Efficacy of essential oils from three Mentha species against postharvest groundnut pest, Caryedon serratus (Olivier) (Coleoptera: Bruchidae)

Indiscriminate use of chemical pesticides has resulted in many negative implications including degradation of the ecosystem, contamination of food products and effect on non-target organisms. Biopesticides is an efficient and ecofriendly alternative to these synthetic pesticides. Herein, we explored the efficacy of plant-extracted essential oils as a natural alternative to manage groundnut pests. Essential oils extracted from three Mentha species (M. arvensis, M. piperita and M. spicata) were detected for their chemical composition, oviposition deterrence, repellency and electrophysiological responses in groundnut bruchid, Caryedon serratus (Olivier). Gas chromatographic analysis revealed menthol (M. arvensis: 30.43%, M. piperita: 30.18%) and carvone (M. spicata: 65.58%) as the most abundant component in essential oils. Among all the four tested concentrations for the three mentha oils the most significant oviposition deterrence was seen in M. spicata (2% v/w) which completely inhibited oviposition followed by 1.5% M. piperita (21 ± 1.53; p < 0.01), 1.5% M. spicata (28 ± 0.58; p < 0.01) and 1.0% M. arvensis (35 ± 0.58; p < 0.01) oil treated groundnuts after 24 h. M. piperita (86%, ♀) and M. arvensis (70%, ♀) showed promising repellence against the females. In contrast, M. spicata was found to be a potent (90%, ♂) male repellent during olfactometer bioassays. Coupled gas chromatography electroantennogram (GC-EAG) revealed consistent sensory deflections in the antennae of female C. serratus from all the three oils. Our findings revealed promising oviposition deterrence and repellent properties of these mentha oils which offers a prospect in developing effective repellent and its application in integrated pest management, safety of human health, environment and agricultural productivity.