Root mites
| Root mites | ||||||||||||
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Rhizoglyphus echinopus - drawing |
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| Scientific name | ||||||||||||
| Rhizoglyphus | ||||||||||||
| Claparédè , 1869 |
The root mites ( Rhizoglyphus ) are a genus of mites . They are economically important pests of many cultivated plants, especially the lily family (Liliaceae). The control of root mites is difficult because they have a high reproductive rate with a very short lifespan, usually occur in combination with other plant diseases and attack a wide range of plants. Control with acaricides and insecticides has also become difficult as a result of resistance . The most important species include Rhizoglyphus echinopus and Rhizoglyphus robini , both of which are believed to be found worldwide. Despite its economic importance, the taxonomic position of the genus as well as its biology and ecology have been little researched.
Way of life
The mites live on the roots, tubers, onions and other underground parts of their food plants, but also in rotting plant material, fungi and nutrient-rich soil. They are also occasionally found on the leaves and stems of plants. They feed on a wide range of different organic materials, such as dead and living parts of plants, seeds, dead arthropods , nematodes , fungi or excrement. A number of species live on the seeds of plants, for example Rhizoglyphus costarricensis can be found inside the seed coats of rice. They prefer moist habitats.
The host plants include, above all, the lily family and there the bulbs ( Allium , but also other genera such as lilies , lilium ). In addition, one finds the animals also sword lily plants (Iridaceae), such as freesia ( Freesia ), Hyacinth ( Hyacinth ) and gladiolus ( Gladiolus ) and beyond nightshade ( Solanum ), such as potatoes ( Solanum tuberosum ) and also carrots ( Daucus carota ), Rice ( Oryza sativa ), rye ( Secale cereale ), wheat ( Triticum ), barley ( Hordeum vulgare ) and seed oats ( Avena sativa ).
The activity of the animals decreases in the cold season, but there is no diapause and they can be found throughout the year in all stages of development. To avoid the cold, they dig deeper into the earth.
Reproduction and Individual Development
In addition to the larval stage, root mites also go through the protonymph , heteromorphic deutonymph and tritonymph stages until they molt into an adult animal. The stage of the deutonymph is lived through only by a few animals, the others "skip" it. The reproduction is apparently exclusively bisexual. The numerical ratio between males and females is balanced. Mating usually takes place one to two days after the adults hatch, usually after the animals have already eaten. The mites mate several times a day for 20 minutes to several hours. The duration of mating is longer, the greater the excess of males. This reduces the likelihood that the female will not mate with another male again. Mating activity is also likely to be related to other factors, such as food availability. The females collect the male sperm in the receptaculum seminis . The eggs are fertilized inside the female body before they are transported through the fallopian tube. Depending on the environmental conditions, a total of around 100 to several hundred eggs are laid, each individually in 25 to 40 days.
The deutonymph represents the stage of spread of the root mites. The spread occurs by phoresis . These nymphs do not have a mouth opening or mouthparts and therefore cannot eat any food. They are heavily sclerotized and have a suction cup-like structure with which they can attach themselves to the transport host. In addition to various scarab beetles , dung beetles and weevils , these include some two-winged and flea species . Depending on the type of root mite, either both sexes or just one can be used as the host.
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- A. Diaz, K. Okabe, CJ Eckenrode, MG Villiani, BM Oconnor: Biology, ecology, and management of the bulb mites of the genus Rhizoglyphus (Acari: Acaridae) . Experimental and Applied Acarology 24 (2000): 85-113.