Kimiko Okabe

Bumblebee commercialization will cause worldwide migration of parasitic mites

We investigated natural populations of three Japanese native bumblebee species to determine the status of infestation by a tracheal mite, Locustacarus buchneri, which we had earlier detected in introduced commercial colonies of the European bumblebee, Bombus terrestris. We also investigated mite infestation in commercial colonies of a Japanese native species, B. ignitus, which are mass‐produced in the Netherlands and reimported into Japan. We detected the mite in both natural and commercial colonies of the Japanese species. Comparison of 555 bp sequences of the mitochondrial DNA (mtDNA) cytochrome oxidase 1 (CO1) gene from the mite showed that there were seven haplotypes, on the basis of combinations of substitutions at eight sites in the gene. The haplotypes of the mites in the Japanese native bumblebees and the haplotypes of the mites in B. terrestris did not overlap; however, mtDNA of mites detected in the commercial colonies of B. ignitus possessed the same sequence as a European haplotype. These results indicate that transportation of bumblebee colonies will cause overseas migration of parasitic mites of different origins.

Biology, ecology, and management of the bulb mites of the genus Rhizoglyphus (Acari : Acaridae)

Bulb mites of the genus Rhizoglyphus (Claparède) (Acari: Acaridae) have been identified as pests of many crops and ornamentals in storage, in the greenhouse, and in the field. The most importanthosts are species in the family Liliaceae (e.g. Allium spp.), but bulb mites will often attack otherimportant crops such as potatoes (Solanum sp.) and carrots (Daucus carota). Despite their economicimportance and broad distribution, the systematics of the genus remains in a state of confusion and is inneed of a comprehensive revision. In addition, the field biology and ecology of these mites is not wellunderstood, and methods for sampling, monitoring, and loss assessment are limited. Management of bulbmites is complicated by their short generation time, high reproductive potential, broad food niche,interactions with other pests and pathogens, and unique adaptations for dispersal. Historically, control ofthese acarine pests has relied on the use of synthetic miticides and insecticides, but this option is nowlimited due to documented resistance and withdrawal of registration of some products. Alternativecontrol strategies, including cultural and biological control, have shown limited success, but need to befurther developed and implemented.

Biodiversity and ecosystem services: lessons from nature to improve management of planted forests for REDD-plus

Planted forests are increasingly contributing wood products and other ecosystem services at a global scale. These forests will be even more important as carbon markets develop and REDD-plus forest programs (forests used specifically to reduce atmospheric emissions of CO2 through deforestation and forest degradation) become common. Restoring degraded and deforested areas with long-rotation planted forests can be accomplished in a manner that enhances carbon storage and other key ecosystem services. Knowledge from natural systems and understanding the functioning novel of ecosystems can be instructive for planning and restoring future forests. Here we summarize information pertaining to the mechanisms by which biodiversity functions to provide ecosystem services including: production, pest control, pollination, resilience, nutrient cycling, seed dispersal, and water quality and quantity and suggest options to improve planted forest management, especially for REDD-plus.

Diversity of Stag Beetle-Associated Nematodes in Japan

ABSTRACT A survey of stag beetle (Lucanidae)-associated nematodes was conducted in Japan to construct a preliminary species inventory and to obtain their molecular profiles as a first step for elucidating their host fidelity and ecological roles. Eight species of stag beetles (94 individuals in total), Dorcus rubrofemoratus, D. montivagus, D. striatipennis, D. rectus, D. titanus, Prismognathus angularis, Prosopocoilus inclinatus, and Lucanus maculifemoratus were collected from 12 localities in Japan, dissected and examined for nematode associates. Isolated nematodes were used to attempt the establishment of voucher cultures. Successfully cultured nematodes were observed under a light microscope for morphological identification at genus or species level, and were sequenced for their near full length SSU and D2/D3 LSU. All investigated lucanid individuals harbored at least one species of nematode, and eight species (Bursaphelenchus sp., Koerneria luziae, K. lucani, Pristionchus cf. pacificus, Pristionchus sp., Pseudodiplogasteroides composites, Pseudodiplogasteroides sp., and Rhabditidoides sp.: 40 populations of nematodes in total), were successfully cultured from the insects. Within these eight species, four species were considered to predominate and had low carrier specificity and wide distribution, i.e., K. luziae, P. composites, Pristionchus sp. and Rhabditidoides sp. were isolated from various species of beetles and from several different localities, and K. luziae, K. lucani, and P. composites have been previously described from native lucanids in Germany. Considering the recent world-wide trade of living insects, especially lucanids as pets, we suggest the use of caution to prevent the invasion of their associated nematodes and other associated organisms.

Plantation vs. natural forest: matrix quality determines pollinator abundance in crop fields.

In terrestrial ecosystems, ecological processes and patterns within focal patches frequently depend on their matrix. Crop fields (focal patches) are often surrounded by a mosaic of other land-use types (matrix), which may act as habitats for organisms and differ in terms of the immigration activities of organisms to the fields. We examined whether matrix quality affects wild pollinator abundance in crop fields, given that the species (Apis cerana) generally nest in the cavities of natural trees. We examined fields of a pollination-dependent crop surrounded by plantations and natural forests, which comprised the matrix. Our analysis revealed a clear positive effect of the natural forest on the pollinator abundance, but the plantation forest had little effects. These indicate that agricultural patches are influenced by their matrix quality and the resulting crop pollinator abundance, suggesting the importance of matrix management initiatives such as forest restoration surrounding agricultural fields to improve crop production.

Succession Influences Wild Bees in a Temperate Forest Landscape: The Value of Early Successional Stages in Naturally Regenerated and Planted Forests

In many temperate terrestrial forest ecosystems, both natural human disturbances drive the reestablishment of forests. Succession in plant communities, in addition to reforestation following the creation of open sites through harvesting or natural disturbances, can affect forest faunal assemblages. Wild bees perform an important ecosystem function in human-altered and natural or seminatural ecosystems, as they are essential pollinators for both crops and wild flowering plants. To maintain high abundance and species richness for pollination services, it is important to conserve and create seminatural and natural land cover with optimal successional stages for wild bees. We examined the effects of forest succession on wild bees. In particular, we evaluated the importance of early successional stages for bees, which has been suspected but not previously demonstrated. A range of successional stages, between 1 and 178 years old, were examined in naturally regenerated and planted forests. In total 4465 wild bee individuals, representing 113 species, were captured. Results for total bees, solitary bees, and cleptoparasitic bees in both naturally regenerated and planted conifer forests indicated a higher abundance and species richness in the early successional stages. However, higher abundance and species richness of social bees in naturally regenerated forest were observed as the successional stages progressed, whereas the abundance of social bees in conifer planted forest showed a concave-shaped relationship when plotted. The results suggest that early successional stages of both naturally regenerated and conifer planted forest maintain a high abundance and species richness of solitary bees and their cleptoparasitic bees, although social bees respond differently in the early successional stages. This may imply that, in some cases, active forest stand management policies, such as the clear-cutting of planted forests for timber production, would create early successional habitats, leading to significant positive effects for bees in general.

Parasitic mites as part-time bodyguards of a host wasp

Some bees and wasps that host mites have peculiar pocket-like structures called acarinaria. These have long been considered as morphological adaptations to securely transfer beneficial mites into nests, and thus are thought to be the product of a mutualistic relationship. However, there has been little compelling evidence to support this hypothesis. We demonstrated that the parasitic mite Ensliniella parasitica, which uses acarinaria, increases the reproductive success of its host wasp Allodynerus delphinalis by protecting it from parasitoid wasps. Every time the parasitoid Melittobia acasta accessed a prepupal or pupal wasp host cell, adult mites attacked it, continuously clinging to it and possibly piercing the intersegmental membrane of the parasitoid with their chelicerae. Subsequent mortality of the parasitoid depended on the number of attacking mites: an average of six mites led to a 70% chance of mortality, and 10 mites led to a 100% chance of mortality. In this way, parent mites protect the food source (juvenile wasps) for themselves and ultimately for their offspring. We propose that wasps evolved acarinaria to maintain this protective guarding behaviour.

Life History of Kurosaia jiju (Acari: Winterschmidtiidae) Symbiotic with a Mason Wasp, Anterhynchium flavomarginatum micado (Hymenoptera: Eumenidae)

Abstract The life cycle of Kurosaia jiju, a mite phoretic on the mason wasp Anterhynchium flavomarginatum micado, is described based on the results of field observations and artificial rearing of the host. One to two deutonymphs of the mite, on average, disembarked from a female wasp and migrated into a host cell while the host was laying an egg or provisioning the cell with prey. The deutonymphs quickly molted to tritonymphs and then to female adults, which copulated with their single sons (small-type males) that they produced ovoviviparously and laid a mean of ≈300 eggs for about 1 wk. Tritonymphs and adults fed on hemolymph of prey provisioned by the wasp and facultatively on host larvae, whereas larvae and protonymphs scavenged various organic debris, including prey feces. Eggs of the mite hatched when nonoverwintering prepupal host turned into pupae, and then larval mites molted to protonymphs on the host pupae. Protonymphs became deutonymphs 12–24 h before host eclosion, and they attached to specific parts of adult host surface. On overwintering hosts, deutonymphs made dense aggregations composed of 50–300 individuals on the ventral surface of the thorax of prepupal hosts during winter. Venereal transmission of deutonymphal mites between host sexes was common. The mite gave no apparent detrimental or beneficial effects on fertility, immature survival, or development of the host. The biology of K. jiju is compared with related mites from the viewpoint of parasite–host interaction are discussed.

A method for both mass and individual rearing of fungivorous astigmatid mites (Acari)

Several species of common fungi were assessed as food for fungivorous astigmatid mites. Hypocrea nigricans, Botrytis cinerea and Flammulina velutipes were generally good food sources for most mites examined. Fungal mycelia growing on PDA (potato dextrose agar) medium were not only nutritionally adequate but the system also maintained high humidity through the water-based agar medium. Among acarid mites, most species of Rhizoglyphinae could be reared easily with the method. Although filter-feeding histiostomatid mites do not feed directly on hyphae, some species were successfully maintained with the same method through multiple generations. Presumably, these mites obtained sufficient nutrition from the agar medium and fungal metabolites leaching into it. Most species ultimately produced dispersing heteromorphic deutonymphs on these media. Individual mites were also maintained in isolation within glass rings on fungal colonies. Using this technique, we were able to compare developmental periods, fecundity and survival periods of mites reared under different conditions.

Bursaphelenchus tadamiensis n. sp. (Nematoda: Aphelenchoididae), isolated from a stag beetle, Dorcus striatipennis (Coleoptera: Lucanidae), from Japan

Bursaphelenchus tadamiensis n. sp. is described. The new species was isolated during a field survey of nematodes associated with stag beetles. It was recovered from the dissected body of a Dorcus striatipennis, from Tadami, Fukushima, Japan. The new species is medium sized for the genus, with males 486-772 μm and females 643-997 μm in body length, and has four lateral lines, six male genital papillae (P1 ventral single papilla is missing or vestigial), mitten-shaped spicule with clear dorsal and ventral limbs, rather large squared bursal flap, vulva lacking flap, female tail long, tapering and ventrally curved. Based upon its diagnostic morphological characters, the new species belongs to the B. fungivorus group and is close to B. thailandae, B. willibaldi and B. braaschae. It is distinguished from these three species by morphology of the male bursal flap and several morphometric values, e.g., the V value of B. tadamiensis n. sp. is clearly larger than that of the above three species. The molecular phylogenetic analyses inferred from near full-length SSU and D2/D3 LSU supported the morphological observations, i.e., the new species is molecularly similar to B. thailandae, B. willibaldi, B. braaschae and B. kiyoharai. The stag beetle association of the new species may be an accidental phoresy, although the nematode could be undergoing carrier (vector) switching, because only two adult (no dauer juveniles) individuals were isolated from only one of 100 beetles examined. The insect organ with which the nematode was associated is unknown.