Formica truncorum | |
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Formica truncorum worker | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Hymenoptera |
Family: | Formicidae |
Subfamily: | Formicinae |
Genus: | Formica |
Species: | F. truncorum |
Binomial name | |
Formica truncorum Fabricius, 1804 | |
Formica truncorum is a species of wood ant from the genus Formica . It is distributed across a variety of locations worldwide, including central Europe and Japan. Workers can range from 3.5 to 9.0mm and are uniquely characterized by small hairs covering their entire bodies. Like all other ants, F. truncorum is eusocial and demonstrates many cooperative behaviors that are unique to its order. Colonies are either monogynous, with one queen, or polygynous, with many queens, and these two types of colonies differ in many characteristics.
F. truncorum is located in many places worldwide, such as northern Japan, the Jura Mountains and many regions from Italy to Norway. The colonies, which can be polygynous and often polydomous (where several nests are occupied by one colony), are spread out in regions of woodland borders, where the ants will make their nests in tree stumps. [1] [ unreliable source? ]
F. truncorum ants are characterized by a grey-brown gaster and bright yellow-red head and thorax. The smaller workers are normally darker in color. They can be distinguished from other species of Formica by the small erect setae covering their entire body. Workers can range in size from 3.5 to 9.0 mm. [2]
F. truncorum is a member of the insect order Hymenoptera, which contains the majority of the eusocial insects. F. truncorum demonstrates some characteristics specific to eusociality. There is cooperative rearing of young, which is thought to provide a sort of 'life insurance' for the female's brood. [3] If the female were to die during the rearing process, others would take her place to finish raising the brood. The value of this cooperation may justify the cost. Another defining characteristic of eusociality is the evolution of specific castes within the species, some of which are sterile. [3] Castes in F. truncorum include the drones, the winged male ants with the sole purpose of reproducing, the queen, who sheds her wings after the nuptial flight, and the sterile workers which can vary in size depending on specialized tasks. [4]
Eusocial behaviour is thought to have evolved as a result of kin selection within monogamous colonies. In multiply mated colonies, the relatedness between siblings is lowered, which diminishes the benefits of altruistic behaviour within the colony. Only in monogamous colonies would the relatedness between individuals in a colony remain high, which could allow the benefits of eusociality to be justified by Hamilton's rule. [3]
The kin selection that is necessary for eusociality to evolve would require a signal that allows for related members of a species to recognize each other. A study [5] has indicated that in F. truncorum this signal may be the hydrocarbon profile located on the cuticle of each ant. Further examination of these hydrocarbon chains has shown that many contain chains longer than 34 carbons, and while there is enough similarity between cuticles to recognize members of the same colony, they are still diverse enough to be distinct between colonies. [6] Ants which are genetically similar have similar hydrocarbon profiles, which could allow kin to recognize one another through this similarity. Studies have shown that there is a correlation between the cuticular hydrocarbon profile and the dispersal tendencies of particular colonies. [7]
The social divisions of the eusocial ants can allow for the creation of subsets of populations with specific duties assigned to them, which can be applied to a variety of tasks, including foraging. Foraging will usually involve the discovery of small caches of food, with some of them being persistent and reliable and others being very transient. This difference in reliability causes the foragers of F. truncorum to divide into two groups with a specific task. [8] One group will patrol the reliable sites, and the other will scan empty food sites in search of new sources of food. Upon discovering a new source, the foragers will recruit from the nest and will not recruit any foragers already outside. Not all of the recruited foragers will carry food back to the nest, suggesting that some are recruited for defense of the site.[ citation needed ]
The foraging habits of F. truncorum were also observed by placing baits near foraging areas and then observing the ability of the ants to recruit additional worker to transport the food back to the nest. This process of recruitment is done in a simple manner, where workers that have discovered food will lay a pheromone trail that connects the food to the nest, and additional workers will detect and follow the scent of this trail. Trails that are currently leading towards additional food will have pheromone trails that are more recently placed, and will also likely have a stronger scent due to multiple ants laying down pheromones, which allows the workers to quickly react to changes in the direction of the food source by following the newest and strongest trails. F. truncorum has demonstrated an interested characteristic of its foraging ability where it can successfully follow a trail in light but not in darkness. [9] This suggests a visual component in addition to the pheromone trail that is not fully understood.
Studies of F. truncorum have shown that the sex ratio varies between being female-biased or male-biased depending on how many times the queen has mated. [10] In cases where the queen is singly-mated, the relatedness between the workers remains high and the ratio is female-biased. This is thought to occur because of haplodiploidy, which causes the females to be more related to their own sisters than to any potential offspring. This increased relatedness between siblings causes the female workers to skew the sex ratio in their favor. In cases where the queen is multiply mated, this relatedness between siblings is lost, and the queen retains control of the sex ratio, which causes it to be male-biased.[ citation needed ]
On average, multiply mated queens have a 37% higher fitness than singly mated queens [11] It is proposed that singly-mated queens remain in the population because the benefits of multiple-mating may have been balanced by the costs of increased predation and risk to disease transmission. The benefits of multiple-mating also decline as it becomes more numerous in the population. Another suggested possibility is that some queens are unable to find a second mate and remain singly-mated.[ citation needed ]
It was observed in F. truncorum that when two males had their ability to sire offspring compared, one of the two would consistently create more progeny. [12] In spite of this, there was no evidence to support the idea that one male would be particularly better at creating more offspring than the other. This indicates that the female is able to store different amounts of sperm from separate males, which would then result in one male producing significantly more offspring.[ citation needed ]
The resource allocation of F. truncorum ants to the formation of new reproductives was compared between monogynous and polygynous colonies by measuring the colony's productivity and mating structure. [13] Monogynous colonies with a high productivity would have excess resources, and they invested these excess resources into the formation of more reproductives. Monogynous colonies typically had a higher ratio of sexuals per adult worker. When they had excess resources, polygynous colonies did not invest in the formation of more reproductives, indicating that the allocation of resources to the formation of reproductives is controlled by the workers.[ citation needed ]
The genetic population structure and sociogenetic organization of F. truncorum were compared between monogynous and polygynous colonies by using allele frequency differences between the populations and estimates of relatedness between different subsets of the colony population. [14] The allele frequency differences between subpopulations were significant in the polygynous colonies but not detectable between the subpopulations of the monogynous colonies. This makes sense because the polygynous colonies would be expected to have multiple reproducing females from different genetic backgrounds, which would lead to differences in the allele frequencies of the workers that made up the population. Also, the polygynous colonies usually had queens that were related to their male mates, which was not the case in the monogynous colonies, suggesting a difference in dispersal between the two types. Based on this data, polygynous colonies have limited dispersal and will usually mate within the colony, while the monogynous colonies rely on outbreeding and a higher degree of dispersal.[ citation needed ]
The propensity to disperse also varies between males and females, with the main effect of this being that females that are less prone to dispersal will be more likely to stay in the colony and switch it from monogynous to polygynous. [15] The ability of the female to leave the colony is affected by its physiological condition, where larger females with greater fat stores will preferentially disperse but smaller females are more likely to remain. Male dispersal is also determined by size, and in the case of both sexes, larger males and females are produced in monogynous colonies in accordance with their greater dispersal.[ citation needed ]
If there is a wide variation in the size of the queens produced, it is likely that monogynous colonies would not remain monogynous for any long period of time, because smaller daughters would remain and form polygynous colonies. To counteract this, queens produced in monogynous colonies must frequently be large. A study of the heritability of queen size shows that there is a significant degree of heritability in size that a daughter can receive from her mother, allowing for monogynous colonies to predictably produce larger queens that will disperse to form independent colonies. [16]
As seen by comparing the relatedness between the queens and their male mates, polygynous colonies will typically mate within the nest. This results in reproduction that is driven by a very limited dispersal where queens will bud off of the main nest to create a large, polydomous colony. While this normally leads to high relatedness between nestmates, and a high degree of genetic structuring within the colony, nests of F. truncorum in Finland were observed to behave differently from this. [17] These nests will shift sites, depending on the time of year, between a nest for the hibernating season and one for the reproductive season. By marking the nests and using microsatellites, researchers found that the relatedness between nestmates in these colonies was almost zero. This indicates the F. truncorum can form unicolonial populations were the workers migrate between genetically different nests.[ citation needed ]
Monogynous colonies and polygynous colonies have shown differences in how they react to nestmate recognition and queen adoption. Monogynous colonies discriminate against, and will not adopt, any non-nestmate female, while polygynous colonies are much more accepting. [18] Monogynous colonies are not totally enclosed, however, and maintain their single-queen status through high female dispersal and low intranidal breeding. While polygynous colonies are more likely to adopt a non-nestmate female, most of the queens still come from adopted daughters within the colony.[ citation needed ]
Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22,000 species have been classified. They are easily identified by their geniculate (elbowed) antennae and the distinctive node-like structure that forms their slender waists.
Formica exsecta is a species of ant found from Western Europe to Asia.
Formica is a genus of ants of the family Formicidae, including species commonly known as wood ants, mound ants, thatching ants, and field ants. Formica is the type genus of the Formicidae, and of the subfamily Formicinae. The type species of genus Formica is the European red wood ant Formica rufa. Ants of this genus tend to be between 4 and 8 mm long. Ants belonging to the Formica genus possess a single knob or bump located between their thorax and abdomen. These ants primarily feed on honeydew, a sugary liquid produced by aphids. Formica ants appear to take on a shepherding role with smaller aphids, relocating them to different parts of plants to ensure a continuous food source for the aphids. By doing so, the ants can establish a relatively sustainable honeydew supply for both themselves and their colony.
Formica rufa, also known as the red wood ant, southern wood ant, or horse ant, is a boreal member of the Formica rufa group of ants, and is the type species for that group, being described already by Linnaeus. It is native to Eurasia, with a recorded distribution stretching from the middle of Scandinavia to the northern Iberia and Anatolia, and from Great Britain to Lake Baikal, with unconfirmed reportings of it also to the Russian Far East. There are claims that it can be found in North America, but this is not confirmed in specialised literature, and no recent publication where North American wood ants are listed mentions it as present, while records from North America are all listed as dubious or unconfirmed in a record compilation. Workers head and thorax are colored red and the abdomen brownish-black, usually with a dorsal dark patches on the head and promensonotum, although some individuals may be more uniform reddish and even have some red on the part of the gastern facing the body. In order to separate them from closely related species, specimens needs to be inspected under magnification, where difference in hairyness are among the telling characteristics, with Formica rufa being more hairy than per example Formica polyctena but less hairy than Formica lugubris. Workers are polymorphic, measuring 4.5–9 mm in length. They have large mandibles, and like many other ant species, they are able to spray formic acid from their abdomens as a defence. Formic acid was first extracted in 1671 by the English naturalist John Ray by distilling a large number of crushed ants of this species. These ants primarily eat honeydew from aphids. Some groups form large networks of connected nests with multiple queen colonies, while others have single-queen colonies.
Carpenter ants are large ants indigenous to many forested parts of the world.
The pharaoh ant is a small (2 mm) yellow or light brown, almost transparent ant notorious for being a major indoor nuisance pest, especially in hospitals. A cryptogenic species, it has now been introduced to virtually every area of the world, including Europe, the Americas, Australasia and Southeast Asia. It is a major pest in the United States, Australia, and Europe.
Lasioglossum malachurum, the sharp-collared furrow bee, is a small European halictid bee. This species is obligately eusocial, with queens and workers, though the differences between the castes are not nearly as extreme as in honey bees. Early taxonomists mistakenly assigned the worker females to a different species from the queens. They are small, shiny, mostly black bees with off-white hair bands at the bases of the abdominal segments. L. malachurum is one of the more extensively studied species in the genus Lasioglossum, also known as sweat bees. Researchers have discovered that the eusocial behavior in colonies of L. malachurum varies significantly dependent upon the region of Europe in which each colony is located.
Formica polyctena is a species of European red wood ant in the genus Formica and large family Formicidae. The species was first described by Arnold Förster in 1850. The latin species name polyctena is from Greek and literally means 'many cattle', referring to the species' habit of farming aphids for honeydew food. It is found in many European countries. It is a eusocial species, that has a distinct caste system of sterile workers and a very small reproductive caste. The ants have a genetic based cue that allow them to identify which other ants are members of their nest and which are foreign individuals. When facing these types of foreign invaders the F. polyctena has a system to activate an alarm. It can release pheromones which can trigger an alarm response in other nearby ants.
Rossomyrmex is a genus of slave-making ant in the subfamily Formicinae. The genus consists of four species, each with a single host from the genus Proformica, and has a very wide range of distribution from China to southeastern Spain, from huge extended plains to the top of high mountains.
Formica sanguinea, or blood-red ant, is a species of facultative slave-maker ant in the genus Formica characterized by the ability to secrete formic acid. It ranges from Central and Northern Europe through Russia to Japan, China, the Korean Peninsula, Africa and also the United States. This species is coloured red and black with workers up to 7 mm long.
Ropalidia marginata is an Old World species of paper wasp. It is primitively eusocial, not showing the same bias in brood care seen in other social insects with greater asymmetry in relatedness. The species employs a variety of colony founding strategies, sometimes with single founders and sometimes in groups of variable number. The queen does not use physical dominance to control workers; there is evidence of pheromones being used to suppress other female workers from overtaking queenship.
The green-head ant is a species of ant that is endemic to Australia. It was described by British entomologist Frederick Smith in 1858 as a member of the genus Rhytidoponera in the subfamily Ectatomminae. These ants measure between 5 and 7 mm. The queens and workers look similar, differing only in size, with the males being the smallest. They are well known for their distinctive metallic appearance, which varies from green to purple or even reddish-violet. Among the most widespread of all insects in Australia, green-head ants are found in almost every Australian state, but are absent in Tasmania. They have also been introduced in New Zealand, where several populations have been established.
Solenopsis saevissima, commonly known in Brazil as formiga de fogo, formiga-vermelha, or formiga-lava-pes, is one of more than 185 species in the genus Solenopsis. It, along with 13 other species, is also a member of the Solenopsis saevissima species group which are popularly known as fire ants.
A gamergate is a mated worker ant that can reproduce sexually, i.e., lay fertilized eggs that will develop as females. In the vast majority of ant species, workers are sterile and gamergates are restricted to taxa where the workers have a functional sperm reservoir ('spermatheca'). In some species, gamergates reproduce in addition to winged queens, while in other species the queen caste has been completely replaced by gamergates. In gamergate species, all workers in a colony have similar reproductive potentials, but as a result of physical interactions, a dominance hierarchy is formed and only one or a few top-ranking workers can mate and produce eggs. Subsequently however, aggression is no longer needed as gamergates secrete chemical signals that inform the other workers of their reproductive status in the colony.
Worker policing is a behavior seen in colonies of social hymenopterans whereby worker females eat or remove eggs that have been laid by other workers rather than those laid by a queen. Worker policing ensures that the offspring of the queen will predominate in the group. In certain species of bees, ants and wasps, workers or the queen may also act aggressively towards fertile workers. Worker policing has been suggested as a form of coercion to promote the evolution of altruistic behavior in eusocial insect societies.
Leptothorax acervorum is a small brown to yellow ant in the subfamily Myrmicinae. It was first described by Johan Christian Fabricius in 1793. L. acervorum is vastly distributed across the globe, most commonly found in the coniferous forests of Central, Western and Northern Europe. The morphology of L. acervorum is extremely similar to that of other Leptothorax ants. The difference arises in the two-toned appearance of L. acervorum, with the head and metasoma being darker than the mesosoma segment of the body, and hair across its body. Following Bergmann's rule—unusually, for ectothermic animals—body size increases with latitude.
Myrmecocystus mexicanus is a species of ant in the genus Myrmecocystus, which is one of the six genera that bear the common name "honey ant" or "honeypot ant", due to curious behavior where some of the workers will swell with liquid food until they become immobile and hang from the ceilings of nest chambers, acting as living food storage for the colony. Honey ants are found in North America, Australia, and Africa. Ant species belonging to the genus Myrmecocystus reside in North America. M. mexicanus in particular is found in the southwestern United States and parts of Mexico.
This is a glossary of terms used in the descriptions of ants.
Liselotte Sundström is a Finnish zoologist. She is professor emerita of evolutionary biology at the University of Helsinki.
Camponotus fellah is a species of ant in the subfamily Formicinae found across the Middle East and North Africa. This species was formally described by Dalla Torre in 1893. A C. fellah queen holds the record for Israeli ant longevity, surviving for 26 years (1983-2009) in a laboratory environment.