Effect of different corn hybrids on population growth parameters of cotton bollworm, Helicoverpa armigera (Lep.: Noctuidae)

The cotton bollworm, Helicoverpa armigera is a serious pest of different agricultural crops in Iran and other parts of the world. The effect of different corn hybrids including SC700, SC704, SC500, DC370 and SC260 which incorporated into artificial diets on population growth parameters of H. armigera was studied at growth chamber conditions (25±1ºC, 65±5% RH and a photoperiod of 16:8 (L:D) hours). The intrinsic rate of increase (rm) on different hybrids varied from 0.1039 to 0.1394 (day -1), which was lowest on SC700 and highest on SC500. The highest net reproductive rate (R0) was on SC500 (203.90 females/female/generation) andthe lowest value of this parameter was on SC700 (68.30). The results showed that longest doubling time (DT) was on SC700 (6.59 days) and shortest one was on SC500 (4.96 days). Because of the higher coefficient of determination (r2) value in Gompertz model, data from different hybrids had a better fit to this model compared to Weibull model. The survival rate (lx) of individuals developed to adults from the initial cohort was 0.36, 0.44, 0.56, 0.46 and 0.48 on DC370, SC704, SC260, SC500 and SC700. The life expectancy (ex) of H. armigera was 13.55, 16.45, 13.53, 13.43 and 13.76 days, respectively at the first day of adult emergence. Our findings indicated that hybrid SC700 was unsuitable host and hybrid SC500 was suitable host for H. armigera.