Insights into Physiological, Reproductive, and Transgenerational Toxicity Induced by Larval Cadmium Exposure in Honeybee (Apis mellifera) Queens

Cadmium (Cd), a pervasive heavy metal
and potent environmental
contaminant, threatens ecosystem integrity, yet its impacts on pollinating
insects remain insufficiently characterized. In this study, we systematically
investigated the consequences of larval-stage Cd exposure on honeybee
(Apis mellifera) queens through integrated
physiological, metabolomic, and proteomic analyses. Sublethal Cd exposure
disrupted hormone balance, induced midgut epithelial degeneration,
and impaired hemolymph lipid homeostasis, collectively retarding queen
developmental progression and physiological maturation. Ovarian proteomic
profiling further revealed the Cd-mediated suppression of key proteins
involved in muscle contraction, tracheal function, neural conduction,
and antioxidant defense, ultimately leading to diminished reproductive
vitality. Critically, high-dose Cd exposure elicited transgenerational
impairments: F1 workers showed reduced body size, lowered sucrose
responsiveness, and impaired olfactory learning, while F1 queens developed
smaller ovaries with fewer ovarioles. Together, these results demonstrate
that Cd imposes substantial multigenerational fitness costs on honeybee
colonies via both direct physiological impairment and transgenerational
toxicity. Our findings underscore the urgency of mitigating environmental
Cd pollution to protect pollinator health and ensure sustainable ecosystems.