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Abstract

The grain protectant efficacy of Makabuhay, Tinospora rumphii stem extract was tested on adult maize weevil, Sitophilus zeamais M. Evaluation of phytochemicals present in the extract was conducted to identify its bioactive compounds. The ethanolic stem extract of T. rumphii contains the following phytochemicals: alkaloids, flavonoids, steroids and tannins. These phytochemicals are known to possess pesticidal activities against insects and other pests. The grain protectant efficacy of T. rumphii against corn weevils was manifested by the percentage of mortality of weevils, number of corn seed holes; weight loss and percentage corn germination. Results revealed that the corn weevils treated with the highest concentration (18%) of T. rumphii manifest the highest percentage of weevils’ mortality and significantly higher (p =0.000) as compared to the negative control and the other treatment concentrations. In addition, the mortality of corn weevils treated with the plant extract is concentration-dependent. The average number of corn seed holes treated the T. rumphii extract is statistically lower as compared to the negative control. Moreover, the highest concentration (18%) of the plant extract showed the lowest average number of holes. This implies that T. rumphii is responsible for the inhibition of the weevils from infesting the corn seeds. Furthermore, result revealed significant decrease (p =0.000) on the average weight loss of corn seeds previously treated with the plant extract. The highest concentration of T. rumphii manifest the lowest percentage weight loss. Result also showed a significant increase (p = 0.000) of percentage germination of corn seeds randomly selected from the control and the treated groups. The highest concentration of the plant extract reveals the highest percentage of germination. T. rumphii stem extract therefore is an effective grain protectant against maize weevis, S. zeamis due to the presence of phytochemicals flavonoids, alkaloids, steroids and tannins which showed synergistic effects in terms of insecticidal action to maize weevil.

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