Seasonal Development of the Diapausing and Non-diapausing Populations of the Citrus Red Mite, Panonychus citri (MCGREGOR) (Acarina

Seasonal development and biological characteristics of the diapausing and non-diapausing populations of Panonychus citri were investigated in two pear orchards, located in the northern part of Chiba prefecture. Females of the diapausing population started to deposit overwintering (diapausing) eggs in mid-September on twigs, and the population showed a conspicuous increase in late October and early November. Overwintered eggs began to hatch in mid-April with a peak in late April. Thus, the diapausing population could complete its life cycle on pear all the year round. On the other hand, the eggs deposited in late fall by the females of the non-diapausing population hatched by the end of January, and none of them survived on the tree until the next spring when the buds started to open. It was suggested that the occurrence of the non-diapausing population on pear may be associated with the presence of immigrants from evergreen trees in the vicinity.