Molecular evidence reveals the absence of wMel Wolbachia in Apis mellifera bees from urban areas of Medellín (Colombia) with large-scale release events of infected Aedes aegypti

Between 2016 and 2017, Medellín implemented a biological control strategy to reduce Aedes aegypti populations by inoculating them with Wolbachia (wMel), a bacterium that induces sterility in insects. While horizontal Wolbachia transmission has been reported in insects, including bees, Colombia lacks a monitoring program to assess its impact after large-scale mosquito releases. This study investigated the presence of Wolbachia in Apis mellifera from urban areas with A. aegypti release events (2018–2019) and rural areas as controls. Molecular analysis of the WSP gene in 240 samples confirmed the absence of Wolbachia in all specimens, challenging the hypothesis of its prevalence in urban environments. However, these findings highlight the need for continuous monitoring to evaluate the interaction between bees, their environment, and human activities.