異なった環境におけるマサキの葉の寿命とマサキタマバエの相互関係

抄録

At six different places in Kagoshima city and its vicinity, the leaf longevity of Euonymus japonicus was investigated between 1972 and 1976,in relation to the number of blister-like leaf galls produced by Masakimyia pustulae. Because the ungalled or lightly galled leaves were seldom shed except in the emergence seasons of the new leaves, stepwise survival curves of the leaves were obtained in seminatural environments. In urban environments, the mean leaf longevity was distinctly shorter than that in natural or seminatural environments. The mean longevity of the heavily galled leaves was considerably shortened in both the seminatural and urban environments. Particularly in the latter environments, the heavily galled leaves suffered from anthracnose disease, (caused by Gloeosporium euonymicolum), more severely than those in the former. Such an earlier fall of leaves was considered to operate as a density dependent mortality factor upon the urban populations of M. pustulae, which is univoltine and inhabits the leaf galls throughout the larval and pupal stages.