关键词: 八字地老虎, 生命表参数, 温度, 发育历期, 种群动态, 两性生命表

Abstract: 【Aim】 To assess the effects of temperature on the growth, development and reproduction of Xestia c-nigrum in Korla, Xinjiang, Northwest China, and to explore its adaptability to environmental temperature. 【Methods】 The egg hatching rates, larval survival rates, pupation rates, eclosion rates, developmental duration and fecundity of X. c-nigrum at 15, 20, 25, 30 and 35 ℃ were compared by using two-sex life table method, and the effects of different temperatures on the life table parameters of the population were analyzed. The developmental threshold temperatures and effective accumulated temperatures of X. c-nigrum at different developmental stages were also determined. During 2020-2022, the relationship between the population dynamics of X. c-nigrum by light-trapping and the daily average temperature change in Korla, Xinjiang was analyzed. 【Results】 At 15 ℃, the larval survival rate, pupation rate, and eclosion rate of X. c-nigrum were lower than 30%. At 30 ℃, the larval survival rate and pupation rate were lower than 10%, and the pupa could not normally emerge. At 35 ℃, the larvae could not survive. The duration of different developmental stages of X. c-nigrum shortened as the temperature rose, and the egg duration was 15.52, 7.40, 5.47, 4.88 and 3.88 d at 15, 20, 25, 30 and 35 ℃, respectively. The larval duration was 109.43, 40.53, 26.47 and 24.55 d at 15, 20, 25 and 30 ℃, respectively. The pupal duration was 41.43, 18.00 and 12.54 d at 15, 20 and 25 ℃, respectively. The pupal duration was 41.4, 18.0 and 12.5 d at 15, 20 and 25 ℃, respectively. The population showed negative growth at 15 ℃, and positive growth at 20 and 25 ℃, with the highest intrinsic rate of increase (r_m) at 25 ℃. The developmental threshold temperatures of egg, 1st-6th instar larvae and pupa were 9.81, 8.43, 9.95, 10.26, 12.52, 13.58, 12.60 and 10.81 ℃, respectively, and the effective accumulated temperatures were 79.62, 92.17, 56.09, 57.03, 39.35, 38.16, 80.72 and 172.39 degree.days, respectively. The monitored data from light.trapping during 2020-2022 showed that X. c.nigrum had three generations per year in Korla, Xinjiang, and the adult peak periods were in mid-May, late July and early September, with the average daily temperature range of 19.5-26.5 ℃. 【Conclusion】The population of X. c-nigrum shows negative growth when the temperature is lower than 15 ℃, and cannot complete its life cycle at over 30 ℃, moreover, 20-25 ℃ is more suitable for its growth and reproduction. This study provides a scientific basis for clarifying the temperature adaptability and its occurrence and dynamics of X. c-nigrum in Korla, Xinjiang.

Key words: Xestia c-nigrum; life table parameters, temperature, developmental duration, population dynamics, two-sex life table