Root bug
| Root bug | ||||||||||||
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Ground bug ( Aphelocheirus aestivalis ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Aphelocheirus aestivalis | ||||||||||||
| ( Fabricius , 1794) |
The ground bug ( Aphelocheirus aestivalis ), from the family of ground bugs (Aphelochiridae), belongs to the order of bugs (Heteroptera) within the suborder of water bugs (Nepomorpha). It lives exclusively aquatic and leads a hidden way of life at the bottom of water in up to several meters depth.
distribution and habitat
The root bug is only native to the Old World . It is widespread throughout Europe , in the Mediterranean area only on the northern edge. To the east it occurs across Asia Minor to the Caspian Sea . It is common everywhere in Germany . In Austria , too , it is possibly more widespread than the scanty findings to date suggest. Due to its hidden way of life, the species has likely been overlooked many times. In Germany it also occurs in larger rivers such as the Weser , Spree , Rhine , Sieg , Nahe , Main , Neckar and Danube .
The bug lives on the bottom of clean, oxygen-rich streams and rivers with little vegetation, less often in lakes up to a depth of 6 meters. It burrows itself in fine layers of gravel or loose sandy soil or wanders around the bottom. She rarely swims.
features
The animals are between 8.2 and 11 millimeters in size. The body is short-oval and unusually flattened. The body surface is dark, mostly black-brown in color, sometimes spotted. The entire body has fine hair. The head is triangular. Point eyes ( Ocelli ) are missing. The proboscis ( rostrum ) is much longer than in all other water bugs and extends to the hips ( coxae ) of the third pair of legs. The scutellum is small.
In contrast to the closely related swimming bugs (Naucoridae), the front legs are not developed as catch legs. Also, the hind legs are not designed as typical swimming legs, as is the case with many other aquatic bed bugs. The hairline is comparatively small. As a rule, the individuals of the species are short-winged ( brachypter ). The cover wings ( Hemielytren ) are mostly reduced to short scales, which reach at most up to the second abdomen segment. The hind wings are almost completely regressed. For this reason, the back of the abdomen is more hardened ( chitinized ) than in fully-winged insects. Long-winged ( macroptere ), flightable animals are seldom observed. Their development is said to be favored by a lack of oxygen.
breathing
Oxygen is absorbed by so-called plastron breathing , that is, a thin layer of air that surrounds the body in cavities in the chest section and under the wings and is held in place by fine water-repellent ( hydrophobic ) hairs. It lies over the breath openings ( stigmas ). The gas exchange takes place according to the principle of the physical gill . The oxygen in the air layer diffuses from the water into it, not through the skin into the animal itself. Plastron breathing allows these bugs to remain submerged for life. The oxygen dissolved in the water can be used directly, unlike most other water bugs, which have to swim to the surface of the water to breathe. The eggs and older larvae of the ground bugs also have a plastron . The young larval stages, on the other hand, absorb oxygen directly through the body surface. The animals need oxygen-rich water, as is found in lively flowing waters.
nutrition
The ground bug feeds predatory on arthropods and molluscs living in the water : caddis flies , mosquitoes , stone flies , mayflies , dragonfly larvae and water snails . Small mussels such as ball mussels (Cyclas) or pea mussels (Pisidium) are sucked out with the long proboscis that the bug pushes into the gap in the shell. At the tip of the proboscis there are chemoreceptors , with the help of which the prey is tracked.
Reproduction and development
In the course of the year, including in winter, all stages of development can be found side by side. Mating and oviposition take place in spring and summer. During mating ( copula ), the male sperm is not brought directly into the female's semen container, but is deposited in the female's vaginal pocket in the form of a seed carrier ( spermatophore ). This form of copulation occurs only in the Micronectinae , a subfamily of the row bugs (Corixidae). After the copula has taken place, the female sticks the fertilized eggs to mussel shells or to pieces of branches of water plants. The larvae hatching from the eggs go through five larval stages, separated by moults.
credentials
- KHC Jordan: Water bugs. The New Brehm Library, Leipzig, 1950.
- E. Wachmann, A. Melber & J. Deckert: Bugs. Volume 1: Revision of the bedbugs in Germany, Austria and German-speaking Switzerland, Goecke & Evers, Keltern, 2006, pp. 49–50. ISBN 3-931374-49-1
