Study demonstrates the importance of nutrition in bees’ survival against pesticides and viruses

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Investigators from the University of Illinois Urbana-Champaign tested the long-held hypothesis that declines in pollinator health could be attributed to interacting biotic and abiotic stressors, including nutritional limitations, exposure to pesticides, and infection with pathogens and parasites.^1,2 In a study that, for the first time, considered all 3 factors, these researchers concluded that good nutrition enhances honey bee resilience against the other factors that threaten their health.

“Multiple stressors are often bad for survival,” Edward Hsieh, the graduate student who led the research alongside University of Illinois professor Adam Dolezal, said in an article on the science news website Phys.org.¹ “However, it is always context-dependent, and you have to be aware of all these factors when you’re trying to make broad statements about how interactive effects affect honey bees.”

The study, published in the journal Science of the Total Environment, demonstrated the complexity of multi-stressor interactions—and the importance of context—with the potential to affect bees’ health and physiology.² Investigators evaluated pollen collected by honey bees from small areas of restored prairie bordering agricultural fields in Iowa, using maximum insecticide and fungicide levels found in bee-collected pollen grains as an indication of chemical exposures in the wild.¹

Groups of caged honey bees were exposed to different dietary, viral, and/or chemical treatments (an organophosphate, a pyrethroid, or a neonicotinoid), and they were fed either artificial or natural pollen.¹ Additionally, some of the bees were infected with the Israeli Acute Paralysis Virus—a known threat to honey bee populations.¹

The study found that artificial pollen-fed bees often died as a result of exposure to the virus. When exposed to the virus and pesticides at the same time, mortality rates were even higher. Bees that were fed natural pollen showed similar reactions to virus exposure, and many of them died. In contrast to the bees fed artificial pollen, though, fewer of the natural pollen fed bees died as a result of exposure to chlorpyrifos and fungicide mixes.¹

“Bees have this inherent ability to deal with stress, and so, if you give them a little bit of stress, like a low-level exposure to a pesticide, it may help them deal with a bigger stress from a pathogen like the virus,” Dolezal said in the Phys.org article.¹ “However, it only works if they have the natural resources to do it.”

Investigators cautioned that chemical exposures should not be disregarded because of these findings. Reactions may vary depending on the chemicals in question. The study proves the complexity of interactions between biotic and abiotic factors within the honey bee system, and that the alteration of any factor within the paradigm could have serious implications.²

“The takeaway from this study is that bees are quite resilient even to the interaction of pesticides and viruses if they have really good nutrition,” Dolezal told Phys.org.¹ “However, we don’t want people to conclude that pesticides are not a big deal for the bees.”

References

1. Yates D. Study finds good nutrition boosts honey bee resilience against pesticides, viruses. Phys.org. September 24, 2024. Accessed September 30, 2024. https://phys.org/news/2024-09-good-nutrition-boosts-honey-bee.html
2. Hsieh E, Dolezal A. Nutrition, pesticide exposure, and virus infection interact to produce context-dependent effects in honey bees (Apis mellifera). Sci Total Environ. July 30, 2024. Accessed September 30, 2024. https://doi.org/10.1016/j.scitotenv.2024.175125