since one member is actually harmed by the relationship.

See The Wayne's Word Article About Acacias
See Stipular Spines Of Swollen-Thorn Acacias
  Necklace & Seed Doll Made Of Acacia Spines  

Whistling Thorn Symbiosis May Be One-Sided:

Additional complexities about Africa's whistling thorn (Acacia drepanolobium) are discussed in a recent article by Maureen Stanton and Truman Young in Natural History Volume 108 (November 1999). Studies by Stanton and Young reveal that four species of stinging ants live symbiotically on A. drepanolobium: Crematogaster mimosae, C. nigriceps, C. sjostedti, and Tetraponera penzigi. Their studies also reveal that the symbiotic relationship between some of these ant species and their host acacia may not be equally beneficial to both partners. Since these different species of ants are rival enemies, they occupy separate trees. If acacia branches containing rival ant colonies make contact, the different species of ants will fight each other, with the loser being evicted from its tree. Unlike the Central American thorn acacias that provide their ant warriors with protein-lipid Beltian bodies on leaflet tips, the whistling thorn provides no such service. This forces the ants to leave the tree to forage for insects and other protein-rich foods which they bring back to the developing ant larvae living inside the swollen thorns. According to Stanton and Young, refuse pushed out of the thorn nests may help to fertilize the tree.

The relationship between some of these ant species and their acacia is not completely mutualistic because it may harm the acacia tree. Crematogaster mimosae and C. sjostedti both tend scale insects that feed on the tree's vascular system, milking the aphid-like insects for their nutritive honeydew secretions. In fact, C. sjostedti pays little attention to herbivores that attempt to feed on the tree. The latter species also nests in hollow spaces within dead and dying branches, rather than in the swollen thorns. Colonies even thrive in the stumps of dead trees. To make matters worse, this species of ant often comes out the winner in battles with other ant species over the possession of a tree. According to Stanton and Young, the balance in a once mutualistic relationship has shifted in favor of one partner (the ant) at the expense of the other (the tree).

Although not as extreme as Crematogaster sjostedti, the relationship between C. nigriceps and its acacia host is also one-sided in favor of the ant. This ant species chews off the tips of growing shoots, including leaf and flower buds, thus pruning and sterilizing the tree. New branches are allowed to grow mainly in the proximity of swollen thorns, thus ensuring nectar-rich petiolar nectaries (glands) on new leaves easily accessible to worker ants inside the thorns. Over time, this pruning by ants changes the growth rate and shape of the tree canopy, compared with trees occupied by other ant species. In addition, pruning is more radical on sides adjacent to rival ant trees, thus reducing the chance of contact with branches of rival trees containing more aggressive ant species.

Central American swollen-thorn acacia (Acacia cornigera) showing Beltian bodies at leaflet tips. As I stated above, there is no other known function for these tiny, yellowish, protein-lipid morsels other than to provide food for the symbiotic ants.

  See The Remarkable Ant Plant  


11. Honeypot Ants

The genus Myrmecocystus is commonly known as "honeypot ants." Worker ants tend special polymorphic ants (repletes) called plerergates. These unusual ants hang from the ceiling deep within the nest and are "living storage units." They store large quantities of nutritious honeylike fluid in their swollen abdomens to feed the colony during times of famine and drought. This is an adaptation for living in extremely hot desert environments with prolonged drought, such as the Salton Sea region. The repletes of some species become the size of small grapes. During leaner times of the year when foraging food is unavailable, workers will tap their antenna upon the head, mandibles and antenna of a replete to solicit food, which is then readily provided to the repletes' nestmates. See the following image courtesy of Wikimedia Commons.

A winged queen and three workers.

Distinctive Myrmecocystus Crater

Entrance to Myrmecocystus nest: Harvester ant nests (Messor and Pogonomyrmex) usually have a distinct crater-like cone covered on the outside with dense layer of seedless husks from nearby shrubs and wildflowers. Myrmecocystus nests may have just a opening in the sand, or resemble shallow craters. Depending on the species and age of the colony, the crater-like nests of some Myrmecocystus can be quite distinct.

Holbrook, Arizona

Subgenus Myrmecocystus

Honeypot Ant (Myrmecocystus)

This may be Myrmecocystus mexicanus
or possibly M. navajo

Honeypot Ants At The Salton Sea (1)
  Honeypot Ants At The Salton Sea (2)  
Honeypot Ants In Holbrook, Arizona


12. Trap-Jaw Ants: Fastest Moving Predatory Appendage

The peacock mantis shrimp (Odontodactylus) has grasping predatory appendages that can move over 50 mph and accelerate like a .22 caliber bullet. They actually have the force to break a glass aquarium, BUT THEY ARE NOT THE FASTEST! According to researchers at UC Berkeley, the long, widespread jaws of the trap-jaw ant (Odontomachus) move up to 145 mph and close shut in 0.13 milliseconds. The peak force exerted is 100,000 times the force of gravity or 300 times the ant's body weight.

Arizona's Trap-jaw Ant (Ponerinae): Odontomachus clarus


Mandibles Locked In Opened Position
Photo by Zach Lieberman. From www.Antweb.org

Mandibles Released In Closed Position
Photo by April Nobile. From www.Antweb.org

  More Information About Trapjaw Ant On Wayne's Word  
Remarkable Trapdoor Of A Bladderwort (Utricularia)

A Relative Of Trap-Jaw Ant On Maui

Remarkable sickle-jaw ants Leptogenys falcigera along the beach walkway in Wailea. They have large, sickle-like jaws and some are specialized predators on various groups of arthropods. They belong to the same subfamily as the remarkable trap-jaw ants. This species is native to Africa.

Remarkable Diversity Of Ant Mandibles (Jaws)

Mandibles (jaws) are a vital tool for many insects, but perhaps in no other insect group are they more diverse and extensively used than ants. Ants use their mandibles like "hands" for a wide variety of tasks, including the manipulation of all sorts of objects, constructing nests, care and movement of eggs and larvae, harvesting and husking seeds, grasping prey, and in warfare. The following four images illustrate some examples of mandible diversity in ants:

A. Messor andrei: Strong, thick mandibles to crack open tough, seed-bearing husks. In harvester ants of the genus Pogonomyrmex, this task is performed inside the nest by younger workers with sharper mandibles. Older (expendable) workers with well-worn mandibles take on the more hazardous task of foraging outside the nest.

B. Myrmecocystus cf. mexicanus: Mandibles used for a variety of tasks, including harvesting honeydew secretions and carrying live and dead insects. According to Dale Ward (Ants of the Southwest), Myrmecocystus will often hang around a Pogonomyrmex (harvester ant) nest. The Myrmecocystus will "frisk" Pogonomyrmex foragers returning to the nest. If the Pogonomyrmex is carrying a seed, the Myrmecocystus will let it pass. If the Pogo is carrying insect prey, the Myrmecocystus will steal it away!

C. Leptogenys falcigera: This is a predatory ant native to Africa. It has large, sickle-like jaws to grasp and kill prey. Some are specialized predators on various groups of arthropods. They belong to the same subfamily (Ponerinae) as the remarkable trap-jaw ants.

D. Odontomachus coquereli: Trap-jaw ants have a pair of large, straight mandibles capable of opening 180 degrees. The jaws are locked in place by a pair of large contracting muscles in the head, and can snap shut on prey or objects when their corresponding latches on the clypeus are triggered. The great instantaneous speed of the muscles is due to elastic energy, like the elastic energy of a crossbow. According to Wikimedia (2013), the jaws of Odontomachus are the fastest moving predatory appendages in the animal kingdom. One study of O. bauri (see next image) at UC Berkeley's Department of Integrative Biology (2006) recorded peak speeds of between 35-64 meters per second (78-145 mph), with the jaws closing within just 0.13 milliseconds (130 microseconds) on average. This is 2,300 times faster than the blink of an eye! The peak force exerted was 100,000 times the force of gravity or 300 times the ant's body weight. The mandibles either kill or maim prey, allowing the ant to bring it back to the nest. The ants were also observed to use their jaws as a catapult to eject intruders or fling themselves backwards to escape a threat.

The Costa Rican trap-jaw ant (Odontomachous bauri).

According to Sheila Patek of the integrative biology research team at UC Berkeley (2006), falcons can dive at speeds up to 300 miles per hour, but they must start from very high altitudes and get a boost from the force of gravity to reach these high speeds (32 feet per second squared). In comparison, animals such as trap-jaw ants and mantis shrimp (which formerly held the record for swiftest strike in the animal world) utilize energy stored within their own bodies. In the plant kingdom, one of the fastest moving structures is the trapdoor of an aquatic bladderwort (Utricularia) that snaps shut in 15 to 20 milliseconds (about 1/60 of a second), roughly the speed of a daylight film camera shutter setting. Compare this rate with 0.13 milliseconds for jaws of Odontomachus bauri! Using the formula Force = Mass X Acceleration, it is easy to see how these small ants can stun or kill small prey with their powerful, fast-moving jaws..

Patek, S.M., Baio, J.E., Fisher, B.L., and A.V. Suarez. 2006. "Multifunctionality and Mechanical Origins: Ballistic Jaw Propulsion in Trap-Jaw Ants." Proceedings of the National Academy of Sciences 103 (34): 12787-12792. Full Article


13. The Excruciating Bullet Ant: Paraponera clavata

Bullet ant (Paraponera clavata), another large tropical ant: This species is native to Central and South America. It is a little smaller than the Malaysian giant ant, but makes up for its size difference with the most painful sting of all insects. It is rated 4.0+ on the Schmidt Sting Pain Index (see following table). It is called "bullet ant" because sting is compared with the pain of a bullet.

According to Schmidt (1986), the venom of Paraponera is a small neuropeptide called poneratoxin. It blocks the central nervous system of insects and is agonistic to mammalian smooth muscle (agonistic toxins mimic the effects of neurotransmitters while antagonistic toxins blocks neurotransmitters). In humans, intense pain may last for 5 hours, then lessen over the next 24 hours. Severe pain may be accompanied by trembling, perspiration, nausea, and inability to use an injured arm or leg. Some South American Indians intentionally apply stings during tribal manhood rituals and medicinally as a counter-irritant to relieve rheumatism and similar ailments. These remarkable ants have reportedly been used for sutures to close open wounds. After locked jaws hold the skin together the heads are twisted off. The unfortunate ants are probably not too happy with this primitive method of suturing. East African indigenous people use siafu or driver ants (Dorylus) in a similar way. They use large-headed soldiers to stich the wound by getting the ants to bite on both sides of the gash, then breaking off the body.

Bullet ants can incapacitate larger animals, including humans. Keepers of these ants in zoos are required to follow strict safety guidelines for dangerous venomous animals. This includes treatment protocols with Benadryl, Prednisone, and self-injectable epinephrine.

Schmidt Sting Pain Index

Sting Rating
Hymenopteran
Comparison Analogy
1.0
Sweat Bee
Like a tiny spark has has singed a hair on your arm.
1.2
Fire Ant
Like walking on a carpet & getting a static electricity shock.
1.8
Bullhorn Acacia Ant
Like someone fired a staple into your cheek or hand.
2.0
Bald-Faced Hornet
Like getting your hand mashed in a revolving door.
2.0
Yellowjacket
Like extinguishing a cigar on your tongue.
2.0+
Honey Bee
Like a burning matchhead that lands on your skin.
3.0
Red Harvester Ant
Like using a drill to excavate your ingrown toenail.
3.0
Paper Wasp
Like spilling a beaker of hydrochloric acid on a paper cut.
4.0
Pepsis Wasp
Like dropping a running hair drier into your bubble bath.
4.0+
Bullet Ant
Walking on hot charcoals with 3 inch rusty nail in your heel.

Man Testing Sateré-Mawé Tribal Initiation With Bullet Ants In Amazon
  The Sateré-Mawé Tribal Initiation Using Bullet Ants In Brazilian Amazon  


14. Arizona's Stinging Harvester Ant Hybrids (Pogonomyrmex)

Clearing 10 feet (3 m) across made by colony of harvester ants (Pogonomyrmex barbatus).
The ants carefully remove all plants and competing root systems from their subterranean nest.

Dark harvester ants (Pogonomyrmex rugosus) or possibly hybrids with P. barbatus.
Harvester Ant Workers: Hybrids Between Pogonomyrmex rugosus & P. barbatus

All Possible
Crosses *
P. barbatus
Queen
P. barbatus
Male
P. rugosus
Queen
P. rugosus
Male
P. barbatus
Queen
-----
Purebred
Queen
-----
Hybrid
Worker
P. barbatus
Male
Purebred
Queen
-----
Hybrid
Worker
-----
P. rugosus
Queen
-----
Hybrid
Worker
-----
Purebred
Queen
P. rugosus
Male
Hybrid
Worker
-----
Purebred
Queen
-----
* Note: Purebred Male Comes From Unfertilized Egg Of Purebred Queen.

Sex determination in the more than 12,000 species of ants is typical of the enormous insect order Hymenoptera, including bees and wasps. The method is called "haplodiploidy." Males develop from unfertilized eggs and are haploid with one set of maternal chromosomes. They are not identical clones of their queen mother because of crossing over and random assortment of chromosomes during meiosis (oogenesis). Deleterious (unfavorable) recessive genes are quickly weeded out in haploid males because they are expressed and cannot be masked by dominant genes. Females develop from fertilized eggs and are diploid with two sets of chromosomes. Some references say that larvae destined to become sexually mature queens are "well-nurtured," presumably similar to royal jelly in honey bees; however, other reputable authorities state that selection of a queen in some ant species is a lot more complicated and may involve special eggs destined to become queens (see next paragraph). Queen ants have one of the longest life-spans of any known insects--up to 28 years in captivity!

In zones of hybridization, Pogonomyrmex harvester ant workers of the southwestern U.S. are hybrids between P. rugosus and P. barbatus. They possess the best genetic traits of two species. The queen of each species mates with the males of opposite species. Sexually mature ants (queens and winged males) are purebreds: They are offspring of queens and males of the same species. Young queens need to mate with their own species to produce more purebred queens. They need to mate with the other species to produce "superorganism" workers. This strategy appears to be evolutionarily advantageous to both species.

  1. Cahan, S.H., and L. Keller. 2003. "Complex Hybrid Origin of Genetic Caste Determination in Harvester  
      Ants." Nature 424 (6946): 306-309.

  2. Schwander, T., Cahan, S.H., and L. Keller. 2007. "Characterization and Distribution of Pogonomymex  
      Harvester Ant Lineages with Genetic Caste Determination." Molecular Ecology 16 (2): 367-387.

  3. Schwander, T., and L. Keller. 2007. "Genetic Compatibility Affects Queens and Worker Caste  
      Determination." Science 322 (5901): 552.

Comparison Of Pogonomyrmex Hybrid Workers With A Mule

If the workers of an ant nest can be thought of as the superorganism's body, and the sexuals (queens & males) can be thought of as the superorganism's genetic material, it is as though an animal with the body of a mule has the genetic make-up of a horse and donkey!

Although Pogonomyrmex hybrid workers form a colony and the mule is a single organism, they make an interesting comparison. They both involve a cross between two species that forms a stronger hybrid offspring with the best traits of its parents. The ant colony of hybrid workers functions as a unit that could be described as a "superorganism." This is similar to the "Borg Collective" in Star Strek: The Next Generation.

The female horse (mare) mates with a male horse (stallion) to produce more male and female horses. If she mates with a male donkey (jackass) she can produce a male or female mule. The mule is a sterile hybrid with the body size of a horse and the sure-footedness and endurance of a donkey. That is why the mule is essentially a "superorganism" used as a powerful pack animal. In the case of Pogonomyrmex, the hybrid "super-ants" are the workers!

An original 20 mule team wagon train used in 1885 to haul borax from Death Valley to Mojave, a distance of 165 miles. The borax weighed 24 tons and the entire wagon train weighed 36.5 tons (gross weight). The last wagon carried water for the mules during the hot, 10 day journey across the Mojave Desert. Today, a load of this size would be pulled by a 600 horse power Kenworth T-2000 tractor with an air conditioned cab!
  More Information About The Mule On Wayne's Word  


Cerapachys biroi: A Queenless Clonal Ant From Asia

Cerapachys biroi belongs to the subfamily Dorylinae (Ecitoninae) that includes the army ants (Dorylus). Although ony 2 mm in length, C. biroi raids the nests of other ant species to feed on the brood. In fact, it is called the "clonal raider ant." It has no queen. Its life cycle includes a foraging phase and a reproductive phase where it lays unfertilized diploid eggs that typically develop into more females. I don't think sex has disappeared in this species, at least not yet! On a more positive note, the rare occurrence of haploid males indicates that it has not lost the potential for sex.

Ulike most ants that have reproductive queens and mostly non-reproductive workers, all individuals in a Cerapachys biroi colony reproduce clonally via thelytokous parthenogenesis. Parthenogenesis refers to the development of egg cells into embryos without fertilization, and thelytokous refers to offspring that are all female. Parthenogenesis does not always result in genetically identical clones. If the haploid cells are formed by normal meiosis (as in the queen honeybee), crossing over during Prophase I of meiosis may result in some genetic variability. Another source of genetic variability is random assortment of chromosomes. If the unfertilized eggs develop from mitotic oögenesis (without the reduction division of normal meiosis), then their offspring will be identical clones of each other.

Ceropachys biroi exhibits an unusual cyclic behavior, shifting between a reproductive (egg-laying) phase and a foraging phase. Some references state that offspring are "almost" genetically identical to parents (mothers). Apparently there is some chromosomal crossing over during oögenesis. Thelytokous parthenogenesis can be apomictic (mitotic) or automictic (meiotic). In C. biroi, the occasional occurrence of haploid males, which are clearly derived meiotically, indicates that meiosis is functional and therefore makes automixis more likely as the mechanism underlying thelytoky. According to D.J.C. Kronauer, et al. (2012), diploidy is restored after meiosis.

  • Kronauer, D.J.C., Pierce, N.E., and L. Keller. 2012. "Asexual Reproduction in Introduced and Native Populations of the Ant Cerapachys biroi." Molecular Ecology 21: 5221-5235.    Get This Article On-Line

15. Harvester Ants In Anza-Borrego Desert (Messor & Pogonomyrmex)

Desert harvester ant (Messor pergandei).

Another species of harvester ant (Messor andrei) that I recently discovered on Owens Peak in San Marcos. It is quite different from our shiny black desert species. Because of its hairiness, it is not shiny and doesn't reflect light with electronic flash like M. pergandei.

Harvester ant (Messor andrei) on Owens Peak: After giving the colony a water-saturated cotton ball and Nature Valley Granola (which they seemed to enjoy), they still went ahead and bit the hand that fed them. At least they can't sting!

Harvester ants carrying the plumose achenes of smooth cat's ear (Hypochaeris glabra). This is presumably the widespread Messor pergandei. Nests of the red California harvester ant (Pogonomyrmex californicus) are nearby and the two species appear to tolerate each other. Harvester ants provide the vital diet for the coast horned lizard (Phrynosoma coronatum). Unfortunately, our native ants have been eliminated throughout coastal San Diego County by the aggressive Argentine ant (Iridomyrmex humilis).

Ant Exhibit At The Anza-Borrego Desert State Park Visitor Center

Harvester ant exhibit in Anza Borrego Desert State Park Visitor Center.

Anthill Art: An amazing use for the nest of the imported
fire ant. Please watch the following video: Anthill Art

Harvester Ants (Messor) & Filaree (Erodium cicutarium)

Harvester ants of the genus Messor and husks of Erodium cicutarium (blue arrow).

Large harvester ant nest (Messor pergandei). After extracting the seeds underground, the empty husks are piled up outside the entrance to the nest.

Saltbush (Atriplex polycarpa) and large harvester ant nest.

The common saltbush species on the north side of the Salton Sea is Atriplex polycarpa (D). The one-seeded fruit (utricle) of this species is collected in great numbers by harvester ants. After extracting the seeds underground, the empty husks are piled up outside the entrance to their nests. See following two images.
An assortment of winged, one-seeded fruits (utricles) of saltbushes (Atriplex) from the Mojave and Colorado Deserts of the southwestern United States. Saltbushes belong to the goosefoot family (Chenopodiaceae). From left: (A) A. canescens, (B) A. confertifolia, (C) A. hymenelytra, (D) A. polycarpa and (E) A. parryi.

Empty husks (utricles) of Saltbush Atriplex polycarpa piled up by harvester ants.

Harvester ant nest on north side of Salton Sea. The 3-ring metal object is an an old, rusty 50 caliber belt link. The steel links interlock and join 50 caliber cartridges into a linked belt for the Browning automatic machine gun. This was apparently a military training site, possibly for World War II.

The 50 caliber cartridges were linked together and fed into the Browning Machine Gun. When each cartridge was fired, the casing and belt link separated and were ejected. This explains the presence of old rusted belt links in the sand.


Carrizo Badlands of Anza Borrego State Park at dusk. All the following images of harvester ants (Messor pergandei) were taken along Hwy S-2 near the overlook to the Carrizo Badlands.

Left: A branch of dyeweed (Psorothamnus emoryi) showing numerous buds and opened flowers of Pilostyles thurberi [see arrow] along the lower portion. The yellowish-orange stain (dye) on the thumb comes from reddish glands on the dyeweed stem. Center: Harvester ant (Messor pergandei) carrying the calyx of dyeweed (Psorothamnus emoryi). Right: Close-up view of a dyeweed calyx showing rows of orange glands.


Pollen-bearing (male) flowers.

Seed-bearing (female) flowers.

Pilostyles thurberi, a minute parasitic wildflower native to the Colorado Desert of the southwestern United States. Like its monstrous Asian counterpart, Rafflesia arnoldii, it lives completely within the stem of its host shrub. The head of an ordinary straight pin shows the small size of the blossoms. The host plant with fuzzy white stems and bright red glands is dyeweed (Psorothamnus emoryi) a member of the legume family (Fabaceae).

Desert Harvester Ants & Dyeweed
Stinking Corpse Lily (Rafflesia arnoldii)
  Harvester Ants On Dyeweed & Pilostyles  


California Harvester Ant (Pogonomyrmex californicus)

California harvester ant (Pogonomyrmex californicus).

A: Magnified view of the head of a desert harvester ant (Messor pergandei). Messor species are also called "smooth" harvester ants. B: California harvester ant (Pogonomyrmex californicus). Note hairs and parallel vertical lines (grooves) on red harvester ant. Pogonomyrmex species are also called "rough" harvester ants.

Until recently I thought the species of Messor on Owens Peak was M. pergandei; however, close examination of the head revealed that it was a different species (M. andrei). It is much hairier than M. pergandei and the head has conspicuous parallel lines (grooves). In fact, it conflicts with the previous definition of "smooth" vs. "rough" harvester ants. M. andrei is clearly monomorphic while M. pergandei colonies in San Diego County are polymorphic (with different sized wokers). In addition, because of its hairiness M. andrei doesn't appear as shiny black as M. pergandei.

The hairs and parallel vertical lines (grooves) on the head of Messor andrei are quite different from the smooth, glossy head of M. pergandei.


16. Argentine Ant: An Ecological Disaster In San Diego County

Argentine Ant (Iridomyrmex humilis = Linepithema humile).
The most common ant in southern California is the Argentine ant (Iridomyrmex humilis). According to Wild (2004), this species was originally described in the genus Linepithema by Mayr in 1866; therefore, the proper binomial should be Linepithema humile. It is a small, dark-colored ant about 3 mm (1/8 inch) long that invades homes in search of food and water. They are especially fond of sweets, but will feed on practically any food. They love the yolks of hard boiled eggs and carry minute yellow clumps of yolk back to their nest in endless ant columns. These ants are extremely well adapted to urbanized areas of the United States with mild climates and well-watered gardens. They pose a serious threat to native wildlife by upsetting delicate food webs. They are especially formidable due to their aggressive behavior and the enormous size of their colonies which can literally "team up" with other colonies.

Insect royalty visited my kitchen this morning: A queen Argentine ant. The royal family resides behind my electrical outlet wall plate.

Argentine ant trail on my backyard patio and on a hard-boiled egg yolk.

If you live in southern California, you probably have seen endless single file columns of uninvited six-legged guests walking through your home. They follow a pre-marked pheromone "scent" trail initially laid down by scouts who were searching for goodies in your pantry. Although they prefer the outdoor life style, they primarily enter houses for food and water. They are fond of sweets, tuna, syrups (even cough syrup), juices, eggs, dead spiders and rodents, vomit, feces and just about any other organic matter they can find. They are essentially scavengers and they play a valuable role in the natural ecosystem--but preferably in Argentina. In hot, dry weather they often search your home for water, including bathroom faucets and drains. I once followed an ant safari into my bathroom where they were neatly stacking their precious cargo of tiny eggs inside my toilet tank. They also relish the "honeydew" secretion of aphids, and protect their aphid friends from natural predators. In the fall months as the nights get chilly, they once again seek the warmth and shelter of your cozy home.

The first Argentine ants set foot on U.S. soils in the late 1890's, as coffee ships from Brazil unloaded their cargo in New Orleans. Being prolific breeders and constantly on the go, they moved across the southern half of the United States. A single colony may contain 10,000 female workers, and there may be hundreds of colonies around your home; the total number of ants could easily reach a million. Although they cannot sting, they can bite; however, they are only about 3 mm long and their tiny mandibles are too small to hurt humans. But, in the world of insects, these ants are truly a living terror. They are very aggressive and readily overtake other ant species, even ants that are much larger and with powerful stings. Argentine ants are relentless and simply outnumber their adversaries until the enemy colony is destroyed. They even attack paper wasp nests under the eaves of a house, forcing the huge wasps to flee their nests in terror. Even nests of large carpenter bees are no match for these relentless ants. An Africanized ("killer bee") nest probably could not withstand an invasion of Argentine ants. They will also attack bird nests, driving off the mother bird and killing the helpless young. They occupy practically every square meter of my yard in San Diego County and live inside the walls and under my house. One possible redeeming quality about these little warriors is that they may attack dry-wood (aerial) termite colonies in your home. I have observed this Lilliputian massacre in a termite infested table in the Palomar College greenhouse.

Argentine ants have also invaded Europe, South Africa, New Zealand, Japan, Easter Island, Australia, and the Hawaiian Islands. There are no native ants on the Hawaiian Islands, but there are more than 50 introduced species. Some of these are an ecological disaster, and pose a serious threat to indigenous species. In fact, the Argentine ant locally threatens insects that pollinate the endemic silver sword on Haleakala, on the island of Maui.

Most ant colonies are very territorial, and will fight different colonies of the same species. Since Argentine ants in the United States originated from the original colonizers in Louisiana, they are all closely related with very similar DNA. They will accept ants from different colonies as members of their gigantic family. In fact, Argentine ants from different colonies will actually "team up" and attack together in vast swarms. They simply outnumber and overpower their enemy.

Argentine ants have become a serious threat to the coast horned lizard (Phrynosoma coronatum) in southern California. The primary food source for these endangered lizards are native harvester ants, particularly the California harvester ant (Pogonomyrmex). I spent many years observing this fascinating red ant while growing up in San Gabriel Valley, and I can personally testify that it has a painful sting. As of 2006, this large red ant is seldom seen in urbanized areas of coastal southern California where Argentine ants thrive.

Urbanization has certainly been a factor in the demise of California harvester ants, but an even greater factor resulting in the elimination of native ants and coast horned lizards is the aggressive Argentine ant. Apparently the horned lizard is not fond of Argentine ants, and is actually attacked by them in enormous swarms. Colonies of Argentine ants need a damp area to survive, and have not invaded some of the dry habitats where native harvester ants and desert horned lizards (P. platyrhinos) still live. Of course, they can readily colonize urbanized desert areas inhabited by people. Well-watered gardens with stepping stones and concrete slabs provide the ideal living requirements for these ants. In their native Argentina they live under rocks.

Coast horned lizard (Phrynosoma coronatum ssp. blainvillii) photographed in a vernal pool field near Palomar College, San Marcos, CA. Image scanned from Kodachrome transparency taken in May 1982. This remarkable lizard has essentially disappeared from the San Marcos area due to urbanization and habitat destruction, and to the disappearance of native harvester ants, its primary source of food. Argentine ants have undoubtedly also played a major role in the loss of harvester ants, especially from urbanized areas.

According to the San Diego Natural History Museum: "The subspecies blainvillii is believed to be extinct in 45% of its original range in southern California. The most serious threat is the destruction of its preferred habitat along the coast. Populations in undisturbed areas seem to fare quite well, although the introduction of Argentine Ants (Iridomyrmex humilis = Linepithema humile ) are now replacing the native ant food base. It was heavily exploited at the turn of the 20th century for the curio trade; horned Lizards were varnished and sold to visiting tourists from the east coast, or simply sold as pets to take home as a souvenir. Later, biological supply companies and the modern pet trade contributed to their exploitation, until 1981, when commercial collecting was banned.

Argentine ants are a terrible nuisance in gardens and orchards because they tend and protect scale insects and aphids. They even carry aphids to the tender buds of your prized roses. In return, the ants consume a sweet secretion from the aphids called "honeydew." In addition, swarms of these ants will invade orchard trees, destroying the fruit crop. This is especially serious in figs (Ficus carica) where the symbiotic pollinator wasps are destroyed.

Left: Ripe, female fig syconium (Ficus carica) covered with Argentine ants (Linepithema humile). On male trees (caprifigs), the ants attack and kill emerging fig wasps, the vital pollinators of this remarkable tree from the Middle East. A metallic green fig beetle (Cotinus texana) is gorging itself inside a fleshy, ripe syconium of the Calimyrna fig (Ficus carica). Although masses of minute, aggressive Argentine ants are also foraging in the syconium, the beetles are protected by their tough, impervious exoskeleton. These attractive beetles spend their juvenile larval stage in the ground, often beneath manure piles, compost and haystacks.

According to entomologist David Faulkner, if you have a 10 x10 foot (3 x 3 m ) patio slab, you could have a million or more individuals and possibly 20 or 30 queens. They get along fine because they're all related to the original colonizers in Lousiana, perhaps from the original gravid (pregnant) female who arrived there. Workers live a month or more as adults, but queens live up to 10 years or more. With other ants, when the queen dies, the one-queen colony dies because no more ants are being produced. With multi-queen Argentine ants, another queen simply moves in and takes over the role of the deceased queen. In fact, a queen from San Diego would be accepted in a colony in San Francisco.

Argentine ants (Linepithema humile): A wingless queen and several workers. Although these ants are only 3 mm long, they are very aggressive and quickly annihilate other ant species, even larger ants with powerful jaws and stings. They overpower other species by their sheer numbers. Argentine ants in the U.S. are descendants of original colonizers that entered Louisiana in the late 1890's, as coffee ships from Brazil unloaded their cargo in New Orleans. U.S. populations are so closely related that different colonies with multiple queens can literally merge together into a supercolony.
Simplified diagram of a genetic bottleneck. If the heterogeneous population of different colored genetic members is reduced to a small number of individuals, the gene pool is greatly reduced. In this diagram, only a few red individuals survive the bottleneck. The few surviving red members pass their genes on to the new generation; however, this new homogeneous red population has a drastically reduced genotypic and phenotypic variability because they are all descendents of the few red individuals that survived the bottleneck. This might explain the reduced genetic and chemical recognition diversity in Argentine ants in the U.S. and the fact that they all appear to accept each other as one gigantic family. According to Neil Tsutsui of the University of California, Davis (2000), they have about half the genetic diversity as their South American coharts.

Argentine Ant Supercolonies In Europe

The Argentine ant was introduced into Europe about 80 years ago and has grown into a supercolony that extends more than 3,700 miles (6,000 km). It extends from northern Italy, through the south of France to the Atlantic coast of Spain, with billions of closely-related ants and millions of nests. According to Laurent Keller of the University of Lausanne in Switzerland and his colleagues (Giraud, T., et al. 2002), the European ants are only 28 percent less diverse genetically than those in South America. Keller and his colleagues have proposed that supercolonies developed through a process called "genetic cleansing." In a new territory away from old enemies, Argentine ants prospered. Genetically similar colonies, that could cooperate, wasted less time fighting and were more successful than the others, until a genetically more compatible supercolony emerged.

  • Giraud, T., J.S. Pedersen, and L. Keller. 2002. "Evolution of Supercolonies: The Argentine Ants of Southern Europe." Proceedings of the National Academy of Sciences 99 (April 30): 6075-6079. Abstract available at http://dx.doi.org/10.1073/pnas.092694199.

  • Torres, C.W., Brandt, M., and N.D. Tsutsui. 2007. "The Role of Cuticular Hydrocarbons As Chemical Cues for Nestmate Recognition in the Invasive Argentine Ant (Linepithema humile)." Insectes Scciaux 54: 363-373. Available online at http://nature.berkeley.edu/tsutsuilab/Torresetal_2007_InsSoc.pdf.

  • Tsutsui, N.D., et al. 2000. "Reduced Genetic Variation and the Success of An Invasive Species." Proceedings of the National Academy of Sciences 97 (May 23): 5948-5953. Available at http://dx.doi.org/10.1073/pnas.100110397.

  • Van Wilgenburg, E., Symonds, M.R.E., and M.A. Elgar. 2011. "Evolution of Cuticular Hydrocarbon Diversity in Ants." Journal of Evolutionary Biology 24: 1188-1198. Available at http://onlinelibrary.wiley.com/doi/10.1111/j.1420-9101.2011.02248.x/pdf.

According to Professor Keller and his colleagues, sooner or later, rivalries between colonies in Europe will emerge as genetically distinct groups of ants turn against each other. When encountering another individual, an ant must decide whether this individual belongs to its colony or not. The recognition cues are genetically based odors on the surface of the ant called "cuticular hydrocarbons" (Torres, C.E., et al, 2007; Van Wilgenburg, E., et al., 2011). These contain up to 100 compounds, including n-alkanes, alkenes and methyl branched hydrocarbons. As long as the ants have the same chemical odor they will not fight. Apparently, ants between San Diego and San Franciso "smell alike" because they do not fight. Interestingly enough, a second population in the Catalan region of Spain has a different cuticular hydrocarbon recognition odor because they readily fight with the other European supercolony.

New Studies At Standford University Dispute The Single Supercolony Theory

Professor Deborah Gordon and her colleagues at Stanford University analyzed DNA from ants in the Jasper Ridge Biological Preserve and found obvious genetic differences among some of them, suggesting that the ants came from different colonies. Gordon's research raises serious doubts about the existence of a single supercolony running through the entire state of California. The Stanford team questions the notion that Los Angeles ants are descended from the same founding population as San Francisco ants, which live 400 miles away. A more likely explanation, they say, is that California has been infested by numerous colonies of genetically distinct Argentine ants during the last 100 years.

  • Ingram, K.K., and D.M. Gordon. 2003. "Genetic Analysis Of Dispersal Dynamics In An Invading Population Of Argentine Ants." Ecology 84 (11): 2832-2842.

I have compared Argentine ants with the "Borg" of Star Trek, a fictional cybernetic race controlled by drones. This is probably not an accurate comparison because the Borg apparently have centralized control by the "Borg Queen." Ant colonies exhibit "swarm intelligence" with the collective behavior of a decentralized system. The individual units (workers & soldiers) are sterile females that operate without a power hierarchy or permanent leader. The queen's role is basically an egg machine to reproduce and perpetuate the colony. The indivuals communicate with each other by the release of pheromones. Extreme warfare in ants arises from a social unity similar to cells in an organism. Cells are recognized as "self" by our immune system because of chemicals imbedded in the cell membranes. Some of these are special proteins (glycoproteins) with unique carbohydrate antennae. Just as foreign bacteria and viruses are recognized as "enemies" by our immune system, ants recognize rival colonies by different pheromones.

Simplified diagram of cell membrane structure. This model shows large protein (glycoprotein) molecules embedded in the membrane. Membrane proteins may serve as carriers in which molecules and ions pass through channels in the protein. Glycoproteins may also be associated with cell recognition in which patrolling T-cells and antibodies recognize the shape of membrane proteins as "self" or "foreign." These membrane proteins often contain unique carbohydrate chains (antennae) which are involved in the cell recognition process.

In their native homeland of Argentina, different colonies of Argentine ants are not so friendly to each other because their DNA has developed much greater variation. Neighboring colonies may fight each other, even though they are only 200 yards (200 m) apart. Also there are many native predators in Argentina, including fungal parasites and bacteria. The narrow genetic variability that has kept all the California populations on friendly terms may eventually backfire due to excessive inbreeding. Perhaps some day these ants may not have the genetic variability to adapt to a changing environment.

Genetically Different Argentine Ant Colonies Found In San Diego County

It is is a known fact that genetically different Argentine ant colonies in Argentina will aggressively attack and kill each other. Closely related Argentine ants (i.e. sisters in the same colony) smell alike because of the same cuticular hydrocarbons; therefore, they accept each other and do not fight. This apples to the supercolony that extends 600 miles from San Diego to San Francisco. Ants from different cities along the way can be placed in a cup ("fight cup test") and they get along just fine. According to Melissa Thomas, an Australian entomologist, Argentine ants have invaded every continent except Antarctica. No matter how many thousands of miles separate individual ants, when two of them are placed together--whether they came from Australia, Japan, Hawaii, or Easter Island--they recognize each other as sisters in the same supercolony.

As I stated above, there appears to be some different opinions among authorites as to the giant superpopulation of Argentine ants in California. A team of researchers at Stanford University state that California has been infested by numerous colonies of genetically distinct Argentine ants during the last 100 years! See Above Paragraph.

But according to David Holway, biologist from UC San Diego, there appears to be more than one genetically different population (colony) in San Diego County, perhaps different introductions from Argentina. In fact, in the city of Escondido, near my home in San Marcos, a battle has been raging between two different "families" or colonies separated by the width of a driveway. The battle is so intense that dead ants have been piling up in the driveway and in the gutter.

  Argentine Ant HTML Body Background or Wallpaper Design  


17. Winter Ant (Prenolepis imparis) Can Repel Attacks By Argentine Ants

The Winter Ant
(Prenolepis imparis)
Subfamily Formicinae

Remarkable Native California Ant
With A Potent Chemical Defence
Against Invading Argentine Ants

Winter ant workers (Prenolepis imparis) feeding on a sunflower seed along steep trail to Owens Peak.

Winter ant workers (Prenolepis imparis) feeding on the stalk of a mushroom (Russula?).

Worker ants of Prenolepis imparis may be able to survive the attacks of Argentine ants. I first noticed these shiny black ants on 3 December 2012 near Palomar College, hence the common name of "winter ant." The thorax (mesosoma or alitrunk) is deeply constricted in center and resembles the shape of an hourglass when viewed from above. These ants are slightly larger than Argentine ants (just over 3.0 mm). According to Trevor R. Sorrells, et al., Department of Biology, Stanford University (2011), winter ants secrete a hydrocarbon mixture that is lethal to Argentine ants, thus providing an effective defense against this invasive species from South America. "Prenolepis workers are more likely to deploy their chemical defense in encounters near their nest than in encounters while foraging on trees. This indicates that P. imparis modifies its behavior according to the value of the resource it is defending. This may be because the production of the secretion is metabolically costly." Please refer to following link in peer-reviewed journal PLOS ONE Volume 6 (4) 2011.

Young workers (repletes) are "overfed" and swell with fat, from which a nutritious glandular secretion is produced that is the main food upon which the year's single brood of workers and alates is reared. After this corpulent stage, the storage workers lose weight and become foragers. The name "false honey ants" comes from the subterranean replete caste, although the stored food is apparently not a sugary (honeylike) solution.


Acrobat Ant (Crematogaster sp.) Formicidae: Subfamily Myrmicinae

This shiny black ant on Owens Peak superficially resembles the winter ant (Prenolepis) except its first antennal segment (scape) is shorter than Prenolepis (not longer than the head). In addition, it has a distinctive heart-shaped gaster, pedicel with two nodes, 3-segmented club, and a pair of dorsal spines on the propodeum. The name "acrobat" refers to the flexible way that a worker holds its abdomen (gaster) up over the rest of its body.


When Placed Side-By-Side Crematogaster & Prenolepis Are Quite Different


18. Biosphere 2 Invaded By Long-Horned Crazy Ant (Paratrechina longicornis)

Although Biosphere 2 was protected from the outside air with a closed air-lock system, it apparently was not impervious to small ants. By 1993 populations of the invasive crazy ant (Paratrechina longicornis) were discovered inside the supposedly closed ecosystems. The crazy ant is named for its peculiar erratic movements. By the late 1990s, virtually all the ants in Biosphere II were Paratrechina longicornis, feeding exclusively on honeydew secretions from scale insects and mealybugs on many of the plants.

  See More Images Of The Crazy Ant  

Biosphere 2 is a three acre complex of glass pyramids and geodesic domes with self-contained biomes, including tropical rain forest, grassland savannah, and marine ecosystems. Described as a "planet in a bottle," it was originally constructed in the late 1980s and early 1990s. By 1993 populations of the invasive long-horned crazy ant (Paratrechina longicornis) were discovered inside the supposedly closed ecosystems.

Did you know that Steve Bannon, executive chairman of Breitbart.com and chief advisor
(strategist) for President Donald Trump, was also CEO of the failed Biospere II project!

  More Images Of Biosphere 2 Complex In Oracle, Arizona  

The crazy ant is named for its peculiar erratic movements. It is easy to identify with its long legs and very long antennal scape (basal segment of antenna). By the late 1990s, virtually all the ants in Biosphere 2 were Paratrechina longicornis, feeding exclusively on honeydew secretions from scale insects and mealybugs (Order Homoptera) on many of the indoor plants. Biospere 1 is the planet Earth, and its terrestrial ecosystems are impacted by introduced ants. One case in point is the ubiquitous Argentine ant invasion of southern California.

Even with all the safety precautions, including sealed doors and elaborate air-lock system, the Biosphere 2 complex has been invaded by this small, long-legged ant from tropical Asia. It can survive in highly disturbed and artificial areas, including ships at sea. Since it can live indoors with humans, there is no limit to the latitude where it can exist. In fact, it has been reported in human habitats from Sweden to New Zealand, and may be the most widely distributed ant species on earth!

The legs of this species are also quite long compared with other species with a similar body size, such as the Argentine ant. In fact, this ant can run quite fast and is difficult to catch between your fingers.

Another South American species of crazy ant in the subfamily Formicinae (Nylanderia fulva), is an aggressive exotic species introduced into the southern and southeastern United States. It is called the "tawny crazy ant" or "Rasberry crazy ant," and is named after the exterminator who discovered it in Texas, Tom Rasberry. Like Paratrehcina longicornis it is called a "crazy ant" because of its random (erratic), non-linear movements. Preliminary studies indicate that supercolonies of this species may be displacing the troublesome fire ant (Solenopsis invicta) and may even be a worse pest. Unlike the fire ant, they don't sting; however, they readily invade homes and even damage electrical equipment.

The Yellow Crazy Ant (Anoplolepis gracilipes) On Maui

Ground nests of the long-legged ant were common near coconut palms at the Maui Tropical Plantation, and in a restroom on Molokai.

There are no native ants on the Hawaiian Islands, but there are more than 50 introduced species. Some of these are an ecological disaster, and pose a serious threat to indigenous species. In fact, the Argentine ant locally threatens insects that pollinate the endemic silver sword on Haleakala. A. The large ant at top is a carpenter ant (Camponotus variegatus). Its body is 14 mm long (just over 1/2 inch); B. White-Footed Ant (Technomyrmex albipes); C. Rover ant (Brachymyrmex obscurior); D. Big-headed ant minor worker (Pheidole megacephala); E. The long-legged ant with long scape (lower right) may be the yellow crazy ant (Anoplolepis gracilipes), not to be confused with the long-horned crazy ant (Paratrechina longicornis); F. The little yellow ant at bottom (Plagiolepis alluaudi) is one of the world's smallest ants with a body only 1/20th of an inch in length (slightly over one millimeter). Nikon D-90.


19. Army Ant Encounter In Superstitions (January 2016)

In January (2016) I made a noteworthy ant discovery in the Superstitions. I found a minute army ant colony of the genus Neivamyrmex under a rock. Based on its minute size and several other distinguishing characteristics, it appears to be the seldom observed species N. nyensis; however, According to Neivamyrmex authority Gordon Snelling (Personal Communication, 26 Jan. 2017), it is N. leonardi! A nearby rock had an equally small species of Forelius, but army ants are easy to distinguish because they do not have eyes. Since they are blind, they must trail closely behind each other, like following the car in front of you in dense Fresno ground fog.

Army ant worker (Neivamyrmex) from under a rock on Superstition Mountain. Based on the description and key to Neivamyrmex in Antwiki.org (and small size), it appears to be N. nyensis, a seldom observed species; however, According to Neivamyrmex authority Gordon Snelling (Personal Communication, 26 Jan. 2017), it is N. leonardi!

More About Army Ants (Subfamily Dorylinae)

Because of their reduced or nonexistent eyes, army ants are blind and follow closely behind the ant in front of them. Imagine the following scenario: You are running as fast as you can, following a pheromone scent trail behind your sisters. For some reason your group becomes separated from the main foraging trail. You are blind and must rely on the recognition scent of the sisters in front of you. Eventually a new pheromone trail is laid down, but you are running in a continuously rotating circle. Your situation is critical because you are in an endless loop and will eventually die of exhaustion. This is precisely what happens to army ants in tropical America. See following image and video:

  Army Ant Encounter In The Superstitions (January 2016)  

20. Best Method Of Argentine Ant Eradication

Place outdoor ant bait stations such as Terro® along major ant trails in your yard. This is probably better than using insecticidal sprays. Smaller, indoor bait stations are also effective placed along ant trails in your home (out of the reach of children and pets). The active ingredients of Terro® is 5.40 percent sodium tetraborate decahydrate (Borax) which is lethal to ants. This salt upsets their digestive system and causes death due to dehydration and starvation. According to Jonathan Hatch ("How to Get Rid of Argentine Ants" ), dehydration and recrystallization of the boric acic (borax?) lacerates the digestive system of ants and their larvae. There are many recipes on the Internet that include mixing borax with a sugary solution. Terro bait stations contain this mixture in convenient disposable plastic trays. It is important for the ants to carry the liquid back to their nest. Borax recipes only contain about 5 percent borax so that ants are not killed immediately. One tablespoon of borax in a cup of water is approximately a 5% solution. You must be patient--this treatment may take several days to a week. In fact, you may need to replenish you bait stations! Some websites state that boric acid is a more effective ant insecticide, but this is debatable. Boric acid is made by reacting borax (sodium tetraborate decahydrate) with an inorganic acid, such as hydrochloric acid (HCl).

Synthesis of Boric Acid From Borax (Sodium Tetraborate Decahydrate) and Hydrochloric Acid:

Na2B4O7.10 H2O + 2 HCL → 4 B(OH)3 [or H3BO3] + 2 NaCl + 5 H2O

One simple on-line recipe calls for one cup of sugar, one tablespoon of borax and 1/2 cup of water. These values can be doubled for a larger yield. The borax concentration is about 10%, but it is apparently very effective. Place mixture in saurcepan and bring to a boil for three minutes. Cool and serve to Argentine ants. Thick syrupy mass can be placed in jar lids so that ants can easily climb over rim. Or, place inside empty soda cans and lay cans on side.

Left: Crystals of borax (sodium tetraborate decahydrate) photographed on black rangetop oven with Nikon SLR and ring flash. Image color was inverted using Adobe Photoshop. Right: Microscopic view of crystals photographed through compound microscope with substage illumination (magnification 100X). Unlike cubical grains of ordinary table salt (NaCl), the crystals are generally polygonal and prismatic (multifaceted) with sharp edges and points. See comparison of crystals in next image.

Comparison of the crystals of borax, table sugar (sucrose) and ordinary table salt (NaCl).


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