Ultra‐structural and physico‐chemical characterization of eggs and egg hairs (setae) of the new invasive pest, fall armyworm, Spodoptera frugiperda (J. E. Smith) in India: A first report

Abstract In this study, we report first time in India on the morphology, ultra‐architectural pattern of the chorion in the egg and egg hair (setae). Further, physico‐chemical characterizations of egg hairs (setae) were studied in the new invasive pest, fall armyworm, Spodoptera frugiperda . The egg is dome shaped with flattened base and curves upward to a broadly rounded point at the apex. HR‐SEM micrographs revealed the surface ultrastructure of eggs chorion and shows structural elements of a marked rosette of petals surround the micropyle followed by micropylar rosette region around the micropyle plate. There was a small single micropylar opening along with 9 micropylar rosette cells and 13 micropylar rosette zones present near to the micropylar pit. In the egg the first order ribs were absent, but around 58–60 numbers of second order ribs were present. All the ventral and lateral cells of the eggs are connected by 19–22 cross striae and not forming a grid pattern, but joints with the longitudinal ribs at several of angles and totally 1,277–1,495 convex cells present at the egg's surface. The physico‐chemical characteristics of egg hairs were studied using Fourier transform infrared (FT‐IR) and thermogravimetric analysis (TGA) analysis. TGA results show that three weight losses occurred at 142, 418, and 880°C, respectively. FT‐IR confirms the presence of amides, sulfoxide, and nitro compounds in egg hairs (setae).