ABSTRACT.
Toxicity of boldo Peumus boldus Molina for Sitophilus zeamais Motschulsky and Tribolium castaneum Herbst

Margarita Ortíz U.1, Gonzalo Silva A.1*, Maritza Tapia V.1, J. Concepción Rodríguez M.2, Angel Lagunes-T.2, Candelario Santillán-Ortega3, Agustín Robles-Bermúdez3, and Sotero Aguilar-Medel4
 

The maize weevil (Sitophilus zeamais Motschulsky) and the red flour beetle (Tribolium castaneum Herbst) are two key pests of stored-grain products worldwide. The insecticidal activity of boldo (Peumus boldus Molina) powder, liquid ethanolic and hexanic extracts against S. zeamais and T. castaneum were evaluated under laboratory conditions. The evaluated variables were mortality, emergence of adult insects (F1), and grain weight loss. The experimental design was completely randomized. The mortality in S. zeamais was 100% even at the lowest powder concentration (0.5% w/w), whereas emergence of F1 adult insects was 0% and grain weight loss was ? 0.08%. For T. castaneum, only 8 and 16% w/w powder concentrations reached 100% mortality. The liquid ethanolic and hexanic extracts caused 100% mortality of S. zeamais, whereas only the ethanolic extract reached this value for T. castaneum. Therefore, the powder and the evaluated extracts of P. boldus were toxic for S. zeamais and T. castaneum and are promising against these and other stored-grain pests.

Keywords: Botanical insecticides, stored grains, maize weevil, red flour beetle.
1Universidad de Concepción, Facultad de Agronomía, Av. Vicente Méndez 595, Chillán, Chile. *Corresponding author (gosilva@udec.cl).
2Colegio de Postgraduados, Programa de Entomología y Acarología, km 36,5 Carretera México-Texcoco, Montecillo, Estado de México, México.
3Universidad Autónoma de Nayarit, Unidad Académica de Agricultura, km 9 Carr. Fed. Tepic-Compostela, Xalisco, Nayarit, México.
4Universidad Autónoma del Estado de México, Centro Universitario Tenancingo, Tenancingo, Estado de México, México.