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Research article2015Peer reviewed

Effects of different insect species on seed quantity and quality in Norway spruce

Rosenberg, Olle; Nordlander, Göran; Weslien, Jan

Abstract

Grafts from selected superior trees are used for establishment of seed orchards. These seeds result in trees with higher growth rates and better wood quality than trees originating from seeds collected in local forest stands. Insecticides are used to reduce damage to seeds in seed orchards. Hypothetically, this may be ineffective because the suppression of one insect species may relieve interspecific competition and trigger corresponding increases in damage caused by another species. Therefore, we investigated the effects of three insect species [Dioryctria abietella Denis and Schiffermuller (Pyralidae), Cydia strobilella L. (Tortricidae) and Strobilomyia anthracina Czerny (Anthomyiidae)], singly and in all possible permutations, on the numbers and quality of seeds in Picea abies cones. Species were manipulated by insecticide treatments. The cones were examined for externally visible damage caused by D. abietella and S. anthracina after which the seeds were extracted, counted and X-rayed to assess seed quality and the number of seeds infested by insects. Finally, the cones were dissected to identify and count C. strobilella larvae. There was no evidence of trade-offs between absence of one species and increased damage by the remaining species. Instead, damage tended to increase as the number of species in a cone increased. The most serious pest species in the present study was D. abietella, reducing the number of filled seeds by approximately 60%. Our results indicate that there is little risk that suppression measures directed towards one particular species will lead to increased damage by other species. The insecticide, -cypermethrin, showed promising results against D. abietella and S. anthracina.

Keywords

Cone insects; Cydia strobilella; Dioryctria abietella; interaction; Picea abies; seed insects; seed orchard; Strobilomyia anthracina

Published in

Agricultural and Forest Entomology
2015, Volume: 17, number: 2, pages: 158-163 Publisher: WILEY-BLACKWELL

        SLU Authors

        UKÄ Subject classification

        Ecology
        Forest Science

        Publication identifier

        DOI: https://doi.org/10.1111/afe.12091

        Permanent link to this page (URI)

        https://res.slu.se/id/publ/68394