Assessing the impacts of nanoencapsulated geraniol on amphibians: A step toward sustainable pesticide alternatives?

Amphibians are vulnerable to the effects of pesticides, and nanoencapsulation of geraniol in zein nanocapsules may provide a more sustainable alternative to synthetic pesticides. These nanoformulations enhance the targeting of active ingredients, reduce the amount of pesticide applied, and may reduce impacts on non-target organisms. Thus, the effects of geraniol (GER), nanoencapsulated geraniol (nGER), and zein nanocapsules (NANO) were evaluated on Aquarana catesbeiana tadpoles after 24 and 96 h exposure. Animals exhibited distinct physiological responses. GER caused pronounced metabolic disruption, including glycogen depletion, hyperglycemia, and neurotoxicity (brain acetylcholinesterase hyperactivity). nGER reduced acute metabolic stress but elicited intermediate effects, such as immunosuppression (lymphocyte reduction), ionic imbalance (elevated plasma K⁺), and muscle acetylcholinesterase inhibition. The empty nanocapsules (NANO) induced transient osmoregulatory disturbances (increased plasma Na⁺ and gill H⁺-ATPase/Ca²⁺-ATPase activity) and caused neurotoxicity after 96 h (55 % brain acetylcholinesterase inhibition). The Integrated Biomarker Response index (IBR) validated the toxicity ranking: GER > nGER > NANO. Therefore, nanoencapsulated geraniol cannot yet be considered safe for A. catesbeiana tadpoles, as the toxicity of individual components and the behavior of nanoparticles in aquatic environments must be considered.