Plant lice
| Plant lice | ||||||||||||
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Soybean aphid ( Aphis glycines ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Sternorrhyncha | ||||||||||||
| Amyot & Serville , 1843 |
The plant lice (Sternorrhyncha, more rarely Sternorhyncha) are a suborder of the Schnabelkerfe (Hemiptera). Of the around 16,000 known species, around 2974 also live in Europe. Most of them are small or very small insects, all of which suckle on plants. The subordination is known from fossil finds from the Permian with nine families.
features
As is typical for the Hemiptera, the mouthparts of the plant lice are transformed into a proboscis (rostrum), in which the mandibles and maxillae are transformed into needle-like piercing bristles that are guided within a channel-shaped labium . The interlocked, mutually movable piercing bristles form two channels inside, through one of which saliva is released and through the second of which the liquid food is sucked in. A characteristic feature of the plant lice is the backward shifted position of the proboscis, the base of which lies directly in front of, between or behind the hips ( coxes ) of the front legs. The group owes its scientific name to this feature, which translates as "chest weevil". Plant lice have simply built, usually long, multi-part antennae whose flagellum is not bristle-shaped. The tarsi consist of only one or two limbs. Parts of the posterior capsule of the head are membranous. The front wings of the animals are not more sclerotized than the hind wings. Your clavus has regressed and has only one anal vein, if any. Radius, media and cubitus are fused together at the base. In the resting position, the wings are usually folded up like a roof over the abdomen, so that the pro- and mesonotum remain uncovered. In many species, the wings and other parts of the body are severely reduced. For example, in addition to the wings, the legs, antennae and compound eyes of many female scale insects (Diaspididae) are stunted.
Way of life
Most plant lice belong to the phloem-suckers: They suckle in the phloem , the sugar and other assimilate-transporting part of the plant vascular bundle. The proboscis is pushed into a cell (sieve element) of the phloem. The salivary glands then usually secrete saliva, which later hardens, seals the suction point and forms a sheath for the proboscis. Phloem juice is rich in carbohydrates but poor in protein, so many plant lice rely on bacterial species in the intestine as endosymbionts . These are usually enclosed in body cells (intracellularly), which are located in special organs (called a bacterioma or mycetoma ). Excess sugar solution that cannot be used by the organism due to a lack of protein is deposited (in all groups) as honeydew . In numerous cases this has led to a (convergent) symbiosis with species of ants that use the honeydew and maintain and defend its suppliers (mainly from the aphid and scale insect groups).
Many other plant lice do not suck in the phloem, but rather stab individual plant cells of the plant tissue ( parenchyma ), the contents of which they suck out completely.
A number of families cause plant gall . Like many other species of beak bug, numerous plant lice are vectors for economically important phytopathogenic viruses because of their diet . Of the around 230 plant louse species that can be associated with it, aphids make up the majority with almost 220 species. Above all, their effective spreading strategies contribute to their great economic importance.
Systematics
Traditionally, the plant lice were combined with the cicadas in a group called " Homoptera ". According to recent findings, this grouping is no longer justified, but it can still be found in many older works.
The newer classifications almost without exception confirm the monophyly of the plant lice. Its systematic position within the Hemiptera is not completely assured; most of the investigators place it basal within the Schnabelkerfe, as a sister group of all other Hemiptera combined.
The plant lice are divided into four large groups (depending on the author in the rank of superfamily or partial orders), whose monophyly is well secured:
- Psylloidea (leaf fleas)
- Aleyrodoidea (whiteflies)
- Coccoidea (scale insects)
- Aphidoidea (aphids)
The aphids comprise three subgroups. The morphologically more original families Phylloxeridae and Adelgidae , in which the females lay eggs, as is typical for insects, and the remaining aphids (Aphidoidea i. E. S.), in which finished young animals hatch ( viviparia ). Adelgidae and Phylloxeridae are each placed in their own superfamily, some authors combine them in a common superfamily Phylloxeroidea. The monophyly of the aphids as a whole is well established.
The relationships between the four groups have not been clarified with absolute certainty. What is difficult for the analysis is that the animals are very small (with numerous morphological regression = reductions) and that the ribosomal DNA, which is often used for molecular pedigrees , has numerous peculiarities that lead to artefacts in the analysis (" long-branch attraction ") ) being able to lead. A sister group relationship between aphids and scale insects is considered highly probable, but the position of the other two is less certain.
swell
Individual evidence
- ↑ a b c Gullan, PJ & Martin, JH (2009): Sternorrhyncha (jumping plant-lice, whiteflies, aphids, and scale insects). In: Resh, VH & Cardé, RT (editors): Encyclopedia of Insects. 2nd edition, Elsevier (San Diego): 957-967.
- ↑ a b Sternorrhyncha in Fauna Europaea , as of March 19, 2015.
- ↑ a b c Hans Strümpel: Homoptera (plant suckers). Manual of Zoology 4 (28), Walter de Gruyter. Berlin, New York 1983, ISBN 3-11-008856-8
- ^ PJ Gullan (1999): Why the taxon Homoptera does not exist. Entomologica (Bari) 33: 101-104.
- ↑ Overview in T. Bourgoin & BC Campbell (2002): Inferring a phylogeny for Hemiptera: falling into the "autoapomorphic trap". Denisia NF 176: 67-82.>
- ↑ Ole E. Heie & Piotr Wegierek: A classification of the Aphidomorpha (Hemiptera, Sternorrhyncha) under consideration of the fossil taxa. Redia XCII: 69-77.
- ↑ Qiang Xie, Ying Tian, Leyi Zheng, Wenjun Bu (2008): 18S rRNA hyper-elongation and the phylogeny of Euhemiptera (Insecta: Hemiptera). Molecular Phylogenetics and Evolution 47: 463-471. doi : 10.1016 / j.ympev.2008.01.024
literature
- Hans Strümpel: Homoptera (plant teat). Manual of Zoology 4 (28), Walter de Gruyter. Berlin, New York 1983, ISBN 3-11-008856-8
