Comparison of development and demographic parameters of Diuraphis noxia (Hem., Aphididae) and its parasitoid, Diaeretiella rapae (Hym., Braconidae: Aphidiinae) Zahra Tazerouni a , Ali Asghar Talebi a * and Ehsan Rakhshani b a Faculty of Agriculture, Department of Entomology, Tarbiat Modares University, Tehran, Iran; b Faculty of Agriculture, Department of Plant Protection, University of Zabol, Iran (Received 16 March 2011; final version received 9 May 2011) Demographic parameters of Diuraphis noxia (Mordvilko) and its parasitoid, Diaeretiella rapae (McIntosh) were investigated under laboratory conditions at temperatures of 20 + 18C, 60 + 5% relative humidity of 60 + 5% and a photoperiod of 16: 8 (light: dark) hours. The survival rates (l x ) and the life expectancy (e x ) at the beginning of adult emergence were 86% and 25.81 days for D. noxia and 100% and 7.36 days for D. rapae, respectively. Based on the Weibull distribution parameters, the survival curves were type I for both D. noxia and D. rapae, which indicates that mortality mostly occurred in older stages. The r m -values in aphid and parasitoid were obtained as 0.22 + 0.002 and 0.19 + 0.003 day 71 , respectively. Mean generation time (T) and doubling time (DT) were 15.93 + 0.202 and 3.15 + 0.031 days for the aphid and 15.33 + 0.071 and 3.67 + 0.054 days for the parasitoid, respectively. The R 0 -values of D. noxia and D. rapae were evaluated 33.19 + 0.961 and 18.07 + 0.761 females/female/generation, respectively. The gross and net fecundity rates were 59.21 + 1.94 and 32.825 + 0.972 nymphs/ female/day for the aphid and 37.59 + 1.46, and 33.8 + 1.51 eggs/female/day for the parasitoid, respectively. The results of this research indicated that D. rapae is an adequate parasitoid for control of Russian wheat aphid. Keywords: life table; Diaeretiella rapae; Diuraphis noxia; intrinsic rate of increase Introduction The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko) (Hem., Aphididae) is one of the most important pests of cereal crops, especially barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), in Iran and many cereal-growing countries of the world (Hughes and Maywald 1990). The RWA causes direct damage by sucking the sap of plants and indirect damage by transmitting plant viruses (Fouche et al. 1984; Kruger and Hewitt 1984; Von Wechmar 1984). Although the RWA prefers cereal crops (Butts and Pakendorf 1984), it also feeds on other cultivated and wild grasses (Kriel et al. 1984; Kindler and Spomer 1986). The aphid is endemic to central Asia, southern Russia, countries bordering the Mediterranean Sea, Iran and Afghanistan (Durr 1983; Hewitt et al. 1984; Dolatti et al. 2005), while extending its area of invasion. It was first discovered in South Africa in 1978 (Durr 1983), in the US in 1986 (Stoetzel 1987), in Chile in 1988 and in Argentina in 1992 (Ortego and Delfino 1994). *Corresponding author. Email: talebia@modares.ac.ir Archives of Phytopathology and Plant Protection Vol. 45, No. 8, May 2012, 886–897 ISSN 0323-5408 print/ISSN 1477-2906 online Ó 2012 Taylor & Francis http://dx.doi.org/10.1080/03235408.2011.599150 http://www.tandfonline.com