ABSTRACT
Abstract Cashew, Anacardium occidentale L. (Anacardiaceae), is one of the most important sources of agricultural income in northeastern Brazil, but many of the arthropods associated with the crop have yet to be identified. We describe here for the first time the damage caused by Holopothrips fulvus (Morgan) (Thysanoptera: Phlaeothripidae) to dwarf-cashew trees cultivated in the municipality of Pacajús, Ceará, Brazil. Leaf tissue injuries were caused by the sucking mouthparts of the insect and were characterized by dark necrotic spots on the epidermis that resulted in yellowing, wilting and, ultimately, abscission of the leaves. H. fulvus also fed on developing kernels and pseudofruits producing injuries that manifested in the form of chlorotic specks. Additional information is given on the pest status and important aspects of the morphology of the insect, including sexual dimorphism, redescription of the adults and description of the second instar larvae.
ABSTRACT
Na busca por controle químico alternativo contra Aedes aegypti L., muitas pesquisas são desenvolvidas e estimuladas no intuito de se descobrirem novas substâncias inseticidas de origem vegetal. Neste trabalho, o efeito larvicida de dez óleos essenciais foi avaliado contra A. aegypti. Os óleos foram obtidos por arraste a vapor e sua composição química foi determinada por cromatografia gasosa acoplada a espectrometria de massa. Os óleos essenciais foram diluídos em solução aquosa de dimetil sufóxido nas concentrações: 100, 50, 10 e 1 mg/ml. A atividade larvicida, baseada na percentagem de larvas mortas, foi avaliada 24h após o tratamento. O óleo essencial de Vanillosmopsis arborea Baker induziu a maior atividade larvicida, com CL50 de 15,9 mg/ml e CL90 de 28,5 mg/ml., enquanto o de O. gratissimum L. apresentou a menor atividade com CL50 de 95,80 mg/ml e CL90 de 102,86 mg/ml. Os resultados indicam que os óleos essenciais avaliados, principalmente o de V. arborea, são compostos por substâncias com efeito larvicida contra A. aegypti.
In the search for alternative chemical control against Aedes aegypti L., many researches are developed and encouraged in order to find new insecticidal plant substances. In this work, the larvicidal effect of ten essential oils was tested on A. aegypti. The oils were extracted by steam distillation and their chemical composition determined by GL-chromatography coupled with massspectroscopy. The essential oils were diluted in aqueous solutions of dimethyl sulfoxide with concentrations of: 100, 50, 10, and 1 mg/ml. The larvicidal activity, based on the percentage oflarval mortality, was evaluated after 24h exposure to the treatments. The essential oil of Vanillosmopsis arborea Baker presented the highest larvicidal activity, with CL50 of 15.9 mg/ml and CL90 of 28.5 mg/ml. On the other hand the essential oil of O. gratissimum L. showed the lower activity with CL50de 95,80 mg/ml and CL90 de 102,86 mg/ml. The results indicate that the tested essential oils, and particularly the V. arborea, are composed by substances with larvicidal properties for A. aegypti.