Winter mortality of the bark beetle Ips typographus in standing trees and in the ground

Abstract

Ips typographus is the most important tree-killing bark beetle in Europe. In the north, it overwinters either in the bark of its host tree or in the ground, while in central Europe, overwintering in trees is most common. Few studies have estimated winter mortality of I. typographus in northern Europe. Mortality of I. typographus adults overwintering in killed trees was estimated by comparing densities per m2 bark of live (one winter) and dead adults (five winters), and proportion of dead adults (one winter), in bark samples collected before and after winter in Sweden. Densities of live and dead larvae of predatory Medetera spp. (Dolichopodidae) were recorded in the bark samples (one winter), as was the amount of bark removed by woodpeckers from I. typographus-killed trees during winter foraging (five winters). Mortality of I. typographus adults overwintering in the ground was estimated by spring sampling of soil (three winters). The density of I. typographus live adults in trees was 3% lower after winter, while densities of dead adults was 6% higher and 5% lower respectively during two different outbreaks (differences after vs. before winters were non-significant). The proportion of dead adults was 4% higher after winter (significant). Winter mortality of adults overwintering in the ground was on average 58%. The density of Medetera was 6% and 8% lower after winter for live and dead larvae, respectively (non-significant). The amount of remaining bark on standing killed trees was on average 8% lower after than before winter (significant).

Keywords

climate warming; Eurasian spruce bark beetle; long-legged flies; Medetera; natural enemies; Norway spruce; outbreak; overwintering behaviour; winter mortality; woodpecker predation

Published in

Agricultural and Forest Entomology
2024
Publisher: WILEY

SLU Authors

• Schroeder, Martin

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Kärvemo, Simon

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Cocos, Dragos

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science

Publication identifier

• DOI: https://doi.org/10.1111/afe.12657

Permanent link to this page (URI)

https://res.slu.se/id/publ/132858