Water dwarf
| Water dwarf | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Water dwarf ( Plea minutissima ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Plea minutissima | ||||||||||||
| Leach , 1817 |
The water dwarf ( Plea minutissima , syn .: P. leachi, P. atomaria ) is a bug (Heteroptera) and belongs to the family of dwarf swimmers (Pleidae) within the suborder of water bugs (Nepomorpha). In Europe it is the only species of the genus Plea . The generic name is derived from the Greek pleo = ship or sail and refers to the animal's ability to swim. Water dwarfs live exclusively aquatic and swim mainly in the supine position.
distribution and habitat
The water dwarf occurs throughout Europe with the exception of the far north. The bed bug species is also native to the Mediterranean region, including North Africa and the Middle East , Central Asia and West Siberia . The bugs live in heavily weed, stagnant and slowly flowing waters of various kinds. They usually climb around between aquatic plants and even under duckweed covers and are very common in places.
description
Water dwarfs are very small, about two to three millimeters in size, sociable bedbugs with a noticeably high arched back. This is still flattened in young larvae. The fore wing covers ( hemielytras ) show the structure characteristic of bedbugs. The hind wings are reduced in most individuals. These are not airworthy. The bugs have large compound eyes , the point eyes ( ocelli ) are reduced. As with all water bugs, their tripartite antennae are shorter than their head. The scutellum is small and triangular. Their forelegs are not designed to be fangs. The legs are not designed like typical swimming legs, but the animals are nimble swimmers and predators. All tarsi are tripartite. Both sexes have organs of sound and hearing between the front and mid- chest.
breathing
As with back swimmers (Notonectidae), row bugs (Corixidae) and swimming bugs (Naucoridae), the body of the dwarf swimmer is covered by an air film ( plastron ), which is held on the back by the wings and on the underside by water-repellent ( hydrophobic ) hairs. Due to total reflection at the interface between air and water, the underside appears shiny silver. This air supply is used for breathing and additionally supplies oxygen according to the principle of the physical gill . A large part of the air supply is held in the water dwarfs on the belly side by means of fine hairs. Larger cones on each abdominal segment expand the air layer considerably, so that these animals can only find a stable balance when lying on their backs.
nutrition
Water dwarfs are predators. They prey on mosquito larvae , mussel crabs , water fleas and other small water arthropods, which they grab with rapid movements and suck out while floating in the water with the help of their proboscis.
Reproduction and development
The adult bugs ( adults ) in mud and under stones appear in open water in spring from around April. Soon after, the mating season begins. When mating, the smaller male first clasps the female from the back, but then copulates from the side . After two to three hours, the animals separate. The females lay their eggs by boring them with the ovipositor into the leaves of aquatic plants. After three to four weeks, embryonic development is over and the larvae hatch from the eggs. Like all bedbugs, the water dwarfs are hemimetabolic , but the larvae go through six instead of five larval stages, separated by moulting, before the full insect hatches.
Sound generation
The stridulation organs are located between the front and middle sides of the chest of both sexes . There is a friction strip on the middle chest. This grinds the sharp-edged protrusions of the front breast with nodding movements. The sounds produced in this way should only be audible by humans when at least seven animals are “singing”. An organ of hearing (tympanum) is also developed in both sexes. It is located on the front edge of the mid-chest piece. The eardrum is clamped in a chitinized frame and is connected to a nerve. A pin is embedded in this nerve, which is excited when the eardrum membrane vibrates. The sounds are probably used to form swarms, especially during the breeding season.
swell
- E. Wachmann , A. Melber & J. Deckert: Bugs. Volume 1: Dipsocoromorpha, Nepomorpha, Gerromorpha, Leptopodomorpha, Cimicomorpha (Part 1), revision of the bugs in Germany, Austria and German-speaking Switzerland, Goecke & Evers, Keltern, 2006. ISBN 3-931374-49-1
- KHC Jordan: Water bugs. The New Brehm Library, Leipzig, 1950.
- E. Security guard: watch bugs - get to know . J. Neumann - Neudamm, Melsungen 1989, ISBN 3-7888-0554-4
