Chemical composition and bioactivities of thirteen non-host plant essential oils against Plutella xylostella L. (Lepidoptera: Plutellidae)

The diamondback moth (DBM), Plutella xylostella (L.), is a globally destructive pest of cruciferous vegetables. Excessive use of synthetic pesticides to control this species results in negative effects on the environment, human health, and nontargeted organisms. The essential oils (EOs) derived from plants may be developed as effective alternatives to conventional pesticides. In this study, thirteen EOs were extracted by hydrodistillation, respectively. Their chemical compositions were identified by gas chromatography-mass spectrometry (GC–MS). Furthermore, the biological activities of EOs such as toxicity, antifeedant activity, and growth inhibition effect, toward DBM larvae were investigated. Against DBM second-instar larvae, the most toxic EO was Pelargonium graveolens (LC 50  = 0.36 μg/μl) after 72 hr of exposure, followed by Polygonum hydropiper (LC 50  = 0.53 μg/μl). The Ocimum basilicum EO exhibited the highest antifeedant effect to third-instar larvae at at all set concentrations. At 15 μg/μl, the EOs of Acorus calamus , O. basilicum , and P . graveolens completely inhibited the feeding activities of larvae (100%). The Ruta graveolens EO showed the lowest relative growth rate and the highest growth inhibition rate towards third-instar larvae at diverse concentrations. And the EOs of P. hydropiper , A. calamus , and O. basilicum showed promising growth inhibition activities. Overall, the five EOs ( P . graveolens , O. basilicum , R. graveolens , P. hydropiper , and A. calamus ) showed moderate to high bioactivity, whereas eight EOs were found to be less active against DBM larvae. These results indicate that the five tested EOs are promising to be developed as novel botanical insecticides to control DBM population.