Temperature-dependent life history and demographic traits of the invasive fall armyworm, Spodoptera frugiperda (J.E. Smith) on maize.

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a major invasive pest threatening maize production in India. Temperature strongly influences its development, reproduction and population dynamics. This study evaluated the biological performance of S. frugiperda on maize across seven constant temperature regimes (14 ± 1°C to 38 ± 1°C) under controlled laboratory conditions, using the age-stage, two-sex life table approach. Developmental time decreased significantly with rising temperatures, while survival and fecundity peaked at 26 ± 1°C and 30 ± 1°C. The highest values of net reproductive rate (R₀ = 499.91 females/female), intrinsic rate of increase (r_m = 0.25 females/female/day), and finite rate of increase (λ = 1.28 females/day) were recorded at 30 ± 1°C, followed by 26 ± 1°C (R₀ = 467.32, r_m = 0.24, and λ = 1.26, respectively). In contrast, thermal extremes delayed development and adversely affected both survival and reproduction. No development occurred at 38 ± 1°C. Population projections indicated rapid generational turnover at optimal temperatures, with up to nine generations annually at 26 ± 1°C. The temperature range of 26-30 ± 1°C was found to be optimal for both survival and reproduction of S. frugiperda, aligning with kharif season temperatures in North India, particularly Punjab. These conditions promote multiple generations annually, whereas extreme summer or winter temperatures may limit population development. The findings advocate for temperature-informed, location-specific pest control strategies. Intervening during critical developmental windows, especially at the egg and larval stages, can limit population buildup. Insights into the pest's thermal adaptability contribute to the advancement of climate-resilient, sustainable pest management frameworks for maize systems in North India and similar agroclimatic regions.