To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: http://dx.doi.org/10.1007/s11829-017-9576-7 Byline: Amene Karami (1), Yaghoub Fathipour (1), Ali Asghar Talebi (1), Gadi V. P. Reddy (2) Keywords: Tritrophic interactions; Life table; Canola; Cabbage aphid; Brevicoryne brassicae; Diaeretiella rapae Abstract: Biological control agents can be used as a complementary control measure that can be combined with resistant host plants to control pests. In this study, the effects of different canola cultivars (Karaj-1, Karaj-2, Karaj-3, Licord, Okapi, Opera, RGS.sub.003, Sarigol, Talaye and Zarfam) on the performance and life table parameters of the cabbage aphid, Brevicoryne brassicae, and its parasitoid, Diaeretiella rapae, were determined under laboratory conditions. Total fecundity of the cabbage aphid differed with cultivar, with the highest value (59.41 nymphs per female) of this parameter observed on Opera and the lowest (1.67) observed on RGS.sub.003. The highest and lowest intrinsic rates of increase (r) of the cabbage aphid were observed on Opera (0.331 day.sup.-1) and RGS.sub.003 (- 0.242 day.sup.-1) cultivars, respectively, suggesting these to be the most susceptible and most resistant cultivars to this pest. However, because the aphid did not settle and feed well on RGS.sub.003, it was not possible to determine demographic parameters for its parasitoid. Consequently, the Okapi cultivar, which was the most resistant cultivar to the cabbage aphid after RGS.sub.003, was used in this study to assess the parasitoid wasp. The parasitoid's intrinsic rate of increase (r) varied from 0.426 day.sup.-1 on the susceptible cultivar (Opera) to 0.341 day.sup.-1 on the resistant canola cultivar Okapi. Aphid performance decreased 93% on the resistant canola cultivar, while parasitoid performance decreased only 20% on the resistant cultivar compared to more susceptible cultivar. Author Affiliation: (1) 0000 0001 1781 3962, grid.412266.5, Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, P.O. Box 14115-336, Tehran, Iran (2) 0000 0001 2156 6108, grid.41891.35, Department of Research Centers, Western Triangle Agricultural Research Center, Montana State University, Conrad, MT, 59425, USA Article History: Registration Date: 17/10/2017 Received Date: 28/04/2017 Accepted Date: 17/10/2017 Online Date: 26/10/2017 Article note: Handling Editor: Miriama Malcicka.