Black flies

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Black flies
Black fly

Black fly

Systematics
Class : Insects (Insecta)
Superordinate : New winged wing (Neoptera)
Order : Fly (Diptera)
Subordination : Mosquitoes (Nematocera)
Partial order : Mosquito-like (Culicomorpha)
Family : Black flies
Scientific name
Simuliidae
Newman , 1834

The black flies (Simuliidae) are a family of the two-winged (Diptera) and belong to the mosquitoes (Nematocera). Around 2000 species of this group of animals live worldwide, more than 50 species are known from Germany. These are mostly small mosquitoes with a body length between two and six millimeters.

The females of almost all black flies species (97.6 percent of species) are obligatory bloodsuckers in warm-blooded host species , including humans.

features

Black flies are small two-winged birds with a body length between two and six millimeters. Their physique is robust and stocky with short legs, so their habitus resembles small flies . As a rule, they are colored black (hence “blackflies”), but some species have a yellow to orange tint or a silvery light pattern.

The sexes can be easily recognized by the formation of the complex eyes: in the males these are very large, they meet in the middle of the head in a broad line ("holoptic"), in the females much smaller and broadly separated from each other by the forehead (frons) . In addition, males have two types of ommatidia ; those of the upper (slightly larger) half of the eye are much larger and usually lighter in color, with their help the females are recognized in the mating flocks. Point eyes ( Ocellen ) are absent in both sexes. The antennae usually consist of eleven segments (rarely less), they are pearl-like (constricted at the limb boundaries), short and usually narrowed towards the tip (conical). The mouthparts form a short proboscis that points downwards. The two elongated, four-part lower jaw probes, the third part of which is enlarged, are conspicuous. It has sensory papillae that serve as taste organs (chemosensors). The head is spherical, it is usually narrower, in the males sometimes as wide as the trunk section.

The body of the black flies is short and arched high, which gives the animals a hunched appearance. The crystal-clear or somewhat smoky, unmarked wings are broad and short, with a rounded oval shape. In the wing veins, cross veins occur only towards the base of the wing. The first three longitudinal veins to the wing leading edge (Costa, Subcosta and first radial branch) are dark colored, bristled and clearly stronger than the other veins. The three pairs of legs have elongated hips and five feet . The last has two strong claws, which in species that suckle on birds have a lobe-like appendage at the base. The elongated oval abdomen narrows slightly towards the tip, it has nine freely visible segments. The copulatory organs of the males at their tip are important for the identification of the species, since the species are very similar in their body shape and otherwise difficult to distinguish.

Suction proboscis and suction act

Both sexes of the black flies have short proboscis. This is only used by the females to suckle blood. The trunk of the males is somewhat simplified in construction. Both sexes suck nectar from flowers for their own nutrition, the blood meal only serves to form the egg clutches. Black flies are pool suckers ; This means that they tear a small wound with their mouthparts and suck up the blood that leaks from injured capillaries and that collects in a small blister under the skin. In other words, unlike mosquitoes , they do not sting blood vessels directly.

The proboscis consists of the labrum , the hypopharynx , the mandibles and the laciniae of the maxillae . In the act of pricking, the elongated triangular labrum and the hypopharynx are first pushed forward and pressed against the skin. There they are anchored by teeth at the end. Then a hole is cut in the skin with the toothed mandibles in a scissor-like movement. The labrum is stretched out into the wound, the lateral edges of which are supported by the laciniae. The toothed laciniae also serve as anchoring so that when the muscles are pulled, the entire trunk is drawn into the wound. The knife-like, serrated long hypopharynx further assists penetration. A food channel through which the blood is sucked is formed between the laciniae and labrum. At the same time, saliva is released through a saliva channel between the hypopharynx and the mandibles, which suppresses blood clotting.

A female blackfly has a meal of blood that takes a few minutes. Often there is a more or less prolonged bleeding. The sting can be very painful, especially when it hits nerves; sometimes it is only noticed when itching occurs due to the saliva released.

Way of life

Both sexes of the black flies are nectar suckers and accordingly fly to plants that have large and open nectaries (such as willow , ivy or parsnip ). Only the females are bloodsuckers of birds and mammals in almost all species . Such a blood meal is necessary for egg development. The host is found both through a carbon dioxide trace ( olfactory ) and optically. If a potential host is found, a test bite is first set; If the liquid found contains adenosine diphosphate (ADP) or adenosine triphosphate (ATP), the soaking process begins. Both the hosts and the positions of the sucking process are species-specific. Simulium equinum prefers to suckle on the auricles of horses and other large mammals, while Simulium erythrocephalum sucks on the abdominal skin of animals. About 2.4 percent of the species have underdeveloped mouthparts and are no longer able to sting; with them the females take no more food. The nutrients for the egg clutch are already stored here in the larval stage (so-called autogenous species).

Reproduction

To find a partner, the black flies form swarms in the vicinity of larger dark objects (e.g. trees). The wind must not be too strong (maximum 10 m / s) and the light intensity must be over 5000  lux . No mixed swarms of different species are formed. However, the mechanism for recognizing conspecifics is still unknown. When flying over these swarms, the females are approached by a male from below, mating begins immediately afterwards in the air and continues on the ground. In the sexual opening of the female, the male leaves a spermatophore . In some species, parthenogenesis , unisexual reproduction without male fertilization, occurs.

Larval development

A black fly dabs its eggs on the surface of a stream
Black fly larva
Larvae aligned in the current
Larval stages: 1) pupa, 2) larva

The number of eggs is species-specific. It ranges from about 50 for Prosimulium ursinum to 1000 for Simulium reptans per female. The eggs are always released on or into running waters. Often this is done by dabbing on the surface of the water. Simulium erythrocephalum lays the eggs on aquatic plants at water level, Simulium equinum submerges and lays the eggs on the underside of floating leaves. Simulium morsitans, in turn, lays the eggs on plant stems or in crevices above the waterline. The clutches are often surrounded by a gelatinous mass that absorbs up to 68% water at the beginning of development. This water-containing jelly acts as a protection against drying out when the eggs fall dry.

The black fly larvae can only be found in bodies of water, whereby the species-specific demands on water quality, flow speed and other factors vary greatly. Some species of black fly larvae therefore serve as control or monitoring organisms to determine the water quality and water quality by means of the saprobic system . Some species of the genus Simulium and Prosimulium are regarded as pointer species for water quality in the range from I to II.

Characteristic of the black fly larvae are the unpaired and retractable pectoral foot (pseudopod) and the hooked ring at the rear end of the larva. Both are reinforced with several hundred hooks that are arranged radially. With the help of the rear hook ring larvae on parts of plants, stones or other substrates are mounted in a web of very elastic silk by glands in the mouth parts is formed (Labialdrüsen) and is removed with the breast feet and applied to the substrate. From this position the body is placed freely in the flow. The larvae move around like the caterpillars , by climbing on a thread or simply by drifting. Breathing occurs through the skin, and anal papillae are also used for osmoregulation through ion uptake.

Most of the black fly larvae have a "catch net" to eat. On the upper lip there are two extensions that can be folded in and out, each carrying a hair fan. These are covered with a tough mucus in which the food particles ( debris and microorganisms) floating with the current get caught. These compartments are drawn along the mandibles for food intake , the mucus remains in the hair bristles above the mandibles. Some black fly larvae do not have a fishing net and feed by grazing on the substrate.

After six to nine larval stages, the larvae are fully grown and spin a slipper-shaped cocoon, which is attached to the substrate. Pupation takes place in this. The front end of the cocoon is open and directed against the current. This is where the pupa's spiracle gills are located . The shape and the number of lamellas on this breathing structure differs depending on the species, just like the shape of the cocoon in which the pupa is hooked with hooks at the rear end. The inside of the gill threads contained in the gill is filled with water via a basal opening, the outer wall consists of numerous vertically protruding, richly branched supports. The cavity system between the supports is filled with air and extracts oxygen from the surrounding water by diffusion. Due to a structure that is still largely unknown, it is connected to the tracheal system and enables the doll to breathe.

Hibernation usually takes place as a larva in Central Europe and as an egg in Northern Europe. The latter are frost-resistant and can be frozen intact. Pupation takes place only after reaching a threshold temperature, which is around four degrees Celsius for the Simulium species examined . This results in a simultaneous pupal development and a synchronization of hatching from the pupal shell in spring. In Central Europe one to six generations are formed per year, in tropical lowland rivers up to 16 generations can be formed per year. In some species, such as Simulium erythrocephalum , there are clear differences between the first generation in spring and later generations ( seasonal dimorphism ).

Harmful effects on humans and farm animals

In the case of black flies, a distinction must be made between species that annoy humans and animals and those that can damage health, for example as vectors of pathogens. Taken together, humans and pets make up about 10 to 20 percent of the species.

Black flies as a nuisance

A number of common black flies can become very annoying due to their large numbers. In addition to numerous stings, the cloud-like, dense swarms in some habitats can lead to a nuisance, as numerous animals enter the mouth and nose and are unintentionally inhaled into the lungs. In Europe, these include the species Simulium truncatum , S. maculatum , S. posticatum , S. reptans , S. erythrocephalum and all species of Simulium , subgenus Wilhelmia .

In some species, humans are also accepted as hosts. The bite is often painful and has a local blood thinning and bruising result, as with the saliva of the mosquito anticoagulant get into the wound. In addition, histamine is released in the wound when it is bitten , which often leads to pseudo-allergic reactions. Symptoms range from wheal and nodule formation to extensive erythema and edema , accompanied by persistent itching, sometimes painful. Lymphangitis can be triggered by uncontrolled scratching . Repeated bites lead to the clinical picture of simuliosis (also "black fly fever") with headache, chills, nausea and nausea, swelling and softness of the lymph nodes, acutely painful joints and fatigue.

In grazing cattle, after frequent stings, the clinical picture of simuliotoxicosis occurs due to an over-sensitive reaction to the toxins contained in the mosquito's saliva. In the worst case, there is a risk of blood poisoning (toxemia).

In the event of mass infestation, black flies can thus cause the death of grazing animals. In addition to cardiovascular failure and massive skin irritation, the animals are particularly harmed as a result of the panic caused by the parasites and the uncontrolled escape associated with it. As a preventive measure, insecticides are therefore used at collection points . The Columbian or Golubatz mosquito ( Simulium colombaschense ) is particularly notorious in the Danube countries in the Balkans . One can read about this species in Brehms Tierleben (1920):

"The most notorious European gnome is the Columbian mosquito, so named after the Serbian villages of Kolubaz, where the superstition of the population lets it escape from a rock cave in which the alleged knight St. George killed the dragon."

It also says there:

“In the regions of the whole lower Danube they spread fear and horror among people and cattle. Thousands and thousands barely escaped big gnats crawling the grazing animals, horses, cattle and sheep in the nose, ears and mouth bite and suck blood, so that the tortured animals from lawn as rabid and eventually collapse dead from exhaustion ". (Note: midges and blackflies were still combined into one family at that time)

The species used to be responsible for up to 22,000 deaths of cattle per year in the Danube valley. The last major outbreak, in 1950, caused around 800 animals to die. Since then the damage has decreased significantly. It is possible that the species was unintentionally displaced by the construction of dams on the Danube because the flow conditions changed. The species no longer occurs in the areas of the Danube that were previously most affected.

Black flies as a disease carrier

Especially in subtropical and tropical Africa, but also in South America, representatives of the black flies are also vectors of the nematode Onchocerca volvulus to humans. This worm is the causative agent of onchocerciasis (river blindness), which leads to blindness in around ten percent of patients. The disease carriers are exclusively some representatives of the genus Simulium , such as S. damnosum and S. neavei in Africa and S. callidum and S. metallicum in Central America, and also S. ochraceum in Central and South America. Other filariasis pathogens, such as Mansonella ozzardi, are also transmitted to humans, especially in the rainforest areas of South and Central America.

See also: Parasites of humans

Phylogeny

In the traditional systematics, based on the work of Willi Hennig , the Simuliidae together with the midges (Ceratopogonidae), the mosquitoes (Chironomidae) and the dark mosquitoes (Thaumaleidae) formed the superfamily of the Chironomoidea within the suborder of the Culicomorpha. More recent studies on a morphological and genetic basis have only partially supported this grouping. It is true that the Culicomorpha consistently proved to be monophyletic. However, the superfamily of the chironomoid could not be maintained. According to the results, the mosquitos, the eponymous taxon, do not belong, while the other three families presumably form a natural unit (named by Borkent, as a superfamily, Simulioidea). According to the results, the sister group of the Simuliidae are the Thaumaleidae. Both families are morphologically similar in shape as imagines (relatively robust, short-legged forms, antennae short, not modified in the males), but they do not show any unambiguous morphological synapomorphies and were usually not considered to belong together in investigations on a morphological basis.

Systematics

The black flies can be divided into two subfamilies, which are listed here with the associated genera. One of the two, Simuliinae , can be further subdivided into two tribes : The Simuliini and the Prosimuliini. The large and species-rich genus Simulium is split up by numerous authors (genera Eusimulium , Nevermannia , Wilhelmia , Boophthora etc.). Today these are mostly understood as sub-genera. The family is morphologically so uniform in both the imaginal and larval stages that, according to Jensen, it would be justifiable to put all species (with the exception of the American genus Parasimulium ) in a single genus.

Black flies family (Simuliidae)

Fossil evidence

The oldest known fossil black fly comes from the Middle Jurassic of Central Asia. In addition, black flies have been found in various amber deposits, but they are rare. At least five species of the genus Simulium have been described from Baltic amber , and individual finds have also been made from other tertiary amber deposits ( Sicilian amber and Dominican amber ). Particularly noteworthy is the discovery of a female black fly in Baltic Amber, which is in copula with a mosquito. The antennae of the male mosquito were apparently infested with nematodes , so that the chosen sexual partner could no longer be identified exactly.

literature

  • Roger W. Crosskey: The natural history of blackflies. John Wiley & Sons, Chichester / New York / Brisbane / Toronto / Singapore 1990. ISBN 0-471-92755-4 .
  • Klaus Honomichl, Heiko Bellmann: Biology and ecology of insects. CD-ROM. Gustav Fischer, Stuttgart 1994. ISBN 0-271-00417-7 .
  • Ke Chung Kim, Richard W. Merritt (Eds.): Black flies. Ecology, population management, and annotated world list. Pennsylvania State University Press, University Park / London 1987. ISBN 0-271-00417-7 .
  • Vincenz Kollar : Assessment of the Dr. Medovics submitted a report to the Serbian government on the development and destruction of the Gollubatz mosquito (Simulia columbaschensis) . In: SB. Akad. Wissensch., Vienna 1848, pp. 92-107.
  • M. Laird (Ed.): Blackflies. Academic Press, London 1981. ISBN 0-12-434060-1
  • G. Seitz: Distribution and ecology of the black flies (Diptera: Simuliidae) in Lower Bavaria. in: Lauterbornia. Mauch, Dinkelscherben 11.1992, 1–230.
  • Tobias Timm: Dormance forms in black flies with special consideration of the egg stage (Diptera: Simuliidae). in: Entomologia generalis. Swiss beard, Stuttgart 12.1987, 133–142. ISSN  0340-2266
  • Tobias Timm: Differences in habitat selection and egg biology in sympatric black flies (Diptera, Simuliidae). in: Communications of the German Society for General and Applied Entomology. Bremen 6.1988, 156–158. ISSN  0344-9084
  • Tobias Timm, Walter Rühm (Ed.): Contributions to the taxonomy, faunistics and ecology of black flies in Central Europe. Essen ecological writings. Vol. 2. Westarp Sciences, Magdeburg 1993. ISBN 3-89432-078-8 .
  • W. Wichard, W. Arens, G. Eisenbeis: Atlas for the biology of water insects. Stuttgart 1994. ISBN 3-437-30743-6 .
  • HP Wirtz: Analysis of the histamine levels in the saliva of different black fly species (Diptera: Simuliidae). in: Communications of the German Society for General and Applied Entomology. Bremen 6.1988, 441-442. ISSN  0344-9084
  • W. Lechthaler, M. Car: Simuliidae - Key to Larvae and Pupae from Central− and Western Europe . Eutaxa self-published, Vienna 2005. ISBN 3-9501839-3-0 .

Web links

Commons : Simuliidae  - collection of images, videos and audio files
Wiktionary: Black fly  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ Douglas C. Currie, Peter H. Adler: Global diversity of black flies (Diptera: Simuliidae) in freshwater. In: Hydrobiologia. 595, 2008, pp. 469-475, doi : 10.1007 / s10750-007-9114-1 .
  2. ↑ Ivan Antonovich Rubtsov: black flies (Simuliidae). Fauna of the USSR, Diptera, Vol. 6 part 6. 1956, engl. Translation of BR Sharma. EJ Brill, Leiden etc., 2nd edition 1990. ISBN 90 04 08871 7 , Part 1 (Introduction, Morphology, External Anatomy).
  3. ^ Peter H. Adler, John W. McCready: Black Flies (Simuliidae). Chapter 13 in Gary R. Mullen, Lance A. Durden (editors): Medical and Veterinary Entomology. Elsevier, Amsterdam etc., 2nd edition 2009. ISBN 978 0 12 372500 4 .
  4. ↑ Harald W. Krenn, Horst Aspöck (2012): Form, function and evolution of the mouthparts of blood-feeding Arthropoda. Arthropod Structure & Development 41: 101-118. doi: 10.1016 / j.asd.2011.12.001
  5. ^ A b Doreen Werner & Jörg Grunewald (2010): Black flies (Diptera, Simuliidae) and their role as disease carriers. In Horst Aspöck (editor): Ill through arthropods. Denisia 30: 233-243.
  6. ↑ Peter H. Adler, Tatiana Kúdelová, Matúš Kúdela, Gunther Seitz, Aleksandra Ignjatović-Ćupina (2016): Cryptic Biodiversity and the Origins of Pest Status Revealed in the Macrogenome of Simulium colombaschense (Diptera: Simuliidae), History's Most Destructive Black Fly. PLoS ONE 11 (1): e0147673. doi: 10.1371 / journal.pone.0147673 (open access)
  7. ↑ Art Borkent (2012): The Pupae of the biting midges of the World (Diptera: Ceratopogonidae) With a Generic Key and Analysis of the Phylogenetic Relationships Between genera. Zootaxa 3879 (1): 1-327. doi: 10.11646 / zootaxa.3879.1.1
  8. ↑ Sujatha Narayanan Kutty, Wing Hing Wong, Karen Meusemann, Rudolf Meier, Peter S. Cranston (2018): A phylogenomic analysis of Culicomorpha (Diptera) resolves the relationships among the eight constituent families. Systematic Entomology 43 (3): 434-446. doi: 10.1111 / syen.12285
  9. ↑ Xiao Zhang, Zehui Kang, Shuangmei Ding, Yuyu Wang, Chris Borkent, Toyohei Saigusa, Ding Yang (2019): Mitochondrial Genomes Provide Insights into the Phylogeny of Culicomorpha (Insecta: Diptera). International Journal of Molecular Science 20, 747 doi: 10.3390 / ijms20030747
  10. ↑ Frank Jensen: Diptera Simuliidae, Blackflies. In: Anders N. Nilsson (Ed.): Aquatic Insects of North Europe. Apollo Books, Stenstrup 1997.
  11. ↑ RW Crosskey: The Natural History of Blackflies . Chichester 1990, quoted in Poinar 1992.
  12. ↑ George O. Poinar, Jr .: Life in Amber. Stanford University Press, Stanford, Cal. 1992, ISBN 0-8047-2001-0 .
  13. ↑ Wolfgang Weitschat, Wilfried Wichard: Atlas of plants and animals in the Baltic amber. Pfeil, Munich 1998, ISBN 3-931516-45-8 .
  14. ↑ Friedhelm Eichmann: From life in the amber forest . In: Working Group Paleontology Hanover , Hanover 2003.