Host tree preference and performance of the Eurasian spruce bark beetle (Ips typographus) on Scots pine

The Eurasian spruce bark beetle, Ips typographus, is one of the most serious pests of Norway spruce (NS, Picea abies), with the ability to infest and kill vigorous trees through pheromone-mediated mass attacks. During outbreaks, I. typographus has been observed to occasionally attack Scots pine (SP, Pinus sylvestris). We investigated in the laboratory whether I. typographus is attracted to SP bark and logs, which semiochemicals mediate this potential attraction, and how beetle fitness is affected by the host tree species.

Ips typographus was attracted to the odors from SP bark plugs in short-range walking bioassays, and did not prefer the bark odors from NS over SP. In two-choice bioassays with logs, the beetles also did not discriminate significantly between the tree species. Analysis of NS and SP bark volatiles revealed quantitative differences in abundant monoterpenes and their enantiomers; however, none of the monoterpenes elicited a behavioral response when tested individually. Furthermore, we showed that I. typographus can reproduce in SP logs but with reduced offspring weight and numbers. Finally, males emitted less of the aggregation pheromone component cis-verbenol when colonizing SP compared with NS.

Our results suggest that I. typographus is attracted to SP bark odors at short-range and can reproduce in SP logs under laboratory conditions but with a reduced fitness. The reduced release of cis-verbenol may suggest a reduced likelihood of pheromone-induced mass attacks on SP. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.