Soils from a sweet potato field were sampled each season and incubated at 5, 15, 25 and 35°C for various periods before extracting nematodes by the Baermann funnel method at 25°C. When the soil was sampled in summer, a larger number of second-stage larvae (L₂) of Meloidogyne incognita were extracted from the soil kept at 25°C, while the recovery of L₂ was more constant when the soil sampled in winter was stored at 5°C. When the soil was kept at 15°C, a larger number of L₂ was recovered throughout the period of investigation. Jpn. J. Nematol. 11: 1-6 (1982)

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Sexual attraction in Bursaphelenchus xylophilus was studied on agar strips in petri dishes. Males were attracted to virgin females but not to 4th-stage female larvae, mated females or gravid females. Males were responsive to female secretions emitted into agar and vaporizing substances from virgin females. Female attraction by males was also observed. No evidence of homosexual attraction was noted in either males or females. Both male and female sex attractants seem to be volatile as well as water-soluble in nature. Jpn. J. Nematol. 11: 7-12 (1982)

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The effect of soil temperature on the manifestation of varietal resistance of the two domestic tobacco varieties “Okinawa” and “Okinawa 12” to Meloidogyne javanica was investigated. The susceptible varieties “Coker 319” and “NC 95” were used as check.
1. Gall formation was rare at 28°C, but slightly more frequent at 30t and at the same level as that of the susceptible varieties at 35°C.
2. Invasion rate: At 28°C the larval invasion rate of the resistant varieties were obviously low compared with those of the susceptible ones. At 35°C there were no differences in the invasion rates between the resistant and susceptible varieties used.
Development of nematodes which invaded the plants: At 28°C the development of nematodes which invaded the resistant varieties was remarkably retarded compared with that in the susceptible ones. At 35°C there were no differences in the development of nematodes between the resistant and susceptible varieties used.
3. Invasion of nematodes and manifestation of resistance: In both the resistant and susceptible varieties nematode invasion into roots was observed at and after 10 hours after inoculation. At the same time the inhibition of nematode invasion presumably due to the hypersensitive reaction of the host accompanied with necrosis was observed in the resistant variety “Okinawa”.
4. From the results mentioned above, it appears that the resistant varieties “Okinawa” and “Okinawa 12” display two types resistance, namely inhibition of nematode invasion and of nematode development. It could be demonstrated, however, that the resistance observed at the soil temperature of 28°C was lower at a temperature of 30°C and was completely lost at 35°C.

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Severe nematode problems have occurred in the vegetable fields of the Miura District, Kanagawa Pref., where three crops are cultivated in the same field in a year. For the purpose of maintaining the soil productivity and decreasing nematode damage, green manure and other crops have been used there in summer. Effects of the plants on the population dynamics of Pratylenchus penetrans (PP) and Meloidogyne incognita (MI) were investigated in field and pot experiments. In the field experiments, one of the following four plants, marigold, peanut, sorghum and watermelon, was cultivated in the summer of the first year with four replications. In the subsequent season crops were planted in the following order in all plots: Japanese radish (winter), watermelon (summer), and Japanese radish (winter). Population density of PP increased gradually and that of MI rapidly by the cultivation of watermelon. PP population became higher after sorghum than waterrmelon, and PP severely damaged Japanese radish after cultivation of sorghum. Population increase of MI was planed by sorghum cultivation. PP and MI populations showed a remarkable decrease during the cultivation of marigold and peanut in the first cropping, but in the next cropping PP and MI populations increased by the cultivation of peanut and marigold, respectively. In the pot experiments, asparagus, Crotalaria spp., star cucumber, sweet potato, taro, upland rice and eight othet crops were cultivated for 3-5 months. PP population decreased by the cultivation of asparagus, sweet potato, taro, and upland rice and asparagus was found to be most effective. The cultivation of three species of Crotalaria was not effective in decreasing the density of the nematode populations.

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In the previous paper four species of genus Nothocriconema were reported from Mt. Aso region, two of which were new to science. Recently the fifth species of this genus from the same locality of N. Palliatum MINAGAWA, 1981 was compared with other species of the genus, and found to be clearly distinctive to all the known species. This is described herein as a new species, N. miscanthi. Specimens used were fixed by TAF and mounted in glycerine.

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Since 1976 in Hokkaido, leaf dying of a Mid-century hybrid lily “Ake-nishiki” has become a disease of economic importance due to the severity of the outbreaks. The symptoms were characterized by a yellowish discoloration of the leaf bordered by the vein. Discoloration gradually spread until the leaf became brown and eventually died. Numerous Aphelenchoides fragariae were isolated from the discolored leaves, but not from the healthy ones. “Ake-nishiki” was the only susceptible variety so far investigated. Since no nematodes were recovered from the tissues of bulbs or roots, it is assumed that the nematodes were ectoparasites.

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Soils from a sweet potato field were sampled after harvest once or twice a month from December to May, then stored at 25°C. After a given period, nematodes were extracted by the following techniques: Baermann funnel (BF), modified sieving funnel (SF), and double-layer centrifugal flotation (DLCF) techniques. SF and BF extractions were carried out at 20°C for 72 hrs. The recovery of M. incognita larvae by the BF method increased after a storage period of 3 to 5 days from January to March. On the other hand, no increase was observed after April. By the SF method, regardless of the sampling time, there was no significant increase or decrease in the number of larvae extracted up to a storage period of 5 days and then the number gradually decreased. Recovery by the DLCF procedure decreased linealy with the increase in the storage period at any sampling time. No significant changes were observed in the recovery of H. dihystera by the SF or DLCF methods. These differences in recovery among the three extraction techniques may depend on the physiological conditions of the nematodes, such as motility, rates of hatching and death, proportion of dead individuals and rates of decay as well as the difference in the mechanism of extraction of the techniques applied.

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Nematicidal and annelicidal activities of 4-phenylazophenol derivatives, which had shown remarkable toxicity against animal parasitic nematodes (Rhabdias bufonis, Ascaris lumbricoides, Anchylostoma canninum) and Eisenia foetida, were evaluated against Panagrellus redivivus and two species of aquatic oligochaetes (Branchiura sowerbyi, Criodrilus bathybates) by applying the immersion test. The most effective compounds against Panagrellus were P-11, 13, and 73, which result from the substitution of Cl, Br or CH₃ in the p-position of the benzen ring. Many NO₂ substituted derivatives were very effective against Branchiura. In particular, P-10, 62 and 99, which derive from the substitution of NO₂ and halogen in the p-position of the benzen ring and the 3, 5-position of the phenol ring, showed a high toxicity. The most effective compound against Criodrilus was P-62. When the toxicity of the azo compounds aginst the four species of nematodes was compared, the effect on Panagrellus was similar to that on Anchylostoma but different from that on Rhabdias. No remarkable difference of toxicity among the three species of oligochates was observed.

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