SOYBEAN S. RAMESH BABU, R. K. KALYNA', RAMGOPAL DUDWAL2AND P. ROKADIA

The aim of this investigation was to observe the effect of various weather parameters on the occurrence of larval and adult population of Spodoptera litura and factors for their outbreak of this pest in soybean. The initial studies indicated that the population of male moths in pheromone trap appeared in week of July and continued upto third week of October. During 2017, weather factors like minimum temperature and morning humidity influenced the male moth population per trap whereas maximum temperature, sunshine hrs and wind speed negatively influenced the male moth population per trap but with non-significant effect. Regression analysis indicated that the various weather parameters caused 46 per cent variations in S. litura male moth catches. The correlation between larval counts and pheromone trap catches were significantly positive (0.652). Initial buildup of larval population in the field was observed during the 3th week of July and continued build uptill mid-September which resulted in severe outbreak of S litura in soybean during August to September. This indicates that the more peaks in pheromone trap catches of S litura in August to September months were invariably followed by an increase in the number of larval population and contributed to the outbreak of the pest in the soybean field. Thus, pheromone traps may serve as a warning device indicating the possibility of potential attack and to initiate timely management of S litura in soybean.