Biometric Traits and Biology of Fall Armyworm (Spodoptera frugiperda) Reared on Maize (Zea mays) under Laboratory Conditions

The Fall armyworm (Spodoptera frugiperda), a formidable pest now widespread in Nepal, poses a major threat to maize production, underscoring the need for detailed biological insights to inform effective management strategies. Therefore, this study was conducted under laboratory conditions to assess the morphometric and biological parameters of FAW on Zea mays. Morphometric traits such as head capsule width and length, body length and width, adult body length, and wingspan were examined. Biological parameters, including the duration of larval instars, pre-pupal, pupal, and adult stages, were also analyzed. In larvae, the smallest measurements were recorded in the first instar (head capsule length 0.20±0.02 mm; width 0.31±0.02 mm; body length 1.48±0.08 mm; body width 0.30±0.03 mm), while the largest were observed in the sixth instar (2.85±0.09 mm, 2.86±0.06 mm, 33.23±0.43 mm, and 5.15±0.14 mm, respectively). Pupae measured 14.45±0.78 mm in length and 4.40±0.04 mm in width. The adult forewing span (30.5±1.6 mm) was larger than the hindwing span (22.6±1.0 mm), with a body length of 13.8±0.9 mm. Egg hatching took 2 days, and the larval stage lasted between 9 and 14.3 days. The pre-pupal and pupal stages lasted 2.20±0.47 and 9.08±0.90 days, respectively, followed by an adult lifespan of 5.50±1.50 days. The results shed light on the lifecycle, essential for understanding its population dynamics and guiding ecologically based management.