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 Xyleborus dispar and other species (Ambrosia beetles)

There are 5 ambrosia beetle species in Turkish hazelnut orchards, including Xyleborus dispar, Xylosandrus  germanus, Xleborinus saxesenii, Lymantor coryli  and Hypothenemus eriditus. First 3 species looks more common. In some past articles in Turkey, X.dispar and X. germanus ; X.saxesenii and L.coryli were confused each others in identifications..

Description

Adult : the female has a hemicylindrical body and a globular thorax; 3 to 4 mm long. The male is less elongated, thorax and abdomen more rounded , about 2 mm. The general coloration of individuals of both sexes varies from very dark brown to black and has a shiny appearence, especially on the abdomen.

Biology and Damage

Extremly polyphagous. It attacks many fruit and forest trees. Adult hibernates in the gallery where it underwent metamorphosis. The female flies away in spring, when the diurnal temperatures reaches 18 °C. It locates another tree and bores through the wood, forming a characteristic network of galleries of a uniform diameter of 2 to 5 mm. The initial gallery is perpendicular to the branch axis, then forks off to form, in the large branches, a concentric ring. From ring , short galleries are dug parallel to the branch axis. 10 to 15 days after the attacks on the trunk , the female lays about 40 eggs in the galleries. Larva appears a few days after laying and develops over 4 to 6 weeks. It does not dig any galleries and feeds on a xylophagous fungi,”Ambrosia”, the spores of which are carried by the female. Pupation lasts 10-15 days.There is one generation per year. The adults stay in the galleries during summer, autumn and winter. They come out of the tree and sworm in the next spring, from mid-March to end of April.

It attacks healthy trees. The drilling of galleries often leads to the death of young hosts and a rapid decline of older trees which dry up suddenly after flowering. In vigorous trees, the sap fills up the galleries and can impede the development of the eggs and the larvae.

Common Names

DE: Ungleicher Holzbohrer, ES: Barrenillo, FR: Xylebore disparate, IT: Xileboro diseguale, GB: European shot-hole borer, TR: Dalkıran