Insecticidal activity of Salvia veneris Hedge. Essential oil against coleopteran stored product insects and Spodoptera exigua (Lepidoptera)

Abstract

Salvia species are very well known for their uses as herbal tea as well as insecticidal activity of their essential oils against stored product insects. Due to their use as herbal tea, Salvia species could be considered as perfect candidates to develop safe natural insect management agents. In the scope of the present study, the essential oil of aerial parts of Salvia veneris Hedge was investigated for insecticidal activity against 3rd instar larvae of Spodoptera exigua (Hübner) (Lepidoptera), Sitophilus granarius L., S. oryzae L., Tribolium castaneum Herbst, T. confusum Jacquelin du Val, Rhyzopertha dominica Fabricius and Oryzaephilus surinamensis L. (Coleoptera). The essential oil produced 63.0% contact toxicity against the S. exigua (beet armyworm) 3rd instar larvae at 100μL/mL and concentration. Highest contact toxicity of the oil was observed at 1μL application volume (10% (v/v: oil/acetone)) and 72h duration against O. surinamensis 81.6%, S. oryzae 71.5% and S. granarius 70.0%, respectively. S. veneris oil produced the highest fumigant toxicity at 1μL/mL application volume (10% (v/v: oil/acetone)) and 48h duration against S. oryzae 100.0%, S. granarius 97.6% and O. surinamensis 90.8%, respectively. The essential oil tested on Tribolium species and R. dominica did not produced any fumigant toxicity. The acetylcholinesterase and butyrylcholinestearase inhibitory activities of the essential oil were 85.9% and 12.2%, respectively. The antimicrobial activity (minimum inhibitory concentration, MIC) of the oil was tested against the pathogens that could be found on stored products namely Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Bacillus cereus and Bacillus subtilis. The oil produced very weak activity on all of the tested microorganisms when compared with the positive controls. The essential oil composition was analyzed by gas chromatography and gas chromatography/mass spectrometry and the aerial parts of the S. veneris was characterized by 1,8-cineole 30.4%, camphor 18.4%, camphene 12.9%, α-pinene 8.2%, borneol 5.8% and β-pinene 5.0%. As a conclusion the essential oil of S. veneris produced considerable insecticidal activity against Sitophilus species as well as acetylcholinesterase inhibitory activity which points out further attention should be given to Salvia species for the development of safe natural pest management agents.