Influence of meteorological factors on population build-up of spotted pod borer, Maruca vitrata Geyer in yam bean under agro-climatic zone I of North Bihar

Abstract

Population build-up studies of spotted pod borer, Maruca vitrata Geyer, on yam bean in relation to meteorological parameters viz; average ambient temperature, relative humidity and rainfall revealed that the pest was active between the second week of October to last week of December, while web formation abruptly stopped after third week of November. It attained and maintained its peak activity during November in both seasons recording a mean larval population ranging 9.51 to 17.51 and 11.31 to 19.31 per flower shoot while number of webs ranged from 1.59 to 3.00 and 1.73 to 3.68 webs per flower shoot during 2009-10 and 2010-11, respectively. Pest population build-up was favoured by a decline in average maximum and minimum temperature (from 30.15 to 26.550C and 16.25 to 12.100C, respectively) and in relative humidity at 7 am and 2 pm (96.30 to 94.70 per cent and 50.90 to 54.40 per cent respectively). No significant correlation existed between the larval and webs population with the factors, except the relative humidity at 2 pm which indicated negative but significant effect on larval and webs population.