Ecological Study of the Tea Red Spider Mite (Tetranychus Kanzawai KISHIDA) (Part 6)

Abstract

This paper reported an account of the habits of tea red spider mite, Tetranychus kanzawai KISHIDA, in the first tea season in Shizuoka-ken.1. Habits of mite on the old leaves.The tea red spider mite usually lived on the under side of old leaves, and their numbers increased from April to plucking season. The mite moved from lower to upper parts of tea plant, and from inner parts to plucking surface with the growth of the young leaves.2. Habits of mite on the young leaves.The adults and nymphs began to move towards young leaves from old ones in about 2-3 weeks before plucking, and the migration continued through the plucking period. Many numbers of mite were found. at the top and low parts of bushes during the plucking period, however, the mite more attacked lower leaves of young shoot. There was no certain relation between the number of damaged leaves and that of developed leaves. It seemed that the mite population density after plucking season was highest.3. Dispersion of mite.As the red spider mite spread from bush to bush by crawling, and it seemed that the wind is an important aid to its spreading. In this observation, a great numbers of adult or nymph were carried out from bushes to other parts by wind. The dispersal season was between April and June, and its number was parallel to the mite populaton density in the field.