Demography of the Bird Cherryoat Aphid, Rhopalosiphum Padi (L.) (Hemiptera: Aphididae) on Different Barley Varieties

Life table parameters of the bird cherry-oat aphid, (rhopalosiphum padi l.) were determined on different barley (hordeum vulgare l.) varieties. experiments were carried out under laboratory condition of 26±1°c, 65±5% rh and photoperiod of 16:8 (l:d) hours. newborn first instar nymphs of the same age were reared on the leaves of six barley varieties using leaf cages. nymphal development time, mortality, longevity and adult fecundity were recorded daily. nymphal survivorship varied from 71% to 88% on the varieties tested. the results revealed significant effect of experimental varieties on demographic statistics of r. padi. the intrinsic rate of natural increase rm, ranged between 0.318 and 0.366 female/female/day; the range of other life table parameters was from 1.37 to 1.44 day^-1 for finite rate of increase λ, 43.83 to 60.65 female/female/generation for net reproductive rate r0, 1.89 to 2.17 days for doubling time dt and 11.19 to 11.86 days for mean generation time t. in conclusion, analysis of biological parameters indicated valfajr and fajr30 as relatively less susceptible varieties to r. padi, while reihan03, kavir and zarjow were considered as relatively more susceptible and nosrat was placed in the same statistical group with other varieties.