Kazuyoshi Miyashita

Biology ofHyphantria cunea Drury (Lepidoptera: arctiidae) in Japan. V. Preliminary life tables and mortality data in urban areas

Studies on the population dynamics of the fall webworm,Hyphantria cunea have been carried out at three survey stations and along selected roads in the urban area of Tokyo since 1966. Twelve survivorship curves obtained during two years and 8 life tables show that the mortality rate in early developmental stages of the fall webworm is remarkably low as compared with that of other lepidopterous defoliaters and the mortality rate in later developmental stages is compensatory high. The low mortality rate in early stages is considered to be due to the protective role of the nest-web and the lack of egg and larval parasites. All but one parasitic species emerge from prepupae and pupae. Spiders living in the nest-web of the fall webworm play an important role in reducing the number of young larvae. Direct observations and caging experiments showed that relatively high mortality during later larval stages is mainly due to predation by birds (in the first generation) and wasps (in the second generation). The generation mortality in the survey stations always exceeded the level where the population is kept at the steady state, and the outbreak of this moth is considered to be continued by the immigration of adults from large trees growing in gardens on which the larvae can escape from predation pressure.

Population dynamics of the chestnut gall-wasp,Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae): II. Distribution of individuals in bud of chestnut tree

As a part of serial study on population dynamics of the chestnut gall-wasp,Dryocosmus kuriphilus, analyses of the distribution of eggs, gall-cells and emergent holes were made from the statistical point of view. Many of distributions of the eggs per bud could be described by the truncated Poisson, but some cases showed slight overdispersion than expected by chance. Because of no linear increase of

The estimation of population density of the green rice leafhopper,Nephotettix cinticeps Uhler, in spring field by the capture recapture method

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Natural mortality of the common cabbage butterfly, Pieris rapae crucivora Boisduval, with considerations on the factors affecting it.

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On the spatial distribution of Pieris rapae crucivora population.

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Estimation of Population Density of the Green Rice Leafhopper (Nephotettix cincticeps UHLER) by the Mark-Recapture and the Sweeping Methods

(expected mean for complete sample), however, the truncated negative binomial seemed to be not so available for whole series. Distributions of the gall-cells and the emergent holes were, on the other hand, well described by the truncated Poisson distribution when the observed frequency was calculated for respective trees. Negative-binomial tendency found in distributions from some stations consisted of a certain number of trees would be resulted from mixture of Poisson populations with different means. Random or slightly concentrated oviposition and random mortality within galls was thus supposed for future study unless the proof favouring other distribution models would appear.