Novel Insights into the Acute and Sublethal Toxicity of Layered Double Hydroxide Nanoparticles in Spodoptera frugiperda Larvae

Abstract

Nanotechnology is increasingly integrated into agriculture, yet some nanomaterials are investigated primarily as delivery platforms, nanofertilizers, controlled-release pesticides, antimicrobials, or oligonucleotide delivery systems, while their intrinsic biological activity remains largely unexplored. Layered double hydroxide (LDH) transition metal containing are widely assumed to be biologically inert despite their tunable metal composition, high surface reactivity, and potential to interact directly with biological systems. Here, we evaluated the acute and sublethal toxicity of LDH nanoparticles containing transition metals (Al–Ni, Al–Co, or Al–Cu) on Spodoptera frugiperda larvae. Laboratory bioassays were performed by incorporating nanoparticles into the larval artificial diet to quantify dose–mortality relationships, estimate LC50 values, and assess impacts on larval and pupal development. All LDH formulations exhibited dose-dependent toxicity, with Al–Cu LDH showing the highest potency and the lowest LC50 (19.1–37.3 mg mL–1). Furthermore, a significant reduction in pupation rate and larval weight was observed, suggesting relevant sublethal effects. These findings provide evidence that metallic LDHs possess bioactivity against an agriculturally important pest, challenging the assumption of LDH inertness and revealing their potential as dual-function materials that combine inherent biological effects with delivery capabilities. This work establishes a new foundation for evaluating LDHs within pest-management frameworks and underscores the need to assess selectivity, environmental fate, and impacts on nontarget organisms before field deployment.