Aggregation ofPlatypus quercivorus (Murayama) (Coleoptera: Platypodidae) on oak logs bored by males of the species

To provide evidence for the aggregation ofPlatypus quercivorus (Murayama) (Coleoptera: Platypodidae) in association with the mass mortality of oak trees in Japan, we compared the number of beetles attracted to oak logs bored by males with the number of beetles attracted to logs that had not been bored. Large numbers of males and females were attracted to the bored logs, and the total numbers increased as the number of entry holes in the logs increased. This result shows that both male and female beetles aggregate on logs bored by the males. We collected a large number of beetles attracted to living trees bored by the beetles, and the total number of beetles collected increased as the number of entry holes/m² on the tree trunk increased. Beetles also aggregated on living trees bored by the males.     

Effects of mating on the termination of aggregation by the oak borer,Platypus quercivorus (Murayama) (Curculionidae: Platypodinae) during host colonization

We conducted a field experiment to determine whether logs bored by male Platypus quercivorus beetle were less attractive to conspecifics after beetles had mated. Bored (with male beetles) and unbored logs were placed in a beetle-infested forest and enclosed within a cage. For half of the bored logs, female beetles were released to mate with the male beetles. Log attractiveness was determined by assessing the number of beetles captured on adhesive paper placed on each cage enclosing the log. On the logs on which female beetles were released, the number of beetles captured decreased distinctly after release, and did not differ from the number captured on the unbored logs. In contrast, the number of beetles captured on logs with only unpaired males was higher than the number captured on the unbored logs. This result confirms that the attractiveness of logs bored by male P. quercivorus beetles declines after mating occurs. To our knowledge, this is the first evidence for the relaxation of aggregation pheromone following mating for beetles in the subfamily Platypodinae.     

Relative dominance of the mold fungus,<Emphasis Type="Italic">Raffaelea</Emphasis> sp., in the mycangium and proventriculus in relation to adult stages of the oak platypodid beetle,<Emphasis Type="Italic">Platypus quercivorus</Emphasis> (Coleoptera; Platypodidae)

Microorganisms associated with the oak platypodid beetle,Platypus quercivorus (Murayama), were isolated from the mycangium of adult females, from the proventriculus of adults of both sexes, and from galleries in the period before dispersal. Fungi isolated from female mycangia were separated into three groups:Raffaelea sp., yeasts (mainlyCandida spp.), and other species.Raffaelea sp. was isolated predominantly from the teneral stage to the dispersal stage, but was not isolated from the mycangia of mother beetles in new galleries. Yeasts were isolated in every beetle stage tested and their isolation rate was over 80% from the teneral stage to the dispersal stage. All three fungal groups were found in the female proventriculus.Raffaelea sp. was isolated only in the dispersal stage at a rate of 40%, whereas the isolation rate of yeasts gradually increased beginning in the mature stage and reached 100% in the rearing stage. In contrast, in the male proventriculus, onlyRaffaelea sp. and yeasts were isolated in the dispersal and rearing stages. The isolation rate in the rearing stage ofRaffaelea sp. was less than 20%, but that of yeasts was 100%, although these rates were almost the same in the dispersal stage.Raffaelea sp. and yeasts were also isolated from cradles containing eclosing pupae. These results suggest thatP. quercivorus acquiresRaffaelea sp. and yeasts in their mycangia from the cradles immediately after eclosion, and maintain them to the dispersal stage. Then, they transmit these fungi from old to new galleries by way of mycangia, and possibly the digestive system.     

Host-tree conditions affecting the oviposition activities of the woodwasp,Sirex nitobei Matsumura (hymenoptera: Siricidae)

Experiments were conducted to elucidate how the oviposition activities ofSirex nitobei Matsumura could be affected by different conditions of the host trees, using logs from felled healthy trees and the dead and living trees ofPinus densiflora Sieb. et Zucc. According to days elapsed after tree-felling, the proportions of oviposition defined as the proportion of eggs laid to the potential fecundity of a female during her lifetime, could be divided arbitrarily into three groups. The proportions of oviposition on the logs within 0–3 days after felling,i.e fresh logs, varied greatly from log to log, and about half of female adults showed proportions of oviposition under 50% (mean ±SD: 39±32%). However, all the females that oviposited on the logs 4–24 days after felling,i.e. intermediate logs, invariably showed proportions of oviposition over 50% (88±1.5%). On the other hand, proportions of oviposition in most of the females that oviposited on the logs over 25 days after felling,i.e. old logs, were less than 50% (26±17%). The proportions of oviposition were significantly different between intermediate logs and old logs. The mean proportion of oviposition on living trees and that for dead trees were 45 and 58%, respectively. Thus,S. nitobei in the field would exhibit its preference for weakened trees ofP. densiflora as oviposition sites, as it did for the logs 4–24 days after felling in this study.     

Pre- and post-dispersal damage to the acorns of two oak species (Quercus serrata Thunb. andQ. mongolica Fisher) in a species-rich deciduous forest

A comparative study of pre- and post-dispersal damage to the acrons of two oaks,Quercus serrata Thunb. andQ. mongolica Fischer, was done over 3 years in a species-rich deciduous forest in central Japan. The numbers of acorns bored into by moth larvae and byKobuzo rectirostris (Roelofs) was low and relatively uniform each year for both oak species, but the numbers bored into byCurculio spp. varied from year to year. The proportions of acorns attacked were independent of the density of acorns produced for both oak species. The proportions of the dispersed acorns of both oak species on the forest floor that disappeared between autumn and spring were less than 27%, and were lower for species in the stand that belong to family Fagaceae. However, by the next summer, most dispersed sound acorns had been infested by moths that specialized on post-dispersal acorns.     

Blue stain fungi associated withIps cembrae (Coleoptera: Scolytidae) in Japanese larch in connection with their brood development

The association between blue stain fungi andIps cembrae Heer (Coleoptera: Scolytidae) was investigated in the Japanese larch,Larix leptolepis Gordon, in the Nagoya University Forest, Aichi Prefecture, central Japan.I. cembrae had one or two generation(s) in a year in this study area. Two blue stain fungi,Ophiostoma piceae andLeptographium sp., were isolated from the body surface of both male adults in mating chambers and female adults in parent galleries, suggesting that this beetle species was a vector of these fungi. Although no blue stain fungi were isolated from non-stained wood, both fungi were isolated from the mating chambers, the center and the uppermost end of the galleries throughout the season. The fact thatO. piceae was consistently isolated with high frequency from adults and from their galleries strongly suggested that this species would be the principal blue stain fungus infecting the beetle-attacked larch trees.     

Spatial distribution pattern of attack of the oak borer,Platypus quercivorus (Murayama) (Coleoptera: Platypodidae), and scolytid ambrosia beetles (Coleoptera: Scolytidae) on fresh logs

The spatial distribution patterns of the attack on fresh logs ofPasania edulis was studied for the oak borer,Platypus quercivorus (Murayama), and two species of Scolytid ambrosia beetles,Xylosandrus crassiusculus (Motschulsky) andXyleborus attenuatus Blanford, in 1994 and 1995. On the logs where onlyP. quercivorus attacked, the entry holes were distributed uniformly when attack intensity was low. However, the distribution pattern became more aggregated with the increase in attack intensity. On logs where bothP. quercivorus and the two Scolytid species attacked, there was a negative association between the spatial distribution of the entry holes ofP. quercivorus and that of scolytids. Simultaneous attack of two scolytids also increased the degree of aggregation of the entry holes ofP. quercivorus. The entry holes of scolytids were distributed in groups irrespective of the attack intensity of scolytids andP. quercivorus. These results suggest an asymmetrical interspecific relationship betweenP. quercivorus and scolytids. Concentration of the entry holes ofP. quercivorus in a small area may cause a considerable decline in the reproductive success in the galleries constructed there.     

Genotype distribution of Raffaelea quercivora in the oak galleries and its composition in the mycangia of Platypus quercivorus

Raffaelea quercivora is the pathogenic fungus that causes Japanese oak wilt. The female monogynous ambrosia beetle, Platypus quercivorus, carries this fungus in mycangia on the pronotum. These beetles bore galleries in oak trees with their partners to produce offspring, and they deposit fungus on the gallery walls from their mycangia. The offspring mature in the gallery, before loading the fungal pathogen and flying from the gallery to other healthy trees. To investigate the unloading and loading modes of the fungus within the gallery, we developed four polymorphic microsatellite markers for R. quercivora and identified the fungal genotypes in the galleries and mycangia of the beetles. Small wood chips were sampled at 5–10‐mm intervals from the walls of five galleries in a dead Quercus serrata tree. The pronota were also sampled from five female adult beetles. The genotypes of the R. quercivora isolates from the wood chips and pronota were identified using the microsatellite makers. The genotypic analysis showed that each gallery was inhabited patchily by 5–10 genotypes of R. quercivora, and the mycangia of each beetle contained 3–6 genotypes. These results indicate that diverse R. quercivora genotypes are unloaded repeatedly from the mycangia of female beetles onto the gallery wall, which results in their patchy distribution on the walls. When the offspring leave the host tree, the fungal clones that proliferate in the walls are also loaded repeatedly into the mycangia of the mature beetles.     

Blue stain fungi associated withTomicus piniperda (Coleoptera: Scolytidae) on Japanese red pine

A number of various species of blue-stain fungi were isolated fromTomicus piniperda adults at various stages of development, as well as from the galleries, pupal chambers and sapwood underneath galleries on Japanese red pine. This study was an attempt to identify the species, composition of blue-stain fungi associated withT. piniperda, the frequency of occurrence of the fungi, and their role in the sapwood-staining of Japanese red pine in Tsukuba City, central Japan. Among the seven species of blue-stain fungi isolated, an undescribed species ofOphiostoma together withO. minus were the dominant species and closely associated withT. piniperda. These two species occurred on newly emerging adults more frequently than the overwintered adults.Hormonema dematioides was also associated with the beetle, however, its frequency of occurrence from the emerged new adults was very low. Although the two other species,O. ips andGraphium sp. were also isolated from emerged beetles, the frequency of these fungi from gallery systems suggested that they were accidentally carried byT. piniperda. Leptographium wingfieldii, known to be associated with the beetle in Europe, was also isolated at a very low frequency and the fungus seemed not to be closely associated with the beetle.Ophiostoma sp. andO. minus appear to be the most important causes of blue-stain of Japanese red pine sapwood after infestation byT. piniperda.     

Sapstain fungi on <Emphasis Type="Italic">Pinus radiata</Emphasis> logs – from New Zealand Forest to export in Japan

Supply of clear, unstained logs from an export country is important economically as well as in reducing the biosecurity risk to an importing country such as Japan. Although conditions found within the holds of ships containing logs are thought to be ideal for rapid colonization of sapstain fungi, no research has been conducted. Research-focussed log export trials were designed to determine the extent of sapstain colonisation at specific points in the processing of logs from harvesting to arrival at the export destination. Two trials were established, in the austral summer and winter, in which mature Pinus radiata logs were harvested in New Zealand and shipped to export ports in Japan. Data loggers placed above and below deck of the ships recorded microclimatic conditions. Nine species of sapstain fungi were isolated from logs during the summer trial; the most common species isolated were Ophiostoma floccosum, Ophiostoma querci, and Ophiostoma setosum. In contrast, ten sapstain species were detected during the winter trial, with Sphaeropsis sapinea, O. querci, O. floccosum, and O. setosum most commonly isolated. This research was the first successful attempt at measuring visual sapstain development and isolating sapstain fungi from the time of harvesting to arrival at an export destination.     

Prediction of Board Values in Pinus sylvestris Sawlogs Using X-ray Scanning and Optical Three-dimensional Scanning of Stems

As the sawmill industry strives towards customer orientation, the need for sorting of logs according to quality has been recognized, and automatic sorting based on measurements by three-dimensional (3D) optical log scanners has been implemented at sawmills. There is even a small number of sawmills using the X-ray log scanner for automatic log-sorting. At the log-sorting stage, the potential of the raw material to fulfil the needs has already been reduced by the decisions taken when the trees were bucked (cross-cut) into logs. Thus, the application of predictions of the boards’ properties at the bucking stage is desirable. This study investigates the possibility of predicting board values from logs based on 3D scanning alone and 3D scanning in combination with X-ray scanning of stems. This study is based on 628 logs scanned by computed tomography that make up the Swedish Pine Stem Bank. Simulated sawing of the logs gave product values for each log. Prediction models on product value were adapted using partial least squares regression and x-variables derived from the properties of the logs and their original stems, measurable with a 3D log scanner and the X-ray LogScanner. The results were promising. Using a 3D scanner alone, R ² was 0.68, and using a 3D scanner in combination with an X-ray LogScanner, R ² was 0.72.     

Types of frass produced by the ambrosia beetle <Emphasis Type="Italic">Platypus quercivorus</Emphasis> during gallery construction,and host suitability of five tree species for the beetle

We studied the biology of the ambrosia beetle Platypus quercivorus in the logs of five tree species to determine: (1) the relationship between the amount of frass produced by beetles and tunnel length, (2) the relationship between frass shape and the morphological characteristics of P. quercivorus mouthparts, and (3) the suitability of five tree species for P. quercivorus reproduction. Five logs each from healthy Quercus crispula, Q. serrata, Castanea crenata, Sorbus japonica, and Cryptomeria japonica trees were used in this experiment. The results showed that there was a linear relationship between the amount of frass and tunnel length. Whenever powdery frass was produced, larvae were found in the gallery in the log, while fibrous frass was present only in galleries that contained just adults. The mouthparts of adults were completely sclerotized, which likely accounts for the fibrous frass production. Host preference of P. quercivorus was examined at two stages using five tree species. The first stage is digging initiation, which concerns male preference for digging a tunnel. More holes were made by males on S. japonica and Q. serrata logs, while fewer holes were made on C. japonica logs. The second stage is characterized by female orientation, mating, and progeny development. Platypus quercivorus could complete its lifecycle only in the two Quercus spp.     

Virulence of Raffaelea quercivora isolates inoculated into Quercus serrata logs and Q. crispula saplings

This study was conducted to compare the virulences of various isolates of Raffaelea quercivora—a fungus that causes Japanese oak wilt disease—towards Japanese oak trees. Five isolates were collected from a wide range of Japan and inoculated into Quercus serrata logs and Q. crispula saplings. The tangential length of the discolored sapwood in the Q. serrata logs differed significantly among the isolates. The trend in isolate virulence was similar for the Q. serrata logs and the Q. crispula saplings. This is the first report suggesting that there is variability in virulence among isolates of R. quercivora.     

Butt rot ofChamaecyparis obtusa (Sieb. et Zucc.) Endlicher trees caused byPerenniporia subacida in Shikoku district, Japan: Pathogen, distribution of damaged trees in the stand, and soil investigation

The rot ofChamaecyparis obtusa (hinoki) trees was studied in the northern part of Kagawa Prefecture, Japan. Among 158 hinoki examined, butt rot was found in 28.6, 58.3, and 100% of trees in the 29, 30, and 34-year-old stands, respectively. All trees with butt rot, and 11 trees without it had rotted roots. Thirteen hinoki were peeled byCervus nippon (sika deer) and all of them were infected with butt rot. The maximum height of rot in deer-damaged trees was 2.6 m from the ground level, but was 1.9 m in undamaged trees. About eighty-two percent of rotted trees showed rotted areas of less than 40 cm² on the cross section of stems at the ground level. White mycelia and black flecks sometimes appeared in the rotted wood. Basidiocarps of polyporaceous fungus were often found on felled logs and rotted stumps of hinoki and identified asPerenniporia subacida. Basidiomycetous fungus was isolated frequently from rotted wood of roots and stems, and determined to beP. subacida by comparative study on cultural characteristics. An inoculation experiment and wood-decay test proved that the fungus was the cause of the rot of hinoki. Few absorbing roots of living trees were found in the clayey subsurface soil of the high dry bulk density and the less soil aeration. Some absorbing roots had root rot and the rot spread from the base of the absorbing root to the central part of the woody root. This is the first report on the rot of hinoki caused byP. subacida in Japan.     

The smell and odorous components of dried shiitake mushroom, Lentinula edodes VI: increase in odorous compounds of dried shiitake mushroom cultivated on bed logs

Odor is one of the most important characteristics affecting consumer preference for dried shiitake mushrooms [Lentinula edodes (Berk.) Pegler]. In our previous studies, we found that the odor content of commercial dried products was too weak for most people, and that the odorous compound content could be increased by adding amino acids to sawdust media. Currently, however, bed-log cultivation is used to produce fruiting bodies for dried products. The purpose of this study was to fi nd a method to increase the content of odorous compounds in dried products cultivated on bed logs. Pressure injection of amino acids from the side of the bed log was the most effi cient method, but it had some problems. Hence, a simpler and less troublesome method was developed, i.e., injecting amino acid solution from small bottles set in deep holes bored in the sides of the bed logs. In fruiting bodies cultivated on bed logs injected with amino acid solution by the improved method, the mean contents of lentinic acid, a precursor of the odorous compound lenthionine, approximately doubled compared to that in the untreated logs, although the infi ltration area of the solution injected by the improved method was smaller than that by the former method.     

Responses ofQuercus sapwood to infection with the pathogenic fungus of a new wilt disease vectored by the ambrosia beetlePlatypus quercivorus

Quercus serrata andQ. crispula wilt during the summer in wide areas along the Sea of Japan. Mass attacks of trees by an ambrosia beetle (Platypus quercivorus) are characteristic before appearance of the wilting symptoms. This study investigated the pathogenic effects of a fungus detected specifically in the wilting trees. This hyphomycete fungus,Raffaelea sp., has a distribution that correlates with the discolored xylem area called wound heartwood in which vessels are dysfunctional. Tylosis formation around the hyphae indicates vessel dysfunction. In areas with discoloration, the fungal hyphae were invading living ray parenchyma cells from the vessel lumen. As a protective reaction the ray cells exuded yellow substances into the vessels, but these substances seemed ineffective against the fungal activity, probably because the fungus disperses along the beetle's gallery before enough substance can accumulate. It should allow wide discoloration in sapwood. Cambium was not necrotic around the fungus. The cytological process in the host was as follows: (1) synthesis of secondary metabolites by the stimuli of oak fungus; (2) exudation of yellow substances into vessels; and (3) dysfunction of vessels and wound heartwood formation. In regard to wilting of trees, the pathogenicity of the fungus should be assessed by its ability to stop sap flow.     

油茶织蛾生物学特性研究

Casmara patrona is one of the main borer pests damaging Camellia oleifera in China. Few reports about this insect were published. The life history, biological characteristics and natural enemies of C. patrona were investigated through field survey and laboratory observation in this study. The results showed that C. patrona had one generation in one year or two years, and overwintered as 3rd-5th instar larva in Zhejiang Province. About 88 percent of larvae began to pupate in early May, and the rest kept feeding till the next year. The adults could be observed from early June to early July, and the peak of emergence occurred in late June. The adults began to oviposit in late June and terminated in early July. The eggs started hatching in early July, and then the larvae bored into the branch to feed. The entrance holes of the larvae distributed predominately in the middle of the eastern and southern part of C. oleifera tree. The larva had five instars, and there were 10-50 days when the larva did not feed between consecutive instars.     

Factors influencing the production of structural plywood in Tasmania,Australia from Eucalyptus nitens rotary peeled veneer

Harvested logs supplied from five fibre-managed Eucalyptus nitens plantation coupes with different growing environments were assessed for quality and stiffness. Billets extracted from the logs were rotary peeled for veneer. When averaged across the five coupes, 30% of veneer recovered could be used directly in structural plywood production and an additional 20–25% could be used after further processing. In visual assessment most veneer was assigned an Australian/New Zealand Standard AS/NZS2269.0:2012 Quality D. Acoustic testing during processing showed veneer peeled from a drier and lower elevation coupe had significantly higher dynamic MOE values than veneer processed from logs harvested from wetter higher elevation coupes. To examine the utility of the E. nitens peeled veneer in the production of structural plywood, it was combined with veneer of a known higher stiffness, rotary peeled from regrowth forest Tasmanian oak species logs. Structural seven-ply panels were manufactured from the veneer prepared in three different ply arrangements. Mechanical testing of the panels in accordance with AS/NZS2269.0:2012 showed that an F17 target stress-grade panel product of 83% E. nitens and 17% Tasmanian oak species could be produced, if E. nitens veneer of higher stiffness were selected from veneer segregated by estimated dynamic Modulus of Elasticity value. Panels with 50% E. nitens and 50% Tasmanian oak veneer could be produced by selecting E. nitens veneer of lower stiffness after segregation. In the majority of panels tested stress-grade rating was limited by perpendicular bending strength. Outcomes from the study indicate that structural plywood can be manufactured using differing proportions of E. nitens veneer, rotary peeled from fibre-managed plantations, provided it can be segregated into stiffness categories and selected to achieve a target stress-grade.     

Electroantennogram responses of Dendrolimus superans (Lepidoptera: Lasiocampidae) to six volatiles of Larix gmelinii

Dendrolimus superans is one of the important pests feeding on the needles of Larix gmelinii. Six standard compounds, (1R)-(−)-α-pinene, (1S)-(−)-α-pinene, ocimene, (1S)-(−)-β-pinene, R(−)-α-phellandrene and camphene, the main volatiles of L. gmelinii were used to test the electroantennogram (EAG) responses of moths. The results show that the order of the EAG responses of moths to seven concentrations of these six compounds were as follows: mated females > virgin females > unmated males, except for 0.1 μL/μL R(−)-α-phellandrene, where the order was: virgin females > mated females > unmated males. There are statistically significant differences between the EAG responses of virgin females and unmated males (p < 0.05), and also between mated females with virgin females and mated females and unmated males (p < 0.01), which suggests that the mated females are more sensitive to the volatiles of host plant. The results of EAG responses of the mated females, virgin females and unmated males indicate that they are more sensitive to R(−)-α-phellandrene than to the other volatile components. The active time for the EAG responses of both mated females and unmated males occurs during the night, i.e., from 20:00 to 04:00 hours. This is consistent with their eclosion, mating and oviposition periods. __________ Translated from Scientia Silvae Sinicae, 2007, 43(7): 55–60 [译自:林业科学]     

Volatile composition analysis by solid-phase microextraction applied to oak wood used in cooperage (Quercus pyrenaica and Quercus petraea): effect of botanical species and toasting process

The purpose of this study was to investigate the sorption of selected volatile substances from oak wood-chip samples (Quercus pyrenaica Willd. and Quercus petraea L.) subjected to different toasting levels, namely, without toasting, with medium toasting, and with strong toasting, through the use of solid-phase microextraction (SPME). The main volatile compounds identified as a function of the toasting level and botanical species were furfural, hexanal, α-pinene, d-limonene, decanal, vitispirane, ethyl hexanoate, cis-3-methyl-γ-octalactone (“oak lactone” or “whisky lactone”), α-terpineol, p-xylene, and nonanal. Considering the data obtained from the toasted woods (medium and strong intensity) in comparison with those of nontoasted woods, it can be pointed out that the average peak area and the number of compounds identified in the gas chromatogram decreased during the toasting process. In general, regarding the compounds analyzed, quantitative differences were found between the two oak wood species under study. High values of volatile compounds were found in Quercus pyrenaica oak wood chips. In addition, for the number of compounds identified in oak wood extracts and directly extracted from solid oak wood chips by SPME, it is concluded that the best extraction process for volatile compounds from oak wood is the use of oak wood-chip liquid extracts.