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Tetranychoidea, Tetranychidae


[R] Superfamily belonging to the subclass Acari and including 1,600 species characterized by long, needle-like chelicerae which are fused basall.
This superfamily comprises 2 important families:.
- the Tetranychidae, commonly known as spider mites; they have well-developed pedipalps, the females measuring up to 6 mm and being visible to the unaided eye.
Important pests in France are the two-spotted spider mite (Tetranychus urticae), the fruit tree red spider mite (Panonychus ulmi), the McDaniel spider mite (Tetranychus mcdanieli), the hornbeam mite (Eotetranychus carpini) and the citrus red mite (Panonychus citri).
- the Tenuipalpidae, more unobstrusive although coloured; they have simple pedipalps.
Development from the egg to the adult includes 3 active stages (6-legged larva, 8-legged protonymph and deutonymph) alternating with 3 quiescent stages.
These mites live on leaves or on the underside of leaves (more advanced species) where they spin silken webs serving as a protective net against predators.
Mites are especially numerous when temperature is high and humidity low. The majority of species spends the winter in a state of diapause. Damage is caused by the punctures made in the plant cells by the needle-like chelicerae, more or less large dead tissue marks appearing .
These mites do not transmit any viruses.

[R] Images

* Tetranychidae: development cycle (INRA)
a: egg; b: 6-legged nymph; c: protochrysalis; d: protonymph; e: deutochrysalis; f: deutonymph; g: imagochrysalis; h: female adult; i; male adult.
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