Comparative infectivity of entomopathogenic nematodes against key stored-product insect pests

The intensification of chemical pesticide use in postharvest storage systems has raised critical concerns, including environmental pollution, pesticide residues, and the development of resistance in insect pests. This study evaluated the biocontrol potential of four entomopathogenic nematode (EPN) strains—Steinernema carpocapsae (All), S. feltiae, Heterorhabditis indica, and H. floridensis (K22)—against four economically important stored-product insect pests: Tribolium castaneum, T. confusum, Rhyzopertha dominica, and Oryzaephilus surinamensis. Laboratory bioassays were conducted at three EPN concentrations (1000, 2000, and 4000 IJs/mL), targeting both larval and adult stages under controlled conditions. Mortality data were collected at 1, 7, 14, and 21 days post-inoculation. Insect mortality was significantly influenced by EPN strain, insect species, and concentration (P < 0.05), with no significant interaction between species and days post-inoculation. H. floridensis and S. carpocapsae consistently caused the highest mortality, particularly in T. confusum (>37.2%) and T. castaneum (>35.8%), while S. feltiae and H. indica exhibited minimal virulence (< 12.2%). Mortality increased with concentration, peaking at 4000 IJs/mL. Species-specific responses were evident, with T. confusum being the most susceptible and O. surinamensis the least. Moreover, nymph mortality was significantly influenced by EPNs, with the highest mortality recorded in O. surinamensis and the lowest in R. dominica. These findings demonstrate that specific EPN strains, particularly H. floridensis and S. carpocapsae, are effective biocontrol agents for managing key stored-product insect pests, offering a potentially environmentally friendly alternative to synthetic pesticides in postharvest systems.