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Abstract
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This study was conducted to evaluate the effect of six common tomato cultivars plus different nitrogen levels on Helicoverpa armigera (Hüb.) life history parameters. Cultivars including Kingston, Riogrand, Earlyurbana, Redston, Superstrain-B and Primoearly were planted in 2000 ml pots and were maintained under greenhouse conditions. The nitrogen fertilization regime included four levels (0, 210, 300, 390 kg Ha-1N as Urea 46%). A colony of H. armigera (Hüb.) was established at laboratory conditions (25 ± 1 °C, 60 ± 5% RH, 16L: 8D h). Fifty eggs of the pest (0-24 h.) were considered as a cohort and reared on each treatment at a.m. conditions. Six cultivars with four N levels were evaluated in a factorial experiment based on randomized complete design with 5 replications. Then mortality, developmental time of immature stages as well as the longevity and fecundity of adult stages was recorded. Data was analyzed based on age-stage, two-sex life table theory. The larval developmental period ranged from 15.44 ± 0.36 to 24.21 ± 0.56 days on Superstrain-B with highest N concentration and Earlyurbana with lowest N concentration, respectively. The longest total pre-oviposition period (41.6 ± 0.28 and 41.9 ± 0.17 days) was recorded for insects on Redston and Earlyurbana + lowest N, respectively. Similarly, the longest and shortest adult longevity for females were observed on Redston + highest N, (13.93 ± 0.35 days) Primoearly + lowest N, (9.04 ± 0.26 days) respectively. Additionally, estimation of population parameters proved that the net reproductive rate (R0) varied from 25.07 ± 7.06 to 91.6 ± 18.9 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 N and the highest ones were 0.15 ± 0.0057 and 1.16 ± 0.0066 day-1 on Superstrain-B + highest N, respectively. The mean generation time (T) of H. armigera for different N leve
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