Population Trend of Canola Aphid, Lipaphis Erysimi (Kalt) (Homoptera: Aphididae) And It’s Associated Bio-Control Agent, Coccinella Septempunctata (Linnaeus) (Coleoptera: Coccinellidae) in Different Brassica Lines

Studies regarding the determination of population trend of Lipaphis erysimi (Kalt) and its associated bio-control agent, Coccinella septempunctata (Linnaeus) in different brassica lines, were conducted at the New Developmental Farm, The University of Agriculture Peshawar during cropping season (2012-2013). Four different brassica lines IBGE-I, IBGE-II, IBGE-III and IBGE-IV were used, which were replicated four times in Randomized Complete Block Design. The data revealed that aphid’s infestation invariably started in all four varieties during 2 nd week of February 2013 (1 st observation). The peak population of 2.47 aphid’s leaf -1 was recorded during 3 rd week of March and lowest population of 1.67 aphid’s leaf -1 was recorded during 2 nd week of April. The specie of ladybird beetle (Coccinella septempunctata) was first time appeared on 14 th February with mean number of (0.22 ladybird beetle plant -1 ). At the time when aphid’s population started to increase, the peak population of C. septempunctata (1.32 ladybird beetle plant -1 ) was recorded on the 3rd week of March. Among all the Brassica lines, IBGE-I showed comparatively more resistance by recording least number of aphids on it as compared to IBGE-III, IBGE-IV and IBGE-II. IBGE-II showed least resistance against Lipaphis erysimi, which was found to be most susceptible cultivar by recording highest mean number of aphid’s population on it. IBGE-I was also found superior in terms of bio-control agents. Maximum number of bio-control agents was recorded on IBGE-I followed by IBGE-III and IBGE-IV. Lowest number of beetles was recorded on IBGE-II. Keywords: Lipaphis erysimi, Coccinella septempunctata, Brassica lines.