Sustainable bio control strategies for managing root grub, Basilepta fulvicorne jacoby (Coleoptera: chrysomelidae) in small cardamom

The current investigation examined the pathogenicity of three indigenous entomopathogenic nematodes (EPNs) - Heterorhabditis indica (ICAR‑NBAIR strain), Heterorhabditis bacteriophora and Steinernema carpocapsae supplied as a powder formulation against the root grub of cardamom. In addition to assessing mortality, the study monitored the attachment and penetration rates of the infective juveniles (IJs) into the target insect. H. indica exhibited the highest penetration efficiency, outperforming H. bacteriophora, while S. carpocapsae showed the lowest entry rate; penetration ability was found to depend on the specific infection strategy of each EPN species.

Application of the EPNs involved placing the novel powder at the base of the plant, a method that is rapid, simple and reduces labour requirements. The wettable‑powder (WP) formulation proved highly effective in controlling root grub, lowering production costs and decreasing reliance on chemical insecticides such as fipronil, chlorpyriphos and phorate in small‑scale cardamom systems. The results indicate that cardamom root grub is susceptible to all three tested EPNs, though their insect‑killing capacities differ. H. indica (ICAR‑NBAIR) and H. bacteriophora (ICAR‑NBAIR) emerged as the most promising candidates for grub management. These nematodes represent ecologically safe, efficient, sustainable and on‑farm recyclable “green” technologies for cardamom cultivation, offering a cost‑effective, value‑added approach to support sustainable agriculture in small‑holder cardamom plantations.