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Research article - Peer-reviewed, 2023

Trap catch data are poor predictors of damage caused by pine weevil (Hylobius abietis) to conifer seedlings

Nordlander, Goran; Bjorklund, Niklas; Hellqvist, Claes; Nordenhem, Henrik; Liziniewicz, Mateusz; Hjelm, Karin

Abstract

Damage to planted conifer seedlings caused by the pine weevil Hylobius abietis (L.) is a severe and persistent threat to successful forest regeneration in Europe. Various countermeasures are available, which vary in effectiveness, costs and environmental impact, but none are ideal for all situations. Therefore, there is strong interest in robust assessments of damage risks, as they would enable more cost-effective and environmentally friendly forest pest management. It has been suggested that numbers of adult pine weevils caught in host-odour baited traps placed in regeneration sites may be valuable in such risk assessments. However, published studies provide at most weak support for the hypothesis that trap catch data provide adequate predictions of damage. Therefore, we conducted a two-year field study, designed to determine the relationship between weevil trap catch and subsequent damage at 10 regeneration sites in central Sweden. Site factors that might influence pine weevil feeding on seedlings were recorded and used as explanatory variables in the analysis. Stoniness was the only site factor identified as having a significant effect; damage mainly increased with increases in stoniness. No significant correlation was detected between damage to planted conifer seedlings and numbers of pine weevils trapped in the same locations. We suggest that this lack of correlation between weevil numbers and damage is due to planted seedlings only constituting a minor part of the weevils food intake and considerable between-site variation in availability of food sources other than seedlings. Therefore, assessment of pine weevil numbers appears unlikely to be useful for predicting damage risk at specific regeneration sites.

Keywords

Forest pest management; Forest regeneration; Mechanical site preparation; Population density; Risk assessment; Site factor; Stoniness

Published in

Forest Ecology and Management
2023, Volume: 537, article number: 120968
Publisher: ELSEVIER