06 Oca 2025 Pazartesi
Bio-insecticidal efficacy of the aqueous extracts of Eryngium foetidium L. and Curcuma longa L. against Maize weevil, Sitophilus zeamais Motsch. (Coleoptera: Curculionidae) in stored maize
Abstract : Experiment was conducted to evaluate the efficacy of leaf extracts of Eryngium foetidum and Curcuma longa for the control of maize weevil, Sitophilus zeamais on stored maize grains. Ten pairs of 1-7 days old unsexed adults of S. zeamais were introduced into each cup containing 20g of grains and covered with muslin cloth to allow aeration and prevent exit or entry of insects. The extracts were applied at 4g, 8g, 12g, 16g and 20g concentrations to study mortality, repellency and seed weight loss. The experiment was laid out in a Completely Randomized Design (CRD) of 7 by 4 (7 treatments and 4 replicates) including standard and experimental controls under laboratory conditions (28±2OC; 74±5% RH) for 96 hours. Data obtained were analyzed using Analysis of Variance and means were separated using Turkey’s post hoc test. Both powders showed the presence of alkaloids, saponins, cardiac glycosides, flavonoids, phenols, terpenes and tannins to which insecticidal properties can be attributed against S. zeamais. There was an increase in mortality with the days of exposure in all concentrations with leaf extract of E. foetidium at 20g recording a highest mortality (1.25± 0.50) when compared with the control. Also, the extracts of E. foetidium and C. longa at various concentrations exhibited repellency ranging from 70% to 94 % from the least concentration when compared to control. The seeds treated with 20g of both extracts gave the lowest seed damage, when compared to the experimental control. The results indicated that extracts used for the control of the weevil significantly (p<0.05) reduced insect populations and offered greater protection and high repellency compared to the control. Since E. foetidium and C. longa extracts are readily available for small farmers and are environmentally safe, they ought to be promoted for use against maize weevils, hence their usage as an alternative to synthetic pesticides in integrated pest management.