''Formica sanguinea'', or blood-red ant, is a species of facultative slave-maker ant in the genus ''

Formica ''Formica'' is a genus of ants of the subfamily Formicinae, 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 ...

'' characterized by the ability to secrete formic acid. It ranges from Central and

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through

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, the

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and also the

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. This species is coloured red and black with workers up to 7 mm long. A colony of ''F. sanguinea'' can live either as a free colony or as a social parasite of ''Formica'' species, most commonly '' Formica fusca'', '' Formica japonica'', '' Formica hayashi'' and '' Formica rufibarbis''.

Raiding

Blood-red ants, ''F. sanguinea'', are facultative slave-makers, meaning colonies can live either alone or be

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

. This allows them to be a good

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

to study the origins of brood stealing. A fertilized ''F. sanguinea''

queen Queen most commonly refers to: * Queen regnant, a female monarch of a kingdom * Queen consort, the wife of a reigning king * Queen (band), a British rock band Queen or QUEEN may also refer to: Monarchy * Queen dowager, the widow of a king * Q ...

will enter the

nest A nest is a structure built for certain animals to hold Egg (biology), eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of ...

of the host ant species and kill their queen. She then takes advantage of the workers who tend to her and her

brood Brood may refer to: Nature * Brood, a collective term for offspring * Brooding, the incubation of bird eggs by their parents * Bee brood, the young of a beehive * Individual broods of North American periodical cicadas: ** Brood X, the largest br ...

. ''F. sanguinea'' workers will also raid nearby nests, stealing

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e and

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

e to become future workers for ''F. sanguinea''. The raids are also not exclusively for acquiring new workers but are sometimes predation events. ''Formica sanguinea'' has not been observed to have division of labor in which certain individuals raid or forage. However, some individuals possess more

Dufour's gland Dufour's gland is an abdominal gland of certain insects, part of the anatomy of the ovipositor or sting apparatus in female members of Apocrita. The diversification of Hymenoptera took place in the Cretaceous and the gland may have developed a ...

compounds than others, so presumably would be more successful in during raiding. ''Formica sanguinea'' uses scouting individuals to locate the nest that will be parasitized. Once a nest has been scouted, the raid will happen. The activities that go on during a raid are composed of digging and fighting at the target nest. Both captive workers and blood-red ant raiders are observed to be carrying the brood back to the ''Formica sanguinea'' nest. If a member of the colony is killed in the raid, individuals will take that carcass back to the nest to be eaten later. Raids were also never observed on rainy or overcast days. This is thought to be because of the detriment rain might have on terrestrial conditions and the effectiveness of alarm pheromones.

Chemical defenses

''F. sanguinea'' uses

formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid. It has the chemical formula HCOOH and structure . This acid is an important intermediate in chemical synthesis and occurs naturally, most notably in some an ...

as well as substances in the

as chemical defence. The substances in the Dufour's gland contain

hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may b ...

such as hendecane, as well as

acetate An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic, or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called ...

s, decylacetate, and dodecylacetate. ''Formica sanguinea'' uses the formic acid and Dufour's gland substances in conjunction with each other. The hydrocarbons in Dufour's substance serve as a wetting before the formic acid is released. Without these wetting agents, formic acid is relatively harmless to other ants. These substances dissolve the fat compounds of the

epicuticle Arthropods are covered with a tough, resilient integument, cuticle or exoskeleton of chitin. Generally the exoskeleton will have thickened areas in which the chitin is reinforced or stiffened by materials such as minerals or hardened proteins. T ...

as well as enter the tracheal system to kill the opponent. Interactions between Formica sanguinea and Lomechusoides strumosus

Reproduction

Most colonies are monogynous, meaning they have only one queen. ''F. sanguinea'' are commonly

polyandrous Polyandry (; ) is a form of polygamy in which a woman takes two or more husbands at the same time. Polyandry is contrasted with polygyny, involving one male and two or more females. If a marriage involves a plural number of "husbands and wives ...

, meaning the singular queen mates with more than one male. In studies observing this, 70% of queens mated with multiple males. ''F. sanguinea'' is observed to have higher levels of polyandry than any other ''Formica'' species. However, when colonies engage in polygyny, having more than one queen, the rates of polyandry drop. It is assumed that colonies utilize either polyandry or polygyny, to increase the

genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...

of the colony. Therefore, two different strategies can be employed. One strategy is that a female mates with many males and then disperses to start a new colony. The second strategy is for a female to mate with a fewer number of males, and stay close to the natal colony with other females who have mated with a fewer number of males. In the case of polygyny, it has been observed that there is one dominating queen who is more sexual reproductive than the others. Polyandrous ''Formica sanguinea'' colonies show paternity skew, meaning that the mated males offspring are not represented equally in the population. Whether this is because of internal selection or

sperm competition Sperm competition is the competitive process between Spermatozoon, spermatozoa of two or more different males to fertility, fertilize the same Egg cell, egg during sexual reproduction. Competition can occur when females have multiple potential m ...

is unclear.

Recognition of individuals

''Formica sanguinea'' analyzes hydrocarbons on the cuticle of another individual to determine if it is an intruder. Low

intraspecific competition Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to ...

and aggressiveness is observed in this species. When members of the same species of a mixed colony were met with individuals from a pure ''F. sanguinea'' colony, they were met with aggressiveness. This is most likely because the identifying hydrocarbons change when individuals are in a mixed colony.

Evolution

''Formica sanguinea'' is one of around 11 species in the ''

'' genus that display this socially parasitic brood raiding behaviour. Molecular analysis of the genus as a whole indicates that this form of social parasitism evolved just once in the ''Formica'' genus, in the common ancestor of the ''Formica sanguinea'' group of closely related species. It is estimated that this happened at least 14 million years ago.

References

External links

* {{Taxonbar, from=Q1350298 sanguinea Slave-making ants Hymenoptera of Europe Hymenoptera of Asia Insects described in 1798 Taxa named by Pierre André Latreille