Abstract
Cabbage aphid, Brevicoryne brassicae L. and mustard aphid, Lipaphis erysimi (Kalt.) are the common insect pests associated with oilseed rapes in the Pakistan. An experiment was conducted to determine the effect of plant spacing on populations of B. brassicae and L. erysimi, yield components and oil contents of late sown canola, Brassica napus L. The crop was sown at 10, 20 and 30 cm plant spacing in Randomized Complete Block Design in three replicates at experimental farm of the Bahauddin Zakariya University, Multan on December 26, 2009. The aphid densities were recorded weekly from the top 10 cm of the inflorescence by gently beating it six times on a white plastic sheet from start of aphid appearance untill the time of harvest. Populations of both aphid species were non-significantly different on plants in all three spacings of B. napus. Yield, plant height, numbers of pods per plant, pod length, number of racemes and oil contents were also non-significantly different among all the treatments.