Acaricidal efficacy of deltamethrin-zinc oxide nanocomposite on Rhipicephalus (Boophilus) annulatus tick.

In the veterinary field, there is a great concern about the issue of acaricides resistance in cattle ticks. A comparative study was designed to evaluate the in vitro acaricidal efficacy of imidacloprid nano-emulsion, zinc oxide nanoparticles (ZnO NPs), silver nanoparticles (Ag NPs), deltamethrin, deltamethrin-ZnO NPs, and deltamethrin-Ag NPs. In addition, the novel formulations of deltamethrin (deltamethrin-ZnO NPs and deltamethrin-Ag NPs) against Rhipicephalus (Boophilus) annulatus were also evaluated by in vivo animal efficacy trials. Nanoparticles and their loaded forms, deltamethrin-Ag NPs and deltamethrin-ZnO NPs, were characterized by Transmission Electron Microscope (TEM) and Fourier-Transform Infrared Spectrum (FTIR). The adulticidal activity of deltamethrin-ZnO NPs at different concentrations; 2 mL/L, 1 mL/L, 0.5 mL/L and 0.25 mL/L induced a significant (P ≤ 0.05) lethal effect on adult ticks compared to deltamethrin-Ag NPs at the same concentrations. The larvicidal efficacy of deltamethrin-ZnO NPs resulted in a complete larval mortality within 24 h of exposure, while deltamethrin and deltamethrin-Ag NPs exhibited 100% immobility of larvae 48 h post-exposure. Furthermore, the in vivo experiments showed a considerable reduction in the tick's survival after using deltamethrin-ZnO NPs. There was no significant effect of different treatments on liver or kidney function tests at pre- and post-treatment of animals. In conclusion, deltamethrin-ZnO nanocomposite was the most effective adulticide and larvicide against R. (B.) annulatus. To the best of our knowledge, this is the first report for using deltamethrin-ZnO NPs as an acaricide.