Suitability of Larvae Food Plants For Orthosia Gothica L. (Lepidoptera, Noctuidae) and Opherophtera Brumata L. (Lepidoptera, Geometridae)

Abstract

Twenty-five different plant species, both deciduous trees and plants from ground vegetation, are compared as food plants for the larvae of Orthosia gothica and Opherophtera brumata. Chemical analysis of the major nutrients and the phenolic contents of the leaves of ten of the plant species are carried out and discussed in relation to larvae mortality and pupae wei ghts of O. gothica, The major nutrients are of basic importance in t he utili za tion of the acceptable food plants. The less acceptable food plants, as Betula pubescens and Alnus incana, have both a relatively high content of the deterrent phenolic compounds, rutin and quercetin present in their leaves. All the larvae fed on Fagus silvatica died before pupation,. probably because of the high tannic content of the leaves and/or the markedly changes in leaf texture from soft to tough in late May and primo June. The experiment shows that the composition of the spring phase plants of the ground vegetation in an area are very important for survival of small, wind dispersed larvae. It also shows that the naturally food plants contribute to great differences in the growth rate of the winter moth populations.