Population dynamics and management of diamond back moth Plutella xylostella (L.) in cabbage ecosystem of West Bengal

An experiment was conducted in cabbage ecosystem of West Bengal in 2013-2014 and 2014-2015 to study the population fluctuation of diamond back moth (DBM) with abiotic factors along with efficacy of eight novel insecticides and bio-pesticides on DBM and subsequent effect on natural enemies. Results revealed that, DBM population had a positive correlation with temperature and sunshine hours and negative correlation to relative humidity and rainfall. Bio-efficacy studies showed that rynaxypyr was most effective in reducing larval population (96.41%) closely followed by flubendiamide (94.86%) and spinetorum (92.62%). Combination of novaluron and indoxacarb also provided good reduction of larval population (92.04%). Bio-pesticides Bacillus thuringiensis var kurstaki and Beauveria bassiana gave 55.82% and 32.24% reduction of DBM larvae respectively. All the imposed test molecules were found soft to prevailing natural enemies. Yield of cabbage was found to be highest in plots treated with rynaxypyr (550.50q/ha) followed by flubendiamide (535.65q/ha) and spinetorum (530.55q/ha).