TOXICIDAD DE POLVOS DE FOLLAJE DE PAICO (Chenopodium ambrosioides L.) Y BOLDO (Peumus boldus MOL.) SOLOS Y EN MEZCLA CON CARBONATO DE CALCIO SOBRE GORGOJO DEL MAÍZ (Sitophilus zeamais MOTSCHULSKY)
Pamela Nuñez O.1, Gonzalo Silva A.1*, Maritza Tapia V.1, Ruperto Hepp G.1†, J. Concepción Rodríguez-Maciel2, y A. Lagunes-Tejeda2
Stored grains are damaged by insect pests like maize weevil (Sitophilus zeamais Motschulsky; Coleoptera: Curculionidae). This study aimed to assess the biocidal properties of powdered foliage of Chenopodium ambrosioides L. and Peumus boldus Molina, both singly and mixed with calcium carbonate at 0.5%, 1% and 2% (w/w), against Sitophilus zeamais Motschulsky under laboratory conditions. In 250 mL jars, 250 g of maize seeds were mixed with the treatments and then infested with 10 insect couples. Mortality and emergence of adult insects (F1), grain germination, fumigant and repellent effects of powders were the evaluated parameters. The experimental design was completely randomized with 19 treatments, with five replicates. The whole methodology was repeated three times in different days. The highest mortality (100%) was obtained with plant powders alone at 2% (w/w) and the lowest adult insect emergence (0.2 y 0.1%) was reached with P. boldus powder alone at 1% and 2% (w/w). Seed germination was not affected by Ch. ambrosioides powder, while the use of P. boldus powder decreased germination respect to the untreated control. The fumigant effects of powders decreased as the proportion of calcium carbonate increased. Powders from both species mixed with calcium carbonate were repellent to S. zeamais. It was concluded that P. boldus powder and Ch. ambrosioides powder, singly and mixed with calcium carbonate, have insecticidal contact action, as well as fumigant and repellent effects on S. zeamais, and that they cause no significant effect on maize germination.
Keywords: maize weevil, stored grains, physical control.
1 Universidad de Concepción, Facultad de Agronomía, Departamento de Producción Vegetal, Avenida Vicente Méndez 595, Casilla 537, Chillán, Chile. Chile. *E-mail: email@example.com
2 Colegio de Postgraduados, Programa de Entomología y Acarología, Km 36,5 Carretera México-Texcoco, CP 56230, Montecillo, Texcoco, México.
† Fallecido Septiembre 2007