Scientific note on the non-specific amplification of honey bee pathogens in a non-target host: the European beewolf (Philanthus triangulum)

Abstract

The European beewolf (Philanthus triangulum Fabricius, 1775) is a solitary wasp that preys on honey bees and has recently expanded its range to the Canary Islands. This study investigates whether P. triangulum could act as a vector for honey bee gut pathogens and evaluates the reliability of their PCR-based detection in non-target hosts. Ninety-four beewolf individuals were screened for microsporidia and trypanosomatids using family and species-specific primers. Amplification was successful for pathogens at family level, but sequencing revealed non-specific amplification of host microsatellite regions. Only in one beewolf individual the pathogen amplicon showed identity with multiple trypanosomatid species, though infection could not be confirmed. These findings highlight the risk of misinterpretation when using primers specific to trypanosomatids and microsporidia to other taxa than honey bees and emphasize the need for sequencing confirmation. Our results underscore methodological challenges in pathogen spillover studies and call for robust diagnostic protocols to avoid false positives and improve pollinator health research.