On the Diapause of the Tea Red Spider Mite, Tetranychus kanzawai KISHIDA

Abstract

The present paper deals with the results of experiments on the diapause of overwintering adults of the tea red spider mite, Tetranychus kanzawai KISHIDA, living on the tea plant in Japan. The results are summarized as follows.The adult females changed the dark red body color to cinnabar toward winter, and they passed the winter season in cinnabar color. After the beginning of March, the mites turned red or dark red in color and they began to lay eggs.The cinnabar adult females did not lay eggs even if they were in a favorable living condition. The mites began to lay eggs when their body color turned dark red or red.The tea red spider mite spent winter in adult female form and in diapause state. The color of mites in diapause state was cinnabar.The diapause of mite took place at the middle or. the end of October to the beginning of November, and except in warm district as Kagoshima-ken it ceased at the end of January to the beginning of February. Though the beginning time of diapause in warm district was as same as in other tea cultivating areas, the closing time of diapause was from December to January. Therefore the diapause period in warm districts was not so long as in the other districts. The Diapause of mite was deepest in December at Kanaya, Shizuoka-Ken.The diapause of the mite could be induced by the following conditions:the temperature was below 20°C. with 8 hrs. of light phase or 3-5°C. with 16 hrs.of dark phase.Awaking the diapause of the mite was promoted by high temperature, 25°C. with 16 hrs. of light phase was a favorable condition for it.