Row bugs
| Row bugs | ||||||||||||
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Fallén's water cicada ( Subsigara falleni ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Corixidae | ||||||||||||
| Leach , 1815 |
Row bugs (Corixidae) are a family of bed bugs (Heteroptera) within the suborder of water bugs (Nepomorpha). They occur worldwide with over 500 species . In Europe 81 species and subspecies are known, in Central Europe there are 35. The animals live in water bodies and only leave them to colonize new habitats. Before mating, the males “sing” ( stridulate ), which is why the bugs are also known as water cicadas .
features
The bugs reach body lengths between 2 and 14 millimeters. They have a streamlined, flatboat-like shape and have a very uniform, dark basic color, which is interrupted yellow on the fore chest and the wing covers. These drawings are very variable. Most species have well developed hind wings and are good fliers. The forewings show the so-called hemielytres characteristic of bedbugs . They are flat on the upper side of the abdomen (swimming abdomen applied).
The hind legs are developed into powerful rowing organs. The thigh ( femur ), splint ( tibia ) and two-part foot ( tarsus ) are flattened and provided with a dense trim of long, bristle-like webbed hair. The coxae of the hind legs are movable and folded. The middle pair of legs is also hairy and is mainly used to hold on to plants or the like. The front legs are shortened and each has a shovel-shaped tarsal link, the pala . Due to their low specific weight, the animals have a tremendous amount of buoyancy, so that they virtually shoot through the distance from the bottom of the water upwards. They are thereby able to pierce the surface skin and immediately go into flight.
Their antennae are very short. They have no point eyes ( ocelli ) and their scutellum is small. The trunk (rostrum) is very short and, unlike other types of bedbugs, has no saliva canal.
Habitats
The animals mainly live in stagnant water. They prefer to stay at the bottom of the water and only occasionally appear to renew the air supply to the water surface. The greatest biodiversity and density of individuals in row bugs occurs in small bodies of water that lack fish. They can only be found in the open water of larger bodies of water in the absence of their predators. But mostly they live in dense aquatic vegetation. Most species live in fresh water, only a few tolerate brackish water and very few species can exist in salt water. So-called dispersion flights to colonize new habitats occur mainly in spring and autumn, when the population densities are high. Possible new habitats are recognized by the shiny water surface.
breathing
The size of the pronotum is striking in row bugs . Underneath there is a cavity that is closed on all sides. The three pairs of thoracic spiracles are associated with this space. In contrast to all other water bugs, the row bug comes out of the water with its front end when breathing. She moves her head and chest forward a few times while sucking air into the cavity. Then she dives headfirst down. Due to the buoyancy, the air is distributed to the end of the body. There is also a supply of air under the wing covers. From time to time the bug brushes its hind legs over the head, front chest and wings to evenly distribute the air layer. The air film is held in place by water-repellent ( hydrophobic ) hairs. Due to total reflection at the interface between air and water, the underside appears shiny silver. This air supply supplies the vital oxygen according to the principle of the physical gill . Younger larvae absorb the oxygen dissolved in the water directly through the body surface. From the third larval stage onwards, they carry a renewable air bubble with them in the chest and abdomen area.
nutrition
The diet of row bugs is still discussed in the literature. In addition to the observation of predatory behavior, the analyzes of intestinal contents speak in favor of the ingestion of plant and animal remains ( detritus ) and algae . Perhaps the most species omnivorous ( omnivorous ) or are in the course of development or gender different diets. The short proboscis ( rostrum ) of the row bugs is very different from that of the other types of bed bugs. The piercing bristles do not form a saliva canal. They are greatly shortened and are used to chop up food. Apparently, larger food particles can also be absorbed into the intestine. In most species, the only phalanxes of the front legs (pala) are designed in a special way: They resemble a more or less wide shovel, with the help of which the waste materials on the ground can be brought to the mouth.
Sound generation
During the mating season, the males of several types of row bugs produce species-specific noises ( stridulation ) that humans can perceive outside of the water . These are promotional, rival or spontaneous chants. In most species there is an extensive shrill field with characteristically shaped bristles on the inside of the fore legs, which is brushed over the sharp side edges of the head. The vibrations are transmitted to an air bubble attached to the chest ( thorax ), which then oscillates at its natural frequency . The song of a single bug usually stimulates other males to stridulate. After a certain break-in period, all males chirp in the same rhythm at intervals of about three seconds. In some species the females are also able to produce sounds. Hearing organs ( tympanic organs ) are located on the mid-chest ( mesothorax ) in both sexes .
Reproduction and development
The mating season begins in spring. The male grabs the female from behind and holds it with the specially designed front legs. The one-limbed foot, the pala, is provided with a series of strong thorns in the males to prevent it from sliding off the female during mating.
After copulation, the egg-laying period begins, which lasts about a month. The females usually stick their eggs to water plants or stones. Row bugs, like all bed bugs, are hemimetabolic . The larvae hatching from the eggs go through five larval stages separated by moults. Depending on the climatic situation, one or two generations are trained each year. Almost all species overwinter as an adult, only rarely do they overwinter in the larval or egg stage.
Species and subspecies in Europe
81 species are currently recorded in Europe. There is also another species, Tichocorixa verticalis verticalis (fever 1851), which comes from North America and is naturalized in Spain
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swell
- ↑ H. Günther (2004): Trichocorixa verticalis verticalis (fever), a nearctic row bug in Europe (Heteroptera: Corixidae) . - 29 (1/2): 45-49.
- ^ Corixidae. Fauna Europaea, accessed December 1, 2006 .
- KHC Jordan: Water bugs. The New Brehm Library, Leipzig 1950.
- Ekkehard Wachmann : watch bugs - get to know . J. Neumann - Neudamm, Melsungen 1989, ISBN 3-7888-0554-4
- E. Wachmann, A. Melber & J. Deckert: Bugs. Volume 1: Revision of the bugs in Germany, Austria and German-speaking Switzerland, Goecke & Evers, Keltern 2006, pp. 22–46, ISBN 3-931374-49-1
