Prasad, RabindraReddy, Nakkala Divakar2020-11-232020-11-232020M/Ento./307/2018-19https://krishikosh.egranth.ac.in/handle/1/5810155574To study the population dynamics of sweet potato weevil in relation to meteorological parameters, varietal screening of sweet potato genotypes and evaluation of field efficacy of some botanical pesticides against sweet potato weevil a series of field experiments had been performed at the research farm, of Tirhut College of Agriculture, Dholi, Muzaffarapur, (Bihar) during September-February, 2019-20. The results of male weevil caught on pheromone trap revealed that maximum number of weevils (815 male weevil/pheromone trap) is recorded during 51st standard week when maximum and minimum temperatures are 18.50C and 9.50C respectively, Relative humidity(%) at 7 am and 2 pm is 100% and 96% respectively and there is no significant rainfall during the period. Correlation of weevil population with the abiotic factors reveals that that maximum, minimum and mean temperature (0C) showed negative correlation coefficient (-0.576, -0.545, -0.587) respectively. Relative humidity (%) at 7 am is non-significantly positively correlated with correlation coefficient of (0.349) whereas; R.H. at 2 pm. is positively correlated with correlation coefficient (0.507) and significant at 1%. Rainfall is negatively correlated with correlation coefficient (-0.60) with the male weevil population and it is non-significant. The coefficient value of determination (R2) computed as 0.3576 indicating 35.76 per cent. The weather parameters when acted together were found to contribute about 35.76 per cent male weevil population fluctuation of Cylas formicarius. Ten genotypes of sweet potato were evaluated for their response against sweet potato weevil. On the basis of vine infestation (%), tuber infestation (%), neck length (cm),vine thickness (cm), colour and shape of tuber and marketable tuber yield (t/ha) genotype-440127 is categorized as resistant, while genotype-TSP-16-3 is categorized as highly susceptible. Ten treatments were evaluated for their field efficacy against the sweet potato weevil. From the data obtained it is found that vine treatment with chlorpyriphos 20 EC @ 1lit/ha + spraying of neem oil @ 2% is effective in reducing vine infestation, tuber infestation and also offered protection to tubers in storage up to 1 month after harvesting. When cost-benefit ratio is considered spraying of neem oil @ 2 % with cost-benefit ratio of 1:14.1 is economical when compared to other treatments.EnglishThesis