Influence of meteorological factors on populaton build-up of spotted pod borer, Maruca testulalis Geyer in early pigeonpea under conditions of North Bihar (India)

Studies on the population build-up of spotted pod borer, Maruca testulalis Geyer, on early pigeonpea cv. UPAS-120, in relation to two important meteorological parameters, viz., average ambient temperature and relative humidity, conducted during 1990–91 and 1991–92 crop seasons revealed that the pest was active between the second week of October and the last week of December. It attained and maintained its peak activity during November in both the crop seasons by recording mean larval population from 7.67 to 12.73 and 8.53 to 17.60/plant in 1990–91 and 1991–92, respectively. For its population build-up, a decline in average maximum and minimum temperature from 30.50 to 26.25°C and 16.15 to 10.35°C, respectively and the relative humidity around 70.00 per cent proved to be conducive. No significant correlation existed between pest population and the temperatures (maximum and minimum). However, a highly significant negative correlation with relative humidity signified a greater pest activity during drier season. Regression analysis did not yield mathematical equations to be considered as models for pest forecasting based on these two weather factors.