Seventeen species of macrochelid mites belonging to the genera Glyptholaspis and Macrocheles are recorded from Sulawesi, Indonesia. They were all collected from dung beetles (Aphodiinae, Scarabaeinae). Except for Macrocheles kraepelini, all the species are recorded from Sulawesi for the first time. Six species, i.e., M. convexus sp. nov., M. donggalensis sp. nov., M. persimilis sp. nov., M. pilosellus sp. nov., M. simulans sp. nov., M. variodecoratus sp. nov., are new to science. A key to 55 species of macrochelid mites recorded from Indonesia is also provided.

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DNA sequences of the internal transcribed spacer 1 (ITS1) of the nuclear ribosomal RNA gene and of mitochondrial cytochrome oxidase subunit I (COI) were analyzed for 13 Tetranychus kanzawai populations collected in northern Hokkaido, Japan. Five and 13 DNA haplotypes were found for ITS1 and COI, respectively, and the COI haplotypes were classified into 5 amino acid haplotypes. Monophyly of all haplotypes found in this study was strongly supported by bootstrap analysis, confirming that all analyzed individuals belonged to the T. kanzawai complex. The geographic distributions of these haplotypes overlapped, showing that populations had differentiated genetically from each other. However, some hybrid individuals were detected, indicating that genetic differentiation was not complete. Large genetic variation in the DNA sequences in the study area and the discovery of ancestral haplotypes strongly suggest that the complex originated in Northeast Asia.

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We used two types of molecular markers to analyze the genetic structure of seven populations of Tetranychus kanzawai complex collected from the Tohoku area of northern Honshu, the main island of Japan. For phylogenetic analysis, we used DNA sequences of the mitochondrial cytochrome oxidase subunit I (COI) gene and the internal transcribed spacer 1 (ITS1) region of the ribosomal RNA gene; for detailed analysis of population structure, we used microsatellite markers. We found that all population pairs were differentiated significantly; this differentiation was enhanced significantly by host plant effect but not by geographic distance among the populations. DNA sequencing of ITS1 and COI regions and microsatellite analysis both showed that the population occurring on Pueraria lobata was deviated genetically from the other populations. Therefore, our analysis suggested that population subdivision in T. kanzawai complex developed because of host plant effects rather than geographic barriers.

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Some polyphagous herbivores prefer the host plants on which they developed. This enhances the genetic differentiation among populations on different host species, and thus they specialize on separate host species. The polyphagous spider mite Tetranychus kanzawai includes populations that have adapted to toxic plants such as Hydrangea macrophylla and Nerium indicum. We examined the influence of the host plants utilized during immature development of the mites on the host preference of adult females, in populations derived from H. macrophylla and N. indicum. When each population was reared on its original plant during the immature stage, they showed significantly higher preference for the original plant than when they were reared on Phaseolus vulgaris (suitable host). Thus, the preference for the host plant from which each population was derived is induced by exposure to the plant during the mite's immature development.

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Neoseiulus californicus has been increasing in number and geographical distribution since the 1990s in Japan, and is considered to be a new prospective predator species against Panonychus citri on citrus. We investigated the occurrence of N. californicus in citrus orchards with different agrochemical spraying programs in Kyushu district, south-western Japan. The occurrence of N. californicus greatly differed among orchards. In conventional control orchards and agrochemical-reduced orchards, N. californicus females were observed in 50–60% of orchards. On the other hand, N. californicus females were rare in agrochemical-free orchards. N. californicus females were observed in all prefectures in the Kyushu district, but the occurrence of N. californicus was different among the prefectures. In Saga Prefecture, N. californicus females were observed in all conventional control and agrochemical-reduced orchards. In Nagasaki Prefecture, Kumamoto Prefecture, and Miyazaki Prefecture, N. californicus females were observed in 60% or more of the conventional control and agrochemical-reduced orchards. In Fukuoka Prefecture, N. californicus females were abundant in the southern area, whereas no N. californicus females were observed in the northern area. In Oita Prefecture, N. californicus females were observed in only 30.8% of the conventional control and agrochemical-reduced orchards. N. californicus females were rare in Kagoshima Prefecture.

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The lethal effects of two types of oxygen absorbers on the eggs of the house dust mites, Dermatophagoides farinae, D. pteronyssinus, and Tyrophagus putrescentiae were studied. For D. farinae, and D. pteronyssinus, the mortality obtained after 2 days in an air-tight container with iron (Fe)-type oxygen absorbers was 100%, while an ascorbic-acid-type oxygen absorber needed 5 days to obtain 100% mortality. On the other hand, the two types of oxygen absorbers showed no significant lethal difference on T. putrescentiae.

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