Demography of the Bird Cherry-oat 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 ۲۶­±­۱ºC, ۶۵­±­۵% RH and photoperiod of ۱۶­:­۸ (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 ۷۱% to ۸۸% 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 ۰.۳۱۸ and ۰.۳۶۶ female/­female/­day; the range of other life table parameters was from ۱.۳۷ to ۱.۴۴ day-۱ for finite rate of increase λ, ۴۳.۸۳ to ۶۰.۶۵ female­/female­/­generation for net Reproductive rate R۰,۱.۸۹ to ۲.۱۷ days for Doubling Time DT and ۱۱.۱۹ to ۱۱.۸۶ days for mean generation Time T. In conclusion, analysis of biological parameters indicated Valfajr and Fajr۳۰ as relatively less susceptible varieties to R. padi, while Reihan­۰۳, Kavir and Zarjow were considered as relatively more susceptible and Nosrat was placed in the same statistical group with other varieties.

Keywords:

Barley , Integrated pest management , Life table , Plant resistance