Striped ambrosia beetle

  • Latin name: Trypodendron lineatum (Olivier)
  • French name: Scolyte birayé
  • Order: Coleoptera
  • Family: Curculionidae
Description

Distribution

British Columbia, Manitoba, New Brunswick, Newfoundland, Ontario, Quebec

Micro-habitat(s)

Lumber

Damage, symptoms and biology

Unlike several species of bark beetles, ambrosia beetles will not usually attack living trees. Also, ambrosia beetles penetrate into the sapwood, producing a whitish sawdust, while bark beetles remain in the bark and produce a brown boring dust. This white sawdust can be seen in bark crevices and on the ground when logs are on land, and floating on the water around boomed logs. The holes in the wood made by ambrosia beetles are very small and perfectly round. A few days after attack, a dark fungal stain will appear around the holes.

Dark-stained ambrosia beetle galleries with branching pupal niches are evident on plywood veneer or on the tangential face of lumber.

In British Columbia there are at least five ambrosia beetle species affecting commercial timber. Of these five species, the striped ambrosia beetles is the most abundant and damaging.

Eggs are laid in niches along the gallery. After the eggs hatch, the larvae feed on fungus and enlarge the niche in which they will pupate and become adult beetles.

Adults overwinter in the forest litter or under the bark of trees in forest margins. Trypodendron spp. have a concentrated spring flight beginning when the temperature exceeds 16oC. Gnathotrichus spp. appear to have overlapping generations. Trypodendron beetles prefer host material felled the previous fall or winter.

This species emerges in the spring and is attracted to suitable wood material by specific chemical odours. The factors that make a log suitable to these beetles are not well understood, but the wood must be of sufficient moisture content, be in the right temperature range, and be of the required soundness to support both fungal and beetle development.

Other information

Ambrosia beetles do not feed on wood, they feed on fungi. The ambrosia fungi associated with these beetles have been identified as Monilia ferruginea Mathiesen-Kaarik (Trypodendron), Ambrosiella sulcati Funk, Raphaella sulcati Funk, and Graphium spp. (Gnathotrichus). The fungal spores adhere to the beetles and quickly germinate in suitable new host material, creating a dark stain around the tunnels.

Canadian Forest Service Publications

Striped ambrosia beetle

Diet and feeding behaviour

  • Mycetophagous : Feeds on the underground mycelium of fungi.
    • Mycetophilous: Feeds on fungi, seeks fungi and feeds on fungi-eating larvae.
Information on host(s)

Most commercial conifer species are susceptible to ambrosia beetle attack but most damage occurs to Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), true firs (Abies spp.), and spruce (Picea spp.).

Main host(s)

Balsam fir, black spruce, Engelmann spruce, jack pine, lodgepole pine, Rocky Mountain Douglas-fir, western hemlock, white spruce, white spruce

Secondary host(s)

Amabilis fir, bigleaf maple, Douglas-fir, eastern white pine, grand fir, Norway spruce, ponderosa pine, red pine, red spruce, Sitka spruce, subalpine fir, tamarack, trembling aspen, western larch, western redcedar, western white pine, white birch, whitebark pine, yellow-cedar

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