The efficiency of a mass extraction method is described for obtaining the white tip nematode, Aphelenchoides besseyi Christie, at low densities from batches of 20, 50, 100, or 150 seeds of rice, Oryza sativa L. In the method, individual rice seeds were split longitudinally and then placed on a stainless wire netting tray. The tray containing spilt seeds was placed in a container with water to soak the seeds for 4 hours at 25°. The proportion of extracted nematodes reached almost or completely 100% irrespective of the batch size of seeds. Consequently, the mass extraction method was applicable for determining the low nematode densities per seed and more efficient than the time-consuming, single seed method of Hoshino and Togashi.

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Two new and a known species of the genus Oriverutus Siddiqi, 1971 is described and illustrated. Oriverutus arcuicaudatus sp. n. is characterized by having 0. 61-0.71mm long body; lip region distinctly offset with protruding labial papillae; 16-17μm long, attenuated odontostyle; amphidelphic gonad with unsclerotized pars refringens vaginae; a small postrectal sac; ventrally arcuate tail and male with a single ventromedian supplement. O. parvus sp. n. has 0.65-0.71mm long body; lip region slightly offset with prominent labial papillae; 13-14μm long, attenuated odontostyle; amphidelphic gonad with sclerotized pars refringens vaginae and elongate conoid, slightly dorsally bent tail. O. occidentalis Peña Santiago and Peralta, 1995 is reported here for the first time from Japan. Jpn. J. Nematol. 32 (2), 31-44 (2002).

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Externally exposed sensilla, amphids and phasmids, in the pine wood nematode Bursaphelenchus xylophilus were examined with respect to their number, wiring, and position in comparison with those reported in the free-living soil nematode Caenorhabditis elegans. When B. xylophilus was soaked in FITC solution at 5°C for a few hours, two pairs of amphid neurons were stained. The staining pattern showed their bipolar processes emanating from the cell body located dorso-laterally: one process extended toward the tip of the head, and the other was projected into the nerve ring. Overnight soaking of the nematode with FITC revealed a teardrop-shaped apparatus with triradiate symmetry at the anterior of the metacorpus and long-shaped structures running toward stylet knobs. By this method, we could not detect phasmids in B. xylophilus, the result being different from those in C. elegans. Jpn. J. Nematol. 32 (2), 45-52 (2002).

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The pinewood nematode (PWN), Bursaphelenchus xylophilus, was cultured on an unidentified fungus, which was related to Contortylenchus genitalicola, grown on potatoglucose-agar medium supplemented with yeast extract in a flattened culture bottle. C. genitalicola is an entomophagous and mycetophagous nematode parasitic to the Japanese pine sawyer, Monochamus alternatus. The mean number of dispersal 3rd stage juveniles (DSJ₃s) and the mean percentage of DSJ₃ in the populations of PWN were 24, 870 and 93.1% at 80 days' culture. Dispersal 4th stage juveniles (DSJ₄s) developed in the culture bottles when B. xylophilus were co-incubated with pupa or adult M. alternatus on the fungus. DSJ₄s (mean number, 9, 105) were recovered from 9-day-oldM. alternatusadults that had been coincubated with B. xylophilus during the pupal and adult stages. The usual theory that occurrence of DSJ₄ is triggered mainly by existence of Monochamus cerambycid pupa and adult has been supported by the in vitro experiment. Jpn. J. Nematol. 32 (2), 53-59 (2002).

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The life history of Rhabdontolaimus psacotheae was examined and compared with that of a species of mycetophagous nematode Bursaphelenchus conicaudatus, which shares its vector and habitat with R. psacotheae. The third stage dauer juveniles of R. psacotheae enter the reproductive tracts of male and female yellow-spotted longicom beetles, Psacothea hilaris, and were transmitted from one Moraceae tree to another. The dauer juveniles of R. psacotheae enter a trees through the oviposition marks of their vector beetles, molt into adults then feed on bacteria proliferaing around the beetle tunnels made in the tree. Although, R. psacotheae was found to be sympatric to B. conicaudatus, R. psacotheae was segregated from B. conicaudatus because of the differences in the food resources in trees and in the organ of the vector beetle where they infest. Jpn. J. Nematol. 32 (2), 60-68 (2002)

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In order to assess the efficacy of red clover as a trap crop of Heterodera glycines, rates of hatching of H. glycines eggs in the root leachate, penetration of red clover roots by H. glycines juveniles and their development in the roots, and the effect of planting red clover on soil infestation of H. glycines were investigated. The rate of hatching of H. glycines eggs in the root leachate from red clover was significantly lower than the rates in the leachate from host plants but significantly higher than the rates in distilled water and in the leachate from fallow soil (no plants) and non-host plants. The number of second-stage juveniles that penetrated red clover roots was similar to the number that penetrated soybean roots, but only a few second-stage juveniles developed into third- or fourth-stage juveniles and none developed into adults in red clover roots. The population density of H. glycines in soil in which red clover had been planted decreased significantly compared with that in fallow soil (no plants) in both pot and field plot tests. From the results of these experiments, it was concluded that the use of red clover as a trap crop is a promising method for controlling H. glycines. Jpn. J. Nematol. 32 (2), 69-76 (2002).

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Differences in resistance of sweet potato cultivars to some populations of Meloidogyne incognita were examined in greenhouse assays. Twenty-four major sweet potato cultivars rooted in 200 g of potted soil were inoculated with approximately 500 juveniles of four M. incognita populations collected from different areas. Reproduction rates (eggs produced per J2 inoculated) were determined after 35 days of growth at 27°. Nine cultivars with reproduction rates higher than 11 were rated as susceptible and five cultivars with reproduction rates lower than one were rated as highly resistant to the four populations. However distinct differences were observed in reproduction rates of those populations on the other 10 cultivars. In an assay similar to the one described above with 13 newly developed cultivars or breeding lines, all four populations produced many egg-masses on three and produced only a few egg-masses on 6 of those cultivars or breeding lines. However, the remaining cultivars or breeding lines did not have a consistent response to the four populations. Among purple sweet potato cultivars grown primarily in Okinawa and Tanegashima Island, two similarly shaped cultivars, Bise and Tanegashima-murasaki 7, exhibited different levels of resistance to two populations as indicated by a marked difference between the numbers of egg masses produced. These results clearly demonstrate that resistance of sweet potato to populations of M. incognita distinctly differs with cultivars or breeding lines. Jpn. J. Nematol. 32 (2), 77-86 (2002).

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