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There are many plant-parasitic species in the root-knot nematode genus (''Meloidogyne'') that attack coffee such as ''M. incognita'', ''M. arenaria'', ''M. exigua'', ''M. javanica'' and ''M. coffeicola''. Study has already shown interspecific variability 〔Carneiro, R. M. D. G., Tigano, M. S., Randig, O., Almeida, M. R. A. & Sarah, J-Louis. 2004. Identification and genetic diversity of Meloidogyne spp. (Tylenchida: Meloidogynidae) on coffee from Brazil, Central America and Hawaii. Nematology 6: 287-298.〕〔Hernandez, A., Fargette, M. & Sarah, J-Louis. 2004. Characterisation of meloidogyne spp. (Tylenchida: Meloidogynidae) from coffee plantations in central America and Brazil. Nematology 6: 193-204.〕 coffee, in which show how this species can be adapting to new hosts and environments. == Morphology and anatomy == ''Meloidogyne exigua'' females are small with medium stylet (12-14 µm) and strong basal knobs.〔Carneiro, M.D. G. & Cofcewicz, T. E. 2008. Taxonomy of Coffee-Parasitic root-knot nematodes, Meloidogyne spp. In: Souza, R. M (Ed). Plant-Parasitic nematodes of coffee. Campos dos Goytacazes, BR, springer, PP. 87-122.〕 This genus has sexual dimorphism; females are swollen and males keep vermiform as adults. The female has a pear shape when swollen. It is not possible differentiate one species from other on coffee in the field due to coffee being a host of several species of ''Meloidogyne''. ''M. exigua'' can be found in Brazil, Guatemala, Colombia and Costa Rica. ''M. coffeicola'' has a long neck and brownish body color. Its stylet is 15-17.6 µm long with no prominent knobs. Females also swell, less than ''M. exigua'', however. This species is found in Brazil, exclusively. Another way to distinguish ''Meloidogyne'' species is by the perineal patterns. The perineal pattern involves anus, vagina and surrounding area. Each species has a unique pattern that can distinguish them, but only a trained nematologist is able to verify those small differences. ''Meloidogyne exigua''‘s perineal pattern has a hexagonal shape, with a dorsal arch above the anus and lateral lines not very pronounced on the perineal pattern,〔 while ''M. coffeicola'' pattern have a more simple conformation with striations between vulva and anus forming a target.〔Castro, J. M. C., Campos, V. P. &Dutra M. R. 2004. Ocorrência de Meloidogyne coffeicola em Cafeeiros do Município de Coromandel, Região do Alto Paranaíba em Minas Gerais. Fitop. bras. 29: 227.〕 Due to difficulties to identify ''Meloidogyne'' species just by perineal pattern, other reliable techniques were developed, such as Isoenzyme characterizations. Oliveira 〔Oliveira, D. S., Oliveira, R. D. L., Freitas, L. G., & Silva, R. V. 2005. Variability of Meloidogyne exigua on Coffee in the Zona da Mata of minas Gerais State, Brazil. Journal of Nematology 37 (3): 323-327.〕 reported difficulties to use perineal pattern and Isoenzymes helped to confirm species without mistakes. ''M. exigua'' is distinguished by its esterase phenotypes E1 and E2,〔 while ''M. coffeicola'' by Est C2.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Coffee root-knot nematode」の詳細全文を読む スポンサード リンク
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