Investigation of viral and parasitic pathogens in Bombus terrestris (Hymenoptera: Apidae) populations

In recent years, with the increase in both abiotic and biotic stress factors, there has been a significant decline in honey bee and bumblebee populations worldwide, which in turn threatens pollination services that are crucial for agricultural production. This study aimed to determine the prevalence and incidence of viral and parasitic pathogens in Bombus terrestris (Linnaeus, 1758) individuals obtained from 23 wild-caught queen bumblebees collected in Ordu Province, Türkiye. For this purpose, analyses conducted on bumblebee samples collected from different businesses revealed that the Acute Bee Paralysis Virus was detected in 26.09% of the samples, the Black Queen Cell Virus in 52.17%, the Deformed Wing Virus in 21.74%, the Apis mellifera Filamentous Virus in 30.43%, Sacbrood Virus in 65.22% of samples, and Varroa destructor-1 Virus in 13.04% of tested individuals. In contrast, Chronic Bee Paralysis Virus, Kashmir Bee Virus, and Israeli Acute Paralysis Virus were not detected in any samples. Among parasitic pathogens, Crithidia bombi showed a positivity rate of 60.87%, while Apicystis bombi and Nosema spp. were not identified in any of the tested samples. Phylogenetic analyses indicate that the agents detected in bumblebees interact with honey bee pathogens in Türkiye as well as with those from geographically distant regions such as Uzbekistan and Argentina. The findings of this study provide comprehensive data on the health status and pathogen prevalence of Bombus terrestris individuals. Furthermore, these results are expected to serve as a valuable reference for future research and to contribute to the development of effective disease management and biosecurity strategies aimed at conserving bumblebee populations.