棉红铃虫自然种群的生命统计特征

THE DEMOGRAPHY OF PINK BOLLWORM NATURAL POPULATION

1978—1988年,在湖北省江汉平原棉区,用编制特定年龄生命表的方法,研究棉红铃虫Pectimophora gossypiella(Saunders),第1至3代的自然种群生命统计特征值。世代存活率(S)为3.23、4.01和1.46;各虫态发育阶段(X)与相应阶段存活率的关系为:Y_1=61.66e^(-0.58#)、Y_2=142.47e^(-0.73#)、Y_3=146.68e^(-0.0(?)#);种群趋势指数(I):1.12、2.03和0.45;每雌蛾平均及最高产卵量:35(253)、51(235)、31(293)粒;自然内禀增长率(r′(?))为0.0390、0.0403和0.0026;净增殖率(R_o):4.39、4.43和2.04;周限增长率(λ):1.0398、1.0411和1.0026;世代长度(T):38、37和276日;种群加倍时间(t)18、17和267天。上列十个生命统计值已成为组建棉红铃虫的计算机辅助决策模型所必须的基质。第二代是全年的关键世代,各代钻蛀期的幼虫数及越冬期的幼虫数是影响下一世代或次年种群数量的关键虫态,钻蛀期幼虫的自然死亡是致死的主导因子。

The pink bollworm Pectinophora gossypiella is an important pest of cotton in Central China. It breeds three generations a year and its mature larva passes over winter. The life tables of its natural population were constructed from 1978 to 1988 in Jianghan Plain and the average values of demographic constants of the first, second and third generation were determined as follows: The survival rates were 3.23 ±1.07, 4.01±1.83, and 1.46±1.09; and the exponential equations were Y1= 61.66 e0.52x, Y2=142.47e-0.73x and Y3 = 146.68e-0.8.x where x = stage of development, the type of curve appeared to fit in with type A of Price(1975), which gave over 80% self mortality from egg to the mature larva in each generation. The population trend indices were 1.12, 2.03 and 0.45. The second generation had the highest index in each year which caused eventually heavy damage to the cotton bolls and resulted in a rapid increase of population density of the third generation. The average and ma-ximal numbers of eggs produced per female moth were 34.8/253, 50.66/235 and 30.79/293. Sex percentage of the female moths were 54.6%, 54.8% and 51.1%. The natural instananeous rate of population increase r were 0.0390, 0.0430 and 0.0026. Net replacement rate R were 4.39, 4.43 and 2.04. Mean length of a generation T were 38, 37 and 276 days. Finite rate of increase were 1.0398, 1.0411 and 1.0026 times. Population doubling time t were 18,17 and 267 days respectively. The population fluctuation was essentially affected by the self mortality of the intrusive borers in each generation and the overwintering larvae, which could be called as the key stages of pest mortality relevant to population density.