Life table parameters of the cotton bollworm, Helicoverpa armigera (Lep.: Noctuidae) on different soybean cultivars

Influence of 13 soybean cultivars (356, M4, M7, M9, Clark, Sahar, JK, BP, Williams, L17, Zane, Gorgan3 and DPX) on the life table parameters of the cotton bollworm, Helicoverpa armigera (Hübner) was studied at 25 ± 1°C, relative humidity of 65 ± 5% and a photoperiod of 16: 8 (L: D) h. The survival rate (lx) of individuals developed to adults from the initial cohort on the mentioned cultivars was estimated 0.87, 0.83, 0.96, 0.96, 0.77, 0.72, 0.81, 0.72, 0.85, 0.74, 0.85, 0.88 and 0.72, respectively. The longest and shortest life expectancy (ex) of the pest was 44.22 and 35.98 days on Gorgan3 and BP, respectively at the beginning of life. The intrinsic rate of natural increase (rm) on different cultivars ranged from 0.1324 to 0.1848 (day -1), which was lowest on 356 and highest on M9. The highest net reproductive rate (R0) was on M7 (354.92 female/female/generation) and the lowest value of this parameter was on 356 (89.35). The values of finite rate of increase (λ), mean generation time (T) and doubling time (DT) on different soybean cultivars were as follows: 1.14 to 1.20 female offspring per female per day for λ, 28.85 to 36.61 days for T and 3.75 to 5.23 days for DT. Because of the higher coefficient of determination (R2) value in Gompertz model, data from different cultivars had a better fit to this model compared with Weibull model. The results indicated that 356, L17, Gorgan3, BP and Sahar cultivars were less suitable host plants, suggesting that they are more resistant to H. armigera than the other cultivars.