Caracterização fitoquímica e atividade biocida dos óleos fixo e essencial de Caryocar brasiliense (CARYOCARACEAE) sobre Musca domestica (Diptera: Muscidae) e Rhipicephalus microplus (Acari: Ixodidae)

Abstract

Compounds of vegetable origin have been seen as a promising alternative in pest control in order to minimize the impacts of the use of synthetic products used in conventional pest control, which promoted the increase of studies in the search for oils and vegetable compounds with action biocidal because they are safer and less aggressive to humans, animals and the environment. In this sense, a phytochemical characterization study of the fixed and essential oils of the fruit pulp of Caryocar brasiliense was carried out and the evaluation of the insecticidal activity of these oils on immature stages of Musca domestica and on engorged females of Rhipicephalus microplus, this being the first study to cover the effect of these oils on these organisms. The results of gas chromatography and mass spectrometry (CG/EM) showed ethyl hexanoate (91.83%) and oleic acid (61.38%) as major constituents of the essential and fixed oil, respectively. In bioassays with M. domestica for the evaluation of larval mortality (ML), observations were made 48 hours after treatment and monitoring of surviving larvae until the adult stage, and these indices were included in the effectiveness of larval treatment (ETL). For pupal treatment efficacy (ETP) of M. domestica, pupal mortality (PM) after six days of treatment and the percentage of adult malformations (PMD) were calculated. Bioassays with M. domestica were performed using in vitro tests where nine oil concentrations were tested, ranging from 0.625 to 50.0 mg/mL. It was verified in the bioassays with larvae and pupae of M. domestica that the mortality and consequently the efficacy of the treatment for both substances in all tested concentrations, did not differ significantly from their respective control groups (p>0.05), indicating that there was no larvicidal and pupicid activity. In the bioassays with R. microplus for the evaluation of the activity on engorged females, the adult immersion test was performed using six concentrations of oils, ranging from 2.5 to 60.0 mg/mL, with a control percentage of less than 50 % in all treatments for the fixed oil, while the essential oil showed moderate activity, with a control percentage of 82.0% at its highest concentration (40.0 mg/mL) tested. Thus, we can conclude that the oils at the tested concentrations do not have insecticidal activity on the immature stages of M. domestica, while the essential oil has acaricidal activity on engorged females of R. microplus, with C. brasiliense being a promising plant in studies with ticks -of- bovines.