Dashad, S. S.Nain, Rohit2016-11-162016-11-162009http://krishikosh.egranth.ac.in/handle/1/85867The present studies were carried out for screening of sunflower genotypes for resistance to Helicoverpa armigera (Hubner), to correlate the H. armigera population with some plant physical characters and abiotic factors, to study the bio-efficacy of some insecticides against H. armigera and to estimate the avoidable yield losses due to H. armigera in sunflower during rabi, 2008 at Oilseed Research Area, Department of Plant Breeding, CCS HAU, Hisar. The results obtained from these studies indicated that four genotypes namely HSFH 1188, HSFH 1067, SH 3322 and KBSH 44 showed good level of resistance to this pest. Two genotypes PSFH 914 and HSFH 1015 considered as most susceptible. Among plant physical characters in relation to oviposition and larval population of H. armigera the results revealed that plant height showed significant negative correlation whereas, head diameter, days to flowering initiation and days to fifty per cent flowering showed non-significant negative correlation with oviposition and larval population of H. armigera. Among abiotic factors temperature showed negative to oviposition and positive correlation to larval population whereas relative humidity showed significant positive to oviposition and negative correlation to larval population. Bright sunshine hours showed significant negative to oviposition and positive correlation to larval population. Rainfall and wind speed showed positive correlation to oviposition whereas showed negative correlation to larval population. Spinosad was found most effective on the basis of mean per cent reduction in H. armigera larval population which was at par with endosulfan followed by quinalphos and indoxacarb. In field conditions, efficacy of insecticides against H. armigera in descending order was spinosad > endosulfan > quinalphos > indoxacarb > thiodicarb > profenophos > fenvalerate > cypermethrin > Bt. Kurstaki. On the other hand cost benefit ratio was maximum in case of endosulfan (1:21.3) followed by quinalphos (1:15.8) and it was 1:5.5 in case of spinosad. Maximum avoidable yield loss (25.10%) and increase in grain yield (33.50%) was recorded in plots treated with spinosad followed by endosulfan.enAnimal developmental stages, Genotypes, Eggs, Planting, Yields, Insecticides, Developmental stages, Sexual reproduction, Land resources, CropsThesis