Insecticidal and oviposition deterrent effects of pure and combined essential oils of Salvia subg. Perovskia species against Phthorimaea operculella

Abstract

Volatile organic compounds especially terpenoid derivatives possess bioactivities including insecticidal effects, and they sometimes act synergistically when mixed. The potato tuber moth (PTM), Phthorimaea operculella Zeller, is one of the most serious pests of potatoes in Iran. Since the potato is an important source of human food, safe and non-chemical control of its pest is indispensable. This study evaluated the fumigant toxicity of pure and two mixtures of essential oils (EOs) of three Salvia subg. Perovskia species against P. operculella. GC–MS phytochemical profiling of species showed 1,8-cineole (12.55%) and linalyl acetate (11.48%), as dominant in S. yangii-EO, geranyl acetate (55.64%), and 1,8-cineole (10.50%) as major constituents in S. abrotanoides-EO, and δ-3-carene (29.29%) and 1,8-cineol (18.08%), as major compounds of S. artemisioides-EO. The EOs, especially combined types were toxic against the pest and showed ovicidal and repellent efficacies. Adults showed considerable sensitivity to the 25:75 mixture ratio of S. yangii and S. abrotanoides EOs (LC50 = 5.82 µL/L air) in comparison to eggs (LC50 = 10.10 µL/L air). The combined EOs also reduced the ovipositional rate. In addition, pure S. abrotanoides EOs showed great fumigant toxicities (11.09 µL/L air) effects against one-old-day eggs. The combination of EOs including 1,8 cineol and geranyl acetate as corresponding compounds, may affect survival, energy resource transfer during oogenesis, and oviposition, which are likely mechanisms involved with essential oil toxicity. As a result, Salvia essential oils can be used for the development of eco-friendly, safe, and effective botanical pesticides in integrated PTM management strategies.