Nanoparticles as effective acaricides against ticks—A review

Ticks serve as vectors of a wide range of infectious agents deleterious to humans and animals. Tick bite prevention is based to a large extent on the use of chemical repellents and acaricides. However, development of resistance in targeted ticks, environmental pollution, and contamination of livestock meat and milk are major concerns. Recently, metal, metal oxide and carbon nanoparticles, particularly those obtained through green fabrication routes, were found to be highly effective against a wide array of arthropod vectors. We summarize current knowledge on the toxicity of nanoparticles against tick vectors of medical and veterinary importance. We also discuss the toxicity of products from both botanical-based and classic chemical nanosynthesis routes, showing differences in bioactivity against ticks based on the chemicals used for the fabrication of nanoparticles. Further research is needed, including to validate the efficacy of nanoparticle-based acaricides in the field and clarify mechanisms of action of nanoparticles against ticks. From a technical point of view, the literature analyzed here showed little standardization of size and weight of tested ticks, and a lack of uniform methods to assess toxicity. Finally, an important challenge for future research is the need for ecotoxicology studies to evaluate potential negative effects on non-target organisms and site contamination arising from nanoparticle-based treatments in close proximity of livestock and farmers.