Natural occurrence and virulence of entomopathogenic nematodes on tea termites in barak valley of Assam, India

Abstract

Survey of entomopathogenic nematodes (EPNs) have been conducted in large areas of Cachar district (Assam) for isolating potentially useful indigenous EPN strains. Out of total 110 soil samples from different habitats representing different soil systems, 9 samples were found to have shown positive results through baiting with last instars of muga silkworm {Anthem assama),en silkworm {Attacus ricini) and greater wax moth {Galleria mellonella). Soil characteristics have influenced the occurrence of EPN. It has also been confirmed that last instar larvae of silkworms could be used as bait insects in isolation EPN strains like Steinernema thermophilum, a heat tolerant EPN described from India. In laboratory bioassays the indigenous isolate of Heterorhabditis indica demonstrated more virulence as compared to S.thermophilum against the termites causing damage to tea plantations {Microtermes obesi Holmgren and Microcerotermes beesoni Snyder).