The Biobrio 13(1 & 2), 2026

Studying the insecticidal activity of Bay leaf (Laurus nobilis) powder and clove (Syzygium aromaticum) powder on rice weevil (Sitophilus oryzae).

Md. Ekramul Hoda*, Gayatri Arya, Swastika Raj & SM Mahboob Hassan

ABSTRACT:

Insecticidal Activity of Clove (Syzygium aromaticum) and Bay Leaf (Laurus nobilis) on Rice Weevil, Sitophilus oryzae (L.) - a Major Stored Grain Pest. Post-harvest losses inflicted by rice weevil, Sitophilus oryzae (L), still constitute one of the most significant barriers to grain storage in India and the increasing prevalence of resistance to the chemical fumigants of this pest warrants further investigation of botanical alternatives. The present study was undertaken to assess the insecticidal efficacy of powder of bay leaf (Laurus nobilis), clove (Syzygium aromaticum) and a mixture thereof against the adult rice weevil under laboratory conditions. Treatments were incorporated into 35 g of rice at increasing concentrations in a completely randomized design with 3 replications, and the number of twenty exposed rice weevils found dead was recorded at the end of days 1, 3, 5 and 7. Bay leaf powder had a minimal insecticidal effect on the weevil, and mortality observed at different doses was not significantly different from that in the control (p>0.05) and showed no dose-response relationship. Clove powder, however, caused a marked and dose and time-dependent mortality on the rice weevil, with a high of 86.1 per cent on the 7th day at the concentration of 1.5 mg/100 g rice, while the median lethal concentration (LC50) value was 1.61 g/100 g rice on the first day but was reduced to 0.61 g/100 g rice on the 7th day. Clove and bay leaf combined treatment showed maximum mortality of 91.1 %, on the 7th day, with a dose of 1.0 mg/100g rice, but the trend of LC50 for the combined treatment did not differ much from the trend for only clove treatment, suggesting that it may be the presence of clove that contributed to significantly higher mortality in mixed treatment, more than a synergy. Thus, this study has identified clove powder as a promising, cost-effective and eco-friendly botanical material to protect stored rice from S. oryzae, though it needs to be explored through various formulation studies for its effective use in the field.

Keywords:    

Sitophilus oryzae; Syzygium aromaticum; Laurus nobilis; botanical insecticide; LC50; stored-grain protection

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