Two forms distinct from Tétranyque Tisserand having very close Biology S and producing the same damage can be met:
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the yellow, more or less greenish form; it is about 2 species Tetranychus urticae Koch and T. turkestani Ugarov and Nikolski (= T. atlanticus Mac Gregor), the latter generally not being in Serre and being southernmost.
- the red form brick: T. cinnabarinus Boisduval.
With the autumn, it appears moreover individuals of definitely orange color, without spots, which are the wintering forms of T. urticae.
- the adults have 2 dark spots typical on the back and 4 pairs of legs. The female is 0,5 mm long; the male, smaller and slim reaches only 0,3 Misters
- Œuf: spherical, of a diameter lower than 0,1 mm, smooth, blanchâtre and translucent after the laying, it opacifies and takes a pearly yellow aspect before hatching. The egg of T. cinnabarinus is pink mauve.
- Larva: of reduced size, it has 3 pairs of legs.
- Nymph: morphologiquement similar to the female.
Biology
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Plant-hosts: this acarina is extremely polyphagous and nearly 200 hosts are likely to accommodate it: wild plants, plants vegetable, floral, fruit-bearing species. It is particularly dreaded on the Vine, the Bean, the Cucumber, the Hop, the Cotton plant, the Clover, the Sunflower, the fruit trees.
- the females having wintered migrate on the adventitious ones or other herbaceous plants and, after one period of food, lay a high number of eggs there; fruitfulness: a hundred eggs at a rate of 10 per day. The 2nd generation turns over on the Vine and other crop plants in June. All the active stages, this Tétranyque weaves with the lower face of the sheets of the silky fabrics which retain moisture and ensure an excellent protection of all the forms against the wind, the predatory ones and the treatments.
- Larve: the larval development lasts 16 days with 20°C and 7 days with 31°C.
Life cycle
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6 to 7 generations of summer.
- the generations are followed at very fast intervals and the Acarina pullulates. The dissemination of Tétranyque is done by passage from one plant to another (if they are touched), by the ground for short distances, by transport on objects or people or by the wind, its wire of silk constituting a aérophore. At the end of the summer, the orange form becomes prevalent and will winter under various shelters or, in the greenhouses, close to the sources of heat.
Damage
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the direct damage is due to the punctures nutriciales: the sheets take a moucheté aspect then are desiccated. In the event of pullulation, the plant can die.
- In addition, the fabrics can enclose the bodies of the plant and block their development. Such indirect damage is to be feared in greenhouse where the colonies of this Acarina can reach very high densities.
Common nouns
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- Gemeine Spinnmilbe, Bohnenspinnmilbe, Hopfenspinnmilbe
- - Glasshouse spider mite, Two spotted spider mite, Dyes with carmine spider mite
- - Araña roja
- - Tétranyque Tisserand, Acarien yellow
- - Ragnetto giallo dei giardini
- - Ácaro amarelo da vinha, Aranhiço amarelo
Source
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Freely drawn from the site of the INRA (French agronomic National research institute)
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