Demography of the Bird Cherry-oat Aphid, ( Rhopalosiphum padi L.) (Hemiptera: Aphididae) on Different Barley Varieties

Abstract

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±1ºC, 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 developm ent time, mortality, longevity and adult fecundity were recorded daily. Nymphal surviv orship varied from 71% to 88% on the varieties tested. The results revealed signific ant effect of experimental varieties on demographic statistics of R. padi . The intrinsic rate of natural increase r m , ranged between 0.318 and 0.366 female/female/day; the range of oth er 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 R 0 , 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 v arieties to R. padi , while Reihan03, Kavir and Zarjow were considered as relatively more susce ptible and Nosrat was placed in the same statistical group with other varieties. Keywords: Barley, Integrated pest management , Life table, Plant resistance.