Ovicidal Toxicity of Some Plant Essential Oils against Pulse Beetle, Callosobruchus chinensis Linn. (Coleoptera: Bruchidae) under Laboratory Conditions

A study investigating the ovicidal activity of nine different plant essential oils viz. Cinnamonum camphora (Camphor), Cymbopogon citratus (Lemongrass), Cymbopogon flexuosus (Citronella), Mentha longifolia (Mentha), Pongamia pinnata (Karanj), Ricinus communis (Castor), Madhuca longifolia (Mahua), Ocimum basilicum (Basil) and Foeniculum vulgare (Fennel) on Callosobruchus chinensis (L.) was carried out at the Department of Agronomy, Birsa Agricultural University, Kanke, Ranchi during the years 2023-24 and 2024-25. The experiment comprised of nine treatments replicated thrice and was arranged in a Completely Randomized Design (CRD). The ovicidal toxicity of the nine plant essential oils was assessed against C. chinensis. Bioassay was conducted in Petri dishes for ovicidal studies, with the inner surfaces of the Petri dishes used to evaluate ovicidal activity. The highest percentage of hatching inhibition was observed with citronella oil at doses of 0.25%, 0.5% and 1% after 35 days. Specifically, the hatching inhibition rates were (21.76±0.38), (26.12±0.34), and (57.78±0.30) for the year 2023-24, and (23.62±0.06), (37.56±0.51) and (61.28±0.58) for the year 2024-25, respectively.