Electrophysiological Activation and Behavioural Modulation of Diamondback moth, <i>Plutella xylostella</i> L. (Lepidoptera: Plutellidae) by Essential Oil Volatiles

The diamondback moth, Plutella xylostella (L.), is a serious pest of cruciferous crops worldwide and cause serious damage, resulting in up to 90 % yield loss. Heavy dependence on synthetic insecticides has led to widespread resistance and raised environmental concerns, demanding an urgent need for safer, eco-friendly pest control options. In this study, we examined the electrophysiological, behavioural responses of P. xylostella to ten Essential Oils (EOs): Pelargonium hortorum, Ocimum basilicum, Acorus calamus, Trachyspermum ammi, Piper betle, Cymbopogon nardus, Rosmarinus officinalis, Zingiber officinale, Mentha piperita, and Eucalyptus citriodora. Electro Antennogram (EAG) analysis showed that all EOs tested elicited antennal response in adult females; however, R. officinalis, A. calamus, Z. officinale and C. nardus caused significantly higher responses than the other oils tested, and this antennal response aids in host and mate selection. In the behavioural assay using the Y-tube olfactometer revealed that A. calamus, P. betel, Z. officinale, R. officinalis and P. hortorum produced highly significant repellency (P ≤ 0.01). Oviposition assays further revealed that A. calamus, P. hortorum, and Z. officinale at 5% reduced egg laying by 91.78%, 86.9%, and 73.86%, respectively and it was 2.4 to 3.0 times more effective than neem Azadirachta indica. Overall, the results demonstrate robust olfactory and behavioural impacts of several essential oils, particularly A. calamus, Z. officinale and P. hortorum, supporting their potential as botanical repellents or oviposition deterrents for integrated pest management targeting P. xylostella.