Japanese Journal of Applied Entomology and Zoology
Online ISSN : 1347-6068
Print ISSN : 0021-4914
ISSN-L : 0021-4914
Volume 23, Issue 1
Displaying 1-11 of 11 articles from this issue
  • II. Estimation of the Threshold Density
    Akio KOJIMA, Kazuo EMURA
    1979 Volume 23 Issue 1 Pages 1-10
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
    In Niigata Prefecture, Oulema oryzae attacks rice plants from May to June. After the attack, the rice plant shows many symptoms in proportion to the intensity of attack. Retardation of growth and decrease in number of leaves and stalks per hill are most frequent. In this experiment, it could be demonstrated that the decrease in number of stalks per hill brought about a direct decrease of the rice yield. Effects on the ripening of grains were negligible. The following formula was developed: Y=-22.24+26.07logX1, which represents the relationship between the rate of yield loss (Y) and the number of 3-4 instar larvae (X1) attacking the rice plant in the peak of the season (middle June). From this formula, the minimum number of insects which caused actual loss of yield was calculated to be 7 per hill. If the lower value of 95% confidence interval for Y was adopted, the minimum number of insects (X1) became 3.5 per hill. Thus, such value can be used to express the threshold density of insects causing actual loss of yield. When the rate of injured leaves (X2) was used instead of the number of 3-4 instar larvae, the formula became Y=-20.22+0.39X2. In this case, the minimum rate and the threshold rate of injured leaves causing actual loss of yield were estimated to be 50 and 20%, respectively. These figures can be used as an index when deciding whether to carry out insecticidal control of the insect.
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  • Zenzaburô ÔGANE, Yasuaki TAKITA, Atsushi NAITO
    1979 Volume 23 Issue 1 Pages 11-16
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
    Parts sucked by nymphs and adults of Nephotettix cincticeps were investigated using feeding marks on potted rice plants placed in a screen cage at four growth stages. Rice plants under natural infestation in paddy field were sampled at the corresponding stages and were examined for feeding marks. These results correlated fairly well with each other. Main parts sucked in rice plants moved upwards as the developmental stages of the insects progressed: younger instar nymphs were found on leaf sheaths in lower parts, mid-instar nymphs on leaf blades in intermediate parts, and late instar nymphs and adults on leaf blades in upper parts. However, few feeding marks were found on rachises and primary or secondary branches of panicles. There were hardly any feeding marks on the surface of paddy. The parts sucked moved upwards to some extent as the rice plants came close to maturity. Thus, the sucked parts were scattered all over the leaf blades on the stem without being concentrated on a fixed part of rice plants. As the leaf-hopper seldom attacked the panicles, no conspicuous decrease in yield was recorded.
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  • Kenji UMEYA, Tamotsu MIYATA
    1979 Volume 23 Issue 1 Pages 17-21
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
    Hyphantria cunea has two generations per year in Japan, and there is seasonal polyphenism in the maculation of male forewings. The male moths emerging from diapause pupae of the over-wintering generation are conspicuously maculated, while those from non-diapausing pupae of the summer generation are pure white. Our experiments showed that black spots were formed by combined effects of low temperature during the pupal stage and short day-length during the larval stage and further that the former was more important than photoperiod. Concerning the relation between diapause and the formation of the maculation, short day-length during the larval stage was likely to cause an increase in the black spots only under the low temperature treatment during the pupal stage. Temperature in the larval stage was not responsible for the appearance of speckles.
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  • Hiroshi NOGUCHI
    1979 Volume 23 Issue 1 Pages 22-27
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
    A convenient and reliable bioassay method for determination of female sex pheromone of Homona magnanima was developed. Male moths were kept under continuous illumination at 25°C after emergence. On the 5th day, the males were transferred to a room at 20°C under continuous illumination and exposed to pheromone source 3 hours after the transfer. By using this method relative activity of the female sex pheromone ranging from 1×10-5 to 1×10-2 (female equivalent) was quantitatively determined. This method combining a lower ambient temperature with continuous illumination is very sensitive and more stable for monitoring the activity of the female sex pheromone than several other bioassay methods used for determination of lepidopterous sex pheromones.
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  • Sex Pheromone Activity Found in Hemolymph of the Female Pupae
    Keizo HAYASHIYA, Motoichi KITAO, Atsuko YAMAZAKI, Masato KUMAZAWA, Yas ...
    1979 Volume 23 Issue 1 Pages 28-32
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
    A strong sex pheromone activity was demonstrated in the ethereal extract of KOH-treated hemolymph of silkworm female pupae. No activity, however, was demonstrated in the untreated hemolymph extract. Such findings suggest that Bombykol or its precursor is accumulated in an inactive form bound to protein in the pupal hemolymph. Changes in the pheromonal activity during the female pupal period were observed both in the hemolymph and in the phromone-producing organ, the alluring gland. The activity in the hemolymph which appeared 4 days before the emergence of adult reached maximum value after 2 days, but the activity in the alluring gland began to increase on the day before emergence. It was concluded that Bombykol or its precursor which was present in an inactive form bound to a protein in the hemolymph was transported to and accumulated in the alluring organ at the end of the pupal period.
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  • Shoji ASANO, Masaharu KAMEI
    1979 Volume 23 Issue 1 Pages 33-38
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
    Toxicity of cycloprate (ZARDEX®, ZR-0856, hexadecyl cyclopropanecarboxylate) to the egg, larva, nymph and adult of Tetranychus urticae was investigated by bioassay method using kidney bean leaves. Toxicity of cycloprate to eggs was evaluated by the hatch inhibition and larval mortality soon after hatching. Both activities decreased with the treatments at the later stage of egg development. Lethal effect of cycloprate on larvae and nymphs was lower in mobile stage than during the time of quiescence, or soon after moulting. The lethal effect on adults was low and the surviving female adults deposited as many eggs as the controls, although the number of offspring was markedly reduced. Sterilizing effect of cycloprate on female adults was only a transitory phenomenon. The reduction in the number of offspring might be due to the hatch inhibition of laid eggs caused by residues of cycloprate on leaves contaminating the eggs. The results of the present experiments show that the reduction in mite population consecutive to field application of cycloprate may be ascribed to the inhibitory effect on both egg hatch and larval and nymphal development.
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  • Kenji KOYAMA
    1979 Volume 23 Issue 1 Pages 39-40
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
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  • Atsushi SUGIMOTO
    1979 Volume 23 Issue 1 Pages 40-42
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
    It has been observed in the laboratory that melon flies emit a smoke while producing a high-pitched buzzing sound at dusk. This smoke has a faint smell of burning.
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  • Fumihiko ICHINOHE, Sanae NAKASONE
    1979 Volume 23 Issue 1 Pages 42-43
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
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  • Hideo YAMADA
    1979 Volume 23 Issue 1 Pages 43-45
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
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  • Takaaki ITO, Chuji HIROSE
    1979 Volume 23 Issue 1 Pages 46-48
    Published: February 25, 1979
    Released on J-STAGE: February 12, 2009
    JOURNAL FREE ACCESS
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