Bioactivity of basil (Ocimum basicilum L.) on control of the spider mite (Tetranychus urticae Koch.) in peanut

Essential plant oils contain biopesticides that could be used to control many crop pests. Tetranychus spp. are mites that cause damage to several crops and are primarily controlled by synthetic pesticides. Literature showed that mites can be controlled with essential oils of plants containing eugenol. In this work, we evaluated the bioactivity of basil (Ocimum basicilum) accessions for peanut-spider mites control based on molecular, biochemical and agronomic assays. RNA from four basil accessions, previously chosen by divergence genetic analysis, were used to estimate the expression of eugenol synthase (EGS I) transcripts, by semiquantitative and polymerase chain reaction (qPCR) assays. Chromatography was, thereafter, performed in order to estimate the eugenol concentration. Feeding bioassays were performed using basil leaf extracts in order to estimate oviposition and mortality of spider mites females. Finally, a validation assay was carried out in greenhouse, using peanut plants previously infested with spider mites and weekly sprayed with basil water-extract. One basil accession, OVRS, revealed high phytotoxicity to spider mite females, at 15% water-extract. The mortality rate was 75% and complete inhibition of fecundity was found in BOD assays. In the greenhouse assay, the most severe damage due to mite infestations was found to plant height, number of pods and pod yield, which were reduced to 28, 53 and 52% in non-treated plants (control). Considering that basil is a short-cycle plant, with easy reproduction and management, these results represent an accessible alternative to organic control spider mites in peanut.Keywords: Basil, chromatography, eugenol, eugenol synthase, qPCR, spider mit

Perfil fitoquímico e ensaio microbiológico dos extratos da entrecasca de Maytenus rigida Mart. (Celastraceae)

Maytenus rigida Mart (Celastraceae), conhecida por "Bom-homem", "Bom-nome", "Cabelo-de-negro", "Casca-grossa" e "Pau-de-colher", é uma arvore de pequeno porte. A entrecasca do caule é empregada popularmente no Nordeste do Brasil no tratamento das dores em geral, infecções e inflamações. O presente trabalho avaliou tanto o perfil fitoquímico de M. rigida por meio de um roteiro analítico, quanto à atividade antibiótica dos extratos pelo método de Kirby-Bauer modificado. Os resultados demonstraram que os extratos etanólico, aquoso, clorofórmico, acetato de etila e hidroalcoólico de M. rigida apresentam atividade antibacteriana contra Escherichia coli, Pseudomonas aeruginosa e Staphylococcus aureus, enquanto que a fração hexânica não exibe qualquer atividade. Catequinas, quinonas, esteróides, triterpenos, saponinas, flavonóides e compostos fenólicos foram detectados na análise fitoquímica