Mukherjee, U.Tudu, Lohit2023-01-062023-01-062022M/ENTO/072/2020-21https://krishikosh.egranth.ac.in/handle/1/5810191377The present investigation entitled “Field screening of Brassica genotypes against Lipaphis erysimi (Kalt.) and its population dynamics” was conducted during 2021-22 cropping season at Research Farm of Tirhut College of Agriculture, Dholi, Muzaffarpur, Bihar. The study focused on evaluation of 41 Brassica genotypes for their susceptibility or resistance against mustard aphid (Lipaphis erysimi) and exploring the population dynamics of mustard aphid and coccinellid beetles in relation to weather parameters. During the screening of 41 Brassica genotypes, overall mean population of aphids/ top 10 cm of inflorescence ranged from 23.46 to 104.78. The genotypes DRMR 2018-19 and PDZ 14 were infested with minimum and maximum numbers of aphid population, respectively, whereas check variety Yellow sarson (66-197-3) had aphid population of 76.17 aphids/ top 10 cm of inflorescence. Based on aphid infestation index (AII), two genotypes were grouped as resistant. 13 genotypes as moderately resistant, 19 genotypes as susceptible and 7 genotypes were grouped as highly susceptible. The highest and lowest AII was recorded in PDZ 14 (4.23) and DRMR 2018-19 (1.65), respectively. Check variety Yellow sarson had aphid infestation index of 3.5. The population dynamics of aphid (L. erysimi) in relation to weather parameters was studied on four rapeseed-mustard varieties viz., T-27, GSC-6, BSH-1 and Rajendra Sufalam. Aphid infestation in all the varieties started from 3rd standard meteorological week (SMW) and except for T-27 (minimum population in 10th SMW) continued till 11th standard meteorological week (SMW). Peak infestation was observed during 7th SMW irrespective of all the varieties, when maximum and minimum temperature were 24.07℃ and 9.74℃ and relative humidity at 07:00 hours and 14:00 hours were 95.86 and 53.86 per cent, respectively. The correlation analysis revealed that among the various weather parameters, minimum temperature had negative significant impact on the aphid population of T-27 (-0.642*) and GSC-6 (-0.638*), whereas relative humidity at 07:00 hours had positive significant correlation with the population build-up of aphids across all the varieties viz., T-27 (0.646*), GSC-6 (0.654*), BSH-1 (0.633*) and Rajendra Sufalam (0.638*). Other abiotic factors had non-significant impact on the population fluctuation of aphids. On the other hand, the population of ladybird beetle was in positive and highly significant correlation with aphids on each variety of rapeseed-mustard.EnglishThesis