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Research article - Peer-reviewed, 2008

Leaf trichome responses to herbivory in willows: induction, relaxation and costs

Bjorkman, Christer; Dalin, Peter; Ahrne, Karin


To circumvent the inherent problem of discriminating between the cost of losing photosynthetic tissue and the cost of producing an inducible defence, the growth response of herbivore-damaged plants was compared with plants damaged mechanically to the same extent but without eliciting the defence.Two experiments were conducted, studying the response of willows (Salix cinerea) to damage by adult leaf beetles (Phratora vulgatissima).In the first experiment, willows produced new leaves with an enhanced leaf trichome density 10-20 d after damage, coinciding in time with the feeding of beetle offspring. The response was relaxed in foliage produced 30-40 d after damage. In the second experiment, which also included mechanical damage, willows exposed to beetle feeding showed an increase in leaf trichome density of the same magnitude (> 70%) as in the first experiment. The cost of producing the defence was a 20% reduction in shoot length growth and biomass production. Willows exposed to mechanical damage had an 8% reduction in shoot length growth compared with control plants, that is, a cost of leaf area removal.The results are the first quantitative estimates of the cost of a plant defence induced by natural and low amounts (3.3%) of herbivory.


induced plant defence; insect herbivory; leaf trichomes; Salix cinerea; tolerance

Published in

New Phytologist
2008, Volume: 179, number: 1, pages: 176-184

    SLU Authors

      • Dalin, Peter

        • University of California Santa Barbara
      • UKÄ Subject classification

        Forest Science
        Environmental Sciences related to Agriculture and Land-use

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