Leaf fleas
| Leaf fleas | ||||||||||||
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| Psylloidea | ||||||||||||
| Latreille , 1807 |
The leaf fleas (Psylloidea) are a superfamily within the suborder of the plant lice (Sternorrhyncha). Of the 3000 known species, 382 live in Europe and 189 are known from Central Europe.
features
The animals reach a body length of one to four millimeters. The hind legs of the leaf fleas are transformed into jump legs and allow the animals to move around by jumping. The thorax is usually strongly built and curved outwards at the back. The wings are well developed and have a wing mark ( pterostigma ) in most species of the Psyllidae . The wing veins are an important characteristic of the species. Leaf fleas usually have three point eyes ( ocelli ). One is centered on the frons , the other two each on top of the sides of the front part of the head ( the vertex ). The antennae of most species have ten segments, only a very few species have those with six, eight or nine segments.
Important determinants of the nymphs are the position of the anus and the arrangement of the pores of the wax glands around it.
Way of life
Adults and nymphs also feed on plant sap as a phytophagus and are phloem suckers . Most species are either monophagous and feed only on a specific type of plant or oligophagous and have several closely related host plants. Very few species are polyphagous and not picky about their food plant choice. Most leaf fleas suckle on young shoots, leaves and petioles. But there are also species that suckle on woody branches or roots,
By piercing the plants, some species cause deformities or plant galls or let plant parts die off. The honeydew, which is excreted in large quantities by the nymphs in particular, can stick together entire branches and leaves in some species. Since the sugary honeydew is also a breeding ground for z. B. Soot thaw fungi can cause secondary damage to the infected plant through fungus growth. These damaged areas are more common on pears in particular. The primary pests in agriculture are u. a. The following species are considered: apple leaf flea ( Cacopsylla mali ) on apples, large pear leaf flea ( Cacopsylla pyrisuga ) on pears or the carrot leaf flea ( Trioza apicalis ) on carrots .
In addition, some species are vectors of plant diseases or their pathogens. These pathogens, originally counted as viruses , have now turned out to be representatives of phytoplasms . These are bacteria without cell walls that multiply in the phloem pathways of the infected plants. The previously identified as vectors psyllids are Cacopsylla picta and Cacopsylla meolanoneura (apple proliferation), the Common pear sucker ( Cacopsylla pyri ) and Cacopsylla pyricola (pears yellowing), Cacopsylla pruni (European stone fruit yellowing), erytreae Trioza and Diaphorina citri (Zitruspest).
development
The animals reproduce bisexually. Only Cacopsylla myrtilli can also reproduce parthenogenetically . The females lay their eggs mostly freely on leaves, shoots and stems. The eggs have a pedicellus that is anchored in the plant tissue. This causes a small pit-shaped bile in some species, in which the nymph stays until the first molt. It is only left in the second stage. The animals go through a total of five stages before they molt to become a full insect. In Central Europe, most species produce one generation per year, but there are also those with two generations. In the warmer regions of the world, however, significantly more are trained each year. Hibernation usually takes place as an imago, either on the host plants or, above all, other plants that offer protection, for example in cracks in the bark. In the spring, host plants are searched for again in order to lay eggs after mating. However, some species also overwinter in the egg stage or as a nymph on the host plant. There are several ways that stridulation can produce sounds. In addition to the sounds, whose mechanism of generation has not yet been fully clarified, the wings are also set in vibration. Similar to other types of plant lice, the leaf fleas also release honeydew , which is collected by ants , flies or bees . Both adults and nymphs produce wax excretions that protect them on the one hand from drying out and on the other hand from the moisture of their own honeydew.
Natural enemies
In addition to predators such as spiders , soft bugs , flower bugs , sickle bugs and ladybirds , it is above all gall midges and parasitic hymenoptera that are considered enemies of leaf fleas. The fungus Entomophthora sphaerosperma is also a relevant enemy of this group of animals.
Systematics of leaf fleas
The leaf fleas found in Europe belong to four different families:
literature
- Daniel Burckhardt: Directory of leaf fleas in Central Europe with host plant information (Insecta, Hemiptera, Psylloidea). In: Werner Witsack (Hrsg.): Contributions to the cicada. No. 5, 2002, pp. 1–9 ISSN 1434-2065 ( public.bibliothek.uni-halle.de PDF; 56 kB).
- Frej Ossiannilsson: The Psylloidea (Homoptera) of Fennoscandia and Demark . EJ Brill, Leiden 1992, ISBN 90-04-09610-8 .
- Bernhard Klausnitzer: Psyllina, leaf fleas . In: Wilfried Westheide, Reinhard Rieger (Ed.): Special Zoology. Part 1: Protozoa and invertebrates. Gustav Fischer Verlag, Stuttgart / Jena 1997, ISBN 3-437-20515-3 .
- DD Jensen, H. Schneider, WH Griggs, CQ Gonzales: Pear decline virus transmission by pear psylla. In: Phytopathology. 54, No. 11, 1964, p. 1346 ff.
- DL Davies, CM Guise, MF Clark, AN Adams: Parry's disease of pears is similar to pear decline and is associated with mycoplasma-like organisms transmitted by Cacopsylla pyricola . In: Plant Pathology . tape 41 , no. 2 , April 5, 1992, ISSN 1365-3059 , pp. 195-203 , doi : 10.1111 / j.1365-3059.1992.tb02338.x .
- Erich Seemüller, Bernd Schneider: 'Candidatus Phytoplasma mali', 'Candidatus Phytoplasma pyri' and 'Candidatus Phytoplasma prunorum', the causal agents of apple proliferation, pear decline and European stone fruit yellows, respectively . In: International Journal of Systematic and Evolutionary Microbiology . tape 54 , part 4, 2004, ISSN 1466-5026 , p. 1217-1226 , doi : 10.1099 / ijs.0.02823-0 , PMID 15280295 .
- Phyllis G. Weintraub, LeAnn Beanland: Insect vectors of phytoplasmas . In: Annual Review of Entomology . tape 51 , 2006, ISSN 0066-4170 , p. 91-111 , doi : 10.1146 / annurev.ento.51.110104.151039 , PMID 16332205 .
Web links
- Australian Biological Resources Study - Psylloidea environment.gov.au
- Homepage psyllids.org
- Identification key for psyllids on Rosaceae in Central Europe psyllidkey.info
Individual evidence
- ↑ Psylloidea. Fauna Europaea, accessed November 1, 2007 .
- ^ Huanglongbing (HLB or Citrus Greening). Center for invasive species research, accessed June 10, 2013 .