Population Trend of Canola Aphid, Lipaphis Erysimi (Kalt.) (Homoptera: Aphididae) and its Associated Natural Enemies in Different Brassica Lines along with the Effect of Gamma Radiation on Their Population

Studies regarding the determination of population trend of Lipaphis erysimi (kalt.) and its associated natural enemies in different Brassica lines along with the effect of gamma radiation on their population were conducted at Agricultural Research Farm, Malakandher, Khyber Pakhtunkhwa Agricultural University Peshawar during spring 2006. Three different Brassica lines F6B3, F6B6 and F6B7 were used, which were replicated four times in Randomized Complete Block Design. The data revealed that aphid infestation invariably stated in all three varieties during last week of February 2006 (1 observation). The peak population of 4.39 aphids leaf was s recorded during 2 week of March and lowest population of 1.02 aphids leaf was recorded during 5 week of March. The species of lady bird beetle (Coccinella septempunctata) and Syrphid fly (Syrphus balteatus) first appeared on 24 February with a mean number of 0.40 lady bird beetle leaf and 0.87 Syrphid fly leaf, respectively. At the time when aphid population started to increase the peak population of C. septempunctata (0.70 lady bird beetle leaf ) and S. balteatus (1.04 syrphid fly leaf) was recorded on the 2 week of March. Chrysoperla carnea appeared in the 1 week of March and their peak population was recorded during the 3 week of March with mean population of 1.46 C. carnea leaf. Among all the Brassica lines, F6B7 showed comparatively more resistance as compared to F6B3 F6B6. F6B3 showed least resistance against L. erysimi, which was found to be the most susceptible cultivar. F6B7 was also found superior in terms of natural enemies. Maximum number of all natural enemies was recorded on this variety followed by F6B6. Lowest number of natural enemies was recorded in F6B3. No significant effect was recorded for the effect of gamma radiation on the population of aphids, natural enemies and on the varieties. Keywords—Canola aphid, Lipaphis erysimi, natural enemies, brassica lines, gamma radiation. Ahmad-Ur-Rahman Saljoqi, Rahib Zada and Hazrat Jabir Alam Khan are with Department of Plant Protection, Khyber Pakhtunkhwa Agricultural University, Peshawar-Pakistan (corresponding author, e-mail: [email protected]; phone: 091-9216554; cell: 03339139959). Imtiaz Ali Khan is with Department of Entomology, Khyber Pakhtunkhwa Agricultural University, Peshawar-Pakistan. Iqbal Munir is with Institute of Biotechnology & Genetic Engineering, Khyber Pakhtunkhwa Agricultural University, Peshawar-Pakistan. Sadur-Rehman is with Agricultural Research Institute, Tarnab, PeshawarPakistan.