Abstract

LOPEZ-PEREZ, Ernesto; RODRIGUEZ-HERNANDEZ, Cesáreo; ORTEGA-ARENAS, Laura D.  and  GARZA-GARCIA, Ramón. Biological activity of Senecio salignus root against Zabrotes subfasciatus in stored bean. Agrociencia [online]. 2007, vol.41, n.1, pp.95-102. ISSN 2521-9766.

The bruchid Zabrotes subfasciatus is the major pest of stored bean in hot climates, and can cause total losses if it is not controlled. A series of experiments, in which the pests were confined and given free election, were conducted under controlled conditions to determine the biological activity of ragwort Senecio salignus root powder on Z. subfasciatus, using a completely random design. The powder at concentrations of 0.01, 0.05, 0.07, 0.1, 0.25, 0.5, and 1%, with diameters of <0.25, 0.25-0.99, 1-2, and >4 mm was mixed with 100 g of bean, and infested with 20 weevils to determine lethal concentration (LC50), lethal time (LT50), susceptibility by sex, size of particle, and mode of action of the powder. LC50 (p≤0.05) decreased over time of treatment (0.15 to 0.05% after 3 d), and mortality was faster (p≤0.05) as concentration increased (3.30 and 1.91 d at 0.05 and 0.07%). Males were more susceptible (p≤0.05) than females. Toxicity of the root was inversely proportional to particle size (p≤0.05); the larger the particle, the less the toxicity. The root acted on contact and there was no fumigant or repellant effect.

Keywords : weevils; stored grains; plant insecticides.

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