Blood-red predatory ant
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Blood-red predatory ant worker ( Formica sanguinea ) |
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| Formica sanguinea | ||||||||||||
| Latreille , 1798 |
The blood-red predatory ant ( Formica sanguinea ) from the subfamily of the scale ants (Formicinae) belongs to the genus of wood ants ( Formica ) and there to the subgenus of predatory ants ( Raptiformica ).
features
Head, mesosoma , stalk limbs and legs are light to dark red, the gaster is black, the back of the head is often dark. Mostly the black spots on the pronotum and mesonotum are missing . The mandibles , the cheeks and the largely hairless forehead are dark brown or only slightly darkened. The strikingly large compound eyes are hairless. The most important distinguishing feature for Raptiformica species is a deep, arched indentation on the front edge of the head shield ( clypeus ). The body length of the workers is six to nine millimeters. The queens are nine to eleven millimeters long, the males seven to ten millimeters long. The sex animals swarm between June and August.
distribution and habitat
The blood-red predatory ant is widespread throughout Europe and is very common in some areas. It prefers dry locations on the edge of the forest or in clearings, but also settles in the open field on dry grass , and can sometimes even be found in man-made structures such as old barns or wooden sheds.
Way of life
The species belongs to the slave-holding ants. From mid-June to mid-August, the workers raid the nest of another Formica species to steal its larvae and pupae . These stages of development, primarily dolls, are transported to their own nest and either used as food or raised as slaves. The slave ants, which are also known as auxiliary ants, usually take on work within the nest and are rarely involved in foraging or raiding. Male or fertile female slave ants are never found in captivity.
The blood-red predatory ant is nowhere near as efficient in its raids as specialized slave hunters, such as the Amazon ant . But she can exist completely without slaves and is in no way dependent on them after the colony has been founded. She is therefore called an "optional slave hunter".
Colony founding in Formica sanguinea occurs through temporary social parasitism in Formica species of the subgenus Serviformica or through adoption in species-specific colonies and branch nest formation.
The workers orient themselves in the field mainly through visual impressions, whereas pheromone traces only play a subordinate role. Among all ants, this species has, in addition to Formica rufa , the best developed compound eyes with the highest number of visual cells ( ommatidia ) and the best resolution. Most of the ommatidia are found in males, in which the eye flap ( Lobi optici ) also makes up 60 percent of the insect's brain . For queens it is 40 percent and for workers 35 percent.
Symbiosis with tufted beetles
The hunchback beetles (family Kurzflügler ) of the genera Lomechusa and Atemeles are brood predators in the ant nests and are nevertheless tolerated by the ants, and sometimes even fed. This behavior is based on the greed of the ants for excretion of the tufted beetle. This excretion is not a waste product of the tufted beetle and studies have shown that it is not a food for the offspring either, but clearly an alcohol-like drug for the ants. For this drug, the ants also accept a partial loss of brood without attacking the tufted beetles. It has already been observed that in the event of danger, the ants first bring the brood of the tufted beetle to safety, then their own brood. It is assumed that the predatory behavior of the blood-red predator ant is used to compensate for the loss of brood due to the tufted beetle.
With excessive reproduction of the tufted beetle in an ant colony, the constant loss of breeding and food leads to the colony becoming extinct. Some biologists have pointed out that the blood-red predatory ant would probably have been exterminated by the tufted beetles if the ants' brooders had not moved the tufted beetle pupae to dry and warm storage locations, just like the ant pupae. However, the tufted beetle pupae tolerate this climate very poorly.
nutrition
The diet of Formica sanguinea mainly consists of honeydew and insects , other sweet juices (e.g. nectar or tree sap) and plant seeds ( elaiosomes ) are also taken.
Nest building
The nests are usually created under the protection of stones or in lying dead wood . Although this species is counted among the "hill-building wood ants", hill nests are only sometimes formed , such as the red wood ant . These are then also significantly flatter.
Danger
The blood-red predatory ant is listed in Germany's red list as not endangered.
swell
- Dieter Otto: The red wood ants. (3rd, revised and expanded edition.) Westarp Sciences 2005, ISBN 3-89432718-9
- Bernhard Seifert: The ants of Central and Northern Europe. Lutra, Görlitz / Tauer 2007, ISBN 978-3-936412-03-1
- Heiko Bellmann : bees, wasps, ants. Hymenoptera of Central Europe. Franckh-Kosmos, Stuttgart 1995, ISBN 3-440-09690-4
- Wolfgang Schwenke : Ants the scented state. Landbuch-Verlag, Hannover 1996, ISBN 3-7842-0309-4
Web links
- Pictures of Formica sanguinea at the German Ant Conservation Center
- Video: Formica sanguinea (Formicidae) - begging for food . Institute for Scientific Film (IWF) 1973, made available by the Technical Information Library (TIB), doi : 10.3203 / IWF / E-2013 .