Seasonal fluctuations of the population of the strawberry nematode, Aphelenchoides fragariae and leaf symptoms of the plants lily in the “Ake-nishiki” field were examined. Damaged leaves were found in early June, and almost all the leaves were attacked in October. The number of nematodes in the leaves increased with time, and reached a peak of about 30 thousands per plant in October. The relatively high level of the nematode population in the bulbs at the end of May decreased to extremely low levels in mid-June, and remained at such levels up to early August. Thereafter the level of the population increased as the nematodes moved from wet leaves during the rains after mid-August, and some of them remained dormant in the bulbs. The nematode population in soil was extremly reduced by the cultivation of nonhost crops such as wheat. Nematodes in damaged lily leaves remained alive for more than 600 days under dry conditions. L. lancifolium and L. concolor var. pulchellum were attacked by the nematodes and developed leaf damage. Infection with the nematodes and damage of L. leichtlinii var. maximowiczii were limited, and no infestation was observed in the case of L. longiflorum, L. auratum, L. dauricum and L. speciosum var. speciosum f. coccineum. Heavy nematode infestation and damage were observed in the case of L.×formolongo, L.×hollandicum and the cultivars of Mid-century hybrids excluding “Enchantment”. Nematode infestation was observed in common weeds growing in the lily “Ake-nishiki” field, i.e. Erigeron annuus, Senecio vulgaris, Solanum nigrum, Rorippa atrovirens, Stellaria media, Chenopodium album and Polygonum blumei.

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Seasonal changes in the number of the pine wood nematode (PWN), Bursaphelenchus xylophilus, in the ratio of the number of dispersal 3rd-stage larvae (LIII) to the total number of PWNs, in the number of free-living (bacterium-feeding) nematodes, and in the occurrence of fungi were examined in the standing trees of Japanese black pine, Pinus thunbergii, inoculated with PWNs in August, 1985. In most of the trees examined, the number of PWNs in December was lower than that in October, but it increased from December to February. Thereafter, the number of PWNs decreased, reaching about 100 per g dry weight of wood in June. In the inoculated trees, species of Ceratocystis and Trichoderma were the most abundant fungi. Species of Phomopsis and Macrophoma were also present, but less frequently. The pattern of seasonal change in the percentage of Lill varied from tree to tree. In most of the trees, however, the percentage of Lill increased with time, but it never reached 50%, even in June. In February in most of the trees examined, there was a significant positive correlation between the number of PWNs and free-living nematodes. Jpn. J. Nematol. 17: 8-16 (1987).

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Activity of acetylcholinesterase (AChE) of the pine wood nematode, Bursaphelenchus xylophilus was examined by applying the radiometric method of JOHNSON and RUSSEL (1975). The optimum pH and temperature of the enzyme were about 7.0 and 35°C, respectively. The values of the two kinetic parameters evaluated for this enzyme were 6.25μ M for the Michaelis constant (K), and 8.7 nmole/min/mg protein for the maximum velocity (Vmax) at pH 7.0 and 25°C. The fraction which showed the highest specific activity was the pellet obtained after centrifugation at 105, 000×g for 60 min, followed by the pellet obtained after centrifugation at 20, 000×g for 30 min. The activity of this enzyme was inhibited 100 or 300 times more strongly by the oxon type of organophosphorus control agents such as fensulfothion, mesulfenphos and thionazin than the thiono type. Anthelmintic agents such as morantel tartrate and levamisole hydrochloride and carbamoyl nematicide/insecticide such as methomyl also showed a potent anti-AChE activity.

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Blockage of water conduction in the xylem of Pinus thunbergii inoculated with Bursaphelenchus xylophilus was examined by dye injection. Nematodes were inoculated onto a branch of 10-year-old pine trees and 1% acid fuchsin in water was injected into the trunks one to five weeks after inoculation. The dye stained pattern on the transverse section of the trunk began to be disturbed around one week after inoculation when a small number of nematodes dispersed in the trunk from the inoculated branch. Water movement in the trunk and the branches was blocked increasingly after that time. The number of nematodes increased rapidly in the trees four weeks after inoculation and water movement almost completely stopped in the following week. Discoloration of the inner bark of the trunk and the branches were observed. Mechanisms of water blockage in pine trees inoculated with the nematodes were discussed. Jpn. J. Nematol. 17: 23-30 (1987).

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Wheat bran was evaluated as medium constituent for the culture of Steinernema feltiae (DD-136). The infective juveniles (IJ) produced 3 weeks after the inoculation was in the order of 10⁴ per kg wet medium which contained wheat bran alone. The nematode productivity increased to 10⁷ when the medium was amended with salad oil and/or fermented with Bacillus spp. The IJ recovered from the media containing living cells of Bacillus cereus or B. thuringiensis transfered these bacteria_to larvae of Galleria mellonella and showed higher pathogenicity on the hosts. The nematodes were subcultured onto the medium containing Bacillus spp., however, IJ productivity decreased with concomitant decrease in the density of Xenorhabdus nematophilus, a natural symbiotic bacterium of the nematode. Jpn. J. Nematol. 17: 31-34 (1987).

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The comparative studies were made at 25°C under laboratory conditions on the infectivity and development of Steinernema feltiae (str. DD-136), S. bibionis and S. glaseri on the last instar larvae of common cutworm, Spodoptera litura, and greater wax moth, Galleria mellonella. For the above three nematode species, S. litura gave more invading nematodes than did G. mellonella, although the mortality of the latter insect was significantly higher than the former. The development and body size of steinernematid nematodes were greater in G. mellonella than in S. litura, regardless of the nematode species and/or numbers of invading individuals. The results suggest that the lower susceptibility of S. litura than G. mellonella larvae was mainly due to the higher resistance level against invading nematodes rather than the higher defense against nematode invasion. Jpn. J. Nematol. 17: 35-41 (1987).

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Twenty-seven varieties of barley, 19 varieties of wheat, 24 varieties of oats, 7 varieties of rye and 2 varieties of other cereals were tested for their resistance to Heterodera avenae populations collected from infested wheat fields in Chiba-Prefecture, Japan. The results showed that the multiplication of the cysts was more active on wheat and barley than on oats in contrast to the general trend observed in Europe. Based on the taxonomic studies on nematodes presented at the EPPO meeting in 1981, the pathotype of the Chiba population was considered to be close to “Ha'31”.

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To establish stable methods of control of the root-lesion nematode (Pratylenchus penetrans) which damages the Japanese radish, the combined application of both D-D and oxamyl granules was evaluated. The treatment with both D-D 92%(15-20l/10a) and oxamyl 1% granules (20kg/10a) showed a superior control effect compared with the treatment with D-D 92%(20l/10a) alone, and was as effective as the treatment with D-D 92%(30l/10a). The control effect obtained by treatment was satisfactory. Application of oxamyl 1% granules (40kg/10a) mixed with the surface soil of a field devoid of nematodes, where the Japanese radishes were grown prevented the nematode attack when the radishes were transplanted to a nematode-infested soil. This effect lasted for about three to four months.

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A nematode belonging to the genus Psilenchus DE MAN, 1921, which is apparently a new record from the Far East, was found around the root of tulip in Toyama, Japan, and this was described here as Psilenchus bilineatus n. sp. Nematodes were separated from soil by the Baermann funnel technique, relaxed by gentle heat, fixed by TAF, and mounted in glycerin after SEINHORST's glycerol-ethanol method.

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A Meloidogyne population reacting as M. incognita race 3 in the host range test was isolated from a mixed Meloidogyne population attacking eggplant in Nagasaki Pref.(Kyushu Is.). This population was derived from a few individuals reproducing on cotton during host range test of the latter and was cultured for several months on tomato before inoculation.

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A population of the bulb and stem nematode, Ditylenchus dipsaci (KÜHN) FILIPJEV, was detected in fields with commercially grown onions on Ohshima Island, Yamaguchi Prefecture, in May 1986. This is the first case of infestation with the nematode recorded in onion fields in Japan. The infested area as of May 1987 covered approximately 48 ares and the population levels of the nematode in these fields were comparatively high. Infested seedlings became twisted and deformed and frequently died in severely infested areas of the fields. Most of the bulbs of the plants which survived in the infested fields showed symptoms characterized by deformity, cracking and/or rotting.

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