Predatory flies

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Predatory flies
Striped hawk fly (Dioctria linearis ♀) with Anthocoris nemorum as prey

Striped hawk fly ( Dioctria linearis ♀) with Anthocoris nemorum as prey

Systematics
Class : Insects (Insecta)
Order : Fly (Diptera)
Subordination : Flies (Brachycera)
Partial order : Asilomorpha
Superfamily : Predatory fly-like (Asiloidea)
Family : Predatory flies
Scientific name
Asilidae
Latreille , 1802
Subfamilies

The predatory flies or hunting flies (Asilidae) are a family of the two-winged flies ( Diptera) and are counted within the flies (Brachycera) to the crevices (Orthorrapha). Over 7000 species are known worldwide, divided into 530 genera . Due to their predatory way of life, the animals have a significant influence on the regulation of ecosystems , especially since they primarily hunt herbivorous insects. These are medium-sized to large flies, the murder flies ( Laphria ) are z. B. up to 30 millimeters in size.

Characteristics of the predator flies

Due to their size, some species of this group are very noticeable, such as the murder flies , which often occur in clearings and old clearcuts, or the hornet- stealing fly Asilus crabroniformis with its black-yellow abdomen and brown chest. The Leptogaster species, on the other hand, are slender like dragonflies . Most predatory flies are also very hairy. In many species the abdomen is very narrow compared to the thorax , in others it corresponds in width to the chest area. The legs serve as catch legs, for this reason they have short and thickened bristles, especially at the tip, and are curved like hooks.

Some features of the head are typical of all predatory flies, such as the frontal furrow between the compound eyes and the cusp with the three point eyes in between . The compound eyes themselves are very large, with the size of the individual facets increasing towards the center. The mouthparts are about head-length and are designed as proboscis and proboscis , although unlike those of mosquitoes or horseflies, they also have to hold the prey. Some species have a real beard made of bristles.

Way of life of the predator flies

Predator fly sucking a wasp

Predator flies mainly colonize open clearings and areas and hunt primarily at higher temperatures. According to various studies, the optimal temperatures for most species are higher than 20 degrees Celsius, and the more cold it gets, they become more inactive. As eye hunters, they prefer well-lit and poorly structured hunting areas, often choosing tree trunks or other higher-lying take-off points.

Predator flies mainly feed on other insects. They have very hard piercing bristles, formed from the hypopharynx and the galeae , with which, for example, murder flies can even pierce the shell of various beetles . Accordingly, jewel beetles and weevils also belong to their prey . In 1978 Musso demonstrated that the saliva of flies contained an insecticidal poison; it also contains digestive secretions which pre-digest the prey. The prey is usually hunted in flight and grabbed with the front legs in a shock flight. The departure usually takes place from slightly elevated positions in wait, such as a tree stump. The prey is likely to be perceived visually and fixed with head movements. A prey specialization of these flies is largely unknown. The wolf flies or hard whiskers of the genus Dasypogon almost exclusively prey on honey bees, bumblebees and other stinging voices and therefore received the English nickname "bee-catcher". Some species also prey on spiders . The prey is often larger than the hunter. Basically, the hunting behavior is very similar to that of dragonflies .

distribution

Striped hawk fly ( Dioctria linearis ♀) with prey ( Anthocoris nemorum )

Predator flies live on all continents with the exception of Antarctica . The greatest biodiversity is currently known from the subtropics , although the tropical rainforests have so far only been insufficiently investigated. Many of the species or genera are typical of the region. Neither introduced nor native species are known from the Hawaii archipelago , while the animals are part of the local fauna on many other archipelagos . Predator flies can be found on almost all archipelagos in Southeast Asia, and there are always some species on the Fiji Islands , Samoa and New Zealand . One species is even known from Christmas Island . At least Clinopogon nicoberensis is known from almost all areas and islands of the Indian Ocean and the eastern Pacific . Not a single species is distributed worldwide to this day.

Most species groups can be assigned directly to regions. The representatives of the Megapodinae, for example, only occur in the Neotropis (tropical region of America), the representatives of the Atomosiini and certain genera of the Damalini ( Holcocephala group) as well as the genera Diogmites (Dasypogoninae) and Nerax (Asilinae) are also concentrated here. The latter two genera probably come from Mexico , but are now also common over large parts of the USA . Representatives of the genera Laphria , Cyrtopogon , Lasiopogon and Asilus are mainly found in the northern hemisphere, i.e. in Eurasia and North America . The Neolophonotus group (Asilinae) and the genus Microstylum (Dasypogoninae) occur mainly in South America. The shiny metallic Maira species can be found in South Asia and the Southeast Asian islands .

By far the largest number of predatory flies live in sandy and largely dry areas; A number of species can be found in deserts and semi-deserts in particular, although here too they tend to be near small watercourses or vegetation islands, as this is where most of the vegetation and the highest number of prey organisms for the flies can be found. In the temperate climatic areas, the animals are often found in forest areas, some species can also live in swamps or damp forests. Within the forests, the flies are mainly in the areas of clearings, even in the tropical rainforest they are mostly found in the transition area to the grassland. Accordingly, there are also many species in the steppes and savannahs , which are probably home to the most species after the semi-deserts. In California alone, about 419 species are known due to the very different habitats and the elongated shape of the country. In the cold regions of the tundra only the Lasiopogon species, which live there along the rivers , apparently penetrate , while Cyrtopogon in the mountains up to an altitude of 4500  m above sea level. NN occurs.

Reproduction

Mating, the male in front below

The mating of the predator flies begins depending on the species in the air or on the ground. In some species it is initiated by chases of the partner, in numerous species, such as Heteropogon lautus and Pycnopogon fasciculatus , the male is known to fly in front of the sitting female. Not only males of the genus Promachus are equipped with special signal transmitters (strikingly colored and hairy legs, etc.) to appease the females. The mating itself also differs between the species. Some species sit on top of each other, others form an angle, look completely in opposite directions or change positions during mating.

Egg laying

The laying of eggs is very different, so the Leptogaster flies and the hawk flies ( Dioctria ) usually drop their eggs in flight ("random egg-dropping"), Laphria species lay the eggs in cracks in wood and bark, Philonicus species dig them with them a special laying tube in the sand. The Dysmachus species lay their eggs on plants , especially the base of leaves .

The eggs are long-oval and up to three times as long as they are wide, but sometimes only 1.5 times as long. The shell is soft and in most species not ornamented. The color varies from white to yellowish to light brown. It is known of some species that the eggs are protected with a silky web and a hard layer of sand while they are being laid ( Dasypogon , Antipalus ). This behavior is very reminiscent of that of the related Wollschweber , but probably developed independently of each other.

Larval development

The larvae are partly slender, partly more stocky and have characteristic bristles on the last and the first three segments as well as creeping warts on the underside. The head capsule is usually narrower than the chest area and directed downwards. It is mostly light brown due to a slight sclerosis and has very strong mandibles on the underside. The larvae have nine abdominal segments, the last two being partially fused, the largest abdominal segment being the seventh.

The larvae hatch after a few days to weeks and live in the ground, under the bark and in the larval ducts of other insects. They feed on other insect larvae, especially herbivorous beetle larvae according to previous knowledge. References to decaying plant material as food can still be found in the literature. This is probably a misinterpretation of the experiments by Melin (1923), who only found that the L1 larvae develop into L2 larvae even without animal food. Musso (1978) could u. a. prove on Machimus rusticus that further larval stages can only be reached through ecto- and endoparasitic nutrition. The larvae of Nerax femoratus presumably feed on locust eggs. The larvae can take several years to develop, with a diapause in winter . In contrast to the larvae of the related stiletto flies , the larvae living in the ground move in deeper layers. Therefore, finding it by digging is very unproductive.

The pupae are mobile and can work their way out of the substrate with the help of hooks and rings of thorns. In the spring or in climatically favorable periods can then be the adult animals ( Imagines watch) in large quantities at hatch from the Puppenexuvien.

evolution

The evolution of most fly families is very vague and relies more on conjecture than on fossil evidence. Often for this purpose (as with other animal groups) the still rather imprecise molecular clock is used, which is based on the calculation of species splitting processes based on genetic differences. In general, it is now assumed that most of the two-winged families were formed in the Mesozoic Era, and according to Papavero (1973), the predator flies should also have originated there.

The fossil record reaches as far as the Cretaceous , possibly even the Jurassic , whereby numerous fossils are also known for the following ages. A lot of evidence comes from amber . On the basis of this fossil record, Hull (1962) still assumes a split within the predatory flies at the beginning of the Eocene ; today this point in time has to be clearly backdated.

Systematics

The predatory flies are assigned to the superfamily of the predatory fly-like (Asiloidea) together with some other fly taxa, the exact systematic relationships within this group have not yet been fully clarified, the predatory flies here either form the sister group of a common taxon of window flies ( Scenopinidae) and lynx flies (Therevidae) or a taxon consisting of Mydidae and Apioceridae , all five families together face the woolly floaters (Bombyliidae).

 Predatory fly-like (Asiloidea)  
  NN  

 ? Window flies ( Scenopinidae) and lynx flies (Therevidae)


   

 ? Mydidae and Apioceridae


   

 ? Predator flies (Asilidae)


Template: Klade / Maintenance / 3

   

 Wollschweber (Bombyliidae)



Female of Choerades cf. fimbriata

The phylogenenetische system within the asilidae is largely unknown to many other insects. The monophyly of predatory flies as such is undisputed, but within the taxon different groupings have been reached in different ways.

The predatory flies are classically divided into four subfamilies: the Asilinae, Dasypogoninae, Laphriinae and Leptogastrinae. This subdivision is based on various morphological features, above all on the bristling on the body, the wing veins and the features of the mouthparts. More recent studies, including on a molecular basis, distinguish up to eleven taxa at the subfamily level. The previously almost exclusively morphological investigation has been supplemented by molecular genetic investigations for a few years now.

Types (selection)

literature

  • Danny Wolff, Markus Gebel, Fritz Geller-Grimm: Germany's predatory flies - discovering, observing, determining. Source and Meyer, Wiebelsheim 2018. ISBN 978-3-494-01733-4
  • Joachim u. Hiroko Haupt: Flies and mosquitoes - observation, way of life. Naturbuch, Augsburg 1998. ISBN 3-89440-278-4
  • Klaus Honomichl, Heiko Bellmann: Biology and ecology of insects. CD-ROM. Gustav Fischer, Stuttgart 1994. ISBN 3-437-25020-5
  • FM Hull: Robber flies of the world. in: Bulletin of the United States National Museum. Smithsonian Inst. Pr., Washington DC 224.1962,1 / 2, 1-907. ISSN  0362-9236
  • RJ Lavigne: Evolution of courtship behavior among the Asilidae (Diptera), with a review of courtship and mating. in: Studia dipterologica. Ampyx, Hall 9.2002,2, 703-742. ISSN  0945-3954
  • JJ Musso: Recherches sur le développement, la nutrition et l'écologie des Asilidae (Diptera - Brachycera). Thèse à l'université de droit, d'économie et des sciences. Aix-Marseille 1978 (unpublished).
  • H. Oldroyd: Tabanoidea and Asiloidea. Handb Ident British Insects. London 9,1969.4.
  • N. Papavero: Studies of Asilidae (Diptera) systematics and evolution. I. A preliminary classification in subfamilies. in: Arquivos de Zoologia do Estado de Sao Paulo. Sao Paulo 23.1973, 217-274. ISSN  0066-7870
  • GC Wood: Asilidae. In: JF McAlpine, BV Peterson, GE Shewell, HJ Teskey, JR Vockeroth, DM Wood (eds.): Manual of Nearctic Diptera. Vol. 1. Research Branch, Agriculture Canada. Monographs. Ottawa 27.1981, 549-573. ISSN  0576-0542

A comprehensive bibliography can be found in this database (currently approx. 3700 titles)

Individual evidence

  1. ↑ tolweb.org
  2. ↑ Details on the system at geller-grimm.de

Web links

Commons : Predator Flies  - Collection of images, videos and audio files
This article was added to the list of excellent articles on June 16, 2004 in this version .