Life History Traits and Intrinsic Rate of Natural Increase of Trichoplusia ni (Lepidoptera: Noctuidae) on Cabbage

Abstract

Life history traits and intrinsic rate of natural increase of Trichoplusia ni (Lepidoptera: Noctuidae) on cabbage were evaluated to determine population growth potential and demographic performance under controlled laboratory conditions. Developmental duration, survival rate, pupation success, adult longevity, fecundity, and sex ratio were recorded across successive life stages when reared on cabbage foliage. Life table parameters were calculated to estimate population growth potential and reproductive efficiency. Results indicated that cabbage provided a suitable host for T. ni development, supporting high survival and successful completion of all life stages. Developmental time varied across larval instars, with favorable nutritional quality contributing to enhanced growth rates and increased adult emergence. Females exhibited high fecundity, leading to elevated reproductive output and rapid population increase. Life table analysis showed a positive intrinsic rate of natural increase, indicating strong potential for population expansion under optimal conditions. Net reproductive rate and finite rate of increase further confirmed the suitability of cabbage as a host supporting sustained pest outbreaks. The study highlights the influence of host plant quality on demographic parameters and population dynamics of T. ni. These findings provide important insights for forecasting population outbreaks and developing targeted integrated pest management strategies in cabbage production systems.