ABSTRACT
ABSTRACT The botanical family Solanaceae has many species producing compounds with insecticidal properties, e.g. nicotine and capsaicin, which are used for pest management in agriculture. This fact provides perspectives to identify insecticidal compounds in Brazilian native species of Solanaceae. In this study, we performed a screening with 25 ethanolic extracts from 17 Solanaceae species in order to evaluate their bioactivity against the Mexican bean weevil, Zabrotes subfasciatus (Coleoptera: Chrysomelidae: Bruchinae). The bioactivity of Solanaceae ethanolic extracts (2,500 mg kg-1) was tested with residual contact bioassays. Adults of Z. subfasciatus were exposed to treated bean grains, and adult mortality, oviposition, F1 progeny and damages on grains were quantified. Most of the ethanolic extracts from Solanaceae reduced the number of eggs per sample, the egg-adult viability, the F1 progeny and the damages on bean grains promoted by Z. subfasciatus, but none of them interfered on its sex ratio. Ethanolic extract from leaves of Solanum lycocarpum A. St.-Hil promoted the most promissory effects on Z. subfasciatus. This ethanolic extracts can be a suitable alternative to control Z. subfasciatus in stored beans, mainly for small farmers and organic farmers.
RESUMEN La familia botánica Solanaceae tiene muchas especies que producen compuestos con propiedades insecticidas, e.g. nicotina y capsaicina, que se utilizan para el control de plagas en la agricultura. Este hecho proporciona perspectivas promisorias para identificar compuestos insecticidas en especies nativas brasileñas de Solanaceae. En el presente estudio se llevó a cabo un cribado con 25 extractos etanólicos de 17 especies de Solanaceae con el propósito de evaluar su bioactividad sobre el gorgojo pinto del frijol, Zabrotes subfasciatus (Coleoptera: Chrysomelidae: Bruchinae). La bioactividad de los extractos etanólicos se evaluó por experimentos de contacto residual. Los adultos de Z. subfasciatus se expusieron a los frijoles tratados con los extractos y se midió la mortalidad de los adultos, la ovoposición, la progenie F1 y el daño en los granos. La mayoría de los extractos etanólicos redujeron el número de huevos, la viabilidad de los huevos, la progenie y el daño en los granos, pero ninguno de ellos interfirió en la proporción sexual de los insectos. El extracto etanólico de las hojas de Solanum lycocarpum A. St.-Hil promovió los efectos más prometedores sobre Z. subfasciatus. Este extracto puede ayudar a controlar a Z. subfasciatus en frijoles almacenados, principalmente a los pequeños agricultores y a los agricultores orgánicos.
ABSTRACT
Fungi are present in the most diverse environments including the interior of plant tissues, living as endophytes without causing apparent damage. These endophytes are producers of secondary metabolites, also known as natural products, such as fungicides. Here, we evaluated the ethyl acetate fractions obtained from endophytic fungiisolated from plants in the genus Begonia. The fractions were submitted to inhibitorytest against the plant pathogens Diaporthe phaseolorum and Colletotrichum gloeosporioides. From the 88 ethyl acetate fractions evaluated, 14.7 % inhibited C. gloeosporioidesand 11.3 %inhibited D. phaseolorum. One fungal isolate displaying an active fraction was selected for chemical investigation. The fungus identified as Neopestalotiopsissp., produced a compound that was active against D. phaseolorum, with a MIC of 312 μg mL-1(1,695.3 μM). The compound was identified by mass spectrometry and 1H NMR as the known compound fumiquinone B. The results highlight that the endophytes are capable of producing compounds that may be used to control plant pathogens. The compound fumiquinone B is reported for the first time as an antifungal agent against D. phaseolorum, a relevant plant pathogen worldwide. This is also the first report of the production of fumiquinone B by the genus Neopestalotiopsis.