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Morioka-shi, Japan

Kanzaki N.,Japan Forestry and Forest Products Research Institute | Maehara N.,Tohoku Research Center | Aikawa T.,Tohoku Research Center | Nakamura K.,Tohoku Research Center
Journal of Parasitology | Year: 2013

The nematode family Aphelenchoididae (Rhabditida: Tylenchomorpha) includes species with various feeding habitats. Bursaphelenchus, a member of the family, has for a long time been considered as a home for plant parasitic or mycophagous species (or both). However, recent intensive biological studies on the family revealed that the genus contains several insect parasitic species. Dauer juveniles of Bursaphelenchus doui were isolated from Acalolepta fraudatrix during a field study of longhorn beetle-Bursaphelenchus nematode associations. Two different insect-associated forms, an "entomoparasitic adult form" and a regular dauer juvenile, were isolated from a single individual beetle in a subsequent laboratory investigation of the B. doui-A. fraudatrix relationship. Thus these 2 distinct, insect-associated forms were confirmed to occur simultaneously. The entomoparasitic form is morphologically similar to that of Bursaphelenchus luxuriosae, with a dome-shaped head and vacuole-like spots assumed to be an internal structure of sensory organ, a stylet, a metacorpus (median bulb), and a moderately-developed and seemingly fully functional reproductive system. It is distinguishable from B. luxuriosae based on male spicule morphology and female tail morphology. A degenerate ingestive-digestive system distinguishes the entomoparasitic form from the propagative form and, unlike dauer juveniles, it has a moderately-developed reproductive system. The presence of this characteristic parasitic adult form is known only in these 2 Bursaphelenchus species. However, these 2 species did not form a clear monophyletic clade within the Bursaphelenchus xylophilus group and, thus, this characteristic parasitic form may occur independently in each species. © 2013 American Society of Parasitologists. Source


Ohnuki Y.,Japan Forestry and Forest Products Research Institute | Ohnuki Y.,Kyushu Research Center | Nik A.R.,Malaysian Forest Research Institute | Noguchi S.,Japan International Research Center for Agricultural science | And 3 more authors.
Japan Agricultural Research Quarterly | Year: 2010

To prevent soil runoff from logging roads and skid trails, buffer zones are commonly established along both sides of streams. These buffers range in width from 10 to 100 m from the center of the stream, depending on stream width, (from 1 to > 40 m) as dictated by the Reduced-Impact Logging Guidelines for Lowland and Hill Dipterocarp Forests in Indonesia. In the Bukit Tarek Experimental Watershed in Malaysia, sediment accumulations were observed along narrow streams after logging despite the presence of 20-m-wide buffer zones, double the width set out in the guidelines. Thus, we examined erosion-accumulation depths on different slopes in 20-m-wide buffer zones to clarify the spatial effects on sediment discharge, particularly as it relates to the microtopography and the vegetation cover, including fallen trees. Some of the accumulation depths at lower elevations and along streams were small, whereas on steep concave slopes and hollows that extend to streams, large accumulations were observed 1 year after logging. These findings indicated that, although a 20-m-wide buffer zone may be partly effective at preventing sediment discharge, it is not adequate on concave slopes (lower side-hollows and channel walls) where surface flows often converge. We compared several physical properties of the surface soil in accumulated areas relative to undisturbed areas and demonstrated that bulk density was larger and total porosity and coarse porosity were smaller in the accumulated soils, especially on lower side-hollows. These results indicate that soils accumulated on concave slopes would accelerate the occurrence of surface flow. Tree distribution was not dense in the buffer zones, but fallen trees and the relatively dense understory vegetation including rattans and palms partly prevented the discharge of sediment into streams. Our findings suggested that 20-mwide buffer zones with dense fallen trees and understory vegetation are partly sufficient to prevent sediment discharge; however, along steep concave slopes and hollows where rain water converges, wider and thicker buffer zones are needed. Source


Kanzaki N.,Japan Forestry and Forest Products Research Institute | Aikawa T.,Tohoku Research Center | Maehara N.,Tohoku Research Center | Thu P.Q.,Vietnamese Academy of Forest science
Nematology | Year: 2016

Bursaphelenchus kesiyae n. sp. is described. The new species was isolated from dead wood of Pinus kesiya during a field survey of nematodes associated with dead pine trees (Pinus spp.). The new species is medium- to large-sized for the genus, with males 690-1059 μm and females 837-1122 μm in body length, and has four lateral lines, six male genital papillae (P1 ventral single papilla is missing or vestigial), a mitten-shaped spicule with clear dorsal and ventral limbs, an indistinctive small and narrow bursal flap, vulva lacking any flap apparatus, and female tail long, tapering and straight or slightly ventrally curved. Based upon its diagnostic morphological characters, the new species belongs to the B. fungivorus group and is closely related to B. thailandae and B. parathailandae, with which it forms a cryptic species complex. However, the new species is distinguished from these two species by the morphology of the male bursal flap and several morphometric values, i.e., the bursal flap of the new species is inconspicuous, or almost lost in many individuals. Molecular phylogenetic analysis 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 and B. parathailandae, but could be distinguished phylogenetically. Further, differences in molecular sequences in SSU and D2-D3 LSU between the new species and its close relatives are slightly higher than those between B. xylophilus and B. mucronatus, thus, identification of the species status for B. kesiyae n. sp. is considered warranted. © Koninklijke Brill NV, Leiden, 2016. Source


Akiba M.,Japan Forestry and Forest Products Research Institute | Ishihara M.,Japan Forestry and Forest Products Research Institute | Ishihara M.,Hokkaido Research Center | Sahashi N.,Japan Forestry and Forest Products Research Institute | And 4 more authors.
Plant Disease | Year: 2012

Pine wilt disease is one of the most serious epidemic tree diseases in Japan, and resistant pine trees have been developed through a breeding program. To evaluate resistance of resistant families of Japanese black pine, Pinus thunbergii, to the pinewood nematode, Bursaphelenchus xylophilus, isolated from the field, and to determine whether differentiation of pathogenicity to resistant pine families appears in the nematode isolates, seedlings of five resistant pine families were inoculated with 25 nematode isolates. Disease incidence 18 weeks after inoculation was significantly different among nematode isolates and among pine families but there was no interaction effect between nematode isolate and pine family. This indicates that nematode isolates did not have differential host specificity to resistant families of P. thunbergii. Isolate Shimabara, a test isolate of the breeding program, showed the same degree of virulence as the highly virulent isolates frequently used in experiments. However, more virulent isolates than Shimabara were found among the isolates collected from natural pine forest. This indicated that B. xylophilus populations with higher virulence than Shimabara exist in the natural population. These findings are important in development of more efficient breeding procedures for resistant pine trees. © 2012 The American Phytopathological Society. Source


Tanaka R.,Japan Forestry and Forest Products Research Institute | Kikuchi T.,Japan Forestry and Forest Products Research Institute | Aikawa T.,Tohoku Research Center | Kanzaki N.,Japan Forestry and Forest Products Research Institute
Applied Entomology and Zoology | Year: 2012

A DNA extraction kit, ISOHAIR® (Nippon Gene), which was originally developed for preparing DNA from hair and nail samples, was used to prepare nematode DNA for PCR and sequencing analyses. The methods provided here, which involved digesting (resolving) a single nematode individual in a tube containing the mixed enzyme solution, enabled the DNA to be prepared within 20 min. The prepared DNA was suitable for PCR amplification of near-full-length small subunit ribosomal RNA (ca 1. 7 kb), of the D2/D3 expansion segments of large subunit RNA (ca. 0. 7 kb), and of partial mitochondrial COI (ca. 0. 7 kb) genes, followed by sequencing analysis. Furthermore, the prepared material could be preserved in a freezer (-30 °C) for at least 20 months, and more than 300 PCR reactions could be performed from a single individual nematode. © 2012 The Japanese Society of Applied Entomology and Zoology. Source

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