VIJAYKUMAR, L.PALLAVI, D.2020-10-072020-10-072019-12-12Th-12552https://krishikosh.egranth.ac.in/handle/1/5810152657The investigation on molecular detection, mechanism of resistance and management of leafhoppers in phytoplasma associated sesame phyllody was undertaken at college of Agriculture, V. C. Farm, Mandya and Department of Entomology, UAS, GKVK, Bangalore from 2017 to 2019. The peak leafhopper population and incidence of phyllody were noticed during second fortnight of April in Summer and first fortnight of October in Kharif during 2017 and 2018, respectively.The phytoplasma was detected from infested sesame plants and leafhoppers through molecular techniques using different primers viz., P1/P7, SECA1/A2,Tuf and obtained 1.8kb, 840bp and 490 bp product size, respectively. The genomic DNA of symptomatic plants and leafhoppers were found to be associated with phytoplasma belongs to 16SrI ‘Candidatus phytoplasma asteris’group. The detection of phytoplasma also confirmed using loop mediated amplification assay. The field evaluation of twenty seven sesame genotypes against leafhoppers and phyllody resulted in identifying four highly resistant genotypes. Among the biochemical constituents studied for resistance and susceptibility, the total phenols showed significant negative association with infestation, while, total sugars, reducing sugars, total free amino acids and crude proteins indicated significant positive relationship with incidence of phyllody. The studies on impact of feeding by leafhoppers on plant morphological and biological attributes in different genotypes under controlled and open field conditions revealed higher incidence, enzymes and nutrients levels in open field than controlled condition. Among nine insecticides evaluated against leafhoppers and phyllody, seed treatment with imidacloprid 48FS @ 5ml/kg with foliar spray of thiamethoxam 25WG @ 0.3g/L was found effective in reducing incidence along with higher seed yield, net returns and C: B ratio compared to other treatments.EnglishThesis