The effects of neem oil (Azadirachta indica A. JUSS) enriched with different concentrations of azadirachtin on the integument of semi‐engorged Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) females

Abstract

Several studies searching for methods to control Rhipicephalus sanguineus s.l., (dog tick) infestations have been developed aiming to minimize the damages caused by these ectoparasites to the hosts and the environment, which is harmed by the indiscriminate use of toxic acaricide products. In this scenario, neem oil has been used as a natural alternative against ticks, once this chemical has repellent properties and interferes in the growth regulation of these ectoparasites, inhibiting ecdysis. The present study evaluated the effects of azadirachtin-enriched neem oil on the integument of semi-engorged R.sanguineus s.l., females through morphohistological techniques. The results showed the occurrence of significant morphological and histochemical alterations, mainly in the females exposed to higher concentrations, which demonstrates the dose-dependent action of the chemical. A decrease in the cuticle thickness was observed, as well as a modification in the distribution of the epithelial cells, which displayed pyknotic and fragmented nuclei, and intensely vacuolated cytoplasm, indicating that these cells would be undergoing death processes. These morphological alterations observed in the integument of the females exposed to the azadirachtin-enriched neem oil encourage the use of this chemical as a strategy to control these ectoparasites.

The bioactive compound carvacrol as a potential acaricide: An assessment of its effects on the integument of female Rhipicephalus sanguineus sensu lato ticks

“…This layer, originally composed of a simple cubic epithelium, became stratified, presenting cells of various sizes and containing pyknotic nuclei, indicating, in addition to structural disorganization, cell death. This demonstrated that the investigated bioactive compound was able to alter cuticle permeability, crossing this layer and reaching the epithelial cells, as reported by Lima de Souza et al (2017) when exposing female R. sanguineus s.l. ticks to neem oil enriched with azadirachtin at different concentrations.…”

“…In this perspective, the use of bioactive compounds present in the extracts and oils of several plants has been considered for use in tick control, as these compounds can interfere in the metabolism of various tick organs, modifying their physiology and making them more vulnerable, in addition to preventing successful feeding and reproduction processes. Furthermore, the use of bioactive compounds results in less environmental effects since they are easily degradable, generating less soil, air, and water residue accumulation (Anholeto et al, 2017; Lima de Souza et al, 2017; Remedio et al, 2014; Rosado‐Aguilar et al, 2017). In this regard, laboratory assessments have demonstrated that plants belonging to the Lamiaceae and Verbenaceae families are strong candidates for the provision of acaricide bioactive compounds, as they present the monoterpene carvacrol, which displays several biological properties, including acaricidal, as their main active ingredient (Koc et al, 2013; Martinez‐Velazquez et al, 2011).…”

Plant-Derived Natural Compounds for Tick Pest Control in Livestock and Wildlife: Pragmatism or Utopia?

“…Similar outcomes were reported after treatment with neem oils containing Azadirachtin [ 150 ], indicating that the changes in morphology are possibly connected with this compound. Furthermore, neem oil also reduces cuticle thickness and distorts epithelial cell morphology of semi-engorged females [ 151 ]. However, neem leaf extracts can negatively affect oocytes and ovaries in mammals.…”

When used in animals, a neem (Azadirachta indica)-based ectoparasiticide performs better than a synthetic one

“…Azadirachta indica has major ectoparasiticides in its various parts, especially in seeds and leaves. Herbal combinations containing A.indica has been found quite useful and efficacious against ectoparasites such as nymphal ticks, fleas, lice and mites (Abdel-Ghaffar et al, 2008;Bhilegaonkar and Maske, 1997;Habluetzel, et al, 2007;Kilonzo, et al, 2001;Lima de Souza et al, 2017). The aqueous extract of A. indica has been shown to have activity against the maturation of parasite oocytes, the oviposition, the reproductive potential and embryonic development of a fish ectoparasite (Banerjee et al, 2014).…”

“…. AZEEM, H. AKBAR, L. AHMAD, M. ASHRAF, S. PUVANENDIRANnan et al, (1996),Borges et al, (2003) and Lima deSouza et al (2017).…”