Assessment of different Lippia sidoides genotypes regarding their acaricidal activity against Rhipicephalus (Boophilus) microplus

Abstract

The aim of this study was to select different genotypes of Lippia sidoides with the highest activity against larvae and engorged females of the tick Rhipicephalus (Boophilus) microplus. The germplasms studied were LSID006, LSID102, LSID103 and LSID104. The LSID104 genotype, that presented carvacrol as a major constituent, was the germplasm with the worst larvicide effect (LC50 2.99 mg/mL). The LSID006 genotype was the least effective against engorged females (LC50 12.46 mg/mL), and it was chemically similar to the LSID102 genotype, which presented the highest acaricide activity (LC50 2.81 mg/mL). We conclude that chemical similarity of the germplasms was not correlated with acaricide activity against R. (B.) microplus. The essential oil of L. sidoides is a potent natural agent. However, the findings of this work provide a better understanding for product development based on this natural product, which must consider synergic effects or the action of minor compounds.

In vitro efficacy of essential oils with different concentrations of 1,8-cineole against Rhipicephalus (Boophilus) microplus

“…microplus larvae (87.7%) at 100 mg/mL. This variation in activity is probably related to each oil's unique mode of action against the specific life stage of the tick (SOARES et al, 2016).…”

“…microplus (HÜE et al, 2015). It is possible that the identified components of essential oils could have antagonistic activity towards each other and consequently reduce the acaricidal action of other major compounds (SOARES et al, 2016).…”

“…The terpenes in essential oils are an alternative means to control parasites (ANTHONY et al, 2005). The chemical variability in essential oils and the relationship among the compounds play important roles in the acaricidal activity (SOARES et al, 2016). It is not possible to affirm that the most abundant chemical compounds in an essential oil are responsible for the observed biological effects (GALINDO et al, 2010).…”

“…It is not possible to affirm that the most abundant chemical compounds in an essential oil are responsible for the observed biological effects (GALINDO et al, 2010). Compounds found in small proportions can act as synergists with other minor or major molecules (SOARES et al, 2016). 1,8-cineole is an oxygenated monoterpene that acts on cell membranes, mainly through its hydrophobicity (HONÓRIO et al, 2015).…”

“…1,8-cineole is an oxygenated monoterpene that acts on cell membranes, mainly through its hydrophobicity (HONÓRIO et al, 2015). This terpene exists, at varied concentrations, in several essential oils with acaricidal activity (PRATES et al, 1998;CHAGAS et al, 2002;SOARES et al, 2016). Studies comparing the essential oils of plants with intermediate concentrations of 1,8-cineole (24 to 35%) are scarce, and understanding of how this compound participates in the activity of natural oils remains obscure.…”