Cold stress induces specific antioxidant responses in honey bee brood

Abstract

Multiple harmful factors cause chronic sub-lethal stress in managed honey bee colonies. In weak colonies, worker bees may not efficiently maintain the optimum temperature (33–36°C) in peripheral brood development areas. A short period at 25°C induces physiological adjustments and increases the mortality in honey bee brood reared in vitro. Molecular damage due to oxidative imbalance can be one of the main causes of mortality when organisms are under stress. Here, we demonstrate that in vitro rearing honey bee brood exposed 3 days at sub-optimal temperature (25°C) does not lead to H2O2 accumulation and oxidative protein damage. Cold-stressed honey bee brood showed increased levels of both total antioxidant status (TAS) and expression of peroxiredoxins PRX1 and PRX4, but not of catalase activity. Results indicate that specific antioxidant defenses induced in honey bee brood under moderated cold stress are enough to keep H2O2 levels under control and avoid major protein damages. It is concluded that the increase of mortality in cold-stressed brood are due to multifactor’s, beyond uncontrolled oxidative injuries.