Óleos essenciais para o controle sustentável de carrapatos: efeitos sobre diferentes estágios de Rhipicephalus (Boophilus) microplus

Abstract

The cattle tick Rhipicephalus (Boophilus) microplus is an ectoparasite present in tropical and subtropical regions of the world and constitutes a major problem for livestock farmers due to the economic impact of the acquisition of synthetic acaricides. Thus, seeking new sustainable alternatives such as the use of essential oils (EOs) found in plants represents a promising source of new acaricides. Some botanical families deserve to be highlighted because they present important secondary compounds with acaricidal and insecticidal activity. The objective of this study was to evaluate EOs from 8 botanical species of different families in the search for sustainable control of the cattle tick R. (B) microplus by applying it at different stages of the ectoparasite, as well as the development of formulations targeting products of plant origin. Leaves of Salvia officinallis L. (sage), seeds of Pterodon emarginatus Vogel (sucupira) and fruits of Cardiopetalum calophyllum (imbira) were collected from typical Cerrado areas of Rio Verde-GO and subjected to hydrodistillation for 4 hours in a Clevenger-type apparatus. Commercial EOs with a purity level of 100% were also purchased from the species of Citrus reticulata (tangerine), Ocimum basilicum (basil), Cinnamomum zeylanicum (cinnamon), Eugenia caryophyllus (clove) and Eucalyptus globulus (eucalyptus). Qualitative chromatography was performed to evaluate the secondary compounds present in the studied species and whether the possible acaricidal effect could be linked to them, being tested in different stages of the cattle tick by the Larval Package Test (LPT) and Adult Immersion Test (AIT). Filter paper packages (Whatmann nº 1) measuring 6 x 6 cm were prepared and concentrations of 0.5%; 2.5%; 5.0%; 10.0% and 20.0% (V/V) of each EO were tested. After 24 hours, mortality and/or motility were evaluated; as well as positive and negative controls, and statistical differences were analyzed with p < 0.05 by the Tukey test. Subsequently, the Accelerated Stability Test (AST) was performed to assess whether the product would be stable and effective, observing its organoleptic properties (color, odor, appearance and pH). The results allowed us to observe that compounds such as eugenol, eucalyptol, D-limonene and linalool can be highlighted as major in different EO studied, being already described with acaricidal activity. It was also possible to observe that the essential oil of C. reticulata (tangerine) was the most effective with 100% in all concentrations tested for the larval stage of R. (B.) microplus. The other EOs showed variations depending on the concentrations tested. In addition, the EO of C. zeylanicum had maximum efficacy (100%) in inhibiting postures at concentrations of 2.5 and 5.0%, different from that observed with the other EOs. The greatest efficacy in TEA was observed in the EO/OS formulation at 0.5% of E. globulus, which caused 97.41% and 71.0% mortality in R. (B.) microplus larvae at temperatures of -20ºC and 4ºC, respectively. Therefore, studies with EOs may be sustainable alternatives to the control of different stages of R. (B.) microplus, seeking new products of plant origin without synthetic additives. However, new tests are needed considering the possibility of encapsulating EOs to maintain their organoleptic properties, aiming for greater efficacy.