Gall mite

A general term for mites in the family Eriophyidae, order Acarina, class Arachnida, phylum Arthropoda. These tiny mites have a body length of around 0.2 mm. Unlike other mites, they have a maggot-like body with many segmented structures (not true segments) in the posterior part of the body. Even adults have only two pairs of legs, making them a very unique mite. Their life cycle is one in which there is no larval stage after the egg stage, but two nymphal stages follow. There are two types of females: normal females (first females) that resemble males, and diapausing females (second females) that are morphologically different from males. Males do not have an inserting organ, so sperm transfer is indirect. That is, the male lays spermatophores on the leaf surface, and the female takes them up. Depending on the part of the host plant that is infested and the type of damage that occurs, there are gall mites that create galls on leaves, blister mites that make the leaf tissue spongy, bud mites that attack buds, erineum mites that cause dense whorl-like hairs to grow on the undersides of leaves, and rust mites that attack leaves and fruit, turning them a rust color. In Japan, important pests include the citrus rust mite (also known simply as rust mite) that attacks citrus fruits, the wolfberry mite (Lucifera punctata) that attacks wolfberries, and the grape leafminer mite (Lucifera nigricans) that attacks grapes. Mites from the Eriophyidae family can transmit plant viruses.

[Mori Fansu]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

節足動物門クモ形綱ダニ目フシダニ科Eriophyidaeのダニの総称。微小なダニで体長は0.2ミリメートル内外。ほかのダニ類と異なり体がうじ虫状、後体部に多数の環節様の構造（真の体節ではない）をもつ。成虫でも脚(あし)は2対しかないなど、きわめて特異な形態のダニ類である。生活環は卵のあと幼虫期を欠き、2回の若虫期が続く。雌には2型があって、雄に似た正常の雌（第1雌）と、雄とは形態が異なった休眠型の雌（第2雌）とがある。雄は挿入器をもたないので、精子の転送は間接的方法による。すなわち、雄は葉面に精包を産み落とし、雌はそれを取り入れる。フシダニ類は寄主植物の加害部位や植物被害様相によって、葉に虫こぶをつくるgall mite、葉肉組織を海綿状にするblister mite、芽を加害するbud mite、葉裏に毛旋(もうせん)状の毛を密生させるerineum mite、葉や果実を加害して銹(さび)色にするrust miteがある。日本では柑橘(かんきつ)類につくミカンサビダニ（単にサビダニともよばれる）、クコにつくクコフシダニ、ブドウにつくブドウハモグリダニなどが重要害虫である。フシダニ科のダニでは植物ウイルスを伝搬することがある。

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