Life Table Parameters of the Tobacco Caterpillar [Spodoptera litura (Fab.)] on Ornamental Roses
Sunita Arya *
Department of Zoology, Dayanand Girls P.G. College, Kanpur, India.
Riya Sachan
Department of Zoology, Dayanand Girls P.G. College, Kanpur, India.
*Author to whom correspondence should be addressed.
Abstract
A life table study of Spodoptera litura (Fabricius) on roses was conducted to assess various population growth parameters. Present research work was carried at farmers field, garden and laboratory of Department of Zoology, Dayanand Girls P. G. College, Kanpur in Cohort-based Observational Design. The Life Table serves as an important analytical framework for examining pupa population dynamics. It offers a comprehensive overview of survival patterns, developmental stages, and life expectancy. The Life table also consolidates essential demographic data for a cohort, detailing the number of individuals dying at each stage (dx) and those surviving (lx). Additionally, it records the mortality rate (qx), where ‘x’ denotes the age interval, along with the corresponding age structure (lx). The findings showed 10% mortality during the egg stage. Maximum duration for egg, larval, and pupal stages was recorded 3, 19, and 10 days, respectively. It was found that out of 100 eggs only 65 individuals survived adult emergence. The highest female progeny contribution (mx = 335.15) occurred on the 41st day of pivotal age. The net reproductive rate (Ro) was 641.39 females, with a mean generation time (Tc) of 41.03 days. The intrinsic rate of increase (rm) was 0.1581 females/female/day, and the finite rate of increase (λ) was 1.17 females/female/day, corresponding to a weekly multiplication rate (λ⁷) of 3.00. At stable age distribution, the percentage contributions of Spodoptera litura on roses eggs, larvae, pupae, and adults were 49.74%, 48.02%, 1.94%, and 0.31%, respectively.
Keywords: Roses, tobacco caterpillars, net reproductive rate, innate capacity for increase, life cycle, population dynamics