Insecticidal and repellent activities of Nezara viridula secretions and hydro-distilled hexane extracts of Petiveria alliacea against Sitophilus oryzae
NJE Vol. 42(1) : 96-115, 2026
DOI.10.36108/NJE/6202/24.0180
Akinbuluma, M. D.1,2, Ayodele, O.1, Adetula, C. A.1 , Ogundola, C. O.3, Oladosu, I. A.3, Alabi, O. Y.1, Ilobolutife, O. P.1, Ayegboyin, I. A.1
1Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan Nigeria
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The Netherlands
3. Department of Chemistry, University of Ibadan, Ibadan, Nigeria
Abstract
The rice weevil, Sitophilus oryzae is a major pest of stored cereals worldwide, causing significant post-harvest losses and reduced grain quality. Synthetic insecticides and fumigants are widely used for its control but their associated problems have necessitated the search for safer and sustainable alternatives. This study evaluated the insecticidal and repellent effects of insect-derived secretions from Nezara viridula and semi-volatile constituents from Petiveria alliacea on adult S. oryzae under laboratory conditions. Secretions from N. viridula were obtained using whole-body extraction and fractionated into hexane, ethyl acetate and methanol fractions, while constituents from P. alliacea leaves were extracted via hydro-distillation and analyzed using Gas Chromatography–Mass Spectrometry. Bioassays were conducted to assess mortality and repellency of S. oryzae at different exposure periods and concentrations using treated rice grains and Y-tube olfactometer assays. Experiments were arranged in completely randomized designs, and data were analyzed using analysis of variance, with means separated using Least Significant Difference at a 5% level of significance. Ethyl acetate fraction of N. viridula had the highest yield (53.4%), followed by methanol (7.77%) and hexane (1.94%). All fractions and crude methanolic extract of N. viridula caused significantly higher mortality of S. oryzae compared to the control, with the crude extract causing up to 62.5% mortality at 72 hours. Similarly, n-hexane constituent of P. alliacea contained twenty-two compounds, with 9-octadecenoic acid (50.63%), hexadecanoic acid (27.40%), and stigmasterol (5.41%) as major constituents. The constituents exhibited strong insecticidal activity, with mortality increasing in a concentration-dependent manner and reaching 80.0% at 30% (v/v) after 96 hours. Both N. viridula secretions and P. alliacea constituents elicited mortality and repellent activity on S. oryzae. These findings suggest that both insect-derived semiochemicals and plant derived oils possess promising bioactive properties for the management of S. oryzae. Their use could provide environmentally friendly alternatives to synthetic insecticides and may be further explored for integration into sustainable stored grain protection strategies
Keywords: Nezara viridula secretions, Sitophilus oryzae repellence, Semiochemicals, Gas Chromatography-Mass Spectrometry