Workers of the Ant Formica fusca in Siberia guard their Queens

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• published: 01 May 2016
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Ants fascinate due to their social communities. A folk consists of workers and one or several queens. Only in the mating period, additionally young winged males and females are produced. The complexity of these social states is not accidentally similar to what we know from bees and wasps. These taxa indeed are closely related to each other and belong to the bigger clade Hymenoptera. Males die shortly after their matings. An ant nest is a female community! Their queens can reach a remarkable age and are reproductive throughout their entire lifes based on only one mating event. She can lay two kinds of eggs: unfertilized eggs develop to males, fertilized ones into females, mostly workers. The ant Formica fusca has a palaearctic distribution and creates smaller nests of about 500-2000 workers. They are omnivorous feeders, preferring hunting smaller arthropods, feeding on honeydew and also accepting vegetarian food. The queen can reach an age of about 8 years. Interestingly this ant species is named a slave ant. This is due to the fact that mainly two other ant species, Polyergus rufescens and Formica sanguinea, use to invade into the F. fusca nests in order to steal their pupae. These then may be simply used as food, but they also breed them into workers, which then need to live and work in slavery. Slaved workers do not produce own alates. They also only rarely leave the nests of their kidnappers, thus are usually not involved in the organisation of food outside. In ants, two different major types of queens exist, active and powerful ones and more or less helpless queens, which are fully depending of their worker's support. Leafcutting ant queens of the genus Atta represent the first type, while Formica queens for example belong to the second one. But although queens of F. fusca can be very fast and self defensive, I observed them resting more or less without any motion, when they felt disturbed. Under such conditions was one of my queens filmed. The footage is visible in the beginning part of the film. Only the second leg of the left side is sometimes trembling. Such leg movements can be a reaction on disturbances and especially material vibrations (Fielde & Parker 1904). There was no indication that the queen was hurt. My queens showed that behavior to rest motionless also inside their natural nest conditions, where they felt still disturbed due to my filming activities. The behavior seems to be a kind of camouflage, because indeed, the queens are thus only hardly visible inside the original nest substrate. But watch, how powerfully the workers react, when they feel their queens in danger. They use to clasp her strongly with their mandibles and guide her into better hideaways. The behavior is well visible in my footage. I mentioned the term "queen" always in its plural form. Indeed the nests of F. fusca can be polygynous, which means that they may have several active queens. This was also in my studied nest samples the case. In the field, a spruce forest nearby the Siberian city Tyumen, under a bigger piece of deadwood, I could see several queens, of which I was taking only 2 with me for filming and research purposes. Interestingly those queens were very easily to find. I just needed to lift up the deadwood. Usually I would expect them being much better hidden. May be this finding situation was due to specific activities around this F. fusca nest. The nest was surrounded by a huge crowd of workers of another Formica species. I could not decide with blank eyes, whether it was F. rufa or F. sanguinea. The possible ant's purposes in the latter case was already explained. Young F. rufa queens are depending on ants such as F. fusca in order to create their colonies successfully. They manipulate F. fusca workers to grow up their broods. I do not know, why an obviously already developed F. rufa ant nest would attack a F. fusca colony, may be just to steal its brood as food ressource. Ant nests are inhabited by numerous organisms with specific adaptations to survive in these unusual conditions. Especially phoretic mites and phoretic nematodes can appear in the nests of different ant species.