عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Life table parameters of the beet armyworm, Spodoptera exigua (HÃ¼bner), on four sugar beet cultivars (Renger, FD0005, Dorothea and Shirin) were studied in laboratory at 27 Â± 1Â°C, 60 Â± 5% RH and a photoperiod of 16L: 8D hours. The larvae successfully developed on all cultivars. The shortest and longest total developmental time were recorded on FD0005 and Renger, respectively. The development index (D.I.) of larval period varied from 4.90 to 5.97 on Renger and Shirin, respectively. The life expectancy (ex) was 26.94, 31.39, 30.51 and 30.16 days on the cultivars respectively at the beginning of life. Life table entropy (H) indicated the survival schedule of S. exigua was convex (type I) on all sugar beet cultivars. The gross fecundity ranged from 1499.93 to 2034.67 eggs on Dorothea and FD0005, respectively. The lowest value of net reproductive rate (R0) was recorded on Renger (253.59 females per female per generation). The intrinsic rate of increase (rm) ranged from 0.2235 on Renger to 0.2309 dayâ1 on FD0005. The mean generation time (T) was found to be significantly different on sugar beet cultivars. Fitting adult survival data to Weibull frequency distribution indicated that the adult survival curve was type I on all cultivars suggesting that the mortality was higher in old individuals. The cultivar Renger was less suitable in comparison with other cultivars in the laboratory. These results provided important information on the effect of four commercial sugar beet cultivars on population growth potential of S. exigua.