Six-toothed bark beetle

Ips sexdentatus

1. Identification

• Common name: Six-toothed bark beetle
• Scientific name: Ips sexdentatus Börner
• Order: Coleoptera
• Family: Curculionidae (subfamily Scolytinae)

2. Pest description

• Adults: Bark beetles of 5–8 mm; dark brown cylindrical body; elytral declivity with six teeth on each side, a distinctive feature of the species.
• Larvae: Apodous, whitish, curved body, brown head; they develop in galleries under the bark.
• Pupae: Whitish, formed in pupal chambers inside the bark.
• Galleries: Typical system with a central nuptial gallery and well-marked radial larval galleries.

3. Main hosts

• Conifers, mainly pines such as Pinus pinaster, Pinus sylvestris and Pinus nigra.
• It preferentially attacks weakened, burnt trees, those felled by wind or subject to water stress.

4. Symptoms and damage

• Borings in the bark with the expulsion of fine sawdust.
• Subcortical galleries that interrupt the flow of sap.
• Progressive drying of the crown, starting at the upper part.
• Premature needle drop and discolouration of the foliage.
• Tree mortality in intense or repeated attacks.
• Possible association with pathogenic fungi carried by the adults.

5. Biological cycle

• Two to three generations per year, depending on temperature.
• Adults emerge in spring and begin excavating egg-laying galleries.
• Eggs deposited in the nuptial gallery; larvae excavate radial galleries.
• Pupation under the bark; new adults emerge and may start new generations.
• Development favoured by hot summers, prolonged droughts and an abundance of weakened wood.

6. Monitoring

• Observation of recent borings and expulsion of sawdust.
• Inspection of crowns with yellowing or drying.
• Assessment of galleries under the bark in suspect trees.
• Reinforced monitoring after storms, fires or periods of drought.
• Use of traps with specific pheromones for detection and population tracking.

7. Management measures

• Cultural: Removal and debarking of infested trees; elimination of fallen wood; proper management of forest residues.
• Preventive: Maintenance of stand vitality; reduction of water stress; avoid wounds to the trunk.
• Integrated protection: Use of pheromone traps for monitoring; intervention only when necessary; practices that reduce the availability of attractive wood.

Bibliographic references

• CABI Invasive Species Compendium – Ips sexdentatus.
• EPPO Global Database – Ips sexdentatus.
• Faccoli, M. (2009). Host preference and ecology of Ips species in European conifer forests.
• Lieutier, F., et al. (2004). Bark and wood boring insects in living trees in Europe.