Sheyda Goldasteh - Department of Entomology, Faculty of Agriculture, Islamic Azad University, Arak, Iran.
Ali Asghar Talebi - Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran
Ehsan Rakhshani - Department of Plant Protection, Faculty of Agriculture, University of Zabol, Zabol, Iran.
Shila Goldasteh - Department of Entomology, Faculty of Agriculture, Islamic Azad University, Arak, Iran.

The life table parameters of Schizaphis graminum (Rondani) (Hemiptera: Aphididae) on four commercial cultivars of wheat (Kohdasht, Pastor, Tajan and Zagros) were determined in laboratory conditions. Fertility life table were constructed using age-specific survivorship (lx) and age-specific fecundity (mx) and subsequently analyzed using jackknife method and ANOVA. There were significant differences among pre-imaginal period and adult longevity of the aphid on the four wheat cultivars. The highest mortality occurred at first nymphal instar on all of wheat cultivars tested. The life expectancy (ex) of one-day-old adults was estimated to be ۲۳.۵, ۲۴.۶, ۳۰.۳۶ and ۲۶.۸۳ days on Kohdasht, Pastor, Tajan and Zagros, respectively. The gross reproductive rate was significantly higher on Tajan (۱۰۲.۳۹ ± ۱.۴۲ females/female/generation) compared with other three cultivars. The net reproductive rate (R­۰) significantly differed on different wheat cultivars examined. The R۰-value was highest on Tajan (۸۲.۲۱ ± ۱.۲۱) and lowest on Zagros (۳۸.۲۳ ± ۰.۶۳ females/female/generation). The highest and lowest values of the intrinsic rate of increase (rm) were ۰.۲۷۶ ± ۰.۰۰۲ (on Pastor) and ۰.۲۲۲ ± ۰.۰۰۱ day-۱ (on Zagros), respectively. The finite rate of increase (l) differed significantly among four wheat cultivars, ranging from ۱.۲۵ ± ۰.۰۰ (on Zagros) to ۱.۳۲ ± ۰.۰۰ days-۱ (on Pastor). Doubling time ranged from ۲.۵۱ ± ۰.۰۲ (on Pastor) to ۳.۱۲ ± ۰.۰۲ days (on Zagros). The longest mean generation time (T) of the aphid was obtained on Tajan cultivar. The results showed that the Zagros cultivar had the highest antibiotic effect on population growth of S. graminum.

Schizaphis graminum, Wheat cultivars, Life table, Population growth parameters