Bursaphelenchus xylophilus (pinewood nematode) and B. mucronatus are closely related species, and constitute a group named “pinewood nematode species complex” (PWNSC) or are placed in a “supraspecies”. But differentiation between these species is difficult because of the limited discriminatory power of the morphological characters which are variable depending on the host or the environmental conditions. DNAbased diagnosis circumvents much of the variation associated with morphology, and has been adopted for taxonomical studies in nematology. We review the up-to-date reseaeches of DNA analysis of Bursaphelenchus species for precise evaluation of their inter-and intraspecific relationships in PWNSC.

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An attempt was made to find out suitable fungal hosts of Ditylenchus angustus for gnotobiotic culture. Seven fungi, Alternaria tenuis, Curvularia oryzae, Drechslera oryzae, Epicoccum purpurascens, Fusarium semitectum, Pestalotia oryzae and Rhizoctonia solani isolated from ufra infected rice plants were tested. Except for A. tenuis and F. semitectum, other five fungi were hosts of D. angustus. The highest rate of its multiplication was on E. purpurascens followed by R. solani, C. oryzae, D. oryzae and P. oryzae. The suitable temperature for gnotobiotic culture of the nematode on E. pupurascens was 25°C at which the rate of multiplication was maximal followed by 20 and 30°C. Ditylenchus angustus failed to reproduce at 15 and 35°C. Jpn. J. Nematol. 25(1): 11-15 (1995).

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Growth and reproductive parameters of Ditylenchus angustus on Botrytis cinerea were examined at 25°C for the nematodes which had been precultured for 1 month either on Botrytis cinerea (herewith BB) or on Epicoccurn purpurascens (herewith EB). Eggs were laid at 2-celled stage and developed in 3 days to the 2nd stage juveniles which hatched out without adding stimuli. One generation time from egg to egg was 10 days. The female adults started to deposit eggs 1 day after becoming adulthood. The oviposition period was 14.80 days and 12.80 days for BB and EB. A single female produced 4.44 and 4.26 eggs per day on average, totally 65.71 and 54.53 eggs, respectively. The net reproductive rate per generation and the intrinsic rate of natural increase were 39.55 and 0.37 for BB, and 33.82 and 0.35 for EB, respectively. Jpn. J. Nernatol. 25 (1): 16-23 (1995).

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Vertical dispersal, host-finding through movement in sand and infectivity to Galleria mellonella and Popillia japonica in three strains of Steinernema glaseri, S. anomali and S. kushidai were evaluated to determine which nematode species/strain showed the best potential for control of soil-inhabiting insects such as white grubs in turf. The dispersal of S. glaseri # 328, S. kushidai and S. carpocapsae was significantly different from S. glaseri # 326 and # 330 and S. anomali in sand columns without host. Steinernema glaseri # 326 and # 330 migrated over 10 cm. Over 58 % nematodes of S. anomali were recovered from 0-10 cm sections, but the few dispersed deeper. A small portion of S. glaseri # 328 and S. kushidai dispersed in the sand column but the majority remained near the top. Three strains of S. glaseri and S. anomali caused higher mortality against G. mellonella than S. kushidai and S. carpocapsae in host-finding through movement in a sand column. Even with the application of 120 infective juveniles of S. kushidai, the mortality of G. mellonela by this nematode was lower than that by 10 infective juveniles of S. glaseri # 326 and # 330. In one-on-one assays, G. mellonella mortalities by S. glaseri # 328, S. anomali and S. carpocapsae were higher compared with those by S. glaseri # 326 and # 330, and S. kushidai. The three strains of S. glaseri, S. anomali and S. kushidai were effective against P.japonica at 1, 000 infective juveniles/larva. Infectivities to G. mellonella and P. japonica also differed among the test nematode species. Jpn. J. nematol. 25 (1) 24-32 (1995).

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Two new Longidorus species collected from the rhizosphere of forest trees in Nagano, Japan are described and illustrated. L. laricis n. sp. is characterized by the expanded and offset lip region, short and bluntly conoid tail, long odontostyle, and extremely posteriorly located guide ring. This new species resembles L. litchii Xu & CHENG, 1992, L. fangi Xu & CHENG, 1991 and L. orongorongensis YEATES, VAN ETTEGER & Hooper, 1992, but differs from L. litchii in having larger a-value, expanded and offset lip region, wider lip region of female, and shorter tail of the first-stage juvenile; from the other two species in having more posteriorly located guide ring, and shorter tail of female. L. naganensis n. sp. is characterized by the broadly rounded and slightly offset lip region, bluntly conoid to almost hemispherical tail, long odontostyle, and posteriorly located guide ring. This new species comes closest to L. litchii, but differs from it in having a longer tail, wider lip region, ‘C’ to spiral shaped body of female, and shorter tail of the first-stage juvenile. Juveniles of two new species are separated into three developmental stages based on the lengths of bodies, stylets, etc. Jpn. J. Nematol. 25 (1) 33-43 (1995).

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A survey for entomopathogenic nematodes was conducted throughout the nine provinces and within three city limits in the Republic of Korea during the summers of 1990 and 1991. Six of the nine provinces and one of the three cities were positive for entomopathogenic nematodes. Out of the total 499 soil samples, 23 (4.6%) were positive for entomopathogenic nematodes with 19 (3.8%) containing Steinernema and 4 (0.8%) containing Heterorhabditis. Heterorhabditis bacteriophora and three distinct groups of Steinernema species were identified. One of the three steinernematid groups was identified as S. carpocapsae based on cross breeding studies. Positive sample sites in each habitat included 15 of the 415 (3.6%) from forests including regrowth areas with shrubs, 1 of the 27 (3.7%) from turfgrass including golf courses and parks, 3 of the 24 (12.5%) from agricultural fields, 2 of the 16 (12.5%) along riparian areas, and 2 of the 17 (11.8%) near the seashore. We advocate that more surveys be conducted for entomopathogenic nematodes before commercial sources of nematodes are widely applied which may obscure the naturally-occurring nematodes.

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[in Japanese]

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[in Japanese]

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