Experimental Population Life Tables of Spodoptera depravata

Based on the rearing data of lab colony of Spodoptera depravata experimental population life tables of the pest were constructed.The results showed that the first generation occurred in mid-July to mid-August and the second in mid-August to mid-September.The larval and pupal stages of the first generation lasted 18.66 and 7.27 days,while those of the second generation were 7.66% and 41.68% longer than the first generation respectively,which differed significantly between the two generations.The survival rate,average fecundity,net reproductive rate(Ro),intrinsic increase rate(rm) and finite increase rate(λ) of the first generation were 53.21%,276.28,74.383 6,0.139 1 and 1.149 2 respectively,and those of the second generation were decreased by 21.01%,17.39% ,33.40%,24.16% and 3.30%,respectively.The mean generation time(T) and the doubling time (DT) of the first generation were 31.222 7 days and 4.983 1,while those of the second generation were 19.52% and 31.85% longer than the first generation,respectively.The data observed in the laboratory showed that survival rate and fecundity of Spodoptera depravata reared on ryegrass were higher.Difference of parameters of the population increase in different generations was significant.The egg stage and the younger star larval stages were the best to control this insect for its high mortality.