Cyclic Synthetic Peroxides Inhibit Growth of Entomopathogenic Fungus Ascosphaera apis without Toxic Effect on Bumblebees

Abstract

In recent years, the number of pollinators in the world has significantly decreased. A possible reason for this is the toxic effects of agrochemicals reducing the immunity of insects that leads to their increased susceptibility to pathogens. <i>Ascosphaera apis</i> is a dangerous entomopathogenic fungus, afflicting both honeybees and bumblebees. We investigated fungicide activity of cyclic synthetic peroxides against <i>A. apis</i> isolated from <i>Bombus terrestris</i> L. The peroxides exhibited high mycelium growth inhibition of <i>A. apis</i> up to 94-100% at concentration 30 mg/L. EC₅₀ values were determined for the most active peroxides. Two peroxides showed higher antifungal activity against <i>A. apis</i> than the commercial fungicide Triadimefon. The studied peroxides did not reduce the ability of bumblebees to fly and did not lead to the death of bumblebees. A new field of application for peroxides was disclosed.