The rice stem borer was daily obtained by means of the light trap situated on the Kyushu Agricultural Experiment Station Farm in Chikugo, Fukuoka Prefecture, throughout the rice cultivation period from 1947 to 1961. Annual fluctuation of the rice stem borer population was analyzed by correlation method. The results obtained were summarized as follows:
1. Seasonal prevalences in each year were conclusively characterized into three types of groups (Fig.1), and reciprocal successive changes among three types were clearly recognized. And that, these three types were closely related to the numerical occurrence in each year, respectively.
2. Annual fluctuations of the rice stem borer population were susceptible to low temperature from May to July or from June to July in each year, and the low temperature seems to have promoted high population of this insect.
3. High sex ratio in the first generation indicates that the population is numerous not only in the first generation but also in that year and in the following year.
4. Sex ratio in the first generation and annual population of this insect changes with fifteen years' cycle.
It could be conclusively suggested that the sex ratio in the first generation would be available for forecasting the occurrence of the rice stem borer. Therefore, when value of the sex ratio is over sixty per cent, the population would be expected numerous not only in that year but also in the following year.

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Four species, the brown planthopper, the white back planthopper, the small brown planthopper, and the green rice leafhopper, were caught in light trap, while their seasonal abundances in a rice field near the light trap site (Fig. 1) were surveyed using sticky trap and suction catcher during the rice-cultivating season in 1960 and 1961. The seasonal prevalences determined by three methods (Fig. 2) were compared with one another only in macropterous adults of each species by means of the correlation method (Table 1). The prevalences determined by sticky trap were similar to those determined by suction catcher in each species except the brown planthopper. In cases of the brown planthopper and the white back planthopper, the prevalences determined by light trap were different from those determined by sticky trap and suction catcher. In cases of the small brown planthopper and the green rice leafhopper, however, the prevalences determined by light trap were somewhat similar to those determined by sticky trap and suction catcher.

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Field tests were conducted to evaluate Sumithion [0, 0-dimethyl-0-(3-methyl-4-nitrophenyl) thiophosphate] against the rice stem borer Chilo suppressalis WALKER.
In 1960 at the young ear formation stage of rice plants, the mortality of released larvae in the field was examined after spraying, and the results were shown in table I. In 1961 at the tillering stage of rice plants, the number of damaged stems by natural infestation of the larvae was examined after spraying, and the results were shown in table 5.
It was concluded that Sumithion was more effective than parathion, but less effective than methyl parathion against the larvae in the stems of the rice plants. Residual effects of Sumithion against the newly hatched larvae seemed to be maintained longer than methyl parathion.

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Studies were conducted on the absorption and translocation of γ-BHC into the rice plant from the soil treated with 12.5, 25.0, and 50.0 mg of γ-BHC per (16 cm in diameter and 19 cm in depth) before planting.
The concentrations of γ-BHC in the rice plant and surface water were determined by means of bioassay using the Azuki bean weevil.
The results obtained were summarized as follows:
1. Some differences in fresh weight of the rice plant were observed among the treatments. The growth of the plant delayed with the increase of γ-BHC in soil.
2. The detected amounts of γ-BHC in the leaf sheath or root were proportional to the dosages of each treatment, while a considerable amount was detected in the leaf blade. The maximum concentrations in the leaf sheath of the plant grown in each plot treated with above dosages were approximately 2, 4, and 8 p.p.m., respectively.
3. The concentrations of γ-BHC in the surface water seemed to reach the maximum in 5 days after treatment. The maximum concentrations in each plot treated with above dosages were approximately 0.18, 0.28, and 0.37 p.p.m., respectively.

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1. Among the nematodes found in Kyushu and identified by the authors, the following are re markable from the viewpoint of nematode distribution and parasitism: (1) Pratylenchus loosi, tea root, Higashi-sonogi Town, Nagasaki Pref., (2) P. coffeae, Citrus root, Tarumizu City, Kagoshima Pref., (3) Radopholus oryzae (?), paddy field (in dry condition), Aino Town, Nagasaki Pref., (4) Tylenchorhynchus claytoni, azalea soil, Kusano Town, Kurume City, Fukuoka Pref., (5) Tylenchorhynchus sp., soybean field, Yabe Town, Kumamoto Pref., (6) Tylenchorhynchus ? sp., sugar cane soil, Okino-erabuzima, Kagoshima Pref.
2. In regard to root-lesion nematodes, four species have been found in Kyushu, that is, Pratylenchus coffeae, P. vulnus, P. zeae and P. loosi.

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The following species of stunt nematodes were collected in Kyushu and identified by the authors.
1. Some specimens of the nematodes extracted from around azalea roots in Kurume City, Fukuoka Pref. were identified as Tylenchorhynchus claytoni. From the population study of nematodes around the roots of normal azaleas and stunted ones, the damage of this nematode on azaleas was supposed.
2. The stnut nematode collected from the soil of soybean field in Yabe Town, Kumamoto Pref. is probably a new species which resembles T. brevidens morphologically.
3. A species of the nematodes found from around the roots of sugar cane in Okinoerabu Island, Kagoshima Pref. is supposed to belong in a new genus. The specimens resemble Tylenchorhynchus species, but have no annule on lip region. They differ from Trophorus species in having didelphic ovaries.

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In his former report the author concluded that cucumber aphids, Aphis gossypii GLOVER migh be indifferent to the transmission of potato virus Y.
The transmission experiment in this case was rather complicated and was tried to transfer the insects from mechanically infected Solanum nigrum to that of the healthy. And then, the latter was tested whether it was infected or not by the use of Nicotiana sylvesfris as an indicator plant. In the present study the transmission experiment of the virus was carried out using N. sylvestris both as the diseased and the test plants. Before rearing the insects on the diseased and on the test plants, the leaves were gently rubbed with heated spatula to wither the hairs of the leaves.
The acquisition feeding of the insect on the diseased leaf was 1 to 10 minutes and the infection feeding on the test plant was 20 to 60 minutes. The results given in Table 1 showed that Aphis gossypii was capable to transmit potato virus Y from diseased N. sylvestris to the healthy especially in the warm season. The transmission experiment of potato virus Y from diseased N. sylvestris to potato that had affected only with potato virus X with the use of Aphis gossypii as the vector was also carried out with success as shown in Figure 1.

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Daikon mosaic virus infected leaves of turnip plant were divided into the following three groups. I. Inoculated leaves ; usually showed no mosaic symptom (the third leaf from below). …… Group A
II. Infected leaves developed after inoculation.
1. Mature leaves with severe mosaic symptom (the fifth leaf from below).……… Group B
2. Young and growing leaves with mosaic symptom (the sixth leaf from below).……… Group C
Respiration rates of the leaves of each Group were compared with those of corresponding leaves from healty plant by measuring O₂ consumption and CO₂ production by Warburg respirometer.
The rates of O₂ consumption and CO₂ production of Group C leaves were 25% and 28% higher, respectively, than those of healthy leaves, while no differences in respiration rate were found for Group A and B leaves.
It appears that this increase in respiration rate is not due to the virus multiplication, but may be attributed to the abnormalities of the host tissue caused by virus disease.

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Experiments were carried out to study the mechanism of which Potato X Virus (PXV) is not transmitted by aphids. Green peach aphids (Myzus persicae SULZER) transmitted only Potato Y Virus (PYV) to the healthy tobacco (Nicotiana tabacum var. Xanthi) plants from Potato crinkle mosaic (PXV+PYV) diseased tobacco, and did not transmit PXV to the tobacco plants. NISHI (1958) have demonstrated the inhibitory effect of substance secreted by aphids on feeding plants upon the infectivity of Tobacco mosaic Virus (TMV). In the present experiments, pressed juice of tobacoo plants affected by PXV was mixed with alcohol precipitated substances in pressed sap from chinese cabbage (Brassica pekinensis RUPR.) on which green peach aphids had been fed. The virus juice was tested for infectivity by local lesion method using Gomphrena globosa. The substances secreted by aphids on feeding plants inhibited the infectivity of PXV strongly as in the case of TMV.

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[in Japanese]

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It was attempted anatomically to ascertain the infection mechanism in reference to the resistance to penetration of uredospore on the resistant-form of oats. As for the duration of time from the inoculation to the formation of substomatal vesicle, there were no differences between the resistant and the susceptible forms The development and elongation of infection hyphae on the resistant form, however, were very much less or did not take place.

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