Aedes vexans

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Aedes vexans
Aedes (Aedimorphus) vexans

Aedes (Aedimorphus) vexans

Systematics
Family : Mosquitoes (Culicidae)
Subfamily : Culicinae
Tribe : Aedini
Genre : Aedes
Subgenus : Aedimorphus
Type : Aedes vexans
Scientific name
Aedes vexans
( Meigen , 1830)

Aedes vexans (sometimes referred to as "Rhine Schnake") is a mosquito that is widespread almost all over the worldand is the most common of the species of the mosquito family occurring in Germany. It is the only species of the subgenus Aedimorphus represented in Europewithin the large genus Aedes .

Because of their way of life they are counted among the "flood mosquitoes". Because of its breeding area in flooded alluvial forests and meadows, this species, which occurs in large numbers , is also referred to as a meadow mosquito or alluvial forest mosquito, just like other mosquito species common there, for example Aedes sticticus , Aedes rossicus and Aedes cinereus . Their massive distribution is countered in various places by targeted biological pest control .

features

Adult Aedes vexans reach a length of about 6 millimeters. Their body is brown to golden brown. The trunk and the short palpi are darkly scaled, with a few light scales at the tip of the palpi. The back and the tapering abdomen have light gray to whitish scales that form B-shaped patterns. The tibiae are dark on top and light on the underside. The tarsi of the hind legs have thin white bands at their ends.

The body of the larva is divided into the head with mouthparts, eyes and antennae, three fused breast segments and nine abdomen segments. On the eighth segment of the abdomen, there is a strong breathing tube with a tuft of hair in the middle or slightly above the middle. The larvae hang upside down on the water surface with the breathing tube. The shape of the breathing tube can be used to differentiate the different types of mosquitoes.

Occurrence

Aedes vexans is distributed almost worldwide and is found in the Holarctic , the Oriental , Mexico , parts of Central America , the Transvaal region, and some Pacific islands.

Way of life

The Aedes males gather in the evening, when the humidity is high or in the afternoon in heavily shaded forest areas, often in swarms of several thousand mosquitos . The males, which move up and down at a height of about 2 meters, generate a species-characteristic buzzing sound through the beat of their wings, which attracts the females. These are captured and mated in flight. After copulation, the female sets out to suckle blood. This is absolutely necessary for the further development of the eggs. The mosquito covers a total of up to 10 kilometers per day. The females migrate from island to island, i.e. zones with living conditions that are favorable to them, especially high humidity, in which they survive the dry heat of the day. In addition to active migration, it also happens that entire swarms are carried away by the wind over long distances. After sucking blood, during which the female mosquitoes have ingested about twice their body weight, they use the proteins contained in the blood within 5 days to build their eggs (egg maturation). With a blood uptake, a female can form up to 100 black elongated oval spindle-shaped eggs 0.7 mm × 0.2 mm in size, which she lays individually in the moist soil of meadows and alluvial forests . The eggs are heavier than water, so they don't swim. After that, the mosquito can produce more eggs without re-mating if it can ingest blood.

The larvae develop in the eggs within an embryonic phase of around 8 days. However, these only hatch when the egg shell comes into oxygen-poor water with a temperature of more than 10 ° C (due to a flood). The lack of oxygen after going into the water causes a muscle to contract, which presses the hatch - a sharp, hardened spike on the head - against the egg shell. The egg shell then breaks open at a pre-formed point . The cap of the spindle-shaped egg flakes off and the embryo can hatch out. Oxygen-rich water inhibits the hatching instinct, which may be a protection against fish swimming in oxygen-rich flowing water. In addition, the strong current would displace the larvae. If there is no flooding, the eggs can survive for at least three years.

The larva develops into a mosquito via four larval stages and one pupal stage. Depending on the water temperature, it takes 1 to 3 weeks for this, the pupal stage lasts 2 to 4 days.

Importance to humans

Aedes vexans spreads various diseases such as tahyna , myxomatosis , encephalitis and Dirofilaria immitis depending on the area through its stings . In the flood-rich summer months, there are more frequent occurrences of mosquitoes than any other species of mosquito on bodies of water such as the Elbe , Danube or Lake Constance , but especially on the Rhine . Aedes vexans makes up over 80 percent of the individuals of the 33 mosquito species found in the Upper Rhine . It is not uncommon for 50,000 Aedes eggs to be detected in one square meter of the bank of a flood pool.

Along the Upper Rhine have because of the mosquitoes plague, mainly because of the mass occurrence and highly migratory readiness of Aedes vexans nearly 100 municipalities, municipal working group to combat mosquitoes plague together and fight with a larvicide based on proteins of the bacterium Bacillus thuringiensis israelensis development the mosquitoes.

Systematics

The subgenus Aedimorphus of the genus Aedes , to which Aedes (Aedimorphus) vexans also belongs, was a separate genus from 2009 to 2015.

In the eastern Palearctic , the subspecies Aedes (Aedimorphus) vexans nipponii ( Theobald ) has been described, which differs from the nominate form by a different scaling of the terga and pleurites .

Individual evidence

  1. ^ Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine, page 30
  2. ^ Norbert Becker: Mosquitoes and their control . Springer, 2003, ISBN 978-0-306-47360-9 , pp. 201-203 .
  3. ↑ a b Jerome Goddard: Physician's guide to arthropods of medical importance . 4th edition. CRC Press, 2003, ISBN 978-0-8493-1387-5 , pp. 272 .
  4. ^ Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine, pages 35, 36, 37
  5. ↑ a b Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine, page 50
  6. ^ Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine . Pages 41, 101
  7. ^ Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine, page 33
  8. ^ Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine, pages 34, 41, 55
  9. ^ Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine, page 44
  10. ↑ Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine, page 47
  11. ^ CM O'Malley: Aedes vexans (Meigen): An old foe. Proc. NJ Mosquito Control Assoc, pp. 90–95, 1990 Online ( December 30, 2013 memento in the Internet Archive )
  12. ^ John F. Reinert, Ralph E. Harbach & Ian J. Kitching: Phylogeny and classification of Aedini (Diptera: Culicidae). Zoological Journal of the Linnean Society, 157, pp. 700–794, 2009 PDF (English)
  13. ^ Richard C. Wilkerson, Yvonne-Marie Linton, Dina M. Fonseca, Ted R. Schultz, Dana C. Price, Daniel A. Strickman: Making Mosquito Taxonomy Useful: A Stable Classification of Tribe Aedini that Balances Utility with Current Knowledge of Evolutionary Relationships. PLoS ONE 10, 7, e0133602, July 2015 doi : 10.1371 / journal.pone.0133602

literature

  • Norbert Becker, Dušan Petrič, Marija Zgomba, Clive Boase, Christine Dahl, John Lane, Achim Kaiser: Mosquitoes and their control . Springer, 2003, ISBN 978-0-306-47360-9 , pp. 201-203 .
  • Norbert Becker, Paul Glaser, Hermann Magin: Biological mosquito control on the Upper Rhine , (commemorative publication) 20 years of communal action group to combat the snake plague, 1996 ISBN 3-00-000584-6

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