author(s)
Imtiaz Ali Khan, Mansoor Ahmad, Sajjad Hussain, Rasheed Akbar, Muhammad Saeed, Abid Farid, Ruidar Ali Shah, Walija Fayaz, Mir Manzar Ud Din, Bismillah Shah, Muhammad Naeem

abstract
The present study on correlation between aphid’s density and loss in yield components of 12 Brassica genotypes under screen house conditions was conducted at the Institute of Biotechnology and Genetic Engineering (IBGE), The University of Agriculture, Peshawar (UAP) during 2006-08. The results revealed that overall mean aphids density was significantly higher (138.9 aphids plant-1) on Rainbow and lower (59.00 aphids plant-1) on T-16-401. The seed losses were significantly higher (57.88%) in Vangard and lower (23.24%) in T-16-401. Overall mean straw losses were significantly higher (46.36%) in Peela Raya and lower (20.35%) in Ganyou-5. The losses in plant height losses were significantly higher (38.78%) in Westar and lower (25.32%) in Peela Raya. There were recorded significantly higher (27.78%) branches losses in Crusher and lower (6.25%) in T-16-401. The losses in siliquae/main raceme were significantly higher (40.20%) in Oscar and lower (16.24%) in Westar. Overall mean losses in leaves were significantly higher (27.63%) in Legend and lower (7.21%) in Westar. Correlation between aphids density and straw losses (r = 0.412) and aphids density and leaves losses (r = 0.317) was non-significant; correlation between aphids density and siliquae/main raceme (r = 0.469) was positively significant; correlation between aphids density and seed yield loss (r = 0.520), aphids density and plant height loss (r = 0.752) and aphids density and branches loss (r = 0.593) was highly positively significant; whereas correlation between aphids density and straw yield (r = -0.443), aphids density and no. of branches (r = -0.402), aphids density and siliquae/main raceme (r = -0.090) and aphids density and no. of leaves (r = -0.280) was negatively non-significant; correlation between aphids density and seed yield (r = (-0.483) was negatively significant and aphids density and plant height (r = -0.712) was negatively highly significant. The present results might be helpful in using host plant resistance in an integrated pest management program against aphids in Brassica genotypes.