Atividades acaricida e alelopática de óleos essenciais de Piper tuberculatum Jacq. e Piper marginatum L.

Abstract

The species Piper marginatum L. is popularly known as "caapeba-cheirosa" and is used to treat liver and gallbladder diseases, besides having antioxidant, ovicidal, and acaricidal properties evidenced by its essential oils. Piper tuberculatum Jacq., on the other hand, is known as "long pepper" and has been used as an antidote for snake bites, stomach disorders, and respiratory problems, in addition to having essential oils with anti-Leishmania properties, which can also act on agricultural pests. This work sought to evaluate the acaricidal effect on Suidasia pontifica Oudemans 1905 and the allelopathic effect on Solanum lycopersicon L. and Lactuca sativa L., of the essential oils of leaves of P. marginatum and branches of P. tuberculatum. For this purpose, the essential oils were extracted by hydrodistillation in a Clevenger apparatus and analyzed by Gas Chromatography coupled to Mass Spectrometry (GC-MS). For this, the essential oils were extracted by hydrodistillation in a Clevenger apparatus and analyzed by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The identification of its chemical constituents was performed by calculating the Arithmetic Index and by comparing the mass spectra obtained by GC-MS with data from the literature. The acaricidal assay, was performed using fumigation methodology at concentrations of 2, 4, 6, 8, and 10μL/L of air for 24, 48, and 72h. The allelopathy assay was conducted in a germination chamber at 25 ºC and 12 h of photoperiod, using concentrations of 0.1 and 1% of each essential oil on twenty seeds of each culture (S. lycopersicon and L. sativa). The results showed that the essential oils of P. marginatum (PM) and P. tuberculatum (PT), both with a yield of 0.16%, are mainly composed of terpenic substances. Therefore, the monoterpenes δ-3-carene (10.5%) and E-β-ocimene (10.0%) were the majority compounds found in PM, while the sesquiterpenes E-caryophyllene (11.5%) and germacrene (13.2%) and the α-pinene monoterpene (9.1%) were the majority in PT. Both essential oils showed a good fumigant effect on S. pontifica, especially PM, which reached 100% mortality at a concentration of 10μ/L of air within 72h of exposure. Regarding the allelopathic effect, both essential oils influenced the germination and development of S. lycopersicon and L. sativa, with emphasis on PM applied at 1%, which was able to cause seed death. These results can serve as a basis for future studies aimed at the development of products with application in agriculture, such as herbicides and fumigants of natural origin.