Grape root aphid - Grape root aphid

It is an insect of the order Hemiptera, suborder Homoptera, family Phylloxeridae. There are several life forms, including sexual, winged, root-knot, and leaf-knot, and its life cycle is also complex. The sexual form is about 0.5 mm long and elliptical like the larvae. The leaf-knot form is about 1 mm long and has an egg-shaped, yellow body. It creates small, pouch-like galls on leaves, lives inside them, and lays eggs by parthenogenesis. The hatched larvae move around a lot and create galls on new leaves, but some of them move to the roots and become the root-knot form. The root-knot form adults are wingless, with egg-shaped, dark yellow bodies. They live in colonies on root galls. The winged form has an orange-yellow body, and the eggs it lays turn into the sexual form. It is distributed worldwide and is well known as a pest of grapes.

[Masami Hayashi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱半翅(はんし)目同翅亜目ネアブラムシ科Phylloxeridaeの昆虫。有性型、有翅型、根こぶ型、葉こぶ型などいくつかの生活型があり、生活史も複雑である。有性型では、体長約0.5ミリで、幼虫に似た楕円(だえん)形。葉こぶ型は体長約1ミリで、体は卵形で黄色。葉に小さな袋状の虫こぶをつくり、その中で生活し、単為生殖により産卵する。孵化(ふか)した幼虫はよく移動し、新葉に虫こぶをつくるが、一部は根に移り、根こぶ型となる。根こぶ型の成虫は無翅型で、体は卵形で暗黄色。根こぶ上に群生する。有翅型は体が橙黄(とうこう)色で、これが産んだ卵から有性型が現れる。全世界的に分布し、ブドウの害虫として有名である。

［林　正美］

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