Overwintering at multiple life stages in Schizotetranychus shii (Acari: Tetranychidae), a specialist of evergreen chinquapin.

Spider mites (Acari: Tetranychidae) overwinter as eggs or adult females, but some do so as multiple life stages on evergreen hosts. However, proximate factors influencing such overwintering stages remain poorly understood. This study investigated photoperiodic responses and life-stage compositions during winter in a population of Schizotetranychus shii, a specialist of Japanese chinquapin (Fagaceae).

Phylogeographical evidence for historical long-distance dispersal in the flightless stick insect .

Exploring how organisms overcome geographical barriers to dispersal is a fundamental question in biology. Passive long-distance dispersal events, although infrequent and unpredictable, have a considerable impact on species range expansions. Despite limited active dispersal capabilities, many stick insect species have vast geographical ranges, indicating that passive long-distance dispersal is vital for their distribution.

Hybridisation between host races broadens the host range of offspring in Eotetranychus asiaticus (Acari: Tetranychidae).

Host adaptation in herbivorous arthropods is one of the first steps to sympatric speciation, and spider mites (Acari: Tetranychidae) are useful model organisms for studying this phenomenon. Many researchers have studied the process of host adaptation via artificial selection experiments. Recent analyses suggest that hybridisation has diversified host ranges, although empirical evidence is scarce.

Development of microsatellite markers for the geographically parthenogenetic stick insect Phraortes elongatus (Insecta: Phasmatodea).

Many plant and animal species exhibit geographic parthenogenesis, wherein unisexual (= parthenogenetic) lineages are more common in their marginal habitats such as high latitude or altitudes than their closely related bisexual counterparts. The Japanese stick insect, Phraortes elongatus (Thunberg) (Insecta: Phasmatodea), is known as a geographically parthenogenetic species due to the existence of both bisexual and unisexual populations. Here, we developed microsatellite markers to infer the genetic variation among populations of P.

Photoperiodic control of reproductive arrest in the oak-inhabiting spider mite Schizotetranychus brevisetosus (Acari: Tetranychidae).

Populations of Schizotetranychus brevisetosus Ehara (Acari: Tetranychidae), which live on the evergreen oak (Quercus glauca), survive the coldest months as either adult females or winter eggs. Adult females comprise the majority of the population in early November and oviposit from late November to early March. Most winter eggs hatch by late March, and adults of the next generation emerge in April.

Production of winter eggs in Schizotetranychus brevisetosus (Acari: Tetranychidae) inhabiting evergreen Japanese blue oak.

The overwintering pattern of parasitic herbivorous arthropods is closely related to host phenology, because defoliation imposes strong selection pressures on various developmental stages. This relationship has been well studied in populations of spider mites (Acari: Tetranychidae) on deciduous hosts, but is little studied in populations on evergreen hosts, probably because their leaves are always available. However, spring defoliation may also influence the life cycle.

Variation in nesting behavior of eight species of spider mites, Stigmaeopsis having sociality.

Nesting behavior is considered to be an important element of social living in animals. The spider mites belonging to the genus Stigmaeopsis spend their lives within nests produced from silk threads. Several of these species show cooperative sociality, while the others are subsocial.

Lethal male combats in Schizotetranychus brevisetosus (Acari: Tetranychidae) on blue Japanese oak (Quercus glauca).

Male spider mites (Acari: Tetranychidae) guard preimaginal quiescent females to reserve paternity. In a few species of Stigmaeopsis that make densely woven silky nests on the surface of host plants, mature males attack and even kill rivals to gain their rights to inseminate young females in the nest. Here we report that the adult males of Schizotetranychus brevisetosus (Acari: Tetranychidae), whose web nest construction behavior evolved independently from Stigmaeopsis spp.

Reproductive isolation between Stigmaeopsis celarius and its sibling species sympatrically inhabiting bamboo (Pleioblastus spp.) plants.

Stigmaeopsis celarius Banks (hereafter Sc) is a spider mite living and feeding on the leaves of various bamboo species such as Moso bamboo [Phyllostachys edulis (=P. pubescens)] and Pleioblastus spp. (Poaceae).

Effectiveness of cervical cancer screening based on a mathematical screening model using data from the Hiroshima Prefecture Cancer Registry.

Here we assessed the effectiveness of cervical cancer screening using data from the Hiroshima Prefecture Cancer Registry regarding patient age at the start of screening and differences in screening intervals. A screening model was created to calculate the health status in relation to prognosis following cervical cancer screening and its influence on life expectancy. Epidemiological data on the mortality rate of cervical cancer by age groups and mortality rates from the Hiroshima Prefecture Cancer Registry were used for the model projections.

Relationship between body colour, feeding, and reproductive arrest under short-day development in Tetranychus pueraricola (Acari: Tetranychidae).

In Tetranychus spider mites (Acari: Tetranychidae), diapausing females have a conspicuous orange body colour, which is used as an indicator of diapause induction in many laboratory studies. However, to which extent body colour reflects reproductive activity is scarcely investigated. In this study, we investigated the relationship between body colour, reproductive arrest, and food intake in the inbred strain of T.

Host suitability of house fly, Musca domestica (Diptera: Muscidae), pupae killed by high or low temperature treatment for a parastoid, Spalangia endius (Hymenoptera: Pteromalidae).

The objective of this study was to establish a high quality progeny production system for the house fly parasitoid, Spalangia endius (Hymenoptera: Pteromalidae), by stockpiling hosts. We performed two host killing methods before host storage: (i) heat-killed by 30 min exposure to 50°C or (ii) freeze-killed by 10 min exposure to -80°C. The average number of parasitoids that emerged from nonstored house fly pupae after heat- or freeze-killing was not significantly different from live pupae.

Coelomic fluid: a noninvasive source of DNA in earthworms.

To investigate whether coelomic fluid secreted by earthworms can be a noninvasive source of DNA, we amplified and sequenced DNA extracted from the coelomic fluid and muscle tissue of eight worms. The sequences obtained using DNA extracted from both sources were identical. All cytochrome c oxidase subunit I (COI) mitochondrial DNA sequences, including those retrieved from GenBank, formed a monophyletic group of Metaphire sieboldi.

Analysis of genetic variation and phylogeny of the predatory bug, Pilophorus typicus, in Japan using mitochondrial gene sequences.

Pilophorus typicus (Distant) (Heteroptera: Miridae) is a predatory bug occurring in East, Southeast, and South Asia. Because the active stages of P. typicus prey on various agricultural pest insects and mites, this species is a candidate insect as an indigenous natural enemy for use in biological control programs.

Overwintering survival and postdiapause fecundity in a population of the Kanzawa spider mite Tetranychus kanzawai (Acari: Tetranychidae) on Orixa japonica (Rutaceae).

In several adult-diapausing insects and mites, long duration of diapause decreases egg production after diapause termination. However, such nonlethal effects are much less studied than overwintering survival. In this study, lethal and nonlethal effects of different periods of diapause were investigated in an adult-diapausing spider mite, Tetranychus kanzawai Kishida (Acari: Tetranychidae), through field experiments.

Effect of host plants on diapause induction in immature and adult Tetranychus kanzawai (Acari: Tetranychidae).

I determined the difference in sensitivity of immature and adult mites to host plants with regard to diapause induction. I used immature and adult polyphagous spider mites, Tetranychus kanzawai Kishida (Acari: Tetranychidae), and two host plants, Orixa japonica Thunb. (Rutaceae) and Phaseolus vulgaris L.

Dominant and recessive inheritance patterns of diapause in the two-spotted spider mite Tetranychus urticae.

In this study, we investigated the diapause incidence in 3 geographic strains of the two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae). Under diapause-inducing conditions of 12:12 light:dark at 15 degrees C, the diapause incidence was nearly 100% in a strain from northern Japan (Sapporo), whereas it was nearly 0% in 2 strains from southern Japan (Itoman and Takanabe). Reciprocal crosses clearly showed that the nondiapause phenotype is inherited in a completely dominant manner, and no maternal effect was detected.

Suppression of ovarian development and vitellogenin gene expression in the adult diapause of the two-spotted spider mite Tetranychus urticae.

Tetranychus urticae (Acari: Tetranychidae) possesses a sac-like ovary with characteristic oocytes that protrude from the ovarian surface. In nondiapause females, transparent oocytes became opaque with yolk deposition between days 0 and 1 in the adult stage at 20 degrees C. In diapause females, however, ovarian development ceased at a stage having transparent oocytes without yolk deposition; this stage corresponded to the day-0 stage of the nondiapause females.

Development times under long- and short-day conditions in the Kanzawa spider mite Tetranychus kanzawai (Acari: Tetranychidae).

In a theoretical framework, the development time of arthropods is closely associated with population growth, so that strong selection pressure may be imposed on development patterns. In this context, selection towards shorter development times may act on female mites in the season when population size is growing. In contrast, such selective pressure may be weaker just before hibernation, because the stage adjustment may be more important than population growth in such seasons.