|scientific name Trypodendron lineatum |
common name Striped Ambrosia Beetle
Adults' flight period is between spring and late summer.
Adults are recognized by their smooth shiny elytral surface, the interspaces usually very minutely and irregularly punctured and raised subapical margin of elytra that gives them a broadly rounded appearance when viewed from above. Elytra are usually bicoloured with alternating patterns of five dark and four pale stripes. General appearance of adults colour is very dark brown to black. Females and males differ in size and sculpture. Length is 3mm – 3.5mm in females and 2.7mm – 3.2mm in males. Frons of females is convex with surface reticulated with sparse granules while in males they are concave with lateral margins ornamented by abundant hair. Anterior margin of pronotum is usually unarmed (without teeth) in both sexes but rounded in females and straight in males (Bright, 1976; Wood, 1982).
Adults over winter in the forest diff or in bark crevices. In spring at temperatures >15°C, adults fly from diff in search of host material. Large broods of adults are attracted to sapwood of wind thrown, fire killed, withdrawn cut and dying trees, stumps and logging slush stored for a long time (at least 3months to <2years). Attack is usually on the shaded underside lying on the ground and exposed surfaces of logs floating on water of most coniferous species within range. Suitable wood is identified by the release of primary attractants perceived by the beetles. Usually it is the female that initiates colonization and causing the release of a species specific secondary attractant (aggregate) pheromone received by both sexes that increases the colonization rate and finally aggregates the beetles onto the host material. Mating takes place on the surface of the bark after which the females bore into the log to form galleries. They then inoculate galleries with ambrosia fungus on which they and their offspring (larvae) feed. Oviposition begins in spring in the first two weeks of gallery construction. Eggs are laid singly in cradles (niches) cut on both sides of the gallery. Larvae hatch in 10days and pupation occurs in a month's time. New adults emerge from the gallery cradles in two months. In mid to late summer (from July through September), the adults emerge from the host logs and fly to nearby forest margins in search for hibernation sites and over wintering for 7-11 months. There is only one generation per year but sometimes vigorous adults may re attack and deposit eggs for a second late season generation (Bright, 1976; Wood, 1982; Dyer and Chapman, 1965).
Any species of conifer within its range, rarely from Alnus spp or Betula spp (Bright, 1976).
Transcontinental in Canada; eastern and western United States and Eurasia (Bright 1976).
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