Insecticidal activity of the essential oil from Schizogyne sericea (Asteraceae) on four insect pests and two non-target species

Salado (Schizogyne sericea) is an aromatic shrub occurring very frequently in the coastal areas of Tenerife, Canary Islands. Herein, we investigated whether the essential oil produced by salado under salt stress could be effective as a botanical insecticide against a panel of target insects such as larvae and adults of the filariasis vector Culex quinquefasciatus, the peach-potato aphid Myzus persicae, the housefly Musca domestica and the tobacco cutworm Spodoptera littoralis. The essential oil, which was characterized by p-cymene, isobornyl acetate and thymol esters, as detected by gas chromatographic analysis, was highly effective against larvae of C. quinquefasciatus (LC50 of 49.1 mL.L-1) and adults of M. persicae (LC50 of 2.1 mL.L-1). On the other hand, little toxicity was found on adult females of C. quinquefasciatus and Al. domestica, as well as on larvae of S. littoralis. Finally, the S. sericea essential oil was not toxic to selected non-target organisms, 3rd instar larvae and adults of the ladybug Harmonia axyridis or adults of the earthworm Eisenia fetida. Overall, the present research supports a possible use of salado oil in eco-friendly insecticidal formulations useful to manage culicine larval populations as well as M. persicae aphids.