Life-fecundity table on incidence of Spilosoma obliqua on jute

Studies on the life fecundity table of Spilosoma obliqua on jute in terai region of West Bengal, India revealed that the net reproductive rate of females 264.435 and innate capacity for increase in number (0.1568) of June-July generation was higher than that in May-June generation (116.34 & 0.0982). Potential fecundity of adult of May-June and June-July generations (618/female & 573.50/female), were higher, shorter length of life cycle during June-July (40 days) and July-August (29 days) along with the faster weekly multiplication rate (3.0074), more number of hypothetical F₂ females (69925.86), faster doubling time (4.4134 days) and shorter mean length of generation during June-July as compared to May-June and July-August generations suggested higher level of Spilosoma population in jute crop ecosystem during June-July. The lowest weekly multiplication rate (0.85547) during July-August along with lower net reproductive rate of adult of July-August generation might be the reason for decline in infestation level after July.