Dwarf leafhoppers

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Dwarf leafhoppers
Meadow leaf hoppers (Evacanthus interruptus)

Meadow leaf hoppers ( Evacanthus interruptus )

Systematics
Class : Insects (Insecta)
Order : Schnabelkerfe (Hemiptera)
Subordination : Risso cicadas (Cicadomorpha)
Superfamily : Membracoidea
Family : Dwarf leafhoppers
Scientific name
Cicadellidae
Latreille , 1825
Eurymeloides bicincta lives in symbiosis with a species of ants
The comb-like rows of thorns on the rails of the hind legs of a gold leaf cicada are clearly visible
A male of the common goblet maiden ( Enallagma cyathigerum ) with a captured dwarf cicada
A freshly moulted specimen of the dwarf leafhopper Igutettix oculatus spreads brochosomes , which are excised from its abdomen, over its body and wings
Rhododendron leaf hoppers mating

The dwarf cicadas (Cicadellidae, Syn .: Jassidae), also called small cicadas , form a family within the subordination of the round-headed cicadas . With more than 20,000 species, it is one of the most species-rich families of insects . 452 species are native to Germany.

features

They are relatively small cicadas that can jump well with the help of their hind legs. The dwarf leafhoppers can reach a body length of 2 to 30 millimeters, but the majority of the species measure less than 13 millimeters. A special distinguishing feature from other cicada families are the long, mostly square rails of the hind legs, which are covered with rows of thorn-like setae . However, these are not rigid, but flexible. The tarsi are tripartite. The spherical to plate-shaped hips ( coxae ) of the middle pair of legs differ from the coxae of the other pairs of legs. They are closer together on the stomach side than the coxes on the other pairs of legs.

On the head there are a pair of compound eyes and a pair of point eyes (ocelles) on the top or on the front of the head. The antennas are short. The thickened part of the antennae ends in a tuft of hair. The dwarf cicadas, like all Schnabelkerfe, have piercing-sucking mouthparts.

Brochosomes

A particular specialty is the excretion of brochosomes , which are secretory granules that are formed in the Malpighian vessels . The granules are microscopic and could not be discovered until 1952 with the help of an electron microscope . The dwarf cicadas distribute the excrement with the help of the comb-like bristles on the hind legs after moulting over their bodies and wings, which thereby acquire a bluish sheen. The excrement is water-repellent and also protects against the honeydew released by the dwarf leafhoppers themselves , a sticky, sugary liquid. The eggs of many species are coated with brochosomes. It is still largely unclear what other protective functions the excrement has in addition to protection against moisture. The effectiveness of the brochosomes against parasites, against dehydration and against ultraviolet radiation is examined.

Differences from other cicada families

These cicadas are typically smaller than most species in other families. In addition, they have no appendages on the pronotum , which are found in many other cicada families of the superfamily Membracoidea . The other families of cicadas do not have thorn-like setae on the rails of the hind legs and do not release any brochosomes. Most dwarf leafhoppers are bright and particularly vividly colored. The Y-vein in the clavus of the forewings is absent, as in all round-head cicadas.

Way of life

The season of the cicadas takes place in the Nearctic and Palearctic from spring to autumn , in the tropical zones it is all year round.

The female lays eggs in the tissue of a host plant, the larvae hatch after a week to a month and develop into an adult animal over five larval stages. The animals usually overwinter as an egg, but in some species also in the larval stage or as adults in matted grass or in leaves .

Most dwarf leafhoppers suckle on the phloem , which is the part of the vascular plant bundle in which nutrients and other assimilates are transported. Not only do they damage their host plants by depriving them of important nutrients, they are also carriers of various viral infections that can quickly spread through the phloem in the plant. In parts of North and South America, the grapevines are severely damaged by the spread of Pierce's disease. The causative agent of this plant disease, Xylella fastidiosa from the bacterial group of the Xanthomonadaceae , which lives in the xylem of the vine plants, is transmitted by dwarf leafhoppers from the subfamily of ornamental leafhoppers.

Like many plant lice , dwarf leafhoppers can live in symbiosis with ants . They supply these ants with honeydew and are therefore guarded and cared for by the ants. The dwarf cicadas are an important link in the food chain as users of plant sap and are worthwhile prey for many predators . Among the vertebrates, this includes many birds and reptiles . Among the arthropods their natural enemies are flower bugs , wood wasps , lacewing larvae , ground beetles , dragonflies , some species of ladybirds , especially those of the genus Coccinella and Harmonia , predatory mites , predatory bugs , parasitic wasps and various spiders .

Occurrence

The species occur worldwide in almost every habitat in which there are vascular plants . These include deserts , steppes , wetlands, and forests . The tropical rainforests are particularly rich in dwarf cicadas, but their biodiversity has not yet been adequately researched. Estimates based on sampling in the Amazon rainforest suggest that the total number of dwarf cicada species could be as high as 100,000.

Systematics

Although many species are easily identifiable from the outside by their size, shape and striking color, there are also species that are adapted to the plants on which they live by camouflage colors and hardly differ from one another. In some genera, similar to some beetles , the species can only be clearly identified by dissecting the male genital tract. There are also color variants that have sometimes been described as different types. The yellow beech leaf cicada Fagocyba cruenta var. Douglasi was previously listed as a separate species Fagocyba douglasi , although apart from its color, it does not differ from the red Fagocyba cruenta in terms of morphology or ecological requirements . The yellow animals ( F. douglasi ) occur in large numbers on deciduous trees, but these populations are mixed with red F. cruenta and connected to them by color transitions. This has led to the belief that they are varieties of the same species. Since the rarer red variety was described as a separate species as early as 1835, the more common yellow specimens must be viewed as a variety of the former species according to the priority rule. In addition to the varieties, there is usually a dimorphism of the two sexes and the different coloring of the larval stages. Worldwide there are between 26 and 40 subfamilies of dwarf leafhoppers. In Europe there are 1236 species in 254 genera from 16 subfamilies of dwarf cicadas, of which 14 subfamilies with 636 species occur in 182 genera in Central Europe and 13 subfamilies with 452 species in 154 genera in Germany.

Subfamilies and species in Europe

European subfamilies and selected species:

More types

African selected species:

Fossils

The dwarf cicadas are a relatively original group in phylogeny, the oldest fossils come from the Lower Cretaceous and are around 125 million years old. Dwarf cicadas from the early modern period were found in Baltic amber from the Eocene and in Dominican amber (Eocene to Miocene ). Despite their age of 23 to 55 million years, these amber inclusions do not differ externally from the dwarf cicadas living in the find area today. The external characteristics have not changed significantly since then. The more precise systematic assignment of fossil animals to today's genera or species is difficult, however, because the anatomical investigations required for fossilization and inclusions are not possible.

supporting documents

Individual evidence

  1. ↑ a b c d C. H. Dietrich: Leafhopper FAQs Center for Biodiversity, Illinois Natural History Survey, 2001–2008 (English).
  2. ↑ a b Herbert Nickel and Reinhard Remane: List of species of cicadas in Germany, with information on nutrient plants, food breadth, life cycle, area and endangerment (Hemiptera, Fulgoromorpha et Cicadomorpha). Contributions to the cicada, 5, pp. 27–64, 2002 full text (PDF, German; 234 kB).
  3. ^ MF Day, M. Briggs: The origin and structure of brochosomes. Journal of Ultrastructural Research, 2, pp. 239-244, 1958.
  4. ↑ GS Tulloch, JE Shapiro and GW Cochran: The occurrence of ultramicroscopic bodies with leafhoppers and mosquitoes. Bulletin of the Brooklyn Entomological Society, 47, pp. 41-42, 1952.
  5. ↑ RA Rakitov: post-moulting behavior associated with Malpighian tubule secretions in leafhoppers and treehoppers (Auchenorrhyncha: Membracoidea). European Journal of Entomology, 93, pp. 167-184, 1996 full text (PDF, English; 1.5 MB).
  6. ↑ Frank Dickert: The domestic dwarf cicadas
  7. ↑ Xylella fastidiosa a scientific and community Internet resource, University of California, Berkeley , 2007.
  8. ^ Herbert Nickel and Reinhard Remane: Directory of the cicadas (Auchenorrhyncha) of the federal states of Germany. Entomofauina Germanica, 6, pp. 130–154, 2003, p. 133 full text (PDF, German; 345 kB).
  9. ↑ Cicadellidae in Fauna Europaea , as of March 2, 2015.
  10. ^ WE Holzinger: Provisional directory of the cicadas of Central Europe (Insecta: Hemiptera: Fulgoromorpha et Cicadomorpha); Preliminary checklist of the Auchenorrhyncha (leafhoppers, planthoppers, froghoppers, treehoppers, cicadas) of Central Europe , as of 2003.
  11. ↑ George O. Poinar Jr .: Life in Amber. Stanford University Press, Stanford (Cal.) 1992, ISBN 0-8047-2001-0 .

literature

Web links

Commons : Cicadas (Cicadellidae)  - Collection of images, videos and audio files