Feeding on roots in the humus layer by adult pine weevil, Hylobius abietis

Authors

  • Kristina Wallertz,

    Corresponding author
    1. Asa Forest Research Station, Swedish University of Agricultural Sciences, SE-360 30 Lammhult, Sweden, * Department of Entomology, Swedish University of Agricultural Sciences, P.P. Box 7044, SE-75007 Uppsala, SwedenandDepartment of Forest and Wood Technology, Växjö University, SE-351 95 Växjö, Sweden
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  • ,a Göran Nordlander,

    1. Asa Forest Research Station, Swedish University of Agricultural Sciences, SE-360 30 Lammhult, Sweden, * Department of Entomology, Swedish University of Agricultural Sciences, P.P. Box 7044, SE-75007 Uppsala, SwedenandDepartment of Forest and Wood Technology, Växjö University, SE-351 95 Växjö, Sweden
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  • Göran Örlander

    1. Asa Forest Research Station, Swedish University of Agricultural Sciences, SE-360 30 Lammhult, Sweden, * Department of Entomology, Swedish University of Agricultural Sciences, P.P. Box 7044, SE-75007 Uppsala, SwedenandDepartment of Forest and Wood Technology, Växjö University, SE-351 95 Växjö, Sweden
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K. Wallertz, Asa Forest Research Station, Swedish University of Agricultural Sciences, SE-360 30 Lammhult, Sweden. Tel.: +46 472263172; fax: +46 472263030; e-mail: kristina.wallertz@esf.slu.se

Abstract

1 The consumption by adult pine weevil, Hylobius abietis, of the bark of roots present in the humus layer was assessed in a field study conducted in southern Sweden during two years (1998 and 2002). The study sites were divided into two areas: (i) a shelterwood where 80–100 mature Scots pine trees per hectare remained after cutting and (ii) a clearcut where no trees were left.

2 On average, 3741 m2 per hectare of root bark was present in the humus layer, of which 135 m2 was not coniferous but comprised species such as bilberry and broadleaved trees.

3 The mean area debarked by pine weevils was 2.9 m2 per hectare; 2.6 m2 of conifer roots and 0.3 m2 of bilberry roots. Roots of broadleaved trees were almost never consumed. No clear preferences for roots of a specific level of vitality were observed.

4 No consistent difference between the shelterwood and clearcut was found, either in the amount of root bark area available or in the extent of root feeding by pine weevil.

5 A weak negative correlation between debarked areas on roots and seedlings was found, indicating that root feeding may have reduced damage to seedlings.

6 It is concluded that conifer roots in the humus layer constitute a major food source for the pine weevil and can be utilized for a considerable period in both clearcuts and shelterwoods.

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