Assessment of Spatial Distribution of Fall Armyworm, Spodoptera frugiperda (JE Smith) on Maize (Zea mays L)

Understanding insect spatial distribution patterns is fundamental to ecology, providing insights into community assembly, biodiversity maintenance and pest management strategies. The present study investigated the spatial patterns of larvae of fall armyworm on maize. The experiment was conducted at the Instructional farm, Rajasthan College of Agriculture, MPUAT, Udaipur, Rajasthan during Kharif 2019 and 2020.The larval population of Spodoptera frugiperda was recorded on sixty randomly selected plants at weekly interval. The data from original counts were arranged in frequency tables for fitting the different statistical parameters. Variance to mean ratio, exponent – K, patchiness index, clumping index, mean colony size, mean clump size, Iwao's patchiness regression and Taylor's power law were analyzed to test the dispersion behaviour of S. frugiperda. The result revealed that clumped or uniform or random distribution of S. frugiperda larvae in maize during both the year. The values of variance to mean ratio exceeded unity, the Lloyd's index was close to 1.0 and regression equation based on Taylor's Power law was computed as log S2 = – 0.507 + 1.398 log x_and log S2 = – 0.141 + 1.108 log x_in 2019 and 2020, respectively. All these values were indicated that the larvae of S. frugiperda showed clumped type of distribution in most of sampling date.