Abstract
Effects of the leaf quality of the host tree, Zanthoxylum ailanthoides, on the larval development of a swallowtail butterfly, Papilio xuthus, were studied in the laboratory. The leaves collected from trees higher than 1m (tall trees) were tough and thick while those from short (young) trees were tender and thin. The relation between the specific leaf area (SLA) and the tree height was not linear. Comparative observations of the transverse sections of the leaflets demonstrated that the thickness of a leaflet, the length of a cell and the number of cells in the palisade layer of tall trees were greater than those of short trees. In addition to these facts, the mortality rates of the populations reared on leaves from short trees were lower than those from tall ones, particularly in the 1st and the last instar stages, due to physiological death caused by diarrhoea, starvation or failure of ecdysis. The rate of larval development when reared on leaves from short trees was also greater than that from tall ones. These results supported the field observations that the mortality rates of populations on tall trees were higher than those on short ones due to leaf textures.
