Chemical composition and broad-spectrum insecticidal activity of the flower essential oil from an ancient Sicilian food plant, Ridolfia segetum

Several species of the family Apiaceae are aromatic herbs that produce essential oils usable on an industrial scale for pharmaceutical, cosmetical and food purposes. Particularly, some essential oils, as green insecticides, may replace synthetic insecticides keeping most of their efficacy and avoiding environmental pollution or human’ poisoning. In the present study, we explored the in-secticidal potential of Ridolfia segetum (L.) Moris essential oil (EO), rich in α-phellandrene (49.3%), β-phellandrene (9.2%), terpinolene (20.7%) and piperitenone oxide (5.9%), against three different pests, Culex quinquefasciatus, Musca domestica and Spodoptera littoralis. For this purpose, the flower EO was obtained by hydrodistillation and its composition was achieved by gas chromatography/mass spectrometry (GC/MS). Concerning mosquitocidal efficacy, the EO showed a noteworthy toxicity against C. quinquefasciatus 3rd instar larvae, with a LC50=27.1 µL L-1 and LC90=42.5 µL L-1. Regarding M. domestica, a different toxicity of the R. segetum EO was found on male and female flies, calculating LD50 values of 10.5 and 50.8 µg adult-1, respectively. The EO was also toxic to S. littoralis 3rd instar larvae, achieving LD50 and LD90 values of 37.9 and 99.6 µg larva-1, respectively. Overall, this flower EO extracted from a traditional Sicilian food plant merits further investigation for the development of green insecticide formulations to be used in the real-world conditions, pending a careful assessment of non-target toxicity on beneficial organisms.