Induced response of the Siebold's beech (Fagus crenata Blume) to manual defoliation |
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Authors: | Naoto Kamata Yutaka Igarashi Seiji Ohara |
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Institution: | (1) Tohoku Research Center, Forestry and Forest Products Research Institute, 020-01 Morioka, Japan;(2) Forestry and Forest Products Research Institute, 305 Inashiki, Ibaraki, Japan |
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Abstract: | Siebold's beech (Fagus crenata) was manually defoliated for two successive years. The beech caterpillar (Quadricalcarifera punctatella) was used in a bioassay to determine insect performance. Survival and body size were low on foliage from defoliated trees.
Reduced foliar nitrogen and increased tannin content were probably the main causes of the low insect performance. Leaves were
less tough on defoliated trees than in controls. Two sucessive years of manual defoliation caused stronger induced resistance
than one year defoliation. The quality, as well as the quality of the foliage, decreased the year following manual defoliation;
total weight of leaves on a tree was less than one half of that before treatment. Severe defoliation may cause a decrease
of leaves the following year and starvation may limit populations. Delayed induced resistance of beech trees is proposed as
a possible cause of the cyclical population dynamics ofQ. punctatella. The delayed induced response also affected folivorous insects other thanQ. punctatella. |
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Keywords: | beech leaf quantity manual defoliation nutritional fitness plant inducible defense |
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