To use resistant cultivars of sweetpotato effectively occurrence and distribution of pathogenic races of M. incognita were examined. Five sweetpotato differential cultivars, ‘Norin-1’, ‘Norin-2’, ‘Tanegashimamurasaki-7’, ‘Elegant Summer’ and ‘J-red’, which were selected from major Japanese sweetpotato cultivars based on resistance response to four M. incognita populations with different virulence were used as differential hosts. A total of 129 M. incognita populations were collected from mainly sweetpotato fields in Kyushu and Okinawa, Japan. Reproduction of the populations was assessed on the differentials based on production of egg-masses and pathogenic races were designated. Nine races, SP1 to SP9, were identified from these populations and 37.2%, 43.4% and 7.0% of the populations were, respectively, race SP1 that reproduces only on ‘Norin-1’, SP2 that reproduces on both ‘Norin-1’ and ‘Norin-2’, and SP4 that reproduces on four of the differential hosts but not on ‘J-Red’. Region specific distribution was observed in these races. SP1 was widely distributed in Kumamoto and northern prefectures. SP2 was predominant in southern Kyushu, in both Miyazaki and Kagoshima Prefectures. SP4 was the major race in Okinawa Prefecture. Other races were detected from limited areas. Jpn. J. Nematol. 35 (1), 1-12 (2005).

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Three isolates of the mycetophagous nematode Aphelenchus avenae collected in Kyushu, Japan, were investigated at 25°C for their propagation and feeding behavior on the hyphae of Rhizoctonia solani (Rs), Botrytis cinerea (Bc), Fusarium oxysporum (Fo), and Verticillium dahliae (Vd). There were large differences in the population growth between the nematode isolates. On 30 days after inoculation with three individuals of 4th-stage juveniles onto the fungi growing on the 1/5 strength PDA medium in a Petri dish (9-cm diam.), the nematode population size was in the range of 21, 000-63, 000 for Bc and Rs, and 1, 000-10, 000 for Vd and Fo. Taking the hyphal diameter of Rs for 1.0, the ratio was almost the same, 0.2, and 0.4 for Bc, Vd, and Fo, respectively. Video-assisted analyses of nematode feeding behavior showed that the nematodes were more preferably attracted to Fo than to the other three fungus species. The frequencies of stylet thrusting per 10 min were 5-12 times for Rs and Bc, and 20-106 times for Fo or Vd. The duration of a single stylet stabbing was 4-9 sec for Rs and Bc, while it was 1-2 sec for Fo and Vd. The pulsation frequencies of median valve per a single feeding were 5-10 pulse for Rs and Bc, and 0.5-1.0 pulse for Fo and Vd. The lower nematode reproduction on Fo and Vd was possibly due to the thinner width of these hyphae than the length of nematode stylet (ca. 8μm). There is no extracorporeal digestion in these three nematode isolates tested. Jpn. J. Nematol. 35 (1), 13-19 (2005).

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The purpose of the study was to determine the extent and ability of wood-decay fungi to attack and kill the pinewood nematode, Bursaphelenchus xylophilus, and to determine the possibility of fungi that inhabit wood to affect the population dynamics of the pinewood nematode in diseased and dead pine trees. The ability of Pleurotus ostreatus, P. pulmonarius, P. eryngii, Lentinula edodes, Lampteromyces japonicus, Neolentinus lepideus, Trichaptum abietinum, Pholiota nameko and Cryptoporus volvatus to prey on the pinewood nematode was confirmed. Nematodes were inoculated on water agar plates on which a single, sparse fungal colony of one of the basidiomycetous fungus grew. Nematodes were immobilized and killed quickly after being inoculated onto plates of the each of the first five fungal species listed above. The other four species of fungi were less effective in attacking and destroying nematodes. The results of multiplication experiments of the pinewood nematode on a fungal colony grown together with Botrytis cinereaon potato dextrose agar paralleled those of the nematophagous ability of each fungus. Nematodes did not reproduce on the fungal colonies of the five species that rapidly killed the nematodes. Jpn. J. Nematol. 35 (1), 21-30 (2005).

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