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Effect of time of year on the development of immature stages of the Large Pine Weevil ( Hylobius abietis L.) in stumps of Sitka spruce ( Picea sitchensis Carr.) and influence of felling date on their growth, density and distribution
Author(s) -
Moore R.,
Brixey J. M.,
Milner A. D.
Publication year - 2004
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/j.1439-0418.2004.00828.x
Subject(s) - felling , biology , weevil , larva , botany , scots pine , horticulture , thinning , ecology , pinus <genus>
Abstract: The time of year and time of felling of a commercial stand of Sitka spruce ( Picea sitchensis Carr.) were both shown to influence the spatial distribution and development of the large pine weevil, Hylobius abietis (L). Stump and root systems were excavated over a 5‐month period in 1997, between 18 and 27 months after felling, and all immature H. abietis removed. On a site with a 6‐month spread of felling dates in 1995, mean larval weights in 1997 were higher in stumps from earlier fellings, but H. abietis numbers were higher in stumps from later fellings. This appeared to be due to the continued presence of older, heavier larvae, laid as eggs in 1995, in stumps from earlier fellings, combined with a greater concentration of oviposition having occurred in 1996 in the fresher stumps of later fellings. Pupae were first found in excavated stumps on 12 June 1997 and adults on 29 July 1997. Emergence of the ‘new generation’ of adult weevils commenced on 7 August 1997. On average, 25% of H. abietis adults emerged in autumn 1997, 41% in 1998 and 34% in 1999. First emergence (1997) was proportionally higher in the areas felled earlier in 1995 than those felled later that year. However, the opposite was found for third emergence (1999) where emergence was greater for stumps created later in 1995. Larger stumps contained greater densities of H. abietis . Total ‘potential’ emergence was estimated to be between 46400 and 170825 H. abietis /ha. However, emergence traps indicated that only 40–80% managed to complete their development and emerge successfully. It is suggested that within‐season felling date may be one of the most important factors affecting larval development, distribution and abundance; as well as subsequent damage levels associated with adult feeding. Consequently, knowledge of felling date could be crucial to developing methods of integrated forest management for this major forest pest.