Saito, Y., 1995. Sociobiological Aspects of Spider Mite Life Types. J. Acarol. Soc. Jpn., 4(2): 55-67. Various life styles(life types)observed in Tetranychinae were examined from the viewpoint of sociobiology. It was demonstrated that most spider mite species have elements of sociality to some degree. The most primitive stage of sociality appeared as a web egg cover in the tribe Eurytetranychini. In the Tetranychini, there were various life types which may reflect different kinds of social organization. Parasocial life(highly developed subsociality)where individuals behave cooperatively was observed in the genera Eotetranychus and Schizotetranychus. Environmental, phylogenetic, life historical and behavioral characteristics were discussed as factors enhancing the social life of spider mites.

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The hexane extract of Hydronothrus crispus Aoki (Oribatida: Trhypochthoniidae) was analyzed by GLC and GC/MS using a capillary column and the following four compounds were identified as the non-hydrocarbon fraction; 2-hydroxy-6-methylbenzaldehyde, neral, geranial and neryl formate. The hydrocarbon fraction analysed based on GLC and GC/MS of their DMDS derivatives consisted of a mixture of tridecane, pentadecane, (Z) -7-pentadecene, (Z) -7-heptadecene, (Z) -8-heptadecene and (Z, Z) -6, 9-heptadecadiene. All the compounds found in the secretions of oribatid mite were commonly distributed as components of opisthonotal gland secretions from astigmatid mites.

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Ohkubo, N., 1995. Species list of Quadroppiidae(Acari: Oribatida)with descriptions of a new genus and two new species. J. Acarol. Soc. Jpn., 4(2): 77-89. All hitherto known species and subspecies of the genus Quadroppia are listed up and separated into Quadroppia s. str. and Coronoquadroppia nov. gen. Two new species, C. parallela and C. expansa are described from Japan; the former is the type species of the genus.

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The developmental success of the citrus red mite, Panonychus citri (McGregor) and its oviposition on47species of plant were studied for five populations collected from the satsuma mandarin, Japanese holly, Japanese yew, orange osman and fortunes osmanthus. The host ranges for three populations (citrus type) that developed on citrus trees but not on any of the oleaceous plants, were similar to one another, and were different from those of the other two populations (oleaceous type) that normally developed on oleaceous plants, although five plants (sour orange, trifoliate orange, pear, fig and kudzu vine) were the common hosts of all five populations. In intrapopulation crosses, all populations produced both female and male progeny. Inter-population crosses between the three populations of the citrus type and between the two populations of the oleaceous type produced both sexes, showing that populations belonging to the same type were compatible each other. Mites of the oleaceous type produced F1 females when mated with the mites of the citrus type. However, these F1 females failed to lay eggs and/or failed to produce fertile F2 females, even if the F1 females mated with the males from the parental populations . This trend indicates that the oleaceous type is reproductively incompatible with the citrus type. This study indicates that P. citri contains at least two different biological entities, which show not only differences in host ranges but also a lack of reproductive compatibility with one another.

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The distributions of Panonychus mori and P. citri occurring on peach in Okayama Prefecture, Japan were investigated. Their susceptibilities to acaricides were also studied for individual populations. Both species were distributed widely on peach trees, and the areas where the distributions of the two species overlapped ranged from intermediate to southern Okayama. The occurrence of each species was consistent in each peach orchard in the areas, and the densities of diapausing eggs of P. mori tended to be lower in orchards where the density of adults of P. citri were higher. All populations of P. mori were susceptible to all acaricides tested, whereas several populations of P. citri exhibited extremely low susceptibilities, in particular, to hexythiazox and fenbutatin-oxide.

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Kuriki, G., 1955. Life cycle of Trhypochthoniellus setosus Willmann in a Sphagnum moor at Yachidaira, Northeast Japan. J. Acarol. Soc. Jpn., 4(2): 113-122. The life cycle of Trhypochthoniellus setosus Willmann, the dominant oribatid mite in a moor at Yachidaira, Northeast Japan, was studied in laboratory cultures and by field surveys. It is demonstrated that T. setosus initiates one generation per year and takes one year for each developmental stage. Adults released larvae between July and early September: around five larvae per female in the field, which is close to the mean clutch size. Some of the factors influencing the decrease in population density in the summer are discussed, with particular reference to soil temperature and soil moisture.

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Yamamoto, S. and S. Noda, 1995. Collecting records of trombicuhd mites in Kagoshima Prefecture in 1993and 1994. J, Acarol. Soc. Jpn., 4(2): 123-127. Surveys on the trombiculid mite distribution at 13sites of Kagoshima Prefecture where have remained unclear in our previous surveys were carried out from November 1993to December 1994. A total of 5, 822trombiculid mites consisting of five genera and 11 species were recovered from 65 Apodemus speciosus: Leptotrombidium scutellare, L. daisen, L. kurosio, L. pallidum, L. murotoense, L. kitasatoi, L. fuji, Neotrombicula japonica, Miyatrombicula kochiensis, Walchia ogatai, and Gahrliepia two L. himiz were recovered from one Urotrichus. Five species, L. scutellare, L. pallidum, L. kitasatoi, L. fuji and M. kochiiensis, were predominant as widely collected in 8 to 12 sites. In Yoshida-cho, four species, L. scutellare, L. palldium, L. kitasatoi and L. fuji, were collected by Tullgren's funnel method, and only L. scutellare was collected by plate method and black cloth method.

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