Studies on seasonal incidence of hairy caterpillar on jute

Abstract

The objective of this research work was to study the seasonal incidence of hairy caterpillar of jute Spilosoma obliua and to study its correlation with different weather paramaters during the kharif season of 2018. The incidence of hairy caterpillar was observed throughout the season with varying degree of intensity. The data on average population of S. obliqua per meter row length were recorded at weekly interval. The infestation of S. obliqua was first observed at 48 DAS in 33rd MW, with larval count of 7.11 larvae per mrl. The higher level of infestation was noticed from 34th to 36th MW. However, the peak infestation of 10.77 larvae per mrl was recorded in 35th MW. Then, the infestation of S. obliqua started to decrease from 36th MW (9.77 larvae/ mrl). The larvae of hairy caterpillar were not noticed at the time of crop harvesting. It was revealed that the infestation of S. obliqua was significantly negatively correlated with maximum temperature (r = -0.704) and significantly positively correlated with evening relative humidity (r = 0.705); while minimum temperature (r = 0.260), morning relative humidity (r = 0.464), wind (r = 0.071) and rainfall (r = 0.109) showed non- significant relation with infestation of S. obliqua and Sunshine (r = -0.493) was negatively but non- significantly correlated with infestation of S. obliqua. There were some variations due to changes in the agro-climatic conditions and cultivar used for the study.