Titanium dioxide nanoparticles (TiO2 NPs) are widely used in industrial, agricultural, and consumer products and are increasingly detected in terrestrial and floral environments that are critical for pollinators. However, the mechanistic and ecological consequences of TiO2 NPs exposure on pollinator health remain poorly understood. Here, we present a multi-level ecotoxicological assessment of dietary TiO2 NPs exposure in the bumblebee Bombus terrestris L. (Hymenoptera: Apidae), integrating colony performance, gut microbiota composition, and host transcriptomic responses. Using both environmentally relevant and worst-case concentrations, we conducted short-term (3-d) and chronic (15-d) exposures to evaluate physiological disruption, microbial dynamics, and potential compensatory or recovery processes. TiO2 NPs ingestion reduced worker survival and syrup consumption, delayed oviposition, and shortened egg development, indicating impaired colony performance. Gut microbiota exhibited pronounced dysbiosis after 3 d, followed by partial converged toward control-like profiles after 15 d, suggesting microbial potential resilience and compensatory restructuring. Transcriptomic analyses revealed dose-dependent activation of immune, oxidative stress, calcium signaling, and programmed cell death pathways. Correlative analyses identified associations between specific microbial taxa, including Apibacter and Klebsiella, and host gene expression linked to immunity, detoxification, and metabolism, highlighting coordinated microbe-host responses under TiO2 NPs stress. This study provides novel mechanistic insight into how engineered nanoparticles affect pollinators across biological scales, from colony physiology and microbial ecology to molecular pathways, and emphasizes the practical importance of safeguarding pollinator health for both wild plant reproduction and crop pollination. The findings advance understanding of nanoparticle ecotoxicology and support evidence-based strategies for sustainable nanomaterial use and pollinator protection.
Yuan et al. (Sat,) studied this question.