Biology of apterous morph of rose-grain aphid, Metopolophium dirhodum (Hem.: Aphididae) on wheat in laboratory condition

Biology of apterous morph of rose-grain aphid, Metopolophiumdirhodum, one of the most abundant  wheat aphids, was studied in a laboratory condition with temperature of 25 ± 1˚ ^C, 50-60% relative humidity, and a photoperiod of 16:8 (L:D) hours. The experiment was carried out by rearing 50 first instar aphid nymphs in leaf cages on wheat (Triticum aestivum cv. Mahdavi). Biological characteristics of aphid were recorded daily and used for estimating population increase parameters according to Carey (1993). Mean nymphal development time of rose-grain aphidwas obtained 10.72 ± 0.37 days. Pre-oviposition period was 1.17±0.09 days and mean generation time of rose-grain aphid (from nymph to next generation nymph) was obtained 11.89 ± 0.37 days. Mean longevity was 42.66 ± 1.87 days. Adult longevity was high (33 ± 2.28 days) and they reproduced during most of their lifespan (17.65 ± 1.37 days). Survival curve of M. dirhodum on wheat was determined as Type І. Regarding to the age specific survival of aphid, nymphs and young adults didn’t suffer any mortality. Like to the development of herbivorous insects on susceptible host plants, there was even no mortality until age 27 (day). Study on stable population parameters revealed that each female produced 33.84 female in next generation (R₀). Intrinsic rate of increase (r_m) was 0.194 female per female per day. Estimating the finite rate of increase (λ) was also indicated 21.4% increment in aphid population per day. Estimation of doubling time (DT) (3.57 days) and mean generation time (T) (18.18 days) was also showed considerable population increase potential of rose-grain aphid on Mahdavi wheat cultivar.