Abstract: The effects of environmental factors such as photoperiod temperature and food quality on the incidence of diapause in the hawthorn spider mite, Tetranychus viennensis Zacher were investigated. The results show that the critical photoperiod for inducton of diapause was 12 hours and 32 minutes. The stages from larva to the protonymph, or from protonymph to the deutonymph, were more sensitive to photoperiod than other stages, however, among these a single developmental stage could not induce diapause. Feeding on the same host plants, the diapause incidence on old, diseased and young leaves were 69.7%, 55.3% and 20% respectively. Short photophase and low temperature (15℃, 18℃, 21℃) enhanced the incidence of diapause (100%, 93.1% and 66.7% respectively). Higher temperature (24℃) inhibited diapause,and diapause did not occur at 27℃.

Key words: Tetranychus viennensis, diapause, photeperiod, sensitive stage, tempe rature, food quality