Zabrus tenebrioides
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The Cereal Beetle, Humped Beetle or Lazy Beetle (Zabrus tenebrioides) is a species of beetlein the Carabidae family, which attacks many plants in the Poaceae family. It is a harmful pest of cereal crops, particularly wheat andbarley.
Description
- The adult is black or dark brown with a slight metallic sheen and has domed elytra with nine longitudinal stripes. The thorax is also domed, hence the vernacular name " zabre bossu ". It is 15 mm long. The antennae, tibiae and tarsi are reddish-brown, the anterior tibiae are enlarged and have spurs on the inner apical angle.
- The larva is whitish with a dark brown head and prothorax. It measures around 30 mm long.
- The eggs are oval and shiny white. They are about 2 mm long.
Biology
The adults appear in late spring and disperse to cereal crops, wheat, barley and, more rarely, oats. At night, they feed on the flowers and seeds that are forming and take shelter in the ground during the day.
The females lay around a hundred eggs, which they deposit in small groups of 3 to 5 in galleries. Incubation lasts two to three weeks.
The larvae dig galleries up to 30 cm deep in the ground, where they take shelter during the day. They emerge at night to feed by gnawing on the leaves, leaving the veins intact. The larvae hibernate in the galleries. In spring, they feed on cereal leaves, pupating around May.
Predators
Among the predators of Zabrus tenebrioides is a parasitoid tachinid fly, Viviana cinerea.
Damage
Damage is mainly caused by the larvae, which live in underground galleries from which they emerge at night to devour the leaf blades of cereals, mainly wheat and barley. The very characteristic attack leaves only the veins. The larvae also insert the tips of the leaves into the galleries so that they can be eaten during the day.
Larval attack can lead to a sharp drop in yield, especially if it occurs on seedlings before the three-leaf stage. The adults, also nocturnal, feed on flowers and seeds.
Sources
Appendices
S'attaque aux cultures
