Termites
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| Brullé , 1832 |
Termites (Isoptera) are a state-forming order of insects that occurs in warm regions of the earth . More than 2,900 species are known. With the also state-forming Hymenoptera ( ants , bees and wasps ) are not closely related. According to more recent phylogenetic studies, they form the superorder Dictyoptera together with the terrors and the cockroaches and should no longer be regarded as a separate order, but as a special development line of the cockroaches (possibly in the rank of a superfamily, e.g. Termitoidae). Many species have a white or yellowish-white body color. As a rule, termites are between 2 and 20 mm long. Sex animals of Macrotermes goliath reach a maximum wing length of 88 mm, the queen of the closely related species Macrotermes natalensis with her abdomen bulging with eggs reaches a maximum body length of 140 mm.
A termite colony can contain several million individuals and usually consists of three specialized groups or " castes ". However, unlike the hymenoptera, all of these castes usually include both sexes. In addition to a breeding pair (rarely several pairs) there are sexually stunted and mostly blind male and female workers who are, among other things, brood keepers, nest builders and food procurers. Nest guards ("soldiers") with a large head and strong jaw protect the termite den. The sex animals, equipped with fully developed compound eyes , lay off their wings after the wedding flight . In contrast to the queen ant, the termite egg layer has to be mated again and again and therefore lives with a "king".
Termites prefer to feed on organic material such as wood, humus or grass. As they eat cellulose, they are dreaded pests, for example on wooden buildings. A particularly large number of species live in the African, South American and Far Eastern tropical forests and savannas. However, termites are native to all warmer regions of the earth up to around the fortieth north and south latitude, in France for example up to La Rochelle .
Termite way of life
Without exception, all termite species are social insects , they form insect states in which the animals belong to different castes and differ morphologically accordingly. Termite states live in permanent nests. When it comes to termite structures, a distinction is made between nests in rotting or fresh wood, earth nests (underground), aboveground termite mounds and cardboard nests (on trees).
Diet, digestive system
Some termite species live on wood almost without exception, this is the original way of life. Others feed on humus from the soil; their intestines are greatly elongated and divided into several successive chambers, each of which has different physicochemical conditions and houses a specific microflora of bacteria. The anterior section of the intestine is extremely alkaline in order to make the organic matter from the soil matrix accessible for enzymatic decomposition in the first place. Other species of termites use grass (" harvest termites "), or a variety of other plant substrates.
Within the termites, two groups can be distinguished with fundamental differences in their way of life: The so-called "lower termites" (the families Mastotermitidae, Kalotermitidae, Termopsidae, Hodotermitidae, Rhinotermitidae, Serritermitidae) live primarily almost exclusively on wood. Their nests are usually within the food substrate they use, which is mostly partially decomposed dead wood, but can also be hard, dry wood (especially Kalotermitidae). However, there are also developments in the lower termites, e.g. B. the "harvest termites" of the family Hodotermitidae, who live on dead grass. The so-called "higher termites" all belong to the Termitidae family (with numerous subfamilies). In this family (evolutionarily derived from the lower termites) the close connection to wood as a food substrate was generally abandoned. The Termitidae use a variety of different food substrates, including humus, leaf litter and grasses. The species of the subfamily Macrotermitinae cultivate mushrooms (convergence to the leaf cutter ants ), which they “feed” with harvested organic matter in fermentation chambers.
Endosymbionts
The intestines of the lower termites always have a large extension of the rectum. In this chamber they accommodate a large number of endosymbiotic eukaryotic single cells (" protozoa "), bacteria and archaebacteria . The symbionts are necessary for survival, without them the termites perish. They make up about a third, up to half, of the animal's live weight. The extraordinarily intricate and complicated relationships of this symbiosis are an active field of research in which new things are discovered every year. As far as we know, the rectum chamber of termites is densely filled with protozoa, which belong to the so-called “ flagellates ”. Recent research has shown that the "flagellates" represent an artificial grouping of not closely related taxa. The species living in the termite intestine belong to three non-closely related lines of development, the Trichomonadea and Hypermastigidea , which belong to the Parabasalia tribe , and the Oxymonadea ( Loukozoa tribe ). More than 450 different protozoan species were identified in 200 termite species examined. These protozoa have cellulose-degrading enzymes ( cellulases ), which are essential for the digestion of the wood mass. It is now known that the termites also have their own cellulases, but these are less active and not sufficient for nutrition alone. For the breakdown, the wood fibers are absorbed ( phagocytosed ) by the flagellates . In a multi-stage reaction, the cellulose is ultimately broken down into acetic acid (acetate), carbon dioxide and molecular hydrogen (bacteria also have cellulases, but their share in digestion is less). Acetic acid is then the decisive source of carbon and energy for the termites themselves. Hydrogen is produced in cell organelles known as hydrogenosomes . The reaction (essentially fermentation) can only take place in an oxygen-free environment. In addition to a few archaebacteria (mainly methane producers of the genus Methanobrevibacter ) there is also an almost unmanageable variety of bacterial species symbiotically in the termite intestine. Some of these are free living, but some are also symbionts of the flagellates that inhabit the intestine. 300 different bacterial genomes have already been identified in one type of termite ( Reticulitermes speratus ) using molecular methods. Similar to protozoa, most symbiotic bacteria are obligate symbionts (i.e., they are not free-living) and are usually host-specific in a termite species or genus. In addition to some more widespread genera (e.g. Spirochaetes , Bacteroidetes , Firmicutes ), a hitherto completely unknown family group was discovered in the termite intestine, which has since been given the name Elusimicrobia. The symbionts of the protozoa sit partly on the surface and partly inside the cell. Curiously, the flagellates can e.g. B. no longer move with their own flagellum at all, but rely on the help of bacteria that are sitting on them. Other functions include B. the fixation of nitrogen (always a deficiency factor with wood as a nutrient medium). They also synthesize essential amino acids and other cofactors. Methane formed enzymatically when wood is broken down is released by the termites. Due to the extreme frequency of termites in the tropics, this has even had a demonstrable effect on the planetary greenhouse effect.
The symbiosis of the lower termites has been demonstrated in the same way in the wood-dwelling cockroaches of the genus Cryptocercus , which are regarded as their sister group (and as model organisms for the emergence of termite states). Other wood-eating cockroaches, e.g. B. the species Parasphaeria boleiriana , however, also have symbionts, but others. Recently it was even possible to directly detect the protozoa in a termite that was fossilized in Burmese amber from the Cretaceous period . This symbiosis has obviously existed since the Mesozoic.
Since the rectum is of ectodermal origin and lined with a cuticle , it is rejected along with all the symbionts living in it with each moult. So that the symbionts are not lost, a new infection is necessary every time. This obviously takes place during the mutual feeding of the termites in the burrow ( trophallaxis ). Perhaps this was a major trigger for the beginning of the social organization of the termite states. The symbionts receive new termite colonies from the winged sex animals (Alatae) that form them.
The "higher" termites of the Termitidae family (around 75% of the recent species) do not contain any symbiotic flagellates (any more). However, all species have symbiotic types of bacteria. They also have a higher level of endogenous cellulases, and these are also secreted in the midgut. Since these species do not have to digest wood, the advantage of the symbiosis has obviously been lost. The mushroom growing Macrotermitinae can also use the cellulases of the cultivated mushrooms for this purpose.
Termites that grow fungi
Termite species of the subfamily Macrotermitinae (family Termitidae) grow fungi of the genus Termitomyces (family knight relatives ) in their underground burrows on pre-digested food and feed on it. The termites swarm out of the burrow and eat wood, dry grass, humus and other organic substances. They deposit their excrement balls in chambers that are either underground or in the structures above ground (termite mounds). Here they form honeycomb-shaped, sponge-like masses that are overgrown by the mycelium. Other types of fungus and parasites are combated. The fungi develop vegetatively grains ("nodules"), which the termites harvest. After a while, older honeycombs are completely consumed and replaced by new ones. Termitomyces does not occur outside of the termite burrows. In most species, however, the fungus is not carried by the sex animals that fly out, but spores have to be picked up from the environment (unlike the leaf cutter ants ); if this fails, the colony perishes. The various termite species each cultivate their own species of fungus, with the pedigrees of both groups of species corresponding almost exactly. This indicates a speciation based on intensive coevolution , which is referred to as “co-speciation” or “co-cladogenesis”.
Termite physique
Adulti (sex animals) of termites are small to medium-sized, relatively softly sclerotized insects. The color ranges from yellowish to brown tones to black, they are monochrome or drawn quite inconspicuously, e.g. B. with yellow leg links. On the round head there are two compound eyes of small to moderate size, depending on the family, two forehead eyes ( ocelles ) are present or missing. The relatively short antennae are conspicuously shaped like a string of pearls, with each limb of the antennae flagella being somewhat narrowed and stalked on the previous one; this form of antenna is rare in insects. The number of antennae is different depending on the species. The mouthparts of the biting-chewing type are strong, and the mandibles in particular reach a prominent size. The thorax and abdomen are cylindrical and more or less the same width. The pronotum is flat or slightly saddle-shaped and pulled down to the side, it can carry humps and other sculptures. The wings are long and always protrude above the tip of the abdomen, sometimes far, but the animals are still very bad flyers. The crystal-clear, sometimes a little milky or gray to black-tinted wings are characterized by a reinforced leading edge and a second reinforced vein parallel to the leading edge in all termites, with the exception of the most primitive families, the rest of the veining is inconspicuous, between the veins there are approximately the same size, reticulated cells. Often the wings have a striking corrugation or other surface sculptures. Both pairs of wings are elongated, oval and almost identical in shape and length (hence the name Isoptera: equal wings). Only in Mastotermes does the hind wing have a slightly enlarged anal field. At rest, the wings are spread flat and carried over one another over the abdomen. At the base of the wing there is a mostly enlarged, conspicuous wing scale, which remains even after the remaining wings have been thrown off after the wedding flight. The rod-shaped legs have tarsi with three or four limbs, only five in Mastotermes . The abdomen consists of ten segments, mostly on the ventral side (ventral side) only nine are recognizable (the first sternite has receded). At the tip of the abdomen are two short cerci with different numbers of segments, which can sometimes be completely absent. The sexes are very similar in termites and can hardly be distinguished at first glance. Prominent external sex organs are barely developed. The tip of the abdomen of the females often looks a bit shortened because segments eight and nine have moved into the enlarged seventh.
A "nymph" (= termite larva with wing sheaths )
Wing sheaths (detail)
head
Life cycle, differentiation from castes
A termite nest is usually established in all species by exactly one winged female and one winged male (it was discovered in 2009 that at least one species also has parthenogenic reproduction as an alternative ). To date, no species has been discovered without fully winged sex animals in both sexes. After the successful establishment of a colony, these are referred to as "queen" and "king". The winged sex animals or "Alatae" can be found on the ground after a wedding flight. To make finding a partner easier, termite species swarm regionally synchronized in mass flights that take place at certain times of the year and are triggered by special weather conditions. In some species, the female attracts the male with a sexual attractant ( pheromone ), in other species no pheromone was detected. Female termites only mate with one male; the pair then stay together to form a new colony. After the wedding flight, the sex animals shed their wings (at pre-formed fault lines), the actual mating takes place on the ground, usually at the new nest location.
As a rare exception, many sex animals that are not necessarily related to one another can found a nest together in a few species. This phenomenon is known as " pleometrosis ". Establishing new colonies by splitting or “budding”, i.e. This means that part of the existing colony (as with honeybees) does not normally split off (there are exceptions, especially with Reticulotermes and Mastotermes ). However, some species form satellite nests that remain dependent on the mother's nest. Rarely and only in a few species does it also happen that neighboring colonies of the same species fuse with one another (merge). Normally, termites are very aggressive towards conspecifics from other colonies of the same species.
In many species it is observed that a colony can persist beyond the death of the founding couple. In this case, some developmental stages (larvae or nymphs) differentiate into secondary sex animals. Such sex animals never have wings and remain larva-like in their morphology, only the sex glands (gonads) mature. Propagation with such larvae-shaped sex animals is called neoteny in biology . Depending on the species, the founding couple can be replaced by numerous new neotenic female and male sex animals or only by a single new pair (e.g. all Kalotermitidae); in the second case the surplus animals are eliminated through aggressive behavior towards one another. Neotenic replacement sex animals are siblings; colonies maintained by them are therefore characterized by high inbreeding rates.
Termites are "hemimetabolic" insects whose body structure is similar to that of adults (sex animals). In the terminology of termite researchers, developmental stages without wings are referred to as "larvae", those with externally visible wing buds ( wing sheaths ) as "nymphs". Nymphs are only formed for the production of new sex animals, since the workers and soldiers are and remain wingless. The eggs laid by the termite queen and fertilized by the king develop differently on different development paths. Since all termite species are social insects and live together in colonies or states, other castes are formed in addition to the new sex animals . All termites have a non-reproductive stage called worker. Furthermore, there is almost always a second non-reproductive caste called the soldier whose sole role is defense. Soldiers occur in all families of termites, including the most primitive representatives; Few species do not have a soldier caste, they were given up secondary. In contrast to the insect states of the hymenoptera, the animals of the non-reproducing castes in the termites are of both sexes, although in many species in individual castes (e.g. in soldiers) one sex can clearly predominate.
Whether a certain individual develops into a winged sex animal, a neotene replacement sex animal, a worker or a soldier is essentially controlled by environmental influences. Which development path is taken in each case is controlled by hormones ; the level of juvenile hormone in particular seems to be extremely important. The hormone level itself is regulated by external signals. The most important thing here are social signals from the colony itself. B. as pheromones effective substances in the cuticle , which the growing larva picks up through direct contact and through mutual feeding (trophallaxis). B. informed all larvae whether egg-laying sex animals are present in the colony or not. A special feature of all "lower" termites is that their development paths remain extremely flexible and can merge into one another. With the exception of the soldiers, in principle all animals can develop into sex animals (and there are exceptions even with the soldiers). But also animals that have taken the development path to sex animals, d. This means that the so-called nymphs (with wing sheaths) can transform themselves back into workers through "regressive" moulting. By stationary molting, workers can molt into workers of the same stage without any further morphological development. Through regressive and stationary moulting, it is possible to differentiate between different stages in the lower termites, but it is not possible to determine the age or the history of an individual animal based on the stage. In contrast to the lower termites, the Termitidae family's future fate is irrevocably determined in an early larval stage. The animals that develop into workers can no longer become normal sex animals with them (only a kind of substitute sex animal with greatly reduced egg production is possible). The number of stages varies depending on the species. Typically the first two larval stages are always without wings. In exceptional cases, winged animals are formed from a single nymph stage, but as a rule there are two or more, which differ in the length of the wing sheaths. Even for the production of functional workers, several stages are often required, separated by skins. Soldiers develop from workers (rarely also from nymphs). The finished soldier is usually preceded by a stage of transformation with non-functional mouthparts (a so-called presoldat). Also (neotene and winged) sex animals usually have at least one inactive transition stage before the gonads mature.
Workers
As mentioned above, workers of Termitidae and the other families are different. Only with the Termitidae (and in addition some more highly developed genera of their sister group, the Rhinotermitidae) is the conversion to (male or female) worker irreversible. Lower termite workers, however, can still molt into sex animals. So all workers of these species are larval stages. To emphasize the difference to the workers of the Termitidae, but also to the workers of the ants and bees, they are often referred to as "false workers" or (derived from the Greek) as pseudo-gates. In the most primitive termite states of the Termopsidae and Hodotermitidae (but not in the morphologically more primitive Mastotermitidae), which build their nests in a single piece of wood and do not swarm out to forage, ultimately almost all animals transform into Alatae when the food supply is exhausted. The animals obviously notice this purely mechanically, based on the different vibrations of the wood. The “workers” of these species are actually misnamed, as they eat automatically from the first larval stage, that is, they take care of themselves without brood care. The workers do not work at all, they do not directly contribute to the maintenance of the colony (although the soldiers of these species do). So workers here do not finally renounce reproduction, they just postpone it for a longer or shorter period of time. The biological sense of this behavior could be in the nest, which is a valuable possession because cheap pieces of wood are scarce and highly competitive (in tropical rainforests between 60% and 100% of the dead wood is broken down by termites). There is always the chance to “inherit” this valuable property as a substitute sex animal.
The workers of the Termitidae do not molt into sex animals, but they are more similar in body shape to the larvae than the winged animals. They are always eyeless and slightly sclerotized, usually yellowish or whitish in color. Only the prominent, heavily sclerotized mouthparts with which the food is treated are dark. The workers of the Termitidae and the pseudergates of the Rhinotermitidae, Hodotermitidae and Mastotermitidae swarm out of the nest in search of food, e.g. B. depending on the type of wood, dry grass, manure, humus or leaf litter. Since the animals shy away from light, they build long, tunnel-like galleries when surface paths are required to reach an abundant source of food. Some higher termites, especially the fungal subfamily Macrotermitinae, have even developed two different worker castes; small workers for the brood care, the care of the mushroom cultivation and for building, big workers for the gathering of the food. The workers' food trains are accompanied by soldiers of these types.
soldiers
The sole task of the soldiers is to defend the colony. For this purpose, they usually have a noticeably altered physique. In many species the head is extremely enlarged relative to the rest of the body. The most important weapon in most species are greatly enlarged mandibles. These serve as biting tools. In many Termitidae of the genus Termes and some related genera, the greatly elongated mandibles are instead hooked into one another and stretched like a spring. When it comes into contact with an enemy, the mandible shoots forward at great speed due to the released spring force and can catapult enemies away or even smash them down. However, some species that live in hard wood have regressed the mandibles. The heavily sclerotized head serves as a plug that closes the passage (e.g. genera Cryptotermes and Calcaritermes ).
In addition to the mandibles, the termites have developed a rich arsenal of chemical weapons. Many species have a special gland in the head capsule (known as the frontal gland) that sprays or hurls a poisonous and / or very sticky secretion at enemies. The frontal gland is sometimes used in addition to the mandibles. The soldiers of a soldier caste of the Rhinotermitidae and all soldiers of the Nasutitermitinae have turned to this chemical defense as their only weapon, the frontal gland sits at the tip of a beak-like elongated rostrum, the mandibles have receded. In the case of Globitermes , the soldiers even forego it, their attack consists in a suicidal tearing open of the body wall with the release of the secretion.
Some termite species of the more advanced lineages that live in large states have developed not only different worker but also several soldier sets. The Macrotermitinae have z. B. small soldiers who accompany the workers' food trains and form a first line of defense. If they encounter intruders in the nest or strong resistance, they recruit the big soldiers by knocking noises made with their heads.
An essential biological task of the soldiers, especially with the smaller nests of the primeval species, is the defense of the nest against other termites of the same species or related species. Defense against ants, which are the most important biological antagonists, is also essential for almost all of them. A number of ant species specialize in termites as food. Only in a few highly developed species with large nests are the soldiers also used as a defense against other predators such as z. B. Vertebrates effectively. Usually the soldiers' special weapons are only effective when defending in narrow cavities. In open spaces they are easily bypassed by the more agile ants and preyed on by attack on the back. Termites therefore try to close holes and damage to their structures and nests as quickly as possible.
Sex animals
In the higher termites, the queen's abdomen is so swollen to accelerate egg production that the animals can no longer move. Such a " physogastric " female can lay 30,000 eggs a day and many millions during her long life (probably 10 years possible). Real growth of the cuticle is involved (almost uniquely in insects). The initially small number of mature ovarioles of the queen is later increased and their length also increases, but not their total number. In contrast to the colonizing hymenoptera (bees, wasps and ants), the male (king) remains alive and later mates with the queen regularly. The males are less conspicuous, they differ mainly in the darker color and the scars of the thrown wings of workers. The eggs are walnut, sometimes curved, rounded at the ends, and of unequal size. Neotenic replacement queens usually have an abdomen that is also swollen, but does not match the dimensions of the original queen. In contrast to the original queen, they are lighter colored and eyeless. They may or may not have wing sheaths when they emerged from nymphs, when they emerged from workers. Very rarely do they develop shortened real wings. In termite burrows, the sex animals usually live closed in a special, thick-walled cell. Winged sex animals are normally neither mated in the burrow nor do they lay eggs here. Your task is to found new colonies, usually far away from the mother's nest.
Termite structures
Termite nests of the most primitive species are created within dead wood, with the Mastotermitidae and Termopsidae in partially decomposed, rotting wood, with the Kalotermitidae in undecomposed, hard wood. Mastotermes often expand their nest into the ground later. Most Rhinotermitidae, especially the genera Reticulitermes and Coptotermes that occur in temperate latitudes , build underground nests. The Serritermitide Serritermes builds nests exclusively in the outer wall of the nests of other termite species. Both tree nests and the spectacular termite mounds of tropical forests and savannahs come from Termitidae species.
Tree nests occur in numerous genera, including Termes and Nasutitermes . The nests are usually connected to the ground via tunnel-like galleries on the tree trunk. The tree nests and galleries consist of a cardboard-like mass of chewed wood. They usually have a particularly thick-walled cell for the sex animals in the middle.
The great termite mounds consist mainly of excavated earth walled in with saliva and are very strong; They contain numerous cells and corridors, of which the former serve as cradles for the brood, the latter for communication between all parts of the structure. The African Macrotermes belliciosus or Macrotermes natalensis and Australian Nasutitermes triodiae build convergent, almost identical looking, huge “cathedral mounds” with numerous turrets and peaks that can reach a height of more than eight meters. Construction continues under the hill more or less underground. Such a construction can contain two to three million individuals with a total weight of more than 20 kg. Some of these buildings are said to have been inhabited for a period of 100 years. Typically, however, the hills are smaller and contain around 5,000 to 200,000 animals with a biomass between 160 g and around 1.4 kg.
The mounds primarily serve to regulate the microclimate in the nest. In addition, with their hard outer walls, they serve as protection against predators. In terms of microclimates, there are primarily two needs to be met that can conflict with one another. Due to the high metabolic activity of the termites, in the case of Macrotermes even more of the fungi cultivated as food, large amounts of carbon dioxide are generated, which must be removed with effective ventilation. At the same time, the temperature in the building should be kept as constant as possible, with temperatures around 30 ° C being optimal. The shape of the hill serves these functions. In the outer wall of the Macrotermes pinnacles, which are closed at the top , heated air rises upwards. The renewal takes place via falling air masses in the central chimney. Other termite species e.g. B. Macrotermes jeanneli and subhyalinus and Odontotermes species build tubes that are open at the top, in which the air in the central vent does not flow downwards but upwards. You use the " chimney effect " for this.
The Australian species Amitermes meridionalis and Amitermes laurensis build hills that have not nearly round shape, but look like thin, high walls and because of their magnetic sense are aligned from north to south. The purpose of this design is to keep the internal temperature as constant as possible. When the sun rises in the east in the morning, a large surface of the building is immediately irradiated and it can recharge its batteries after the cold night. At noon, when the sun is vertical in the sky, the radiation nest offers a minimal surface and it does not heat up any further. In the evening, when the sun shines from the west, it shines again on a large area and the termite mound can once again store heat for the cold night.
Tenants and Termitophiles
Termite nests are not only inhabited and used by their builders. They are miniature ecosystems (or synusia) with numerous adapted species. In addition to species that parasitize on termites, there are roommates in almost all nests who feed on waste or leftovers and are neither harmful nor in any way useful for the termites. These are known as commensals . Roommates in nests are generally referred to as equilines, regardless of whether their way of life is commensal or parasitic. Many insect species are only known from termite nests: many fish of the Ateluridae family, many beetles, v. a. Short-winged beetles , stub beetles and scarab beetles , numerous two-winged beetles such as termite flies and other humpback flies and many others. In Brazil, glowing termite nests are remarkable, caused by the bioluminescence of a beetle ( Pyrearinus termitilluminans Costa, 1982 family Elateridae ) that often burrows in the nest shell . In addition, numerous termite species that belong to other species than that of the builder of the nest occur regularly as equilines. Some species of ants also only nest in termite nests. These can even be useful to their host by defending him against other predatory ants. After the death of the termite colony, the buildings in the savannah provide a breeding ground for numerous plant species that would otherwise not be found here. As a result, woods or thickets sometimes form in otherwise uniform grassland. For this reason and because of the high biomass and material turnover in the tropics (termites can make up 90% of the total population of the soil in tropical forests), they are called "ecosystem engineers".
In Australia, one species of bird, the golden shouldered parakeet , depends on termite burrows as a breeding ground.
Damage and control
“Many species are considered a horror of the hot countries; they penetrate in droves into human dwellings and destroy woodwork in particular, by completely eating away at the inside, but sparing the outer surface, so that apparently intact objects collapse with a slight shock. The termites only carry out their work at night and also undertake long migrations; their worst enemies are the ants, which literally go into the field against them. ” ( Meyers Konversationslexikon 1880)
A number of termite species are dreaded pests. Around 180 species are known worldwide that can cause damage to timber and buildings, 83 of them serious. Termites that damage buildings are primarily the ground-nesting species, above all the genera Reticulitermes and Coptotermes . These require moistened wood (or at least a source of water) and are therefore grouped together as "moist wood terms". The “dry wood termites” of the Kalotermitidae family also attack completely dry wood, but the damage they cause is less. Since dry wood termites nest inside processed wood and can live permanently, they are easily transported around the world. The earthening species, on the other hand, are mostly distributed locally, at least two species, Coptotermes formosanus and Reticulotermes flavipes , but now occur almost worldwide. In tropical countries, building-damaging termites are often barely controlled because this would be pointless due to their ubiquity. In the United States, annual termite control expenditures are estimated to be well over a billion dollars a year as early as the 1990s, excluding the cost of building damage. In Australia, the annual damage is estimated at $ 100 million. Although one would hardly trust such a "relic species", Mastotermes darwiniensis is the most feared pest in Australia, which can attack almost any wood, including impregnated telegraph poles; the species was introduced to New Guinea in the Second World War. In Europe, the control costs in France alone are estimated at around 200 million euros per year, the total costs at 500 million euros per year.
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Much more damage can be traced back to termites, e.g. B. They can destroy large areas of the PVC sheathing of electrical underground cables or unobserved termite structures can become an obstacle.
The most important control methods include infestation prevention through earth barriers and wood impregnation and direct control, mostly with poisoned bait. In the USA it is common to preventively poison large areas of the soil under and near houses with insecticides; this is sometimes prescribed by government agencies or insurance companies. The active ingredient class of cyclodienes (e.g. aldrin and dieldrin ), which used to be the most widely used , is now associated with massive damage to the environment and health.
In the tropics, some termite species are also important as agricultural pests that attack living plants or parts of plants, often the roots and from there the stems. An often affected crop is z. B. the peanut . In forestry, they are especially a problem where exotic timber such as eucalyptus species are planted.
Termites in Germany
In Germany none of the ten European termite species are originally ( autochthonous ) wild. Introduced species, which occasionally can settle permanently, are observed. The best known is a focus of infestation in the port of Hamburg, where termites were discovered in timber in the 1930s. For decades the species was given as the yellow-footed soil termite Reticulitermes flavipes , according to recent studies it is not said to be this (American) species, but the southern European Reticulitermes lucifugus . The termites apparently still live there today. Foci of infestation, favored by underground district heating pipes, are in the area of the General Hospital in Hamburg-Altona and in the judicial district in Hamburg-Mitte. Further introductions have so far been rare and isolated, mostly Reticulitermes species, very rarely others, e.g. B. Cryptotermes brevis in Berlin. However, this species can presumably not persist in Central Europe.
Use of termites
The protein and fat-rich sex animals of some species are an important food for the indigenous population of Africa and South America. But already paleolithic humans or pre- humans used tools to extract termites. The use of tools for this purpose (prey especially Macrotermes spp.) Was also regularly observed in chimpanzees and does not appear to be innate in them either, but rather to be passed on culturally. The extraction of termites is one of the few examples of the earliest tool use and is of importance for human evolution.
Systematics
At the moment 2929 termite species are known, which are traditionally divided into seven families: Mastotermitidae, Termopsidae, Hodotermitidae, Kalotermitidae, Serritermitidae, Rhinotermitidae, Termitidae. These names are used in almost all articles and publications. A more recent study, taking into account recent and fossil species, recently led to some changes to this classic classification. The authors show that the previous Termopsidae family is paraphyletic. The families Archotermopsidae and Stolotermitidae are newly formed for the recent species. The genus Stylotermes is separated from the Rhinotermitidae, for them the new family Stylotermitidae is formed. Other authors repeatedly suspect that the Rhinotermitidae family may be paraphyletic to the Termitidae. This suspicion arises u. a. based on some molecular studies. However, the current data basis is not yet sufficient for an actual split. Nine families are now recognized:
- Archotermopsidae (3 genera, 11 species)
- Stolotermitidae (2 genera, 10 species)
- Hodotermitidae (3 genera, 19 species)
- Mastotermitidae (1 species, Mastotermes darwiniensis )
- Kalotermitidae (21 genera, 449 species)
- Rhinotermitidae (12 genera, 316 species)
- Stylotermitidae (1 genus, 43 species)
- Serritermitidae (2 genera, 3 species)
- Termitidae (8 subfamilies, 247 genera, 2026 species)
Fossil record
The oldest fossil termites come from the older Cretaceous . Since these are differentiated representatives of today's termites, their actual origin must be older, probably in the Jurassic . Termites are therefore the oldest known social insects and precede the evolution of hymenoptera by around 30 million years. Most of the meaningful termite fossils are found in amber, where they occur in almost all deposits in a rich variety of individuals and species. This also applies to the Baltic amber. New finds of a presumably social, wood-dwelling cockroach from the Lower Cretaceous France give an idea of the termite root group within cockroaches. Most of the early finds belong to the recent Mastotermitidae family, which was then distributed worldwide (the surviving species today only in Australia). Cretaceous fossils are available from derived families such as the Rhinotermitidae (only from core group representatives), so that an early radiation can be assumed. The most species-rich family, Termitidae, evidently did not emerge until the Tertiary; the oldest known fossil comes from the Oligocene of Brazil. In Miocene amber of the Dominican Republic a diverse fauna of this family is already documented. In the Eocene Baltic amber are numerous termites, but has found no Termitidae.
Termites in the literature
The Belgian writer Maurice Maeterlinck received the Nobel Prize for Literature in 1911 for “The life of termites and the life of ants”. He later published Termite Life , a more detailed work on termites alone. Both books are designed as a scientific non-fiction book with philosophical considerations. It is based on the evaluation of literature studies, not on our own observations. Maeterlinck has been sharply criticized for this work because it is largely a plagiarism of the book The Soul of the White Ant by the South African author Eugène Marais .
supporting documents
Individual evidence
- ↑ Death of an order: a comprehensive molecular phylogenetic study confirms that termites are eusocial cockroaches. The Royal Society, April 13, 2007, accessed June 29, 2016 .
- ↑ Moriya Ohkuma: Symbioses of flagellates and prokaryotes in the gut of lower termites. In: Trends in Microbiology. 16 (7), 2008, pp. 345-362. doi: 10.1016 / j.tim.2008.04.004
- ^ Andreas Brune, Ulrich Stingl: Procaryotic symbionts of termite gut flagellates: Phylogenetic and metabolic implications of a tripartite symbiosis. In: Jörg Overmann (Ed.): Molecular basis of symbiosis. (= Progress in molecular and subcellular biology. Volume 41). Springer Verlag, 2005, ISBN 3-540-28210-6 .
- ↑ Michael A. Yamin: Flagellates of the orders Trichomonadida Kirby, Oxymonadida Grasse, and Hypermastigida Grassi & Foa reported from lower termites (Isoptera families Mastotermitidae, Kalotermitidae, Hodotermitidae, Termopsidae, Rhinotermitidae, and Serritermitidae feeding roachryptermitidae) and from the wood Dictyoptera: Cryptocercidae). In: Sociobiology. 4, 1979, pp. 3-117.
- ↑ George O Poinar Jr: Description of an early Cretaceous termite (Isoptera: Kalotermitidae) and its associated intestinal protozoa, with comments on their co-evolution. In: Parasites & Vectors. 2, 2009, p. 12. doi: 10.1186 / 1756-3305-2-12 open access
- ^ G. Tokuda, N. Lo, H. Watanabe, G. Arakawa, T. Matsumoto, H. Noda: Major alteration of the expression site of endogenous cellulases in members of an apical termite lineage. In: Molecular Ecology. 13, 2004, pp. 3219-3228. doi: 10.1111 / j.1365-294X.2004.02276.x
- ↑ DK Aanen, JJ Boomsma: Evolutionary dynamics of the mutualistic symbiosis between fungus-growing termites and Termitomyces fungi. In: F. Vega, M. Blackwell (Eds.): Insect-Fungal Associations: Ecology and Evolution. Oxford University Press, Oxford 2005, pp. 191-210.
- ↑ Kenji Matsuura, Edward L. Vargo, Kazutaka Kawatsu, Paul E. Labadie, Hiroko Nakano, Toshihisa Yashiro, Kazuki Tsuji: Queen Succession Through Asexual Reproduction in Termites. In: Science. 323, 2009, p. 1687. doi: 10.1126 / science.1169702
- ↑ Barbara L. Thorne: Termite-termite interactions: workers as an antagonistic caste. In: Psyche. 89, 1982, pp. 133-150.
- ^ H. Muller, J. Korb: Male or female soldiers? An evaluation of several factors which may influence soldier sex ratio in lower termites. In: Insectes Sociaux. 2008. doi: 10.1007 / s00040-008-0996-3
- ↑ Tobias Weil, Katharina Hoffmann, Johannes Kroiss, Erhard Strohm, Judith Korb: Scent of a queen-cuticular hydrocarbons specific for female reproductives in lower termites. In: Natural Sciences. 96, 2009, pp. 315-319. doi: 10.1007 / s00114-008-0475-8
- ^ SE Johnson, NL Breisch, B. Momen, BL Thorne: Morphology and gonad development of normal soldiers and reproductive soldiers of the termite Zootermopsis nevadensis nevadensis (Isoptera, Archotermopsidae). In: MS Engel (Ed.): Contributions Celebrating Kumar Krishna. ZooKeys. 148, 2011, pp. 15-30. doi: 10.3897 / zookeys.148.1672
- ↑ Barbara L. Thorne, James FA Traniello: Comparative social biology of basal taxa of ants and termites. In: Annual Revue of Entomology. 48, 2003, pp. 283-306. doi: 10.1146 / annurev.ento.48.091801.112611
- ^ Judith Korb: Workers of a drywood termite do not work. In: Frontiers in Zoology. 4, 2007, p. 7 doi: 10.1186 / 1742-9994-4-7
- ^ Marc A. Seid, Rudolf H. Scheffrahn, Jeremy E. Niven: The rapid mandible strike of a termite soldier. In: Current Biology. Volume 18, Issue 22, pp. R1049-R1050. doi: 10.1016 / j.cub.2008.09.033
- ↑ C. Bordereau, A. Robert, V. Van Tuyen, A. Peppuy: Suicidal defensive behavior by frontal gland dehiscence in Globitermes sulphureus Haviland soldiers (Isoptera). In: Insectes Sociaux. Volume 44, Number 3, 1997, pp. 289-297. doi: 10.1007 / s000400050049
- ^ Yael D. Lubin, G. Gene Montgomery: Defenses of Nasutitermes termites (Isoptera, Termitidae) against Tamandua anteaters (Edentata, Myrmecophagidae). In: Biotropica. 13 (1), 1981, pp. 66-67.
- ^ Christian Bordereau: Ultrastructure and formation of the physogastric termite queen cuticle. In: Tissue and Cell. 14 (2), 1982, pp. 371-396. doi: 10.1016 / 0040-8166 (82) 90034-9
- ↑ Wilfried Truckenbrodt: About the imaginal ovarian enlargement in connection with physogastry in Odontotermes badius Haviland (Insecta, Isoptera). In: Insect Sociaux. 20 (1), 1973, pp. 21-40. doi: 10.1007 / BF02223559
- ^ Pedro Wygodzinsky: Thysanura associated with termites in Southern Africa. In: Bulletin of the American Museum of Natural History. 142 (3), 1970, pp. 211-254.
- ↑ Steen Dupont, Thomas Pape: A review of termitophilous and other termite-associated scuttle flies worldwide (Diptera: Phoridae). In: Terrestrial Arthropod Reviews. Volume 2, Number 1, 2009, pp. 3-40. doi: 10.1163 / 187498309X435649
- ↑ Cleide Costa, Sergio Antonio Vanin: Coleoptera Larval Fauna Associated with Termite Nests (Isoptera) with Emphasis on the “Bioluminescent Termite Nests” from Central Brazil. In: Psyche. 2010. doi: 10.1155 / 2010/723947
- ↑ z. B. Kent H. Redford: The Termitaria of Cornitermes cumulans (Isoptera, Termitidae) and Their Role in Determining a Potential Keystone Species. In: Biotropica. 16 (2), 1984, pp. 112-119.
- ^ S. Higashi, F. Ito: Defense of termitaria by termitophilous ants. In: Oecologia. 80, 1984, pp. 145-147.
- ↑ Nan-Yao Su, Rudolf H. Scheffran: A review of subterranean termite control practices and prospects for integrated pest management programs. In: Integrated Pest Management Reviews. 3, 1998, pp. 1-13.
- ↑ Berhan M. Ahmed, John R. French, Peter Vinden: Review of Remedial and Preventative Methods to Protect Timber in Service from Attack by Subterranean Termites in Australia. In: Sociobiology. Vol. 44, No. 1, 2004, pp. 1-16.
- ^ Report of the UNEP / FAO Global IPM Facility Termite Biology and Management Workshop. February 1-3, 2000. Geneva, Switzerland (PDF) ( Memento of the original from October 20, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , P. 18.
- ↑ G. Henderson, C. Dunaway: Keeping Formosan termites away from underground telephone lines. In: Louisiana Agriculture. 42, 1999, pp. 5-7.
- ^ Herbert Weidner: Termites in Hamburg. In: Journal for plant diseases (plant pathology) and plant protection. 47, 1937, pp. 593-596.
- ↑ Herbert Weidner, Udo Sellenschlo: 9 termites. In: Storage pests and domestic pests: Determination tables for Central Europe. 7th edition. Springer Verlag, 2010, ISBN 978-3-8274-2406-8 .
- ^ H. Hertel, R. Plarre: Termites in Hamburg. COST Action E22 Final Workshop, Estoril, Portugal, 22-23 March 2004. 2004. DOCUMENTS FOR DOWNLOAD ( Memento from February 24, 2005 in the Internet Archive )
- ↑ Holzfragen.de
- ↑ G. Becker, U. Kny: Survival and development of the dry wood termite Cryptotermes brevis (Walker) in Berlin. In: Scoreboard for pest science, plant protection, environmental protection. 50, 1977, pp. 177-179.
- ^ Rudolf H. Scheffrahn, Jan Krecek, Renato Ripa, Paola Luppichini: Endemic origin and vast anthropogenic dispersal of the West Indian drywood termite. In: Biological Invasions. 11, 2009, pp. 787-799. doi: 10.1007 / s10530-008-9293-3
- ↑ F. d'Errico, LR Backwell, LR Berger: Bone tool use in termite foraging by early hominids and its impact on our understanding of early hominid behavior. In: South African Journal of Science. 97, 2001, pp. 71-75.
- ↑ Crickette Sanz, Dave Morgan, Steve Gulick: New Insights into Chimpanzees, Tools, and Termites from the Congo Basin. In: American Naturalist. 164 (5), 2004, pp. 567-581.
- ↑ K. Krishna, DA Grimaldi, V. Krishna, MS Engel: Treatise on the Isoptera of the World. In: Bulletin of the American Museum of Natural History. 377, 2013, pp. 1–200. doi: 10.1206 / 377.1
- ↑ Michael S. Engel, David A. Grimaldi, Kumar Krishna: Termites (Isoptera): Their Phylogeny, Classification, and Rise to Ecological Dominance. In: American Museum Novitates. Number 3650, 2009, pp. 1-27. doi: 10.1206 / 651.1
- ↑ The species numbers follow the termite database (as of January 17, 2012, see under web links).
- ↑ Michael S. Engel, David A. Grimaldi, Kumar Krishna: Primitive termites from the Early Cretaceous of Asia (Isoptera). In: Stuttgart contributions to natural history. Series B: 371, 2007, pp. 1-32.
- ↑ P. Vrsanansky: Cockroach as the Earliest Eusocial Animal. In: Acta Geologica Sinica - English Edition. 84, 2010, pp. 793-808. doi: 10.1111 / j.1755-6724.2010.00261.x
- ↑ Kumar Krishna, David A. Grimaldi: The First Cretaceous Rhinotermitidae (Isoptera): A New Species, Genus, and Subfamily in Burmese Amber. In: American Museum Novitates. Number 3390, 2003, pp. 1-10. doi : 10.1206 / 0003-0082 (2003) 390 <0001: TFCRIA> 2.0.CO; 2
- ↑ Kumar Krishna, David Grimaldi: Diverse Rhinotermitidae and Termitidae (Isoptera) in Dominican Amber. In: American Museum Novitates. Number 3640, 2009, pp. 1-48. doi: 10.1206 / 633.1
- ↑ Michael S. Engel, David A. Grimaldi, Kumar Krishna: A synopsis of Baltic amber termites (Isoptera). In: Stuttgart contributions to natural history. Series B (geology and paleontology). 372, 2007, pp. 1-20.
- ↑ Maurice Maeterlinck: The life of the termites. DVA, Stuttgart 1927, orig. La Vie des Termites. 1926.
- ↑ Eugene Marais: The Soul of the White Ant. Langen Müller, Munich 1970. ( English full text )
literature
- Judith Korb: Cathedrals in the savannah. Termites and their nests . In: P.-R. Becker, H. Braun (ed.): Nestwerk - architecture and living beings . Isensee, Oldenburg 2001, ISBN 3-89598-814-6 , p. 122-129 .
- Judith Korb: Termites, hemimetabolous diploid white ants? In: Frontiers in Zoology . No. 5 , 2008, p. 15 , doi : 10.1186 / 1742-9994-5-15 (open access).
