SubstÃncias OrgÃnicas para o Controle de NematÃides em Cafeeiros. / Organic Substances for Nematode Control in Coffee Plants.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Two projects were carried out in order to contribute to the development of new methods to control the nematode Meloidogyne exigua Goeldi, 1887, which is widespread through Brazilian coffee plantations. In the first one, the bacteria Acinetobacter jonhsonii and Staphylococcus aureus, previously isolated from tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annum L.), respectively, were cultivated in liquid medium to afford metabolites that were separated from bacterial cells and freeze-dried. As the dichloromethane soluble metabolites presented nematicidal activity during an in vitro assay with second stage M. exigua juveniles (J2), they underwent fractionation by column chromatography and high performance liquid chromatography to afford uracil, dihydrouracil and 9H-purine. All substances were active against J2, being dihydrouracil the most efficient. Such substance presented LC50 of 204 Âg/mL against the nematode, while a LC50 of 30Âg/mL was observed for the commercial nematicide Aldicarb. Regarding the second project, 149 chalcones and analogues, prepared by aldolic condensations, were submitted to in vitro assays with M. exigua J2. The most active substance was 2,4,5-trimethoxy-4â-nitrochalcone, which presented LC50 of 171Âg/mL against J2, while a LC50 of 24Âg/mL was observed for the commercial nematicide Aldicarbe under the same conditions. When an experiment with M. exigua inoculated coffee plants was carried out, the above-mentioned chalcone was as efficient as Aldicarb when used at a concentration 14 times greater than the nematicide. Although less active than Aldicarb, both dihydrouracil and 2,4,5-trimethoxy-4â-nitrochalcone present potential for M. exigua control, since such structures can be easily obtained at low cots. Furthermore, they are less toxic than the commercially available nematicides and can be used as leading molecules for structural modifications aimed to increase the activity against the nematodes.

ASSUNTO(S)

1. nematicide. 2. meloidogyne exigua. 3. staphylococcus aureus. 4. acinetobacter jonhsonii. 5. chalcone. 6. acylhydrazone. 7. plant coffee quimica organica 1. nematicida. 2. meloidogyne exigua. 3. staphylococcus aureus. 4. acinetobacter jonhsonii. 5. chalcona. 6. acil-hidrazona. 7. cafeeiro

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