Impact of honey bee migratory management on pathogen loads and immune gene expression is affected by complex interactions with environment, worker life history, and season

Simone-Finstrom, Michael; Strand, Micheline K.; Tarpy, David R.; Rueppell, Olav

Impact of honey bee migratory management on pathogen loads and immune gene expression is affected by complex interactions with environment, worker life history, and season

2022

Simone-Finstrom, Michael | Strand, Micheline K. | Tarpy, David R. | Rueppell, Olav

The effects of management, such as intensive migratory beekeeping, are of ongoing debate concerning the causes of honey bee health problems. Even though comparisons of disease among differently managed colonies indicate some effects, the direct impact of migratory practices on honey bee diseases are not well understood. To test the long- and short-term impact of managed migration on disease loads and immunity, experimental honey bee colonies were maintained with or without migratory movement and individuals that experienced migration as juveniles (e.g., larval and pupal development), as adults, or both were compared to control colonies that remained stationary and therefore did not experience migratory relocation. Samples at different ages and life history stages (hive bees or foragers), taken at the beginning and end of the active season, were analyzed for pathogen loads and physiological markers associated with health or stress. Bees exposed to migratory management during adulthood had increased levels of the AKI virus complex (Acute bee paralysis, Kashmir bee, and Israeli acute bee paralysis viruses) and decreased levels of antiviral gene expression (dicer-like, hsp90). However, those in stationary management as adults had elevated gut parasites (Nosema and trypanosomes). Effects of environment during juvenile development were more complex and interacted with life-history stage and season. Age at collection, life-history stage, and season all influenced numerous factors from viral load to immune gene expression. Overall, these data shed light on the complexity of how management practices can influence individual bee exposure to pathogens, health, and resiliency.

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