Electrophysiological techniques have been used to examine nematode sensory responses and stylet protractor muscle activity, and the electrical signals generated in plants in response to nematode invasion. Examples of these three uses of electrophysiology with second-stage juveniles (J2s) of Globodera rostochiensis are presented.
The concentration-dependent sensory responses of J2s to acetylcholine were examined and the delay in response was quantified. Stimulation of J2s with potato root diffusate (PRD) elicited significant increases in spike activity, whereas non-host root diffusate and female sex pheromones elicited no response. Incubating J2s in an amphid-specific antibody and in DiTera^®, a biological nematicide, blocked the response to PRD.
Electropharyngeogram (EPG) analysis of stylet protractor muscle activity in response to various concentrations of serotonin were obtained and correlated with stylet movement using video analysis. The antagonist, gramine, incorporated with serotonin, almost completely eliminated stylet thrusting and prior exposure of J2s to DiTera^® significantly reduced subsequent stylet activity.
Distinct patterns of electrical activity were recorded from the roots of susceptible and resistant potato cultivars after applying J2s. More marked responses were obtained from susceptible roots than from resistant roots. Electrical activity in response to mechanical and bacterial exoenzyme stimuli did not account for the electrical activity recorded from susceptible roots. Jpn. J. Nematol. 34 (1), 1-10 (2004).

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Cylindrocorpus anoplophoraen. sp. is described and figured. The dauer juveniles of C. anoplophorae n. sp. were isolated from the genital capsule of the white-spotted longicorn beetle, Anoplophora malasiana, and were reared on an Asparagine-Mannitol (A-M) agar. Specimens of adult nematodes for description and measurements were collected from a 2 week-old culture on the A-M agar. The males of the new species have body length of ca. 830-1070μm, the value a of ca. 19-26, the value b of ca. 5-6, the value c of ca. 8-12, ca. 29-35μm length of slightly arcuate spicules, ca. 17-20μm length of thorn shaped gubernaculum, 43-62μm of tail conoid, nine pares of caudal papillae, and very narrow and tape like leptoderan bursa. The females of new species have body length of ca. 980-1260μm, the value a of ca. 17-23, the value b of ca. 6-7, the value c of ca. 7-9, ca. 114-161μm length of elongated tail, and the values V of ca. 50-55. The new species is distinguished from the other species within the genus by the morphometric values of male and female, number and arrangement of male caudal papillae, shape and length of male bursa, and tail shape of male and female. Jpn. J. Nematol. 34 (1), 11-19 (2004).

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The ability to capture Meloidogyne incognita was compared among 17 species of nematode-trapping fungi isolated from soil in Okinawa Island. In particular, Monacrosporium ellipsosporum had not only the highest trapping ability but also formed many trapping organs per unit area (1 mm²), catching nematodes more rapidly than other trapping fungi. A test for selection of the optimum medium for proliferation of M. ellipsosporum revealed that 1% glucose·yeast extract·malt extract (GYM) liquid medium was the most suitable. This fungus produced 5.2×10¹⁰ cells (hyphal bodies) in shaking culture (200 rpm/min, 25°, 100 ml). When a mixture of culture medium including viable cell and vermiculite was mixed into soil at the rate of 10, 20, 30 or 50g per plot, root-knot indexes of tomato roots after 3 months of cultivation were 40, 10, 15 and 10 for the 10, 20, 30 and 50g treatment plots, respectively. The index was 50 in the control. A granular nematicide, fosthiazate had an index of 5.0. Fosthiazate, cadusafos and oxamyl had no effect on the in vitro hyphal growth of M. ellipsosporum. Jpn. J. Nematol. 34 (1), 21-29 (2004).

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Crimson clover and woolly pod vetch, which have been recognized as antagonistic plants on Heterodera glycines (SCN) during the spring cultivation, were tested as post crops of winter wheat in a SCN (race 3) infested field in Assabu town, Hokkaido for 70 days from Aug. 12 th. The results obtained from the plot planted with crimson clover showed that the population density of second stage juveniles in the soil was at its peak one month after seeding, and that the number of eggs in the soil decreased to 28% compared with that of preplanting. Susceptible soybean (Bansei-Hikariguro) grown in the following year as an after crop of crimson clover showed a low cyst index and a yield of 216 kg /10 a of dry matter. On the contrary, in the woolly pod vetch plot, no peak of second stage juveniles was observed and egg reduction was not recognized as well as wild oats (Avena strigosa). The cyst index of soybean after crop of woolly pod vetch was high, and yield was 170 kg/10 a. The results of present study indicate that crimson clover effectively inhibited H. glycines (race 3) but woolly pod vetch did not. Jpn. J. Nematol. 34 (1), 31-37 (2004).

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[in Japanese]

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