Seasonal incidence of Maruca vitrata Geyer and Helicoverpa armigera Hubner on black gram (Vigna mungo L. Hepper)

Abstract

The field experiment was conducted on the seasonal incidence of spotted pod borer, Maruca vitrata Geyer and gram pod borer, Helicoverpa armigera Hubner on black gram at Chatha Farm, SKUAST- Jammu during summer 2018. The data on seasonal fluctuations of spotted pod borer and gram pod borer larval population was first observed during 10th standard week with an initial population of 0.36 larvae/ m2 area and 0.46 larvae/ m2 area, respectively. The maximum larval population of M. vitrata (12.53 larvae/ m2 area) was recorded during 15th standard week, whereas, the maximum incidence of H. armigera (9.53 larvae/m2 area) was recorded 18th standard week of sown crop. Thereafter, the spotted pod borer and gram pod borer larval population decreased till 23rd standard week up to 4.42 larvae and 0.26 larvae/ m2 area, respectively on the same crop. A highly significant positive correlation was existed between weekly mean maximum temperature (0.633**) and spotted pod borer larval density, positively significant correlation with minimum temperature (0.586*), significantly negative correlation with relative humidity morning (– 0.551*) and evening (– 0.593*). While, the positive correlation between weekly mean maximum temperature (0.466) and gram pod borer larval density, positive correlation with minimum temperature (0.362), negative correlation with relative humidity morning (– 0.457) and a significant evening (– 0.498*) and non-significant negative correlation with rainfall (-0.252) and significant positive correlation with wind speed (0.489*) were recorded. The regression analysis indicated that all the weather parameters together were responsible for a significant variation of 62.50 and 54.10 per cent on the larval incidence of spotted pod borer and gram pod borer, respectively.