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Insecticide action of Ricinus Communis L. on Plodia Interpunctella Hbn. (Lepidoptera: Phycitinae)

Abstract

La aplicación de insecticidas sintéticos como principal sistema de control de plagas de granos y productos almacenados ha originado el desarrollo de poblaciones de insectos resistentes a dichos químicos, la contaminación del medio ambiente y la acumulación de sustancias tóxicas en los alimentos. En este trabajo se evaluaron los efectos de la aplicación de molido de hojas de ricino sobre larvas de la «polilla de las harinas» (Lepidoptera: Phycitinae). Los molidos vegetales se obtuvieron a partir de hojas de Ricinus communis L. secadas en estufa a 40 ± 2 °C durante 48 horas y posteriormente molidas hasta lograr un polvo de textura similar a la harina de maíz, material con el que se mezcló a fin de lograr concentraciones de 5, 10 y 15 % y un testigo sin ricino. Las unidades experimentales consistieron en cajas de Petri con seis larvas de primer y segundo estadio y se efectuaron cinco repeticiones por tratamiento (n=120). Se registró el número de larvas, pupas y adultos vivos, cada cuatro días, hasta que las larvas sobrevivientes llegaron al estado adulto. Se calcularon los porcentajes de eficacia mediante la fórmula de Abbott. Los resultados se evaluaron por ANVA y test de Tukey. Se determinaron el tiempo efectivo medio (TE50) y concentración efectiva media (CE50) por el método Probit. Los resultados de mortalidad indicaron que la concentración al 15 % superó significativamente al resto de los tratamientos y al testigo.The application of synthetic insecticides for control stored grain pests has developed resistant populations, environment contamination and the accumulation of toxic substances in foods. In this work were evaluated the effects of the application of shattered leaves of castor on larvae of the «Indian Meal Moth» (Lepidoptera: Phycitinae). The shattered plant material were obtained from leaves of Ricinus communis L. dried in stove to 40 ± 2 ºC for 48 hours and subsequently shattered until achieving a dust of similar texture to the flour of corn. Then it was mixed with flour of corn to achieve concentrations of: 5, 10 and 15% and a control without castor. The experimental units consisted of Petri dishes with six larvae of first and second stadium being performed five replications by treatment (n=120). The number of larvae was registered, pupas and alive adults, each four days, until the surviving larvae arrived al state adult. The percentages of efficacy were calculated by the formula of Abbott. The results were evaluated with ANOVA and Tukey test. They were determined the half effective time (TE50) and the median effective concentration (CE50) by the Probit method. The pest mortality with the concentration at 15 % surpasses significantly 10.5 % and control treatments. The relative mortality along this study indicates that there is differentiate significant between castor treatments and control from 24 days. CE50 was of 2.76 %.Fil: Collavino, Marcelo.Fil: Pelicano, Alicia.Fil: Giménez, Rosana A.

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