Pollen Contaminated with a Triple-Action Fungicide Induced Oxidative Stress and Reduced Bee Longevity Though with Less Impact on Lifespan in Bees from Well Fed Colonies

There is increasing evidence that besides insecticides, fungicides also affect bee health. However, there has been little research on how bees are affected by recently developed modern fungicides that contain various active ingredients to help overcome fungal pathogen resistance. Experiments were conducted to determine how this type of fungicide affects bees and whether annutritional supplements can ameliorate eventual negative impacts for bees. Newly-emerged bees from well fed and from nutritionally restricted honey bee colonies were maintained in groups of 20 in plastic cages in an incubator and fed for five days with pollen from sunflower plants that had been sprayed or not during flowering with a three-component commercial fungicide containing bixafen, prothioconazole and trifloxystrobin. Bees from the well-fed colonies were significantly larger and consumed more uncontaminated pollen in the cage tests. They also had increased glutathione peroxidase activity and higher concentrations of pyridine nucleotides. Feeding on the fungicide-contaminated pollen resulted in decreased catalase activity of bees from well-fed colonies and damage to cell membranes of bees indepent of nutritional condition. Bee longevity was reduced by both fungicide contamination of the pollen diet and poor nutritional condition of the donor colony. In conclusion, the triple action commercial fungicide adversely affected bees fed with contaminated pollen, though nutritional supplementation of bee colonies that provided the bees partially compensated for these effects.