Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is a major cruciferous crop pest worldwide with resistance to multiple insecticide classes, highlighting the need for sustainable alternatives. Entomopathogenic fungi (EPF) are promising biocontrol agents, but their efficacy is limited by slow pathogenicity, environmental sensitivity, and low persistence on insect cuticles. This study evaluated integrated formulation strategies to enhance the virulence of Beauveria namnaoensis PM-02 against P. xylostella under laboratory and greenhouse conditions. Putative copper and zinc nanoparticle preparations were generated using fungal biomass extracts, with nanoparticle formation inferred from visual changes in the reaction mixtures. Oil-emulsified fungal formulations and combinations with emamectin benzoate were also evaluated. Larval mortality increased significantly with concentration, indicating a clear dose-dependent response. The combined treatment of oil-emulsified fungus and emamectin benzoate, along with emamectin benzoate alone, resulted in the highest larval mortality (100%), whereas fungus alone caused the lowest mortality (43.3%). Lethal concentration (LC50) analysis indicated high toxicity of the combined treatment, while lethal time (LT50) values demonstrated more rapid mortality for emamectin benzoate (0.176 days) and the combined treatment (0.830 days) compared with fungus alone (6.25 days). Under greenhouse conditions, the combined treatment showed the highest efficacy, reducing larval survival to 30% and demonstrating enhanced insecticidal activity. Overall, integrated formulation strategies significantly improved fungal efficacy against P. xylostella.
Riaz et al. (Fri,) studied this question.