Environmental antibiotic and fungicide exposure differentially affects survival and carbohydrate-fueled flight performance in Apis mellifera.

Environmental contamination by antibiotics and fungicides is an emerging concern due to their widespread occurrence in agricultural ecosystems. The western honey bee, Apis mellifera, a key managed pollinator, is exposed to these contaminants through multiple pathways, including treated crops, contaminated water, and residues from apiculture, livestock waste, agricultural runoff, and wastewater discharges. The agrochemicals tetracycline and boscalid disrupt cellular energy metabolism and mitochondrial function in non-target organisms and may consequently compromise bee survival and the sustained flight required for effective pollination; however, their effects at environmentally relevant concentrations remain poorly understood. In this study, we examined how exposure to tetracycline and boscalid affected honey bee survival, carbohydrate-fueled flight performance, and inferred carbohydrate utilization across different sugar diets. Consumption of tetracycline increased mortality risk 56-fold relative to controls, reducing mean survival from 37 to 14 days. It also decreased flight duration and total wingbeats per flight bout, with lesser effects on wingbeat frequency. Effects on sustained flight were most pronounced under energy-matched monosaccharide fueling regimens, suggesting possible impairment of carbohydrate utilization downstream of sucrose hydrolysis. In addition, both tetracycline and boscalid exposure increased total wingbeat variability, suggestive of sublethal impairment not captured by conventional mean-based endpoints. In contrast, boscalid exposure had no detectable effects on survival or mean flight performance under the conditions tested. Overall, tetracycline and boscalid produced distinct patterns of impairment, indicating that agrochemical impacts can extend beyond mortality and mean performance, with potential consequences for pollination services in agricultural landscapes.