Pantnagar Journal of Research

Abstract

An investigation was carried out to study the population dynamics of some cabbage pests, viz., cabbage aphid (Brevicoryne brassicae), tobacco caterpillar (Spodoptera litura) and gram pod borer (Helicoverpa armigera) and the effect of weather parameters on them at Vegetable Research Centre of Govind Ballabh Pant University of Agriculture and Technology, Pantnagar during Rabi 2020. During the crop season aphid population marked its appearance in the 46th MSW (2nd week of November) with 1.05 aphids per plant, which progressively touched its peak in the 2nd MSW (2nd week of January) with 111.97 aphids per plant. Tobacco caterpillar and Gram-pod borer were both recorded first time in the 47th MSW (0.46 and 0.39 larvae/ plant, respectively) that gradually reached its peak in the 4th MSW (2.96 and 2.64 larvae/plant, respectively). Correlation studies revealed that aphid population was positively affected by morning and evening humidity (r = 0.778 and 0.853, respectively), wind velocity (r = 0.607) and rainfall (r = 0.277) whereas a negative impact was observed with minimum and maximum temperature, i.e., r = -0.527 and -0.832, evaporation and sunshine hours (r = -0.702). In case of Tobacco caterpillar rainfall (r = 0.303), wind velocity (r = 0.369) and morning relative humidity (r = 0.813) had a positive correlation with the pest population whereas minimum temperature (r = -0.588), maximum temperature (r = -0.802), evaporation (r = -0.658) and sunshine hours (r = -0.677) have had a negative correlation. Gram-pod borer population was positively associated with morning relative humidity (r = 0.825), evening relative humidity (r = 0.771), wind velocity (r = 0.381) and rainfall (r = 0.344) whereas maximum temperature (r = -0.768), minimum temperature (r = -0.556), evaporation (r = -0.627) and sunshine hours (r = -0.647) were in a negative correlation.