Acaricidal Efficacy of Biosynthesized Zinc Oxide Nanoparticles Against Hyalomma dromedarii (Acari: Ixodidae) and Their Toxic Effects on Swiss Albino Mice

Abstract

Purpose: The current study aimed to investigate the efficacy of zinc oxide nanoparticles (ZnO NPs) synthesized by Melia azedarach aqueous extract to control Hyalomma dromedarii tick, and to evaluate their toxic effects on Swiss albino mice.

Methods: ZnO NPs were synthesized using M. azedarach aqueous extract. UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy were used to characterize the synthesized NPs. Egg, nymph, larva, and adult immersion tests were used for bioassay of tick stages with the synthesized ZnO NP. A toxicity study was performed on Swiss albino mice after treatment with 1/10 of the oral LD₅₀ of ZnO NPs (8437 mg/kg) for 5 successive days by oral gavage.

Results: The LC₅₀ of ZnO NPs on the eggs, larvae, and nymphs was 11.6, 8.03, and 3.9 mg/ml, respectively. The reproductive performance of females treated with ZnO NPs was lower than that of untreated females. The hematological results showed an insignificant increase in the level of white blood cells with normal red blood cells, hemoglobin, in addition to normal platelet count. The biochemical analysis showed an insignificant increased level (P > 0.05) of alkaline phosphatase and alanine aminotransferase. The liver and kidney suffered few histopathological changes after oral administration of ZnO NPs.

Conclusion: These results suggest that ZnO NPs have good acaricidal activity against eggs, larvae, and engorged nymphs of H. dromedarii. ZnO NPs minimized the number of eggs laid by engorged females and the hatchability of their eggs. ZnO NPs did not affect unfed adults. The toxicity results of the mice revealed insignificant changes in the hemogram, biochemistry, with liver and kidney suffering few histopathological changes. Future studies are needed to assess application routes (topical vs oral). Based on these findings, ZnO NPs may be incorporated in the control of camel tick H. dromedarii.

Keywords: Camel; Hyalomma dromedarii; Melia azedarach; SEM–EDS; Toxicity; Zinc oxide nanoparticles.