Mycotoxins as an Underestimated Honeybee Stressor: Aflatoxin, Contaminated Pollen, and Colony-Level Risk

Pollinators play a critical role in agricultural productivity and the maintenance of flowering plant diversity, yet their health is increasingly threatened by multiple environmental stressors. While research has traditionally focused on pathogens, pesticides, habitat loss, and nutritional limitation, fungal secondary metabolites, mycotoxins, remain an underappreciated risk factor. This review synthesizes current knowledge on the presence, exposure pathways, and biological impacts of key mycotoxins, including aflatoxin B1, ochratoxin A, deoxynivalenol, zearalenone, and T-2 toxin, in bee-collected pollen and bee bread. We discuss how contaminated food matrices act as reservoirs of chronic exposure, linking forager activity, nurse bee physiology, brood development, and colony-level outcomes. Evidence from laboratory studies highlights sublethal effects on survival, hypopharyngeal gland development, immunity, and gut microbiota, with potential interactions with pathogens, nutritional stress, pesticides, and climate change. Furthermore, we extend these insights to wild pollinators, emphasizing differences in colony size, diet breadth, and detoxification capacity. Analytical methods for detecting mycotoxins, including HPLC, LC-MS/MS, and ELISA, are evaluated in terms of sensitivity, specificity, and relevance to field exposure. By integrating environmental concentrations with laboratory toxicity thresholds, this review identifies critical knowledge gaps and proposes a mechanistic framework linking mycotoxin exposure to colony-level risk. The findings underscore the need for targeted monitoring, improved risk assessment, and multi-stressor evaluation to safeguard both managed and wild pollinator populations.