Insecticidal Assessment of Cow Horn Ash as Grain Protectant Against Maize Weevil, Sitophilus Zeamais Motschulsky (Coleoptera: Curculionidae)
NJE Vol. 41: 75-89, 2025
DOI.10.36108/NJE/5202/14.0160
Okparavero, N. F.1, 2, Babarinde, S. A.*2, Olaniran, O. A.,2 and Odewole, A. F.2
1 Durable Crops Research Department, Nigerian Stored Products Research Institute,P.M.B 1489, Ilorin, Nigeria
2 Department of Crop and Environmental Protection, Faculty of Agricultural Sciences, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Nigeria
Abstract
The growing dependence on synthetic pesticides raises challenges about environmental concerns, health risks, and pest resistance. Therefore, sustainable alternatives to mitigate the challenges and enhance food security should be prioritized. This study investigated the bioactivity of Cow Horn Ash (CHA) as maize protectant against maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Cow horns were sourced, at Mandate Market, Ilorin, Kwara State and was cleaned, sun-dried, converted into ash powder, and tested in the laboratory (temperature of 30±1°C and 70±4% relative humidity). A bioassay was conducted using varying concentrations of 2.0 g, 4.0 g, and 6.0 g CHA per 100 g of maize alongside permethrin as a positive control. Mortality data were obtained at 3-, 5-, and 7-Days Post Treatment (DPT). In another experiment, maize grains treated with the listed dosages of CHA were stored for 3, 6 and 9 weeks and assayed for persistence of bioactivity against maize weevil. Results showed a dose-dependent increase in mortality rate. At 2.0 g/100 g maize, mortality reached 56.25% at 3-DPT and 71.25% at 7 DPT, at 4.0 g/100 g maize, mortality was 70.00% on 3 DPT and peaked at 75.00% at 7 DPT; and at 6.0 g/100 g maize, mortality rates reached 85.00% at 7 DPT. Cow Horn Ash significantly reduced F1 progeny emergence, with no F1 emergence at the highest dosage (6.0 g/100 g maize). Likewise, there was no grain damage when CHA was applied at 6.0 g/100 g maize, and germination rates remained high (91.25% to 95%) across all treatments. The bioactivity persistence of CHA diminished over time, with mortality dropping to 36.25% on Day 3 and 45.00% at 7 Day Post Weevil Introduction (PWI) after 9 weeks of storage of treated grains with 2.0 g/100 g maize. The findings suggest that CHA could serve as a viable, eco-friendly alternative for managing S. zeamais in stored maize, with significant efficacy, minimal grain damage, and high seed viability observed across different dosages. However, effective storage of CHA is recommended to retain its efficacy over reasonable timeline.
Keywords: Cow Horn Ash (CHA), Sitophilus zeamais, Pest Management, Eco-friendly Insecticide, F1 Progeny Emergence