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چکیده
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Abstract: A study was conducted to evaluate the effect of six common tomato cultivars plus nitrogen levels on Helicoverpa armigera (Hüb.) life history parameters. Cultivars including Kingston, Riogrand, Earlyurban, Redston, Superstrain-D and Primoearly were planted in 2 Lit pots and were maintained under greenhouse conditions. The nitrogen fertilization regime consisted of four levels (0, 210, 300, 390 kg Ha-1N as Urea 46%). Then, a colony of H. armigera (Hüb.) was established in laboratory at 25 ± 1 °C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) hours. Fifty eggs of the pest (0-24 hrs age) were considered as a cohort and reared on each treatment at a.m conditions. Totally 24 treatments (6 cultivars × 4 N levels) were tested. Observations were noted down on mortality, developmental time of immature and longevity and fecundity of adult stages. Data was analyzed using age-stage, two-sex life table approach. The larval period ranged from 15.44±0.36 to 24.21±0.56 days on Superstrain-D with highest N concentration and Earlyurban with lowest N concentration, respectively. The insects reared on Redston and Earlyurban+lowest N, had the longest total pre-oviposition period (41.6±0.28 and 41.9±0.17 days), respectively, compared with that on Superstrain-D+highest N (28.6±0.22 days). Similarly, the longest adult longevity for female was observed on Redston+highest N, (13.93±0.35 days) and shortest one occurred on Primoearly+lowest N, (9.04±0.26 days). Calculation of population parameters proved that the net reproductive rate (R0) varied from 25.07±7.06 to 91.6±18.9 female/female/generation on Redston+lowest N, and Riogrand+highest N, respectively. The lowest values of the intrinsic rate of increase (r) and finite rate of increase (λ) were 0.07±0.0065 and 1.07±0.0069 day-1 on Redston+lowest Nand the highest ones were 0.15±0.0057 and 1.16±0.0066 day-1 on Superstrain-D+highest N, respectively. The mean generation time (T) of H. armigera on cultivars with different N levels ranged
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