关键词: 棉花粉蚧, 光周期, 发育历期, 生命表, 种群增长能力

Abstract: 【Aim】 To reveal the effects of different photoperiods on the developmental duration, fecundity and dynamics for the laboratory population of the cotton mealybug, Phenacoccus solenopsis Tinsley, and provide the scientific basis for control measures of the mealybug. 【Methods】 The mealybug population was fed on Hibiscus rosa sinensis under the conditions of temperature 27±1℃, relative humidity 70%±5%, illumination intensity 4 000 lx. The developmental duration, survival rate, and fecundity of the mealybug were observed, and the life tables were constructed under different photoperiods (8L∶16D, 10L∶14D, 12L∶12D, 14L∶10D and 16L∶8D, respectively). 【Results】 The developmental durations of the 1st and 3rd instar nymphs and the fecundities of female adults varied significantly among different photoperiods, while the survival rates of all nymphal stages were not significantly different. The developmental rate of the 1st and 3rd instar nymph of P. solenopsis accelerated as the light period increased, which were 5.43 and 6.35 d under 8 h light period, and 4.16 and 4.75 d under 16 h light period, respectively. The whole nymphal durations under 8 h and 16 h light periods were 15.54 and 12.74 d, and the generation durations were 27.75 and 23.45 d, respectively. The female adults produced offsprings earlier and had higher fecundity under longer light period. The pre-ovipositional durations for the female under the light periods of 16, 10 and 8 h were 18, 22, and 22 d, respectively. The number of offsprings produced per female under 16 h light period was 417.06, which was significantly higher than those under the 12, 10, and 8 h light periods (353.59, 347.61, and 336.00, respectively). The population trend indices (I) and growth potential were bigger under the longer light periods. The I values under 16, 10 and 8 h light periods were 175.37, 133.94 and 141.99, respectively. The net reproductive rate (R₀), the intrinsic rate of increase (r_m) and the finite rate of increase (λ) showed a gradually increasing trend with light periods, which were 88.57, 86.85, 100.77, 124.16, and 126.86 under the light periods of 8, 10, 12, 14, and 16 h, respectively. The r_m values varied from 0.1616 to 0.2066, and the λ values varied form 1.1754 to 1.2294 when the light periods increased from 8 h to 16 h. Contrarily, the population doubling time (t) decreased from 4.29 d to 3.36 d as the light periods increased from 8 h to 16 h. 【Conclusion】 Longer photoperiods are favorable for the development and fecundity of the cotton mealybug population, and the generation duration decreases while the population growth pontential increases as the light period increases.

Key words:  Phenacoccus solenopsis, photoperiod, developmental duration, life table, population growth potential