Potential repellent activity of the essential oil of ruta chalepensis (Linnaeus) from Chile against aegorhinus superciliosus (Guérin) (Coleoptera: Curculionidae)

Abstract

The objective of this study was to evaluate the repellent effect of the essential oil of the rue (Ruta chalepensis) against the weevil Aegorhinus superciliosus, an important pest of fruit crops in Chile. Rue essential oil was obtained by steam distillation, and its components were identified by GC-MS. Their effect on adult A. superciliosus insects was evaluated using four-arm olfactometric bioassays. The extraction process had a yield of 0.3% on a dry weight basis, and a chromatographic analysis showed the presence of nine compounds, which represented 89.3% of the total components. The major compounds were 2-nonanone (41.7%) and 2-undecanone (40.1%). Behavioral bioassays showed that the rue essential oil elicited a repellent effect against male and female A. superciliosus (p ≤ 0.05) at a concentration of 1.92 x 107 ng/cm2. However, at a lower concentration of the oil (285.7 ng/cm2), only females were repelled (p ≤ 0.05). The repellency observed against A. superciliosus could be attributed to high concentrations of both ketones, suggesting that rue essential oil can be considered as a potential repellent that could reduce the infestation of this weevil. The role of the compounds identified and the repellent activity of this evergreen shrub are discussed.