RESUMO
Red clover (Trifolium pratense L.) is a perennial plant widely used as a forage resource for several animals. This plant is the exclusive host of Hylastinus obscurus (Marsham) which causes irreparable damages to the root system affecting their persistence. It has been reported that the presence of the isoflavonoid formononetin in roots of red clover could act as an antifeedant on H. obscurus. There are not studies related to the formononetin content in red clover roots to the antifeedant effect elicited by experimental lines and cultivar of red clover. Six red clover genotypes were investigated in both formononetin content and their respective antifeedant action. The results showed to Sabtoron High and Superqueli-INIA with both the highest formononetin content in red clover roots and antifeedant effect, allowing to suggest that this secondary metabolites could be used as a chemical factor for red clover plants. Moreover, a rapid methodology for searching red clover genotypes with high formononetin content is reported.
El treÌbol rosado (Trifolium pratense L.) es una planta perenne ampliamente utilizada como fuente de forraje de variados animales. Esta planta es el exclusivo hospedero de Hylastinus obscurus (Marsham) el cual causa irreparables danÌos al sistema radical afectando seriamente su persistencia. Se ha reportado que la presencia del isoflavonoide formononetina en raiÌces del treÌbol rosado podriÌa actuar como antialimentario sobre H. obscurus. Actualmente no existen estudios que relacionen el contenido de formononetina en raiÌces de treÌbol rosado con el efecto antialimentario elicitado por liÌneas experimentales y cultivares de treÌbol rosado. Seis genotipos de esta leguminosa fueron evaluados en cuanto a su contenido de formononetina y actividad antialimentaria. Los resultados mostraron que los cultivares Sabtoron High y Superqueli-INIA presentaron altos niveles de formononetina en sus raiÌces y efecto antialimentario sobre H. obscurus, lo que permite sugerir que este metabolito secundario podriÌa ser usado como factor quiÌmico para incrementar la persistencia de plantas de treÌbol rosado. AdemaÌs, se informa una metodologiÌa raÌpida para la buÌsqueda de genotipos con altos contenidos de formononetina.
Assuntos
Besouros/efeitos dos fármacos , Controle Biológico de Vetores/métodos , Trifolium , Comportamento Alimentar/efeitos dos fármacos , Isoflavonas/farmacologia , Besouros/fisiologia , Produtos AgrícolasRESUMO
The beetle Hylastinus obscurus Marsham (Coleoptera: Curculionidae), endemic to Europe and Northern Africa, is one of the most important red clover pests in Chile. As commercial insecticides are less effective against this pest, plant secondary metabolites have been considered as an alternative for its control. Here, we have investigated the chemical composition of essential oil (EO), petroleum ether extract (PEE), and dichloromethane extract (DCME) from Pilgerodendron uviferum heartwood. Additionally, the effects of EO and extracts on the feeding behavior (% of weight shift) of H. obscurus have been evaluated. The composition of EO, PEE, and DCME were analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The results showed the presence of a similar mixture of sesquiterpenes in the essential oil and in both of the extracts, which accounted for circa 60% of the total mixture. Sesquiterpenes were further isolated using chromatographic methods and were structurally characterized by optical rotation, GCâ»MS, FTIR, and 1D and 2D NMR experiments. The physicochemical properties of the isolated sesquiterpenes, including lipophilicity and vapor pressure, were also determined. The sesquiterpenes were identified as the following: (-)-trans-calamenene (1), cadalene (2), (-)-cubenol (3), (-)-epi-cubenol (4), (-)-torreyol (5), and (-)-15-copaenol (6). The antifeedant activity of EO, extracts, and isolated sesquiterpenes were evaluated using artificial diets in a non-choice test. Relative to the control, the EO, DCME extract, and the isolated sesquiterpenes, namely, (-)-trans-calamenene (1), cadalene (2), and (5) torreyol, were found to be the most effective treatments against H. obscurus. Our study showed that the compounds occurring in P. uviferum heartwood were effective in reducing the adult growth of H. obscurus. The physicochemical properties of the isolated sesquiterpenes might have been associated with antifeedant effects.
