UTTAR PRADESH JOURNAL OF ZOOLOGY

A comparative study was conducted to assess the biological parameters and developmental progression of the fall armyworm, Spodoptera frugiperda, when reared on maize, pearl millet, and sorghum leaves under standard laboratory conditions. The incubation period was observed to be shortest for maize (49.67 hours) and longest for sorghum (57.00 hours). Hatching percentage ranged from 74.27 % in pearl millet to 80.49 % in sorghum. Larval periods were maximized on pearl millet (17.67 days) and minimized on sorghum (15.67 days). Growth analysis through successive larval instars revealed that sixth instar larvae attained maximum lengths on maize (29.00 mm) and minimum on sorghum (21.67 mm). Head capsule width also showed considerable increments between instars across host plants. Dyar’s rule applied to average larval length and head capsule width generated consistent growth ratios, with averages from 1.46 to 1.60 for head capsule width and 1.48 to 1.49 for larval length, confirming the regular progression of instar development. Pupation traits and adult morphometrics, such as body length and wing span, varied with host plant, underlining the biological influence of food source. The findings provide clear evidence of host plant effects on major developmental and biometric parameters of S. frugiperda, and validate Dyar’s rule as a robust tool for monitoring larval instar transitions. This research enhances understanding necessary for pest management strategies and facilitates developmental biology studies.