Developmental biology and morphometric traits of fall armyworm Spodoptera frugiperda (J.E. Smith) under controlled environment

Background The fall armyworm, Spodoptera frugiperda (J.E. Smith) is an invasive and destructive pest of maize and several other crops, that causing significant losses worldwide. Understanding its developmental biology and morphometric traits is essential for its accurate identification and effective pest management. This study investigated the lifecycle, developmental duration and morphometric traits of S. frugiperda under controlled laboratory conditions. Results The study was conducted at Banda University of Agriculture and Technology, Banda, Uttar Pradesh, India at 26 ± 2°C temperature and 75 ± 2% relative humidity. Egg masses collected from maize fields were reared on fresh maize foliage. Females laid 97–392 eggs each (mean 246.1 ± 103.59), preferred upper leaf canopy. Eggs were 0.47 ± 0.04 mm in length and 0.36 ± 0.03 mm in width, hatched within 2–3 days and the hatchability ranging from 86.66 % to 92.56%. Larvae passed six instars in 13–15 days (mean 13.35 ± 0.61 days), showing progressive increases in body size and head capsule width. Sixth instar larvae measured 33.98 ± 1.60 mm in length and 7.88 ± 0.28 mm in width. The pupal period lasted 7–9 days (mean 7.18 ± 0.54 days) and sexual dimorphism was observed in both pupal and adult stages, with males slightly larger than females. Adult females lived longer (8.53 ± 0.79 days) than males (6.52 ± 0.78 days). The total lifecycle duration averaged 30.01 ± 1.10 days for females and 29.06 ± 1.25 days for males. Two braconid parasitoids, Aleiodes laphygmae and Stenobracon deesae , alongwith one dipteran parasitoid were recorded, caused 3.5% larval parasitism. Conclusion The study demonstrated rapid development, high reproductive potential and distinct morphometric variations across developmental stages in S. frugiperda . These findings provide baseline information useful for accurate identification and the development location-specific integrated pest management strategies.