Bee pathogens in Apis florea samples accidentally introduced into Malta and Italy

Introduction
Apis florea, the red dwarf honey bee, is a wild bee species native to Asia. Its adaptability and nesting behaviour make it a potential alien invasive species, raising concerns about its competition with Apis mellifera and the introduction of novel pathogens. This study investigates the presence of known and emerging honey bee pathogens in A. florea to increase the available knowledge on this species.

Methods
In 2024, after the first detection in Europe of a fully established colony of A. florea in Malta, a small nest was found in the same area, near the Malta Freeport Terminals, a very busy cargo and transhipment port in the southern part of the island. In May of the same year, in Italy (port of Gioia Tauro, Calabria region), a small nest of A. florea was discovered on the wall of a container coming from India. Specimens of A. florea, collected from both locations before the destruction of the nests, were analysed for species identification by the sequencing of a cytochrome c oxidase subunit I (COI) region of mitochondrial DNA, and for the presence of possible honey bee pathogens (fungi, viruses and trypasonomatids).

Results
The sequencing of the COI region confirmed the species A. florea in both samples and only bee viruses were detected. Whereas viral co-infections (DWV, ABPV, SBV, BQCV and AmFV) were present in samples from Malta, only SBV was found in A. florea from Italy.

Conclusion
The spread of A. florea in the Mediterranean region due to global trade poses an ecological risk to local biodiversity. Furthermore, the presence of pathogens in the A. florea populations raises concerns about their potential spread to local honey bee populations, highlighting the need to monitor the potential presence of A. florea nests through an early warning system and to take prompt action for their eradication.