Exposure to a widely used mito-toxic fungicide negatively affects hemolymph protein and vitellogenin levels in honey bees (Apis mellifera)

Mito-toxic fungicides used in crop protection negatively affect pollinating insects. The fungicide formulation Pristine® (ai: 25.2 % boscalid, 12.8 % pyraclostrobin) induces precocious foraging, reduced lifespan, impaired homing abilities, and reduced body size at field-relevant concentrations. However, the underlying physiological mechanisms for these outcomes are poorly understood. To assess the hypothesis that Pristine® negatively affects the nutritional status of honey bees, we collected workers from colonies that were fed field-relevant concentrations of Pristine® fungicide. Workers were collected concurrently from two experiments in which colonies were subjected to long- or short-term fungicide exposure. Pristine® exposure significantly reduced hemolymph protein concentration in bees from the long-term but not short-term study, and reduced vitellogenin levels during the short-term summer exposure. These findings suggest that mito-toxic fungicides can negatively affect the nutritional status of honey bee workers inducing detrimental behavioral and health outcomes which ultimately impact colony health and growth patterns.