Atividade acaricida e efeitos reprodutivos de óleos essenciais de Cananga odorata L (ylang-ylang), Illicium verum (anis estrelado), Foeniculum vulgare (funcho doce), Murraya paniculata (L.) Jack e Spiranthera odoratissima em fêmeas ingurgitadas de carrapatos

Abstract

Rhipicephalus microplus negatively impacts the agricultural sector, as it reduces cattle productivity. The main form of control is based on the use of synthetic acaricides. However, these compounds harm the environment and non-target organisms and their control effectiveness has been reduced due to the development of resistance in R. microplus. On the other hand, studies indicate that the components present in essential oils can become a promising alternative in combating ticks. Essential oils from plant species Cananga odorata L (Ylang-Ylang) (OCO), Illicium verum (Star Anise) (OIV), Foeniculum vulgare (Sweet Fennel) (OFV), Murraya paniculata (L.) Jack (OMP) and Spiranthera odoratissima A. St. Hil (OSO) have parasiticidal potential. Therefore, the objective of this study was to evaluate for the first time the acaricidal potential and the effects on the reproductive system of diluted essential oils of Cananga odorata L, Foeniculum vulgare, Murraya paniculata (L.) Jack and Spiranthera odoratissima A. St. Hil (OSO) in DMSO, in engorged female R. microplus ticks. It is added that these same activities of Illicium verum essential oil, diluted in DMSO in R. microplus were also evaluated for the first time. The engorged females were exposed to concentrations each essential oils (diluted in DMSO) that varied between 1μL/mL to 50μL/ml (treatment groups) and to DMSO solvent (control group C). The test used was the adult immersion test (AIT) and the parasites were monitored for mortality for up to 14 days. After, the lethal concentration for 50% of the ticks (LC50) was determined using Probit analysis. The following parameters were evaluated: female weight before oviposition, pre-oviposition period, egg mass weight, egg production index, incubation period, hatching rate, fecundity rate, percentage of oviposition reduction, percentage of hatch reduction and product effectiveness. The main constituents found in OCO, OIV, OFV were germacrene D (32.81%) and (E)- anethole (95.6% and 75.93%), respectively and for OMP and OSO they were the trans-β- isomers caryophyllene (23.8%) and β-caryophyllene (23.8%), respectively. The LC50s (with 95% confidence intervals) of OCO, OFV, OMP and OSO obtained for R. microplus were 34.424 μL/mL (28.343 - 40.857), 40.599 μL/mL (32.575 - 58.207), 11.30 μL /mL (08.45 - 24.51) and 29.24 μL/mL (26.38 - 33.93), respectively. However, the LC50 of OIV was not calculated, as there was not sufficient mortality at the concentrations evaluated. Efficacies of 86.19%, 91.35%, 97.17%,81.10% and 64.98% were determined for the highest concentrations of OCO, OIV, OFV (40μL/mL), OMP (15μL/mL) and OSO (25μL/mL), respectively. Efficacy results were linked to greater reduction in egg mass weight and lower hatching rates in the case of OCO, OIV, OFV and lower hatching rates in the case of OMP and OSO. Therefore, the results of the present study suggest that these essential oils diluted in DMSO have acaricidal potential and affect the reproduction of engorged females of R. microplus.