‘Flying agents’: hoverflies as a multitool for pollination, vectoring of beneficial microbes and biological control of grey mould disease in strawberries

Abstract Sustainable strategies are needed to manage plant pathogens and pests without disrupting ecological functions provided by beneficial organisms. Hoverflies (Diptera: Syrphidae), such as Eupeodes corollae , provide ecosystem services and are applied especially in cultivations of horticultural crops: adults serve as pollinators, while larvae prey on pests like aphids. Here, we investigated whether E. corollae can also function as an entomovector for delivering microbial biocontrol agents into flowering crops, similar to systems developed for bees. Targeting the strawberry ( Fragaria × ananassa )–grey mould ( Botrytis cinerea ) pathosystem, we tested the yeast Metschnikowia fructicola (isolate UDA10) for its suitability in hoverfly entomovectoring and suppression of grey mould. Dual culture assays confirmed that M. fructicola inhibits B. cinerea growth. We further demonstrated that E. corollae effectively vectors M. fructicola to strawberry flowers. In a greenhouse experiment, we tested whether hoverflies and yeast, alone or combined, can suppress grey mould in postharvest strawberries from flowers artificially inoculated with B. cinerea . Hoverfly activity significantly reduced the fungal infection (lesion and mycelial coverage) on cold stored fruit by 50–70% after two weeks, especially in combination with the yeast. Additionally, fruits from hoverfly-pollinated flowers were of higher shape quality, indicating improved pollination. Our findings add value to E. corollae as a multifunctional ‘ flying agent ’ for integrated pest and pollination management, capable of enhancing pollination, entomovectoring for targeted plant pathogen suppression and controlling pests via larval predation. The ‘ flying agent ’ multitool can potentially be extended to other horticultural systems, contributing to both quality and yield improvements, while reducing reliance on chemical inputs for pest and disease control.