Cannibalistic Nature and Time of Habitat Occupancy of Invasive Maize Fall Armyworm, Spodoptera frugiperda are the Key Factors for Competitive Displacement of Native Stem Borer, Sesamia inferens in India

Invasion of fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) has been implicated in reducing the incidence of native stem borers in India. The present study aimed to verify the reasons for the displacement of native stem borers using S. frugiperda and pink stem borer, Sesamia inferens (Walker) (Lepidoptera: Noctuidae). Field incidence of FAW and S. inferens was recorded during the 2020 and 2021 wet seasons, indicating negligible field incidence of S. inferens compared to FAW. In controlled greenhouse experiments, the competition was measured by releasing larvae at different densities into the maize whorl and also by varying their release at two-day intervals among the two species tested. In competition assays, the frequency of cannibalism increased with increasing density. The study documents that cannibalistic nature and early habitat occupancy in the whorls by FAW are the key factors involved in reducing the incidence of native stem borer, S. inferens