Ant queens: April 2010 Archives

This is a great question and fits well with our post below on "What is the largest ant in the world?"

Leaf-cutter ants of the genus Atta are well known for cutting and carrying bits of leaf material back to their nest. They then chew this leaf material up into a fine paste to use as the substrate to grow their food - fungus! This is where they get their other common name, fungus-growing ants. Since fungus growing ants have been cultivating fungus for ~50 millions of years, this makes them the worlds first farmers.

Atta texana worker w_leaf.jpg

Worker of Atta texana carrying leaf material back to the nest. Photo by Alex Wild (www.alexanderwild.com).


In a leaf-cutter ant colony there are many sizes of individuals from minute workers to large soldiers to the giant queen herself. The queen of leaf-cutter colonies such as Atta cephalotes can be 22 mm in length. Not quite as long as the the African driver ants mentioned in the post below, but still very large.

Atta texana queen.jpg

Queen and workers of Atta texana on fungus garden. Photo by Alex Wild (www.alexanderwild.com).


Borgmeier, T. (1959) Revision der Gattung Atta Fabricius (Hymenoptera, Formicidae). Studia Entomologica (N.S.) 2: 321-390.
Schultz, T.R. & Brady, S.G. (2008) Major evolutionary transitions in ant agriculture. PNAS 105: 5435-5440


- Corrie Moreau & the AntAsk Team

Ryan, this is a good question. The answer is not that easy though. Different ant species can have different numbers of queens in their colonies. In the majority of ant species, a single female establishes a new colony on their own (only one queen). When we talk about ant colonies that have one queen we use the term "monogyny" (mono = single; gyn = female/queen), and when talking about ants with multiple queens we use the term "polygyny". Polygyny occurs when young queens get together in groups of young founding queens (primary polygyny). Still others return to the nest they were born into and join their mother and sisters in this already established colony to also lay eggs (secondary polygyny).

Also, a single queen can mate with one or more males before starting her colony. There are quite a variety of different colony structures that have been discovered in ants ranging from the "standard system" of one singly-mated queen per colony to colonies with multiple queens or queens that mated multiple times. A good overview of different colony structures can be found in Heinze (2008). In analogy to the terms monogyny and polygyny we refer to mating once as "monoandry" (mono = single; andr = male/mate) and mating several times as "polyandry". The queens of army ants and leaf-cutter ants show extreme cases of polyandry and mating with 20 males is not unusual for these ant species. Monoandry is often common in ant species that have multiple queens. So there seems to be a trade-off between queen number and matings per queen.

Sometimes the only way to know how many queens a species has in the nest is to dig up the entire colony to count them. With over 14,000 ant species there are many that have never had their nests studied, so for many species we still do not know how many queens are in a nest or how many times she has mated.

Heinze J (2008) The demise of the standard ant (Hymenoptera: Formicidae). Myrmecological News 11:9-20

- Steffi Kautz & the AskAnt Team

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Dear Eric,

Thanks for your question - this is a common one that many people might be curious about.  Ants and termites share a number of remarkable similarities in their colonial lifestyle, but there are three key physical differences to tell them apart.

  1. Ants have elbowed antennae, where the first segment is much longer than the segments that follow. By contrast, termites have straight antennae that appear like a string of tiny beads.
  2. Ants also have a characteristically constricted "waist" while termites do not. In termites the body segments are much more broadly attached.
  3. Forewings of reproductive (queen and male) ants are larger than hindwings, while reproductive termites have two sets of wings of similar size and shape, often twice the length of their body.
AntAsk ants v termites 1.gif

(http://www.daff.gov.au/aqis/avm/vessels/fact-sheets/termite)


Both ants and termites live in colonies or nests where one or relatively few individuals reproduce while non-reproductive individuals cooperate to care for brood, maintain the nest, and defend the colony. These features - reproductive division of labor (only the queens lay eggs), overlapping generations (you have all ages in the nest), and cooperative brood care (all individuals care for the young, not just the queens) - are hallmarks of eusociality, a condition achieved in relatively few insects. Although all ants and termites are eusocial, both groups vary broadly in colony size and social sophistication. Mature colonies of certain species may contain fewer than 100 physically similar individuals, while colony membership can swell to several million individuals in other ant and termite species and include several morphologically and behaviorally specialized castes (e.g. soldiers, several classes of workers).

AntAsk ants v termites 2.jpg
Camponotus sansabaenus - worker ants vary in size, color, and body proportion. Photo by Alex Wild (www.alexanderwild.com).


Despite these similarities, ants and termites are not very closely related and developed social behavior independently. As such, there are several key distinctions between ants and termites in the details of social life. In colonies of ants, bees, and wasps, virtually all nestmates are sisters, and the nest is typically headed by one or a limited number of queens. Males are produced only at certain times of the year and serve as short-lived mobile reproductive machines, emerging from the nest to mate with virgin queens and then quickly die. Once mated, a queen founds her colony (sometimes with the aid of workers from her natal nest) and uses sperm stored from her first mating event for the rest of her life. By contrast, termite colonies are founded by a king and queen, which meet in a mating swarm and together select a nest site. The pair is monogamous and must periodically re-mate. Unlike the female-only colonies of ants, males are an integral part of a termite colony's workforce and may be workers, soldiers, or both, depending on the termite species.

Thumbnail image for AntAsk ants v termites 3.jpg

Prorhinotermes inopinatus worker and soldier termites in a rotting log.  Photo by Alex Wild (www.alexanderwild.com).


Complex social organization and large colony size has facilitated the success of many ants and termites, which are critical to ecosystem functioning around the world. Ants and termites are essential bioturbators, overturning and enriching soil by excavating tunnels and amassing nutrient-rich resources at nest sites. Ants also play a host of other roles, serving as predators, prey, and seed dispersers to a variety of organisms, while termites recycle otherwise inaccessible nutrients into the ecosystem by decomposing wood with the aid of gut bacteria or protists. Perhaps because of their ecological success, several ant and termite species are familiar household pests, including carpenter ants (Camponotus) and the Formosan subterranean termite (Coptotermes formosanus).

Whether ant or termite, social insects are a fascinating and important part of global biodiversity.

- Tim O'Connor & the AntAsk team

Dear Mary, this is a great question!

Almost every ant you ever encounter is female! In ants, all individuals that perform work for the colony are females. We usually refer to these ants as "workers", but in some ant colonies that have different roles, specific workers are sometimes referred to as "soldiers" or "nurses". Regardless of the name and task of these ants, they are all female. The sexuals or reproductives in ants are called "alates". Females are called queens or gynes, while males are usually just called males. In the case of male alates, their only function is to reproduce. They usually stay in their home colony until they are fully developed and then they fly away to mate. Almost all male and female alates have wings and often they mate in the air on nuptial flights. Males usually only mate once and then they die--having fulfilled their purpose in life. The female queens, on contrary, try to found a new colony after mating with one or several males. They then shed their wings and find a suitable place to start a new nest.

When you see a winged individual, you can recognize males based on their small head and their long antennae. Males usually have more antennal segments than the females. When you see a wingless individual, queens have already removed their wings are larger in size than the workers, have a wider thorax due to the wing muscles and they show wing scars. Ant colonies or nests are almost entirely made up of females. So the next time you see an ant without wings, you will know it is female.

 

4casts2.jpg


In this picture, we see (A) a male, (B) a winged young queen, (C) queen after shedding her wings, and (D) a worker of the acacia-ant Pseudomyrmex peperi. The male has long antennae and a small head with large eyes. The winged young queen can be recognized on base of her wings and at the same time shorter antennae. The wingless queen has no wings, but you can still see wing scares. The gaster (rear end) of most egg-laying queens becomes distended with eggs, a state that is called "physogastric". The queen is larger in size than the workers. The worker has short antennae, no wings and no wing scars.


- Steffi Kautz & the AntAsk Team

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