Title: Consumption of Apical Buds as a Mechanism of Alleviating Host Plant Resistance for Epirrita autumnata Larvae
Abstract: Epirrita autumnata (Lep. Geometridae) larvae are free-feeding folivores, which also consume apical buds of mountain birch (Betula pubescens ssp. tortuosa). In spring they damage both swelling apical buds and unfurling leaves, and, in mid-summer, apical bud initials enclosing leaf primordia for the following year. Previous studies have shown that removal of dormant or swollen apical mountain birch buds in spring increases the size and resource status of leaves emerging from remaining buds, and such leaves may become a better quality diet for herbivores. Assuming that larval damage to apical buds results in a similar increased resource status, larvae have a potential to increase the susceptibility of mountain birch leaves either rapidly, during the same season, or in a delayed manner, due to damage to buds of the following year. Our experiments showed that experimental damage to bursting buds in spring did not lead to an induced susceptibility of leaves in the same season, but mid-summer damage to apical winter bud initials significantly interacted with simultaneous defoliation, alleviating the delayed inducible resistance of birches in the following year. However, compared to undefoliated control trees, no overall increase in susceptibility of foliage was observed. Thus, delayed amelioration due to consumption of apical buds may prolong E. autumnata outbreaks, but the absence of overall ameliorative effects suggests that bud consumption only does not contribute to the increase in density. Effects of debudding significantly varied among trees, and, for unknown reasons, larvae in experiments consumed apical bud initials only at certain sites and in certain trees. Sources of these variations have to be elucidated to be able to further generalize our results.
Publication Year: 1997
Publication Date: 1997-03-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 21
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