Seasonal difference in the abundance of the spruce beetle (Ips typographus japonicus Niijima) (Col., Scolytidae) within and outside forest in a bivoltine area

Abstract

In Hokkaido (Japan), the spruce beetle (Ips typograpaus japonicus) kills standing spruce trees after selection cutting. The seasonal change in the number of beetles captured in 18–21 traps within or outside forest was analysed, with reference to a control strategy for this species in a bivoltine area. The number of beetles captured in traps had two peaks: one, which was small, in early June, and the other, which was a large peak, in July. However, the number of beetles captured in traps outside the forest had only one small peak, in June. The difference between the inside and outside of the forest was caused by the difference in the number of newly emerged beetles captured in traps. Beetles were distributed contagiously within the forest and there was no remarkable change in distribution pattern throughout seasons. Beetles were distributed at random in June when beetle activity was high outside forest. Overwintered beetles must undertake long‐range dispersal irrespective of whether they are within or outside of forest for finding suitable breeding materials. Nevertheless, the most important point is that newly emerged beetles stayed inside the forest and only a few individuals dispersed outside the forest. This study recommends that different control methods are adopted according to the seasons for the control of spruce beetles.

Quantifying spatio-temporal dispersion of bark beetle infestations in epidemic and non-epidemic conditions

“…Within-year dispersal, as discussed e.g. by Botterweg (1982) and Furuta et al (1996), could not be analysed with our data.…”

Efficacy of synthetic lures for pine bark beetle monitoring

“…The approximately equal abundance of I. typographus at all localities indicates the general high population density of this species in the landscapes and its considerable tendency to migrate (Lubojacký, Knížek 2021;Hlásny et al 2021). This serious pest can be observed even at a distance of several kilometres from the nearest spruce trees (Furuta et al 1996). Primary attraction together with upwind flight are the prerequisites for the reproductive success of I. typographus (Gries et al 1989).…”

Population dynamics in changing environments: the case of an eruptive forest pest species

“…After completing the first brood, adult beetles may re‐emerge to start a second (or even third) “sister” brood (Christiansen & Bakke, 1988), involving dispersal distances similar to (Botterweg, 1982), or less than (Zolubas & Byers, 1995) those of beetles first emerging from the soil in spring. In a bivoltine situation, the overwintering generation disperse more extensively than the summer generation (Furuta, Iguchi & Lawson, 1996).…”