This paper consists of two parts, one the identification of nematode species associated with tea roots collected at 15 localities which involve the principle tea growing areas in Japan, and the other the observations and tests on the nematode bionomics carried out at Makinohara Tea Plantation, Shizuoka, one of the biggest tea growing areas in Japan.
1. The following are thought to be the major nematode species attacking tea roots in Japan.
Helicotylenchus dihystera Helicotylenchus erythrinae Hemicriconemoides kanayaensis Meloidogyne incognita var. acrita Paratylenchus curvitatus Pratylenchus loosi Tylenchorhynchus nudus
2. The nematode populations in the soil were studied. Most of Hemicriconemoides and Paratylenchus are found relatively deep (around 30cm depth), whereas most of Pratylenchus and Helicotylenchus in the relatively upper layer of soil (around 10cm depth). Population densities of most nematodes are usually higher at west side of row than at east side of row; each row of tea plants being commonly set up from north to south.
3. Hemicriconemoides around tea root was observed and recorded in drawings.
4. The seasonal fluctuation of Hemicriconemoides population was examined. Throughout a year, adult females occupy most portion of Hemicriconemoides population and very few males are found, as far as the Baermann funnel technique is applied. The ratio of larvae to adults comes upon the maximum in July. Single female contains usually 14∼15 eggs and egg cells. Oviposition by single female lasts for 15∼20 days in June and July according to the observations in laboratory.
5. The nematode population was studied at the tea garden where the double amount of the nitrogenous fertilizer was applied. It seems that the population of Hemicriconemoides is reduced owing to the excessive amount of the fertilizer, while the reverse is the case with Pratylenchus.
6. A species of soil fungus was commonly found to attack adult Hemicriconemoides.

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The present work was undertaken to determine if varietal differences of rice plant in the rice stem borer resistance were estimated by means of rearing larvae on newly germinated seedlings of several rice varieties. Larvae of the rice stem borer were reared aseptically on steam-sterilized rice seedlings, of 12 to 13 varieties, which were nourished with albumen alone, and growth rate of larvae and pupal weight were recorded.
There was a negative correlation between the heading date inherent of respective varieties and the percentage pupation during the rearing period, while the body weight of pupae grown on seedlings of late-heading varieties was heavier than that of pupae on seedlings of early-heading varieties. The body weight of pupae grown on the varieties of the heavy-ear type was heavier than that of pupae on the multi-ear type varieties.
This suggests that it may be possible to compare the rice stem borer resistance among rice varieties by means of this aseptic rearing method using newly germinated seedlings. If it is true, this method will be appreciated as convenient for testing the insect resistance in rice plant and for breeding new resistant varieties, because it is able to rear the borer larvae in small space in a short period, regardless of the rice culture season.

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As has been reported in the preceding paper, different varieties of tea plants are infested by the tea red spider mite, Tetranychus kanzawai KISHIDA, in a very different measure; the varieties Asatuyu, Benihomare, Tamamidori, U-4 and Y-1 are susceptible to the infestation by the mite, while Y-3, Y-5 and Z-1 are resistant. In order to make clear the causes of the varietal differences, some indoor experiments on food-plant selection were undertaken. The mite has an ability to elect tea leaves as a food, in turn, leaves of the susceptible varieties are preferable to resistant variety leaves. The mite also prefers young leaves to mature leaves within a variety. These finding are in good agreement with the results from the field observations. Among two phases of insect behaviour by which food-plant selection is brought about, the first phase (food finding behaviour) seems to be less important for the food-plant selection of this mite, because the mites attain initially on both susceptible and resistant variety leaves of tea in equal numbers when they are allowed to choose tea leaves. It is considered, therefore, that the second phase of the food-plant selection, food acceptance, is responsible for determining the food-plant selection of the mite, and, consequently the mite infestation of tea plants.

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Seit dem Jahre 1957 haben wir die Pratylenchus-Arten in Japan untersucht. Die gefundenen Arten sind im folgenden gegeben:
(1) Pratylenchus penetrans (COBB, 1917) FILIPJEV & SCHUURMANS STEKHOVEN, 1941
Verbreitung: Hokkaido, Honshu und Kyushu.
Wirte: Arctium Lappa, Möhre, Erdbeere, Chrysanthemum, Panax Schingseng, Phaseolus angularis-Boden, Sojabohne-Boden, Zuckerrübe-Boden, Trifolium repens-Boden, Apfel-Boden u.s.w.
(2) Pratylenchus neglectus (RENSCH, 1924) FILIPJEV & SCHUURMANS STEKHOVEN, 1941
Verbreitung: Hokkaido, Honshu und Kyushu.
Wirte: Kartoffel-Boden, Sojabohne-Boden, Möhre-Boden, Amorphophalus Konjac-Boden, Gerste-Boden, Zuckerrübe-Boden u.s.w.
(3) Pratylenchus crenatus LOOF, 1960
Verbreitung und Wirte: Hokkaido (Arctium Lappa-Boden) und Honshu (Erdbeere).
(4) Pratylenchus vulnus ALLEN & JENSEN, 1951
Verbreitung: Hokkaido (Nishizawa, 1958), Honshu, Shikoku und Kyushu.
Wirte: Kartoffel (Knollen), Erdbeere, Apfel-Boden, Rose-Boden, Photinia glabra-Boden, Eriobotrya japonica-Boden u.s.w.
(5) Pratylenchus coffeae (ZIMMERMANN, 1898) FILIPJEV & SCHUURMANS STEKHOVEN, 1941
Verbreitung: Honshu, Shikoku und Kyushu.
Wirte: Kartoffel (Wurzeln und Knollen), süsse Kartoffel (Wurzeln und Knollen), Sojabohne, Bergreis, Poncirus trifoliata, japanische Zeder, Colocasia Antiquorum var. esculenta, Saccharum officinarum-Boden, Convallaria majalis-Boden u.s.w.
(6) Pratylenchus loosi LOOF, 1960
Verbreitung: Honshu, Shikoku und Kyushu.
Wirte: Teestrauch und Poncirus trifoliata.
(7) Pratylenchus zeae GRAHAM, 1951
Verbreitung: Honshu und Kyushu.
Wirte: Mais, Bergreis-Boden, Saccharum officinarum-Boden, Zoysia matrella var. tenuifolia-Boden u.s.w.
(8) Pratylenchus thornei SHER & ALLEN, 1953
Verbreitung und Wirt: Kyushu (Goto, Nagasaki Präf., Ackerboden).
(9) Pratylenchus convallariae SEINHORST, 1959
Verbreitung und Wirt: Honshu (Niigata Präf., Convallaria majalis).
(10) Pratylenchus sp. 1
Weibchen: n=4 (Präparate in Laktophenol, nachdem man die Tiere in F.A. eintauchte.); L=429∼610μ; V=84.2∼86.4%; a=22.2∼27.8; b=?; b'=8.3 (n=1); c=15.3∼17.4; G₁=29.3% (n=1); G₂=3.4% (n=1); U=1.0 (n=1); E.P.=17.9% (n=1); Schwanzlänge/Breite in der Höhe des Afters=2.5∼3.3; Schwanzlänge/Abstand von der Vulva bis zum After=71∼87%; Stachel=17.5∼20.0μ [b'=Körperlänge/Abstand von dem Kopfende bis zur Mitte des Ösophagusbulbus; U=Länge des postvulvaren Uterussacks/Breite in der Höhe der Vulva; E.P.=Exkretionsporuslage (%)]
Morphologische Merkmale: Lippengegend rund, mit drei Körperringen (Fig. 2-H). Stachel lang, Basalknöpen gross und rund. Ösophagusdrüsen blattförmig. Vulva light mehr hinten. Spermatheca nicht gesehen. Schwanz Lang und charakteristisch (Fig. 3-I, J).
Männchen unbekannt.
Fundort: Eriobotrya japonica-Garten, Mogi, Nagasaki Präf; Apfel-Garten, Tatsuno, Nagano Präf.
Um die Verbreitung von japanischen Pratylenchus-Arten überblickend aufzufassen, möchten wir vorläufig folgende Gebiete absondern und jedes von ihnen mit den charakteristischen Arten benzeichnen:
A. Hokkaido-Nordgebiet in Japan
Charakteristische (häufige) Arten: Pratylenchus penetrans und P. neglectus; andere (nicht häufige) Arten: P. crenatus und P. vulnus.
B. Honshu-Mittelgebiet in Japan
Charakteristische Arten: P. penetrans, P. neglectus, P. vulnus, P. coffeae, P. zeae und P. loosi; andere Arten: P. crenatus, P. convallariae und P. sp. 1.
C. Kyushu-Südgebiet in Japan
Charakteristische Arten

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Because of taking long incubation period, the method of virus inoculation for the plant by means of insect which has been often applied to discriminate a viruliferous insect is not considered practical.
The adipose tissues of abdomens of the insects were pressed out on a slide glass and a drop of nile blue saline solution (0.5per cent dye in 0.9per cent saline) was added to it. In the healthy individuals, the whole adipose tissues are stained deeply blue with nile blue solution, while in the affected ones many globules of various sizes, stained red with nile blue solution, are observed in the blue stained cytoplasm.
As reported in the previous paper (TAKAHASHI & SEKIYA, 1962), the fact that the adipose cells of the viruliferous insects are conspicuously reticulated in the paraffin preparations, may be due to dissolving of the lipids by various solvents such as alcohol, tolol and xylol which are used during the course of the preparation.
In the examinations of fatty tissues by the paraffin section method, 90per cent of individuals show characteristic reticular structure in the viruliferous leafhoppers, with exception of 10per cent in which the cytoplasm seems to be normal. In the nonviruliferous group, however, the cytoplasm is generally normal, i.e., 86per cent of individuals are homogeneous in structure and 14per cent are reticular. Similar results are obtained from the observation by means of the simple procedure mentioned above. Namely the red globules are observed in insects of 82per cent from the affected group, and of 25per cent from the non-affected ones.
The new method was applied in the actual survey of the insect vectors in several localities of Nagano Prefecture where the virus disease was highly prevailing, and good results were obtained in general. The data from this method coincide with ones from the standard section method as well as the direct transmission method.

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The Japanese termite was used for study of the caste differentiation of termites, particularly of the differentiation of soldiers and supplementary reproductives.
Emergence of soldiers was examined in 200 experimental colonies starting each with a royal couple, and some relation between the emergence of soldiers and the number of larvae plus workers was noticed. Soldiers appeared in only 4 out 53 artificial colonies containing less than 5 larvae plus workers, the emergence ratio, 7.4per cent. Among the 25 colonies containing more than 10 larvae plus workers, on the contrary, 20 colonies yielded soldiers. Ratio of soldier emergence reached 80per cent here. It follows therefore that the emergence ratio of soldiers increases with the number of larvae plus workers in the colonies and a certain number of larvae plus workers is needed for the initiation of soldier differentiation.
Another series of experiments demonstrated that the supplementary reproductives could develop either from larva-workers or nymphs, but most frequently from nymphs combined with considerable numbers of workers.
From these results it can be concluded that the caste differentiation in the Japanese termite is easily influenced by the construction of members in the colonies. From the result, a diagram of the caste differentiation in the Japanese termite was made.

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Parasitism of the two species of egg parasites of Nezara viridula, namely Asolcus mitsukurii and Telenomus nakagawai was the centre of the discussion based on the analysis of the data obtained from the field censuses mainly carried out at Asso in 1961 and 1962 for the successive generations of the host. In the first generation of the host, the egg masses parasitized by both species produced more A. mitsukurii significantly than T. nakagawai without hyperparasitism, but in the second one this tendency could not be detected. The mean size of egg masses parasitized by different species increased but the value of c.v. decreased in the order of A. mitsukurii, T. nakagawai and both species. Such a tendency was not observed in the second generation, because of the increase in the mean size of egg masses. These facts showed that interspecific interference in the first generation of the host occurred through more or less direct coactions of female parasites, but this was not the case in the second generation.
Measurement of the degree of interspecific association was made by using the COLE'S index of interspecific association and the results obtained were discussed by a plausible mechanism of interspecific interference brought about by fighting behaviour of the females of both species; A. mitsukurii wins over T. nakagawai by fighting. Percentage of parasitism of both species remarkably decreased in the second generation of the host as compared with that of the first generation. This was probably due to the poor synchronization of the parasites with the host eggs owing to the difference in the dispersal ability between host and parasites.
At Kogawa area where two species of Nezara are co-existing, T. nakagawai dominated A. mitsukurii, in contrast with the reversed case at Asso. This is possibly ascribed to the difference in the climatic conditions between the two areas. There could not be seen the severe interspecific interference in the first generation of the host as observed at Asso.
The possibility of biological control of Nezara population by liberation of parasites was proposed from these considerations.

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[in Japanese]

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