Impacts of a novel controlled-release TiO2-coated (nano-) formulation of carbendazim and its constituents on freshwater macroinvertebrate communities

Insights from a Long-Term Outdoor Mesocosm Study: eDNA Metabarcoding Reveals Exacerbated but Transient Impacts from a Nanoenabled Pesticide Formulation (Nano-TiO2-Coated Carbendazim) on Freshwater Microbial Communities

Fungicides currently encompass the second-most-used class of agricultural pesticides globally. Residues are frequently detected in freshwater, leading to undesired ecological impacts. Nanoenabled pesticide formulations have recently gained prominence in the scientific literature and have been suggested to exhibit favorable properties over conventional pesticide formulations by facilitating reductions in emissions toward nontarget locations. However, data on unintended effects on nontarget aquatic communities are scarce, especially concerning microbial communities. In this study, long-term effects of nano titanium-dioxide- (nTiO2)-coated carbendazim and its constituents on (pelagic) freshwater microbial communities in simulated agricultural ditches were investigated over a period of 14 weeks using environmental DNA (eDNA) metabarcoding. Impacts on bacterial diversity (α and β) were observed 2 weeks after the treatment application and most pronounced in the nTiO2-coated carbendazim treatment, followed by its active substance, i.e., noncoated carbendazim. The observed patterns possibly imply that nTiO2-coated carbendazim imposed more pronounced and potentially delayed or extended effects compared to the noncoated form of carbendazim. Bacterial communities also proved to be resilient under the tested conditions as they returned to the control-state within 5 weeks after the treatment application. Overall, our data suggest that eDNA metabarcoding data on microbial communities can help uncover time-dependent effects of nanoformulated pesticides.

Zooplankton community turnover in response to a novel TiO2-coated nano-formulation of carbendazim and its constituents

Novel nanomaterial-based pesticide formulations are increasingly perceived as promising aids in the transition to more efficient agricultural production systems. The current understanding of potential unintended (eco)toxicological impacts of nano-formulated pesticides is scarce, in particular with regard to (non-target) aquatic organisms and ecosystems. The present study reports the results of a long-term freshwater mesocosm experiment which assessed responses of individual zooplankton taxa and communities to a novel TiO2-coated nano-formulation of the fungicide carbendazim. Population- and community trends were assessed and compared in response to the nano-formulation and its constituents applied individually (i.e. nano-sized TiO2, carbendazim) and in combination (i.e. nano-sized TiO2 & carbendazim). Minimal differences were observed between effects induced by the nano-formulation and its active ingredient (i.e. carbendazim) when applied at equivalent nominal test concentrations (4 μg L-1). Nano-sized TiO2 was found to affect zooplankton community trends when applied separately at environmentally realistic concentrations (20 μg L-1 nominal test concentration). However, when nano-sized TiO2 was applied in combination with carbendazim, nano-sized TiO2 was found not to alter effects on community trends induced by carbendazim. The findings of the current study provide an extensive and timely addition to the current body of work available on non-target impacts of nano-formulated pesticides.