Toxicity and behavioral impact of plant-derived zinc oxide nanoparticles and essential oil on the cattle tick Rhipicephalus microplus.

BACKGROUND

The escalating challenge of acaricide resistance and the environmental concerns associated with synthetic tick control agents necessitate the development of sustainable, eco-friendly alternatives. The utilization of invasive plants for the synthesis of bioactive nanomaterials presents a promising strategy within integrated pest management.

OBJECTIVE

This study aimed to evaluate the toxicity and behavioral effects of zinc oxide nanoparticles (ZnO-NPs) and essential oil (EO) derived from the invasive weed Ageratum conyzoides against the cattle tick, Rhipicephalus microplus.

Methods

ZnO-NPs were synthesized using an aqueous leaf extract of A. conyzoides and characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), and Fourier-Transform Infrared (FTIR) spectroscopy. While the analysis confirmed the crystalline wurtzite structure and phytochemical capping of the ZnO-NPs, their specific particle size and morphological characteristics were not determined in this study. The essential oil was extracted from the same plant via hydrodistillation. The contact toxicity of both the biosynthesized ZnO-NPs and the EO was tested.

RESULTS

Characterization confirmed the successful synthesis of crystalline ZnO-NPs with a wurtzite structure and surface functionalization by plant phytochemicals. Bioassays revealed a potent, dose-dependent effect for both formulations. The ZnO-NPs induced rapid immobilization and mortality at the highest concentration (15%), while the EO caused complete paralysis, with both treatments showing significant intoxication and locomotor impairment (p < 0.001). Statistical analysis confirmed a highly significant effect of both concentration and behavioral category for both ZnO-NPs and EO, underscoring their dose-dependent efficacy.

CONCLUSION

This study successfully demonstrates that A. conyzoides is a valuable resource for generating effective acaricidal agents. The biosynthesized ZnO-NPs and the EO both show high potential as sustainable, green toxicants/control agents against ticks.