COMPOSIÇÃO QUÍMICA DO ÓLEO ESSENCIAL DE PEQUI (Caryocar brasiliense Cambess) E ATIVIDADE NEMATICIDA NO CONTROLE DE Meloidogyne javanica

Abstract

Phytonmatoids cause great damage to agricultural crops worldwide. Its main control is carried out with chemicals of high toxicity for man, animals and environment. An alternative way of controlling these parasites is the use of essential oils, which are a complex mixture of several classes of compounds produced by the secondary metabolism of plants. In this context, the objective of this work was to identify the chemical compounds of the essential oil (EO) of the pequi fruit (Caryocar brasiliense Cambess), using the gas chromatography technique coupled to the mass spectrometer (GC-MS), in addition to checking its nematicidal activity in the control of Meloidogyne javanica. The pequi fruit was collected in the rural area of the municipality of Buriti Alegre, in the southern region of Goiás. The extraction of the essential oil was carried out by hydrodistillation using the Clevenger apparatus. The chemical compounds were identified by comparing the mass spectra obtained with the spectra present in the equipment library, Nist08. The biological assay was carried out using juvenile second stage nematodes (J2). From the chemical analysis performed at the GC-MS, eleven compounds were identified, a result different from the same analysis performed with the pequi EO in the previous year (2018), which presented several compounds that were not present in the analysis of the current oil (2019). This discrepancy in the composition of the EO may have occurred due to the period which the fruit was collected, a factor that directly interferes in the chemical composition of essential oils, as well as the location and seasonality. Of the compounds identified in 2019, 77.8% are esters, a class of compounds used commercially as flavorings. The esters identified were ethyl 2-methylbutanoate; Ethyl 3-methylbutanoate; sec-butyl butanoate, isopentyl 2-methyl propanoate; ethyl octanoate and the major compound was ethyl hexanoate that is used commercially as a pineapple flavoring. The 22.2% of the identified compounds were monoterpenic compounds, the α or β – ocimene and D-limomene. From the biological test, was obtained a mortality less than 5% with volumes of 0.8 and 1.6μL. For the 0.2 and 04μL, was obtained a mortality rate of 29% and 16.5%, respectively,. In both cases the number of dead J2 was small considering the amount of nematodes in the treated solutions. The low nematicidal activity of the EO can be explained by the composition of the oil, which is mostly made up of esters, which are compounds that do not have nematicidal activity reported in the literature. Thus, it can be concluded that the volumes of pequi essential oil used in this sample are not recommended for the treatment of Meloidogyne javanica, since the mortality rates obtained were very small in view of the large amount of J2 that were present in the biological test.