Impact of bark beetles on forests and forestry in Sweden¹

Abstract

The impacts of bark beetles in Sweden and the role and management of bark beetle breeding substrate are discussed. Of the six important species damaging living trees, Tomicus piniperda and Ips typogruphus have the greatest impact. The damage caused by Tomicus adults feeding in pine shoots is directly related to beetle numbers, which in turn depend on the availability of non-resistant breeding substrate. Intensity of shoot pruning, tree size, and geographic region are important factors determining the extent of losses, which can amount to 45 % of the annual volume growth. The extent of tree mortality caused by Ips typographus attack depends on interactions between host tree vigour, densities of colonizing populations, and the availability of other, non-resistant breeding substrate. During the latest outbreak, the trees killed represented about 6 million cubic meters of wood. The heaviest losses were reduction of timber quality, unsalvaged timber, and the cost of control measures. The economic impact of reduced growth depends on the shortening of rotation by insect attack and on interest rates. During the 1960s and 1970s bark beetle attacks and their impact increased owing to natural causes and forestry practices. Hereafter, integrated forest protection efforts, based on research, organisation, information, and legislation, reduced bark beetle attacks to a low level.

Response of <I>Tomicus yunnanensis</I> (Coleoptera: Scolytinae) to Infested and Uninfested <I>Pinus yunnanensis</I> Bolts

“…T. yunnanensis is regarded as one of the most aggressive species of Tomicus, being able to attack and kill live, apparently healthy P. yunnanensis trees Lieutier 1997, Lu et al 2014). T. minor is often considered to be more of an opportunist, usually infesting host trees that are already infested by other Tomicus species such as T. piniperda or T. yunnanensis, which could facilitate tree death (Bakke 1968, Långström 1983, Eidmann 1992, Ye and Ding 1999, Lieutier et al 2003, Chen et al 2009. In this study, we discovered that T. brevipilosus preferred to breed in trunks of P. yunnanensis trees that were already infested by both T. yunnanensis and T. minor.…”

Pityogenes chalcographus (Coleoptera, Scolytinae) at the southernmost borderline of Norway spruce (Picea abies) in Greece

“…chalcographus is considered as an important spruce pest within Europe, responsible for damages of conifer forests during the last centuries (Ehnström et al 1974, Christiansen et al 1987, Christiansen and Bakke 1988, Eidmann 1992, Göthlin et al 2000, Schroeder 2001, Bouget and Duelli 2004. Mass outbreaks are often in concert with Ips typographus (Coleoptera: Scolytinae) something that facilitates a successful colonization of the host tree (Schwerdtfeger 1929 Pityogenes chalcographus is further associated with blue-stain fungi, mainly Ophiostoma spp.…”

Future of biodiversity in the Barents Region

“…The European spruce bark beetle can cause substantial damage to spruce stands and is able to rapidly become very abundant (Wermelinger 2004). Weakened spruce stands are particularly susceptible to outbreaks of this species (Wermelinger 2004), but rarely occur in the Barents Region today (Eidmann 1992;Eriksson et al 2005). This is because current climatic conditions only allow the species to reproduce once a year (Sauvard 2004).…”