Antifungal, antiaflatoxigenic, and insecticidal efficacy of spearmint (Mentha spicata L.) essential oil

• Mentha spicata essential oil (EO) against food deteriorating moulds and insect.
• Chemical characterization of M. spicata EO.
• Non-phytotoxic and non-mammalian toxic nature of M. spicata EO.
• Antioxidant potency and ergosterol biosynthesis inhibitory action of M. spicata EO.
• Recommendation of M. spicata EO as plant based pesticide.

This study reports on the chemically characterized essential oil (EO) from Mentha spicata L. which was tested as a plant-based pesticide in because it showed efficacy against food-deteriorating molds, aflatoxin production, lipid peroxidation, and the insect pest Callosobruchus chinensis. The chemical characterization of this EO through GC/GC–MS analysis depicted 13 compounds comprising 97.09% of the EO, carvone being the major component (59.6%). The EO significantly inhibited growth and aflatoxin B1 production by the toxigenic strain of Aspergillus flavus [LHP(C)-D6] at 1.0 and 0.9 μl ml-1levels, respectively. The EO also had a broad fungitoxic effect against 19 food-deteriorating molds. The oil caused 100% mortality to C. chinensis during a fumigation test with an LC50 value of 0.003 μl ml−1 air after 24 h of treatment and 100% repellency at 0.025 μl ml−1 air concentration. The EO of M. spicata at 0.1 μl ml−1 air concentration was recorded as the effective fumigant, showing 98.46% oviposition deterrency, 100% ovicidal activity, 88.84% larvicidal activity, 72.91% pupaecidal activity, and 100% antifeedant activity against C. chinensis. The phytotoxicity assay showed 100% germination of EO-treated chickpea seeds. The EO had a low mammalian toxicity with an LD50 of 8342.33 μl kg−1 for oral toxicity on mice. The 50% inhibitory concentration (IC50) value of EO was 18.55 μl ml−1 during a DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay.