Salvia officinalis, Lavandula angustifolia, and Mentha pulegium essential oils: insecticidal activities and feeding deterrence against Plodia interpunctella (Lepidoptera: Pyralidae)

Abstract

In this study, the chemical compositions of essential oils obtained from three plants, namely Salvia officinalis, Lavandula angustifolia, and Mentha pulegium, along with their insecticidal activities and feeding deterrence against Plodia interpunctella, were investigated. The chemical composition of S. officinalis essential oil was majorly dominated by α-thujone (26.99%) and camphor (25.50%); on the other hand, limonene (66.12%), eucalyptol (66.12%), and camphor (14.31%) were the major compounds of L. angustifolia essential oil whereas for M. pulegium EO a dominance of pulegone (83.06%) was attained. M. pulegium essential oil showed important contact toxicity (100%) at 3 hours of exposure with the 0.25 μL/cm2 concentration, followed by S. officinalis and L. angustifolia with 90% of mortality reported with the highest concentration of 0.50% within 3 hours. A relative growth rate (RGR) of 0.08 mg/mg/day and -0.31 mg/mg/day was recorded with S. officinalis and M. pulegium oils, respectively, with the highest concentration of 32 μL/pellet. With L. angustifolia the lowest RGR of -0.08 mg/mg/day was attained with the 16 μl/pellet concentration. The food deterrence index experienced an increase to 89% with S. officinalis and L. angustifolia oils for the three concentrations; with M. pulegium, 68.18% was recorded with the 32 μL/pellet. In conclusion, this study suggests that these essential oils could potentially serve as an effective contact toxicant and a potent eco-friendly inhibitory of the feeding behavior of Plodia interpunctella larvae.