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

摘要

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 2nd week of February 2013 (1st observation). The peak population of 2.47 aphid’s leaf -1 was recorded during 3rd week of March and lowest population of 1.67 aphid’s leaf -1 was recorded during 2nd week of April. The specie of ladybird beetle (Coccinella septempunctata) was first time appeared on 14th 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.