Abstract: Aim】 The solenopsis mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), is an important alien invasive pest recorded in China in the past several years and has a potential threat to cotton. In this study, the effects of constant and fluctuating temperatures on the growth and development of P. solenopsis on cotton was studied. 【Methods】 Under laboratory conditions (photoperiod 12L∶12D, RH 70%±5%), the developmental duration, developmental rate, survival and fecundity were investigated under a series of temperatures, and the effective accumulated temperature, developmental threshold temperature and optimal development temperature were analyzed. 【Results】 The results showed that the temperature had significant effect on the development of P. solenopsis. Within the constant temperature ranging from 17 to 32℃, the developmental duration of each stage of P. solenopsis shortened as the temperature rose gradually, and the developmental rate showed a significant positive correlation with temperature. The mealybug had higher developmental rate, survival rate and fecundity during the constant temperatures of 22-32℃. However, under the constant temperature of 37℃, the development was suppressed obviously and the mealybug died before completing a whole life span. In the fluctuating circumstance (25-40℃), P. solenopsis showed a better acclimatization, and had shorter developmental duration, higher survival rate and faster developmental rate. The minimum temperature thresholds (T_min) of females and males were 9.0 and 8.1℃, respectively. The effective accumulated-temperatures (K) of females and males were 322.6 degreedays and 344.8 degree-days, respectively. By analyzing the nonlinear regression relationships of the developmental rate and temperature, we calculated the optimal temperatures (T_opt) of females and males (30.5 and 29.95℃, respectively), and the maximum temperature thresholds (T_max) of females and males (36.6 and 35.8℃, respectively). 【Conclusion】 P. solenopsis has a wide range of adaptive temperature and can adapt to high temperature threshold under the fluctuating temperatures. These results will be helpful for predicting the distribution of this pest in the cotton regions in China.

Key words: Phenacoccus solenopsis, temperature, developmental duration, fecundity, effective accumulatedtemperature, developmental threshold