Bee-friendly approach to strawberry grey mould biocontrol with the yeast Papiliotrematerrestris PT22AV

The grey mould pathogen Botrytis cinerea poses a significant threat to strawberry production, particularly during the flowering stage when receptacle colonization initiates infection. In this study, we evaluated the biocontrol potential of the yeast Papiliotrema terrestris strain PT22AV (YSY (R) formulation) applied as a spray during flowering and assessed its compatibility with honeybee pollinators. The experimental trials demonstrated that PT22AV at optimal concentration (10(8) CFU ml-1) effectively reduced disease incidence, with 80% of decay reduction in post-harvest and 42-82% of decay reduction in greenhouse at an efficient dose of 1.0 kg ha-1. PT22AV exhibited rapid colonization dynamics on strawberry flowers, with preferential persistence in receptacle tissues, which is a primary infection site for B. cinerea. Experiments with artificial nectar showed that PT22AV can grow across a range of sugar concentrations, confirming its adaptability to the floral environments. Importantly, pollinator interaction studies revealed that PT22AV treatment did not alter the honeybee visitation frequency but significantly increased visit duration by 25-31%, potentially enhancing pollination efficiency. Further assays indicated a clear bee preference for yeast-supplemented nectar. These findings highlight PT22AV as a promising biocontrol agent combining effective pathogen suppression with pollinator compatibility, supporting its potential integration into sustainable strawberry disease management programs.