In vitro antifungal activity of ZnO, CuO, and SiO₂ nanoparticles against Lecanicillium lecanii isolated from honeybee (Apis mellifera)

Objective: The entomopathogen fungus Lecanicillium lecanii threatens the health of the honeybee (Apis mellifera). Due to the increasing resistance of fungi to conventional antifungal agents, environmental concerns have led to a focus on nanoparticle-based alternatives. This study aimed to evaluate the antifungal activity of zinc oxides (ZnO) and copper oxides (CuO), and silica (SiO₂) nanoparticles (NPs) against L. lecanii. Methods: The fungal isolate was identified using molecular techniques targeting the internal transcribed spacer (ITS) region, sequencing and phylogenetic tree analysis. In vitro antifungal activity was determined by the broth microdilution at 0, 10, 100, and 500 µg/mL for each nanoparticle. In the same way, the sensitivity of L. lecanii to Amphotericin B, Nystatin, Fluconazole, and Griseofulvin (four common antifungal agents) was also tested. Results: ZnO nanoparticles exhibited the highest mycelial growth inhibition, followed by CuO and SiO2 NPs. The effect of ZnO was significant at higher concentrations. Amphotericin B and Nystatin were highly effective drugs, Fluconazole had moderate activity, and Griseofulvin had little effect. The prominent antifungal activity of ZnO-NPs might be attributed to their ability to produce reactive oxygen species (ROS), causing cell damage. Conclusion: ZnO-NPs demonstrated antifungal activity comparable to some conventional antifungals, suggesting their applicability as a safe and environmentally sustainable option for managing fungal infection in honey bees. Further in vivo and molecular studies are needed to evaluate their safety and mechanisms of action.