Comparative assessment of food consumption, longevity, thermoregulation, and molecular health markers in mite-resistant and Italian honey bee stocks

Identifying traits for adaptation to different management and environmental regimes is key to maintaining robust honey bee populations under global climate change. We compared mite-resistant (Pol-line and Russian) and Italian honey bee stocks in variable-temperature cage experiments (200 bees per cage) with respect to food consumption, thermoregulation, gene expression, and lifespan, in 3 experiments over 2 years. The Italian stock bees consumed more syrup and pollen on average than the mite-resistant stocks, but the mite-resistant stocks maintained higher cluster temperatures and had median lifespans 8 days longer, consistent with the increased expression of vitellogenin relative to Italian stock. Model results indicated that, to maintain the same colony size as the mite-resistant stocks, Italian stock colonies would need about 13% more sealed brood to offset reduced worker lifespans. These differences among bee stocks likely influence colony-level productivity and health, and showed the importance of experimental replication.