Investigating the Effects of Microbial Biopesticides as Biocontrol for Honey Bee Varroa Mite: Progress Report

This progress report documents field trials evaluating Metarhizium brunneum as a biological control for Varroa destructor mites in honey bee colonies. An initial spring 2024 application method using spore-coated rice failed to reduce mite loads. A revised fall 2024 trial applied spores directly as a spray solution inside hives, resulting in significantly higher mite drop in treated colonies compared to controls. Statistical analysis indicated meaningful differences in mite mortality following treatment, suggesting potential efficacy of M. brunneum as an integrated pest management tool. Ongoing work includes PCR analysis of bee samples to assess impacts on colony health and the development of fungal strains with greater tolerance to high hive temperatures. If successful, this research could support development of cost-effective, environmentally responsible biocontrol products for mite management and reduce reliance on chemical miticides.