Insecticidal Activity of Aqueous Extracts of Selected Medicinal and Aromatic Plants against Diamondback Moth, Plutella xylostella (L.)
Kamala Devappa Gaddennavar *
Department of Entomology, College of Horticulture, Bengaluru, (Karnataka), India.
Gangadhar Narabenchi
Department of Entomology, COH, Kolar, (Karnataka), India.
Jayashree Ugalat
Department of Biochemistry, COH, Devihosur, (Karnataka), India.
Amrutha P
Department of Fruit Science, COH, Bengaluru, (Karnataka), India.
Nikita. L. T
Department of Entomology, College of Horticulture, Bengaluru, (Karnataka), India.
*Author to whom correspondence should be addressed.
Abstract
The diamondback moth (DBM), Plutella xylostella (L.), is one of the most destructive pests of cruciferous vegetables, causing severe yield losses. To date, pesticides have remained the primary method of managing this pest at the farmer level; however, control is often unsatisfactory due to the rapid development of resistance to most chemical insecticides. Therefore, the present study aimed to evaluate the insecticidal activity of selected medicinal and aromatic plants against P. xylostella. A laboratory experiment was conducted at the College of Horticulture, Bengaluru, using aqueous extracts of 20 plant species, including seed extracts of neem, pongamia, custard apple and jatropha; leaf extracts of datura, lantana, mehandi, tulasi, bael, nagadali, madhunashini, vitex, hebbevu and calotropis; rhizome extracts of sweet flag, turmeric and ginger and extracts of cinnamon bark, marigold flower and garlic bulb. Bioassays were carried out using the leaf dip method against early third instar larvae of the DBM. The results revealed that neem seed kernel extract (NSKE) at 2.5 per cent concentration was the most effective treatment, recording 93.33 per cent larval mortality at 120 h after treatment and significantly reducing pupation and adult emergence, indicating both toxic and growth-inhibitory effects. High efficacy was also observed with pongamia (90.00%), turmeric rhizome (86.67%), bael (83.33%) and hebbevu (83.33%) extracts. Moderate efficacy was recorded with datura (80.00%), calotropis (76.67%) and cinnamon bark (73.33%), whereas jatropha and sweet flag were the least effective, each recording 40.00 per cent mortality. A clear dose-dependent response was observed for all extracts. These findings highlight the potential of selected medicinal and aromatic plant extracts as eco-friendly components of Integrated Pest Management (IPM) programs for sustainable management of diamondback moth, thereby reducing reliance on synthetic insecticides and mitigating resistance development.
Keywords: Diamondback moth, medicinal and aromatic plants, aqueous extracts, insecticidal activity, larval mortality, NSKE