INTRODUCTION: The aim of the present study was to analyze the larvicidal activity of different crude extracts of Larrea cuneifolia and its most abundant lignan, nordihydroguaiaretic acid (NDGA), against Culex quinquefasciatus. METHODS: Chloroform, methanol, and aqueous extracts from L. cuneifolia and NDGA were tested against larvae of Cx. quinquefasciatus under laboratory conditions. RESULTS: The chloroform extract showed the highest larvicidal effect, with an estimated LC50 of 0.062 mg/ml. NDGA also demonstrated significant larvicidal activity with an estimated LC50 of 0.092 mg/ml. CONCLUSIONS: These results indicate that the chloroform extract of L. cuneifolia and NDGA are promising insecticides of botanical origin that could be useful for controlling Cx. quinquefasciatus.

The essential oil of the aerial parts of Baccharis salicifolia was examined by GC and GC-MS and the major components were identifed as α-pinene, camphene, β-pinene, α-phellandrene, α-cubebene, β-cariophyllene, 6,9-guaiadiene, germacrene D and germacrone. The essential oil was tested against eight Gram positive and Gram negative bacteria. The essential oil was found to exhibit moderate antibacterial activity against Gram positive bacteria tested with MIC values from 0.47 to 0.94 (µg/ml).

Toxic and repellent properties of whole essential oils from four Eupatorium (Asteraceae) species (E. buniifolium Hook. et Arn, E. inulaefolium Kunth, E. arnottii Baker, and E. viscidum Hook. & Arn) were investigated in different concentrations toward Tribolium castaneum Herbst adults. The essential oils were isolated by hydrodistillation techniques from the aerial parts. The analysis was performed by GC-FID and GC-MS methods. Contact toxicity assays showed that all the evaluated essential oils were toxic. Furthermore, in all the cases mortality was dose dependent. The main repellency was observed for the essential oil recovered from E. buniifolium.

Se evaluaron las propiedades tóxicas y repelentes de los aceites esenciales de cuatro especies del género Eupatorium (Asteraceae): E. buniifolium Hook. et Arn, E. inulaefolium Kunth, E. arnottii Baker y E. viscidum Hook. & Arn, en diferentes concentraciones frente a adultos de Tribolium castaneum Herbst. Los aceites esenciales se aislaron de las partes aéreas de las plantas, mediante técnicas de hidrodestilación y se analizaron por los métodos GC-FID y GC-MS. Los ensayos de toxicidad por contacto demostraron que todos los aceites fueron tóxicos y la mortalidad fue, en todos los casos, dependiente de la dosis. El aceite esencial de E. buniifolium presentó la mayor actividad repelente.

Duration of the pupal stage, toxic activity and nutritional indices induced by oleanolic acid (I), maslinic acid (II), and daucosterol (III) isolated from the native plant Junellia aspera and chemical derivatives, were determinated on larvae, and adults of Tribolium castaneum (Herbst). The current study shows that these triterpenes acts as acute toxic compounds when were applied topically and/or incorporated into the food of the red flour beetle. Nevertheless, no activity related with the nutritional status of this insect was produced.

Se determinó la duración del estado pupal, actividad tóxica e índices nutricionales sobre larvas y adultos de Tribolium castaneum (Herbst) inducidos por ácido oleanólico (I), ácido maslínico (II) y daucosterol (III) aislados de Junellia aspera y derivados químicos. Se demostró que los triterpenos evaluados actúan como tóxicos agudos cuando se aplican por topicación y/o son incorporados en el alimento. Los compuestos ensayados no presentaron actividad relacionada con el estado nutricional de los insectos.

In order to evaluate the allelochemical activity of some sesquiterpenes isolated from the native plant Tessaria absinthioides (Hook. et Arn.) DC, and some semi synthetic derivatives against Tenebrio molitor L. larvae, we have developed bioassays directed to quantify repellency, larval mortality, and its effects on the development. Although costic aldehyde caused the maximum repellent effect, all the compounds showed a significant effect at some dose or time, indicating behavioral avoidance. The topical application of costic aldehyde produced the largest increase on the duration of the pupal stage. Tessaric acid exhibited the highest toxicity by topical application at the experiment closure. Both eremophilane-1(10),2,11(13)-triene-12-oic, and <img border=0 width=7 height=11 src="../img/a02%20Simbolo%20g.jpg">-costic acids induced some morphological deformities.

Con el objeto de evaluar sesquiterpenos aislados de la planta nativa Tessaria absinthioides (Hook et Arn) y algunos derivados semisintéticos frente a larvas de Tenebrio molitor L., se desarrollaron bioensayos orientados a la cuantificación de la repelencia, mortalidad de larvas y efectos sobre el desarrollo. Aldehído cóstico produjo el mayor incremento en la duración del estado pupal por aplicación tópica. Acido tessárico exhibió el más alto porcentaje de mortalidad al finalizar el período de experimentación. Los productos eremophilan-1(10),2, 11(13)-trien-12-oico y ácido <img border=0 width=7 height=11 src="../img/a02%20Simbolo%20g.jpg">-cóstico dieron lugar al mayor número de malformaciones. Si bien aldehído cóstico mostró la máxima actividad de repelencia, todos los compuestos evaluados produjeron efectos significativos en el ensayo de elección.