Ryanodane diterpenes from two Erythroxylum species

Ryanodane diterpenes, named 14-O-methyl-ryanodanol and ryanodanol, were isolated from ripe fruit of Erythroxylum passerinum. Compound 2 was also found in the leaves of this species, while 1 was obtained from the leaves of E. nummularia. Compound 1 showed insecticidal activity against Aedes aegypti larvae. (c) 2007 Elsevier Ltd. All rights reserved.

Toxicity of extracts and isobutyl amides from Piper tuberculatum: potent compounds with potential for the control of the velvetbean caterpillar, Anticarsia gemmatalis

The isobutyl amides pellitorine (compound 1) and 4,5-dihydropiperlonguminine (compound 2) were extracted from the seeds of Piper tuberculatum Jacq. (Piperaceae) in yields of 6.10 and 4.45% respectively. The acute toxicities to the velvetbean caterpillar, Anticarsia gemmatalis (Hubner) (Lepidoptera: Noctuidae), of extracts of seeds, leaves and stems of P. tuberculatum, and of compounds 1 and 2, were evaluated by means of contact bioassays. The extracts caused 80% mortality when doses higher than 800.00 mu g insect(-1) of extract of seeds, leaves and stems were administered to the velvetbean caterpillars. Compounds I and 2 showed 100% mortality at doses of 200 and 700 mu g insect(-1) respectively. The LD50 and LD90 values were respectively 31.3 and 104.5 mu g insect(-1) for compound 1, and 122.3 and 381.0 mu g insect(-1) for compound 2. The potential value of extracts and amides derived from P. tuberculatum as efficient insecticides against velvetbean caterpillars is discussed. (c) 2007 Society of Chemical Industry.

Toxicity of sesame extracts to leaf-cutting ant Atta sexdens rubropilosa (Hymenoptera: Formicidae)

Extracts of different sesame plant (Sesamum indicum, Linnaeus) organs were tested through ingestion and contact experiments to investigate their toxicity to Atta sexdens rubropilosa (Forel) workers. Dichloromethane extracts of seeds were toxic to the leaf-cutting ants and the factor responsible for the toxicity does not show seasonal occurrence.

Astilbin toxicity to leaf-cutting ant Atta sexdens rubropilosa (Hymenoptera: Formicidae)

The toxicity of astilbin, isolated from Dimorphandra mollis, was tested in laboratory ingestion bioassays for the leaf-cutting ant Atta sexdens rubropilosa Forel. Worker ants that were fed an artificial diet daily to which astilbin was added had a higher mortality rate than the controls. The substance astilbin was incorporated into the diet with and without the utilization of a solvent. Results for both methodologies utilized were similar and indicate that astilbin reduces the median survival of ants. All concentrations tested showed toxic effects against ant workers, and the statistical comparison of survivorship rates from control and treated groups was significantly different, confirming the insecticidal properties of the substance astilbin.

Toxicity of Cedrela fissilis to Atta sexdens rubropilosa (Hymenoptera: Formicidae) and its symbiotic fungus

Crude extracts from roots, stems, branches, fruits and leaves of Cedrela fissilis were tested to verify their toxicity to Atta sexdens rubropilosa workers and to their symbiotic fungus Leucoagaricus gongylophorus. The workers that were fed daily on an artificial diet to which crude extracts from this plant were added had a higher mortality rate than the controls, especially for the hexane, dichloromethane and methanol crude extracts from roots (RH, RD and RM) and from leaves (LH, LD and LM). Fungal growth was inhibited by the hexane (RH) and dichloromethane crude extract from roots (RD). The RH, RD and FD crude extracts were fractioned and their fractions were tested. All the fractions tested presented toxicity to the ants and some fractions (RH-H, RH-D, RD-4 and RD-5) completely inhibited fungus development. The possibility of controlling these insects in the future using Cedrela fissilis compounds that can simultaneously target both organisms is discussed.

Evaluation of the toxicity of Virola sebifera crude extracts, fractions and isolated compounds on the nest of leaf-cutting ants

The phytochemical study of Virola sebifera leaves led to the isolation of three lignans: (+)-sesamin, (-)-hinokinin, and (-)-kusunokinin and three flavonoids: quercetin-3-O - L-rhamnoside, quercetin-3-O - D-glucoside, and quercetin-3-methoxy-7-O - D-glucoside by using techniques as high-speed counter-current chromatography and high-performance liquid chromatography. The crude extracts, fractions, and isolated compounds were evaluated for their insecticidal and fungicidal potential against Atta sexdens rubropilosa and its symbiotic fungus Leucoagaricus gongylophorus. The bioassay results showed a high insecticidal activity for the methanol crude extract of the leaves of V. sebifera and its n-hexane, dichloromethane and ethyl acetate fractions. The fungicidal bioassay revealed high toxicity of the lignans against L. gongylophorus. © 2012 Keylla Utherdyany Bicalho et al.

Chemical characterization and acaricide potential of essential oil from aerial parts of Tagetes patula L. (Asteraceae) against engorged adult females of Rhipicephalus sanguineus (Latreille, 1806)

Rhipicephalus sanguineus, commonly known as the brown dog tick, is one of the most widely distributed species of tick. In dogs, it can cause anemia and provide the transmission of pathogenic microorganisms such as Babesia canis, Ehrlichia canis, Hepatozoon canis, Anaplasma platys, and Mycoplasma haemocanis. To man, it can transmit the intracellular parasites Rickettsia rickettsii and Rickettsia conorii, the causative agents of the Rocky Mountain spotted fever in the Americas and Mediterranean and spotted fever in Europe and North Africa. Its control is performed by applying synthetic formulations composed of pyrethroids; however, continued use of these products results in environmental damage and acquisition of resistance. Alternatively, studies with botanical insecticides have been increasingly recurrent. Therefore, this study aimed to test the efficacy of essential oil of Tagetes patula, a ruderal species widely described in the literature for its insecticidal properties, in engorged females of R. sanguineus by the adults immersion test (AIT) and impregnated paper disk test (IPDT). The essential oil used, through gas chromatography coupled to mass spectrometry, revealed the presence of 55 compounds, being the 4-vinyl guaiacol and gamma terpinene the majority ones. The AIT compared to the IPDT was more efficient in inhibiting oviposition of tick; however, the eggs laid by the females submitted to saturated atmosphere with essential oil, from IPDT, not hatched, interrupted their development cycle. Besides being a pioneer work, the results presented here contributes to new researches, aiming the incorporation of essential oil in an acaricide for use in the environment. © 2013 Springer-Verlag Berlin Heidelberg.

Toxicity of hydramethylnon to the leaf-cutting ant Atta sexdens rubropilosa forel (hymenoptera: Formicidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Identificação de genes cry1 em isolados de Bacillus thuringiensis e expressão do gene cry1la em Escherichia coli visando o controle de pragas da cultura algodoeira

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise da expressão gênica em isolados de Bacillus thuringiensis por PCR tempo real visando o controle de Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) de diferentes populações brasileiras

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito de óleos essenciais e extratos de diferentes espécies botânicas sobre bemisia tabaci (Gennadius) biótipo b (Hemiptera: aleyrodidae) em tomateiro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Investigação de metabólitos secundários de folhas de Derris urucu (Killip et Smith) Macbr. com atividades biológicas

Derris urucu, pertencente à família Leguminosae/Fabaceae, é conhecida popularmente como “timbó”. As raízes desta espécie são utilizadas comumente como pesticidas e veneno para peixe. Do gênero Derris foram relatados muitos estudos fitoquímicos, sendo as raízes a parte mais estudada das plantas desse gênero. A denominação “timbó” é mais generalizada para as espécies Derris urucu e Derris nicou que são as espécies que produzem, nas raízes, substâncias da classe dos rotenóides como a rotenona e a deguelina, de onde deriva a importância dessas plantas. Os extratos, bem como, as substâncias isoladas deste gênero são responsáveis por um vasto conjunto de atividades biológicas, principalmente a atividade inseticida. Do extrato etanólico das folhas de D. urucu, doze substâncias foram isoladas e purificadas por Cromatografia Líquida de Alta Eficiência: cinco estilbenos, seis diidroflavonóis e uma flavanona. A identificação estrutural foi feita com base na análise espectrométrica de massas, de RMN 1H e 13C e técnicas de RMN bidimensionais, além de comparação com dados encontrados na literatura. O extrato etanólico das folhas de D. urucu foi submetido a bioensaios para avaliação do seu potencial alelopático, tendo exibido relevantes percentuais de inibição da germinação de sementes e do desenvolvimento de plantas invasoras de pastagens. Com o objetivo de detectar as substâncias responsáveis pela atividade alelopática, três estilbenos e três diidroflavonóis foram selecionados e submetidos a bioensaios de inibição de germinação e de desenvolvimento da radícula e do hipocótilo de plantas daninhas. Os ensaios alelopáticos foram realizados com as substâncias isoladas e com a combinação delas, visando também avaliar o sinergismo entre elas, no entanto, as inibições observadas foram de magnitudes muito baixas. Por outro lado, quando as substâncias foram testadas em misturas observou-se um aumento significativo dos percentuais de inibição, por isso essas substâncias em misturas, podem ser consideradas promissoras para futuros estudos, envolvendo atividade alelopática. Foram realizados, também, bioensaios de atividade antioxidante com oito substâncias, sendo três estilbenos e cinco diidroflavonóis frente ao radical DPPH. Neste bioensaio, não foi observada uma atividade antioxidante relevante, justificada pela presença de poucas hidroxilas fenólicas nas estruturas das substâncias testadas.

Composição química e toxicidade de óleos essenciais para o pulgão-verde Schizaphis graminum (Rondani, 1852)

Este trabalho teve como objetivo identificar e quantificar os constituintes dos óleos essenciais de Illicum verum, Ageratum conyzoides, Piper hispidinervum e Ocotea odorifera, bem como avaliar a toxicidade para o pulgão-verde Schizaphis graminum. A qualificação dos constituintes foi realizada por meio de um cromatógrafo gasoso + espectrômetro de massas, e a quantificação, por um cromatógrafo gasoso + detector de ionização de chama, ambos com uma coluna DB5. O método de hidrodestilação promoveu um rendimento (p/p) de 3,81% para I. verum, 0,46% para A. conyzoides, 2,85% para P. hispidinervum e 0,68% para O. odorífera. Já os componentes majoritários foram: precoceno (87,0%) e (E)-cariofileno (7,1%) para A. conyzoides; (E)-anetol (90,4%), limoneno (2,6%) e metil-chavicol (1,3%) para I. verum; metil-eugenol (81,2%) e safrol (10,6%) para Ocotea odorífera; e safrol (82,5%) e α-terpinoleno (13,4%) para P. hispidinervum. Pelos testes de toxicidade aguda (24 horas) com folhas de sorgo ou papel-filtro contaminados, verificou-se que o óleo de A. conyzoides foi o mais tóxico para o pulgão, com CL50 de 7,13 e 7,08 µL óleo/cm2 respectivamente, seguido por O. odorifera com CL50 de 11,80 e 103,00 µL óleo/cm2 respectivamente; I. verum de 51,80 µL óleo/cm2 em ambos os substratos; e o menos tóxico foi o óleo essencial de P. hispidinervum, com CL50 de 62,50 e 143,00 µL óleo/cm2, respectivamente. Dessa maneira, sugere-se que o uso dos óleos essenciais pode representar uma nova ferramenta em programas de manejo integrado de pragas.

Bioatividade de extratos de anonáceas e piperáceas sobre Tuta absoluta (Meyrick) (Lepdoptera: Gelechiidae) em tomateiro

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Botanical extracts: alternative control for silverleaf whitefly management in tomato

Bemisia tabaci (Hemiptera: Aleyrodidae) biotype B is one of the most limiting pests of tomato crops in the world. Tomato yield is currently dependent on the use of pesticides, which are problematic to farmers, consumers and the environment. A promising alternative to reduce the harmful effects caused by the indiscriminated use of synthetic insecticides is the use of insecticides of botanical origin. This study aimed to evaluate the effect of 3% (w/v) aqueous extracts from different structures of thirteen botanical species on the behavior of B. tabaci biotype B adults, as well as insecticidal activity of such aqueous extracts on B. tabaci eggs, nymphs, and adults infesting tomato plants. A distilled water solution was used as a negative control, and thiamethoxam insecticide (18 g/100 L of water) as a positive control. Leaf extract of Toona ciliata was observed to have the most efficient inhibitory effect in tests of extracts on whitefly behavior. Furthermore, the use of leaf extract of Toona ciliata led to the most drastic reduction in the number of adults and eggs on tomato leaflets. Leaf extract of Piper aduncum led to the greatest observed ovicidal effect (78.00% of non-hatched nymphs); however it was not effective against nymphs and adults. The leaf extracts of Trichilia pallida, Trichilia casaretti, and Toona ciliata showed the highest control indexes (67.9, 60.3, and 55.1%, respectively). For adults mortality, T. pallida was the most effective (72.8%). Our results indicate that application of extracts of T. pallida, T. ciliata, and T. casaretti are promising strategies to manage B. tabaci biotype B on tomato.