Seasonal Changes in Oak Leaf Tannins and Nutrients as a Cause of Spring Feeding by Winter Moth Caterpillars

Abstract

Abstract. Concentration in the spring of feeding by caterpillars of the winter moth, Operophtera brumata L., and other species of Lepidoptera on oak trees in England is believed to be related to seasonal changes in the texture and chemical composition of the leaves. Increasing leaf toughness is a proximate, though probably not ultimate, factor preventing late larval feeding by the winter moth, the commonest spring species on oak. Early feeding coincides with maximum leaf protein content and minimum leaf sugar content, which suggests that availability of nitrogen, rather ·than of carbohydrate, may be a limiting factor for spring-feeding larvae. The content of oak leaf tannins, which inhibit the growth of winter moth larvae, increases during the summer and may render leaves less suitable for' insect growth by further reducing the availability of nitrogen and perhaps also by influencing leaf palatability. Oak trees are extensively damaged by insect attack, and it is likely that leaf tannins have a defensive function against insects as well as against other herbivores and against pathogens.

Previous herbivore attack of red alder may improve food quality for fall webworm larvae

“…The new leaves sometimes have different defensive and nutritional chemical characteristics than original leaves (Feeny 1970, Raupp and Denno 1983, Williams et al 1983a. In our experiment, young and mature leaves of UBC alders were equally good food for fall webworm larvae.…”

“…The reduction of food quality may occur within hours or days (Green andRyan 1972, Carroll andHoffman 1980) or may persist over several seasons (Baltensweiler et al 1977). Food quality may also deteriorate as a regular seasonal occurrence (Feeny 1970, Dement and Mooney 1974, Scriber 1977, Mooney et al 1981. Several hypotheses of plant defense have been proposed to explain rapid changes in plant chemistry Schultz 1983), and poor growth of insects reared on recently-damaged plants Niemelfi 1977, Rhoades 1983).…”

“…Deterioration. Herbivore attack reduces the photosynthetic productivity of plants and food quality deteriorates, possibly as a result of leaf area loss, reduced leaf water or nutrient contents, or increased fibre content (Feeny 1970, Baltensweiler et al 1977, Haukioja 1982, Myers and Post 1981.…”

Foliar Phenolics are Differently Associated with Epirrita autumnata Growth and Immunocompetence

“…Since the classic paper by Feeny (1970), many analyses of the chemical defenses of woody plants have focused on phenolic compounds. The results have been variable; correlations between individual phenolic compounds or groups of compounds and insect performance have often ranged from negative to zero, but positive correlations have also been reported (Karban and Baldwin 1997).…”

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“…Phenolic compounds and especially tannins (polyphenols) are widely recognized as effective herbivore deterrents in terrestrial (Feeny, 1970;Hagermann and Butler, 1991) and marine systems (Steinberg and van Altena, 1992) but not in freshwater plants. Submerged aquatic angiosperms generally contain lower concentrations of phenolic compounds compared to emergent or floating leaved macrophytes (Gross, 1999;Smolders et al, 2000).…”