Development and evaluation of an oil-based Beauveria bassiana (Deuteromycota: Hyphomycetes) formulation for control of Galleria mellonella (Lepidoptera: Pyralidae) and its safety to Apis mellifera caucasica (Hemiptera: Aphididae)

The greater wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae), is a major pest causing serious damage to honeycombs and apicultural products. In this study, 9 indigenous Beauveria isolates were screened for their pathogenicity, and HpA-5 was identified as the most virulent isolate based on mortality, LT50, and LC50 values. This isolate also showed higher tolerance to abiotic stress factors, including temperature, UV-B radiation, and humidity. An oil-based mycoinsecticide formulation (WaxGuard) was developed using spray-dried blastospores of the HpA-5 isolate. Under laboratory conditions, WaxGuard caused 86.6% mortality in G. mellonella larvae within 7 d and exhibited comparable efficacy to a commercial product. The non-target effects of WaxGuard were evaluated on honey bees, where only 3.3% mortality was observed after 10 d, classifying the formulation as nontoxic according to IOBC standards. Overall, the results demonstrate that the oil-based formulation of a locally adapted B. bassiana isolate combines high insecticidal efficacy against G. mellonella with minimal adverse effects on honey bees. This study highlights the potential of WaxGuard as a safe and effective biological control agent for sustainable pest management in apicultural systems.