Entomopathogenic Potential of Heterorhabditis bacteriophora Against Soil-Inhabiting Larvae of Agrotis ipsilon in Maize

Abstract

Entomopathogenic potential of Heterorhabditis bacteriophora against soil-inhabiting larvae of Agrotis ipsilon in maize was evaluated to assess its efficacy as a biological control agent under soil conditions. Laboratory and pot experiments were conducted using different concentrations of infective juveniles applied to soil containing larval stages of A. ipsilon. Parameters such as larval mortality, time to death, nematode penetration efficiency, and reproductive potential within host cadavers were recorded. Results indicated that H. bacteriophora exhibited strong pathogenicity against A. ipsilon larvae, with mortality rates increasing significantly with higher nematode concentrations and longer exposure periods. Infected larvae showed characteristic symptoms including reduced movement, discoloration, and eventual tissue disintegration. The nematodes successfully penetrated the host through natural openings and released symbiotic bacteria, leading to rapid host mortality. Reproduction within cadavers confirmed successful establishment and completion of the nematode life cycle. Environmental factors such as soil moisture and temperature significantly influenced infection efficiency, with optimal conditions enhancing nematode survival and virulence. The study highlights the strong biocontrol potential of H. bacteriophora against soil-dwelling stages of A. ipsilon in maize ecosystems. These findings support its integration into integrated pest management programs as an environmentally safe alternative to chemical insecticides for managing cutworm populations.