Recently two new ant species were discovered in Poland, which, together with those that were already known, adds up to a total
of 100 species. Some question these insects' usefulness in forests. Ants are accused of limiting biodiversity-the gravest crime according to modern ecology. So, what is the need for these tiny creatures?

So far, the dogmas of natural science, taught to children as early as kindergarten, claimed that ants were useful because they protected the forest by eating the larvae and carcasses of tree parasites. While ants have not changed their culinary tastes, when an emphasis on biodiversity developed, various self-taught "ecologists" started to discover that the population of insects, invertebrates and spiders decreased in the proximity of forest anthills. They arrived at a simple conclusion: ants destroy everything they find within their territory. In addition, close to the anthill, the number of aphids bred by ants is growing, which poses a danger to trees.

This new trend in scientific thought is disturbing for Assistant Professor Wojciech Czechowski from the Zoology Institute of the Polish Academy of Sciences in Warsaw. According to Czechowski, creator of a key for identifying Polish ants, this perspective is a reflection of the belief that what you cannot see doesn't exist. Ant critics limit their observations to animals that are easy to observe, such as the larger invertebrates and arthropods and forget about microscopic organisms that are less easily observed such as mites and springtails that are ignored by ants. These important soil-forming creatures find excellent conditions for development in and near anthills.

In areas colonized by ants, the soil has a different chemical composition and structure of microfauna and microflora, which has great significance for the forest biocenosis. Moreover, the larvae of the chequered blue butterflies mature in ant nests (for example, those of the Myrmica ants), without which meadows would be much less colorful.

Aphids actually do not pose a threat to healthy trees and at the same time form the basis of the food chain for many organisms. These include not only ants that feed on the sweet secretions of aphids, but numerous aphid-eating animals, such as ladybugs, lacewings and flies, or the hymenopterans that are parasitic to the aphids-a basic food for birds. So ants increase biodiversity and at the same time maintain it on a higher level, stabilizing the forest biocenosis.
Ants are non-specialized predators, which means they eat whatever is at hand, effectively eliminating overpopulation of different organisms, particularly caterpillars that destroy tree leaves. Unfortunately, ants do not attack ticks which are too tough a prey.

Masters and servants
The population of red wood ants is dropping throughout Europe. The main reason is the overall rejuvenation of tree stands connected with the forest economy that involves tree cutting and forest planting. Red wood ants are unable to live outside the forest and even thickets are not conducive to their development. Red wood ants are social parasites. In a young forest, the first hosts to settle, as a rule, are large black Formica fusca ants. Only then do red wood ants start their invasion of the forest.

A red wood ant, fertilized during the nuptial flight, chooses one of two life strategies. The future queen may found a nest on its own. This involves finding a hiding place where it lays its eggs. The queen waits for the larvae of the worker ants to incubate, then feeds them until they grow and start taking care of her. Over that period, the female does not hunt and uses only the reserves accumulated in her own body-so these must be quite extensive.

The other method, using scent camouflage to enter the nest of Formica fusca ants, is much easier. The red wood ant female gets rid of the local queen-by killing or expelling her, or uses special pheromones causing the workers to start taking care of her and neglect the previous queen which eventually dies of starvation. After getting rid of her competitor, the conqueror starts to lay her own eggs, and the new servants take care of them.

In this way a mixed colony emerges with two species of ants, both black and red wood ants. Gradually the Formica fusca ants die out and after two to three years the nest is inhabited solely by red wood ants which build a large mound that is often seen in the forest.

On the attack
The core of an anthill is usually formed by a rotted tree stump. The outer layer of the mound is hard and water-proof-even during heavy downpours rainwater does not penetrate the anthill deeper than 2-3 centimeters. The number and size of entrances constantly varies, since they are closed or opened depending on external conditions, so that a stable temperature and humidity can be maintained inside the nest.

Hundreds of thousands of ants live in a typical anthill, and in a very big nest, their number may reach 2 million. There may be one or many queens, for example, in the nests of the Formica polyctena ant there may be thousands of females. The ants penetrate the surrounding area within a distance of 200 meters. That range is determined by the limit of profitability of transporting food.
If a nest becomes too big and too difficult to maintain, it is divided and a branch colony is established. The poorer the environment, the more dense the distribution of such colonies. Typical polygenic colonies (originating from one anthill) may include several hundred nests. The European record belongs to a colony in the Alps that includes 2,000 nests.

In any given area, the ant species that inhabit it are subject to a strict hierarchy. The lowest position is occupied by species that only defend their own nest, followed by ants that defend their nest as well as regular food sources (for example, aphid colonies) and finally ant species that also defend their territory-red wood ants belong to the latter group. In this way, up to 20 ant species may coexist in a single area.

The subordinated species usually retreat without a fight when they encounter ants from the "higher class" species. If a fight occurs however, the ant uses both ends of its body-cutting the opponent's body with its jaws and then using a poison gland at the end of its abdomen, squirting formic acid on the wound. This method is aimed primarily at disabling insects whose joints are paralyzed after the ant's attack.

Initially, all ants had stingers, but in the course of evolution these weapons disappeared from most species, and only poison glands were left. Now, out of ants found in Poland only Myrmica ants have stingers. These ants are reddish just like red wood ants, but are half their size.

The protein obtained in group hunting and from carcasses is usually used by the larvae and the queen. Ordinary workers feed on carbohydrates from aphid honey.

Protect the ants
Many nonsensical legal provisions have always existed in the field of ant protection. The initial regulations forbidding the destruction of ant nests in the forest was impossible to implement, because in walking through the forest, it is impossible to avoid destroying a certain number of small nests hidden under sticks or leaves. Lawmakers had large anthills in mind, but the regulations did not state that precisely.

Now a change has been introduced which involves the protection of two species of red wood ants-strict protection for Formica rufa and partial protection for Formica polyctena. "Show me a forester, berry picker or producer of home-made ant elixirs, who will be able to tell the difference between them," says Czechowski. In making the spirit-based ant elixir, which helps to treat rheumatism, only the Formica polyctena may be used but it seems likely that the layperson will find it hard to distinguish between these species.

Instead of the laborious study of biological nuances, it may be better to focus on common-sense issues. For example: should anthills be fenced in or not? In Czechowski's opinion, this is not a policy that should be applied throughout the forest. "The anthills should be fenced in only in places that are particularly endangered by wild pigs or in locations near roads used by forest vehicles," he says.
In addition, more attention should be paid to anthills during work in the forest since Czechowski notes that even if tree cutting is supervised by a forester, the vehicles may still drive across the anthills or destroy them by dragging logs. Tree cutting alone is a big problem for ants.

Konrad T. Lewandowski

Forest Ants
Polish forests are home to six species of red wood ants. The most common are the Formica polyctena and Formica rufa red wood ant while rare species include the Scottish wood ant (Formica acquilonia) and Northern wood ant (Formica lugubris). Together these four species make up the Formica rufa group and are indistinguishable for non-experts. Two other, more recognizable, species are the trunk ant (Formica truncorum) and the hairy wood ant (Formica pratensis). The black or gray Formica fusca, used by red wood ants as slave labor, is classified into the Serviformica subgenus. The stinging ants found in forest meadows belong to a separate genus, Myrmica.