Ant (Formicoxenus provancheri)

GenusFormicoxenus (1)

Formicoxenus provancheri is classified as Vulnerable (VU) on the IUCN Red List (1).

Formicoxenus provancheri belongs to a genus whose species are known as ‘guest-ants’, social parasites that live in colonies of other ant species. Formicoxenus provancheri inhabits the nest of Myrmica incompleta, an ant species three to five times larger than itself (2).

There are three morphs of Formicoxenus provancheri. The winged morph has completely developed ocelli and thoracic structures. The wingless morph lacks ocelli and has a fused thorax. A third morph is intermediate between the two, and has no wings and reduced structures (2).

All female Formicoxenus provancheri have a spermatheca (a receptacle in which sperm is stored after mating) and are able to mate and produce fertilised eggs, although only one female in a nest is fertile and will breed (2).

Formicoxenus provancheri can be found in Canada and the United States (1).

The nests of Myrmica incompleta which are inhabited by Formicoxenus provancheri are found in clumps of moss and under logs and stones in damp meadows and bogs (2) (3).

Formicoxenus provancheri forms separate, small nests at the edge, or in the wall of, the larger Myrmica incompleta nests. The colonies do not mix as the galleries of the Formicoxenus provancheri nest are too small to allow the larger hostants to enter. Myrmica incompleta seem to show little aggression towards the parasitic Formicoxenus provancheri, and the two species mutually accept each other. However, the broods of the two species are always kept in separate chambers as Myrmica incompleta will prey on Formicoxenus provancheri larvae (2) (4).

Each colony of Formicoxenus provancheri contains only one fertile female. Unlike other ant species, only a few Formicoxenus provancheri remain in the nest and tend to the brood that the queen produces. The largest numbers of Formicoxenus provancheri are found in the Myrmica incompleta nest. These individuals are strongly attracted to both Myrmica incompleta adults and larvae, and will frequently mount and lick the host ants in order to receive regurgitated food. This behaviour, known as ‘shampooing’, may also be used to obtain the Myrmica colony odour. Formicoxenus provancheri do not forage, and are instead completely dependent on the larger host ants for food (2). 

Formicoxenus provancheri has also been shown to possess the ability to follow scent trails deposited by Myrmica incompleta workers. This trail allows Formicoxenus provancheri to follow hosts to new nest sites (5).

There are currently no known threats to Formicoxenus provancheri.

There are currently no specific conservation measures known to be in place for Formicoxenus provancheri.

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  1. IUCN (September, 2011)
  2. Errard, C., Fresneau, D., Heinze, J., Francoeur, A. and Lenoir, A. (1997) Social organization in the guest-ant Formicoxenus provancheri. Ethology, 103(1): 149-159.
  3. Kannowski, P.B. (1957) Notes on the ant Leptothorax Provancheri Emery. Psyche: A Journal Of Entomology, 64(1): 1-5
  4. Lenoir, A., Errard, C., Francoeur, A. and Loiselle, R. (1992) Biological and ethological observations on the interactions between the parasite ant Formicoxenus provancheri and its host Myrmica incompleta. Insectes Sociaux, 39(1): 81-97.
  5. Lenoir, A., Detrain, C. and Barbazanges, N. (1992) Host trail following by the guest ant Formicoxenus provancheri. Experientia, 48(1): 94-97.