German cockroach
| German cockroach | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
German cockroach ( Blattella germanica ) |
||||||||||
| Systematics | ||||||||||
|
||||||||||
| Scientific name | ||||||||||
| Blattella germanica | ||||||||||
| ( Linnaeus , 1767) |
The German cockroach ( Blattella germanica ), also Swabian beetle, Prussian, Russian, French and others. a., and like the common cockroach ( Blatta orientalis ) also called cockroach (cockroach) , is a type of cockroach . It is known as a stored product pest , which can also cause health damage by transmitting pathogens to humans.
features
Adult cockroaches are 13 to 16 mm long and light to dark brown in color. There are two parallel black longitudinal stripes on the prothorax . The females are darker in color than the males.
Compared to the males, their abdomen is wider and rounded at the back. The adult animals have wings but cannot fly. In the case of the lighter males, one can only observe a gliding flight . But the German cockroach is a good runner and can travel up to 29 cm per second.
The German cockroach is oviparous and produces 6 to 9 mm long, light to medium brown colored egg containers. The egg packets ( oothecae ) are usually more than twice as long as they are wide and slightly curved into a sickle shape. The first two larval stages have a dark brown to black colored breast. There is a light brown stripe on the back. The later larval stages are lighter in color.
The German cockroach is generally nocturnal and spends around 75% of the day in its hiding place. Animals roaming around during the day usually indicate a very strong infestation and a high density of stocking in the hiding places.
confusion
The amber forest cockroach ( Ectobius vittiventris (A. Costa, 1847)), which looks very similar to the German cockroach in size, shape and color, has been observed in southern Europe, in the Alpine region and in recent years increasingly in southern Germany . The most noticeable difference is that in the amber wood cockroach the disc of the pronotum has no parallel dark longitudinal stripes. In addition, at least the males of Ectobius vittiventris are relatively good fliers. Mostly it is these that get lost in human dwellings, but in contrast to the German cockroach do no damage, but perish after a few days. Control measures are therefore not necessary when the amber forest cockroach occurs. The forest cockroach feeds on decomposed plant material and, in contrast to Blattella germanica, often shows daily activity.
Another similar and harmless wood cockroach is the Lapland wood cockroach ( E. lapponicus ), which occurs mainly in Northern Europe and has already got lost in houses there.
development
The adult cockroaches copulate just a few days after molting , and the first ooth is formed after 1 to 2 weeks. The mean life expectancy of the adult animals is 100 to 200 days.
During this period, the females produce approx. 4 to 8 ooths (on average 5), each of which can contain 18 to 50 eggs, mostly approx. 36. The egg containers are carried around by the females during embryonic development and supplied with moisture and nutrients. The females reduce their activity while carrying the oothecae.
Shortly before the larvae hatch, the females seek a source of water and increase their haemolymph pressure by absorbing water , which can cause the ootheca to be rejected. The obligatory water intake of the females ensures that the newly hatched larvae, which only have a narrow radius of action, have a source of moisture available. The larvae remain in their hiding places for the last three days before the next molt and prepare for this process. The first two larval stages have only a small radius of activity in the area of their sources of moisture.
The development from egg to sexually mature imago can be completed after 40 days under optimal conditions. It usually lasts 2 to 3 months, rarely more than 7 months.
The adults as well as the older larval stages can go hungry for up to 40 days if sufficient moisture is available.
Occurrence
The German cockroach is the most common species in the moderate latitudes and occurs in restaurants, large kitchens , hotels, hospitals, but also in (mostly centrally heated) apartments.
The focus of the attack is often in kitchens or rooms in which food is processed. Due to the high temperature and humidity, laundries are also popular with the German cockroach and can play an important role in their distribution, especially in hospitals. Zoological gardens and pet shops also often have cockroach problems due to the high temperatures there.
Modern shopping centers are particularly at risk because of the warmth, the diverse food supply and the numerous hiding spots. Cattle sheds (especially pig stalls) on farms can also be populated by the German cockroach.
In the open air this species can only survive in favorable warm conditions, e.g. B. in red landfills . Areas with a temperature of more than 20 ° C, near a source of food and moisture (behind sinks, kitchen cabinets, heat exchangers from refrigerators, but also in electrical devices) are preferred. The animals are regularly found behind rub strips, door frames, defective tiles, wall joints , pictures and mirrors.
Shafts with hot water, drainage and heating pipes, district heating systems and garbage disposal systems are also ideal hiding places and at the same time serve for distribution. During the activity time, the animals can also stay in cold areas (e.g. to eat). However, below 4 ° C the animals are no longer active. Its upper temperature limit is 42 ° C.
Every gap in the vicinity of a food source can be used as a hiding place during the day, whereby the cockroaches show a conspicuous aggregation behavior that is controlled by so-called aggregation pheromones that are released with the feces. In the first larval stage, gaps 1 mm in height are sufficient, the adults need at least 5 mm.
The animals are usually brought into the living area in food packaging (e.g. corrugated cardboard), in pallets and the like, but also in used electrical devices (refrigerators, televisions, microwaves, etc.). Continuous immigration into the area can take place from a favorable source of infestation (e.g. an inn).
nutrition
The German cockroach is omnivorous. However, as an unspecialized species, unlike monophages, it is dependent on materials that are easily digestible in terms of energy. Wood, leather or paper alone are not enough. The activity of the animals depends on the one hand on the availability of food and on the stage of development or on the physiology .
Harmful effect
The feeding damage caused by the German cockroach to food and supplies, but also to leather , textiles and paper is mostly minor. The contamination of food with feces , however, crop content or secretions from the salivary glands are a not to be underestimated health risk. On farms occurs due to the transmission of pathogens by scraping on the cattle losses in meat and milk yield.
Because of the pollution and the bad smell caused by the cockroaches, contaminated food is no longer suitable for human consumption.
German cockroach as a disease carrier
It is without a doubt the carrier of the following diseases: anthrax , salmonellosis and tuberculosis . It is also an intermediate host for roundworms .
A study conducted in the United States in 2005 by the National Institute of Environmental Health Sciences (NIEHS) and the National Institute of Allergy and Infectious Diseases (NIAID) found that cockroach-derived allergens can cause symptoms of asthma to a greater extent than other known triggers.
In Central Europe, the species is of no particular importance as a vector of diseases.
Combat
The timely detection of infestations is important. Detectors (glue traps) with appropriate attractants are ideally suited for this.
German cockroaches can be fought by using bait or sprays . In this case, baiting with food poisons is to be preferred, as they pose the fewest risks for the environment. Since combating cockroaches by individual measures does not bring any resounding success, only continuously carried out and checked control according to a fixed system can lead to a permanently effective result. Chemical controls should only be carried out by knowledgeable pest controllers.
The development of German cockroaches is heavily dependent on the food and water supply in the infested areas. Therefore, cleanliness and the absence of water increase the rapid eradication success in combats and reduce the risk of resettlement.
German cockroaches use all crevices in the masonry , on machines etc. as nesting sites. Therefore, all cracks in walls, on the floor etc. should be closed.
literature
- Sophie Hutter: Food scent neurons in the cockroach's antenna lobe: reactions to continuously increasing scent concentration. Vienna, Univ., Thesis 2003.
- Mike Dombrowski: Investigations on the behavior of the German cockroach, Blattella germanica L., towards vegetable repellents . Potsdam, Univ., Dissertation 1992. 133 Bl.
- Barbara Auer: On the epidemiological significance of the cockroach (Blatta orientalis L.). Vienna, Univ., Thesis 1993.
Web links
- Leaflet from the Pest Control Advice Center of the City of Zurich: The German Cockroach (PDF file, 139 kB).
Individual evidence
- ↑ Hannes Baur, Isabelle Landau Lüscher, Gabi Müller, Marcus Schmidt, Armin Coray (2004): Taxonomy of the amber wood cockroach Ectobius vittiventris (A. Costa, 1847) (Blattodea: Blattellidae) and its distribution in Switzerland. Revue Suisse de Zoologie 111 (2): 395-424.
- ↑ Arndt Reuning , The Scent of the Cockroaches Deutschlandfunk, Research News on December 8, 2015.
- ↑ M. Faulde, G. Hoffmann (2001): Occurrence and prevention of vector-associated diseases in humans in Germany with consideration of zoonotic aspects. Federal Health Gazette 44 (2): 116-136. doi : 10.1007 / s001030050422 .