Seasonal and interspecific variation in the biochemical composition of some British fern species and their effects on Spodoptera littoralis larvae

摘要: Fern-feeding insects in Britain are mainly found on mature fronds late summer. Six fern species (Dtyopteris filix-mas, D. dilatata, borreri, Phyllitis scolopendrium, Polyslkhum setiferum and Polypodium vulgare) were analysed for fibre, lignin, cellulose, tannins, cyanogenesis thiaminase activity an attempt to determine the biochemical basis this seasonal pattern of attack. A bioassay was also carried out, using frond material incorporated diet Spodoptera littoralis, effects changes toxins a non-adapted, insect herbivore. The young all six had high protein content low fibre-lignocellulose; levels decreased cell wall materials increased as matured. Tannin concentrations showed less consistent pattern. Tannins present highest concentration Polystichum with season; similar activity. The other no strong seasonality either tannins or thiaminase. No cyanogenic detected any species. Frond from survivorship growth rates larvae. Larval performance diets containing immature generally poorer than fronds, collected later season. Neither tannin nor closely corresponded observed interspecific patterns larval development mortality, must be involved. It is concluded that ferns highly toxic non-adapted herbivorous but adapted unknown. restricted occurrence small number exhibiting specialized feeding habits suggests, however, properties attack limit which able exploit food resources.