We conducted phylogenetic analyses of Japanese Heterorhabditis nematodes and their symbiotic Photorhabdus bacteria based on the mitochondrial cytochrome oxidase I (CO I) gene and 16S rRNA gene (16S rDNA) sequences, respectively. Three H. megidis isolates from Japan clustered with the H. megidis isolates from Europe and their symbiotic bacteria clustered with European P. temperata. Five Japanese H. indica isolates formed a cluster with H. indica from India and three out of five bacterial isolates from Japanese H. indica fell into P. luminescens subsp. akhurstii cluster. However, the other two bacterial isolates clustered with P. asymbiotica subsp. australis known as an Australian clinical pathogen. These data suggest that some Japanese isolates of H. indica have mutualistic association with P. asymbiotica.

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Steinernema abbasi was isolated from Iriomote-jima Is., Okinawa Pref., Japan. This is the first record of the natural occurrence of the species in Japan. The morphometrics and the morphological features of the infective third-stage juveniles (IJs) and the first generation male and the morphological features of the first generation female of the Japanese isolate were studied. The morphometrics of the IJs almost agreed with those of the Taiwanese isolate, but body length, maximum diameter and ratio a were different between the Japanese isolate and the type isolate from Oman. The RFLP profiles did not show the intraspecific variation. The pathogenicity against the last instar larvae of the turnip moth, Agrotis segetum, was investigated at 15, 20, 25, 30 and 35°C under the presence of soils. High pathogenicity against the lepidopteran larvae was obtained at 25 and 30°C. At 15°C the nematode could not kill the turnip moth larvae. At 30°C, 10,000 IJs caused 100% mortality against five last instar larvae within two days, 5,000 and 2,500 IJs caused more than 80% mortality for three and five days respectively and 1,000 IJs caused 60% mortality within four days.

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A root-lesion nematode population collected from rhizospheres of Chrysanthemum morifolium in Kyushu Is., western Japan, is described as Pratylenchus kumamotoensis sp. n. The new species is characterized by its esophageal glandular lobe (EGL) inconsistently overlapping the intestine (dorsal, lateral and ventral overlap in varied frequencies), 2-3- annules in lip region, average spear length 14-15 μm, moderately distanced vulva (V = 76- 77), and thin tail terminal cuticle (< 2 μm). The new species is distinguished from closely related P. coffeae, P. pseudocoffeae, P. loosi, P. jaehni, and Apratylenchoides homoglans. The new species was placed in the genus Pratylenchus because of the lack of clear differences with the genus Pratylenchus. However, an inconsistent overlap of the EGL in the new species creates grave doubt about the separation of Pratylenchus and Apratylenchoides.

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A positive correlation was obtained between the number of eggs and the total nematodes in roots of native herbaceous plants in Hokkaido, and after 2 years of long-term growth a positive correlation was recognized between the number of eggs in roots and the population density of nematodes in soil. In the above investigations, number of eggs or number of nematodes in the roots were used as an index of the nematode reproduction. The plants that had large numbers of eggs and produced high reproduction of nematodes were Agastashe rugosa, Vicia cracca, Thermopsis lupinoides, Lotus corniculatus var. japonicus, and Iris setosa. The plants that were not suitable as a host were Patrinia scabiosifolia, Lysimachia clethroides, Astilbe odontophylla, and Eupatorium makinoi. The rate of nematode population decline on the native species of P. scabiosifolia was superior to the cultivated variety “Wase Ominaeshi”. The efficacy depended on the number of eggs in roots. Long term cultivation of Rudbeckia laciniata led to a meager population of nematodes. Rudbeckia hirta also showed a superior reduction of nematodes, as shown in a previous report.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Abstracts of papers presented at the 15th annual meeting of the Japanese Nematological Society

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Erratum to“Emergence of suppression of root-knot nematodes in sweet potato cropping systems treated with Pasteuria penetrans”
Jpn. J. Nematol. 37(1), 1-9 (2007).

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Erratum to“Antagonistic effect of solanaceous plants on Globodera rostochiensis”
Jpn. J. Nematol. 37(1), 21-35 (2007).

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[in Japanese]

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