Contact Toxicity and Repellent Activity of a Powder Extracted from Tridax Daisy (Tridax procumbens) against Maize Weevil (Coleoptera: Curculionidae)1

Abstract

Abstract The maize weevil (Sitophilus zeamais Motschulsky) is a significant pest affecting stored seeds and grains, leading to substantial losses in both quantity and quality. Utilizing crushed plant powders derived from specific natural plants offers a promising alternative to synthetic insecticides, which pose risks to both consumers and the environment. This study aimed to evaluate the contact toxicity of Tridax daisy (Tridax procumbens L.) plant powder derived from its aerial parts against S. zeamais when incorporated into jasmine brown rice, Oryza sativa L., grains. Laboratory experiments were conducted at 30°C ± 5°C and 70% ± 5% relative humidity following a completely randomized design with four replications and five treatments. Jasmine brown rice grains were treated with different application rates of 0 (control), 20, 40, 60, and 80 g/kg, with five pairs/replicate of 7-d-old S. zeamais. Results showed that T. procumbens powder exhibited a contact toxicity of 93.08 g/kg of grain after 12 d, resulting in a mortality of 27.5%. Additionally, the F1 generation comprised 51 adults, indicating an 85% reduction in adult progeny emergence. These findings demonstrate the potential of T. procumbens powder as a natural grain protectant to control S. zeamais populations in storage.