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.     

Discrimination among host tree species by the ambrosia beetle Platypus quercivorus

The ambrosia beetle Platypus quercivorus is a vector for the fungus that causes Japanese oak wilt, and susceptibility to infestation by P. quercivorus varies by tree species. We postulated that P. quercivorus discriminates among host tree species differing in susceptibility to attack. To test this postulate, we counted the number of flying male beetles (NFM), the number of holes bored by male beetles (NH), and the number of flying female beetles (NFF) per unit area of bark surface in three fagaceous tree species: Quercus crispula (with high susceptibility to infestation) and Q. serrata and Castanea crenata (both with low susceptibility). NFM and NH were used to calculate the proportion of male beetles that bored holes out of those that flew to the tree (PBM). We used generalized additive models to predict NFM, NFF, and PBM. The locations of trees, expressed as x and y coordinates, numbers of weeks after the first male beetle’s flying (WEEK), diameters of trees 130 cm above ground (DBH), and tree species (SP) were incorporated into the models as candidate explanatory variables. The best-fit models for NFM and NFF included WEEK and DBH and the effect of location; SP was not included in the models. For PBM, the best-fit model included WEEK, DBH, and SP. The results indicate that male P. quercivorus prefer Q. crispula to Q. serrata and C. crenata and that selection is made before boring holes on trees, but that P. quercivorus do not discriminate among host species when they fly to trees.     

Inducing infection of oak logs by a pathogenic fungus carried byPlatypus quercivorus (Murayama) (Coleoptera: Platypodidae)

This study examined the frequency of infection by an unidentified pathogenic fungus of oak logs bored into by males alone or by both males and females ofPlatypus quercivorus (Murayama) in the field. The fungus, which is associated with mass mortality of oak trees in Japan, was not isolated from logs bored into by males alone, which bored only short entrance galleries. However, it was isolated from logs bored into by both males and females, which together bored longer galleries and reproduced successfully. This suggests that it is difficult for the fungus to colonize logs bored into by males alone. The fungus was not isolated from a log in which the beetles failed to reproduce, and in which the galleries were significantly shorter than in logs where reproduction succeeded, but it was unclear whether the shortness of the galleries prevented colonization of the log by the fungus. The study also revealed that some gallery-initiating males survived for at least 2 months in the absence of females, and that females elongated entrance galleries that had been bored by the gallery-initiating males.     

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.     

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.     

A low <Emphasis Type="Italic">Platypus quercivorus</Emphasis> hole density does not necessarily indicate a small flying population

The ambrosia beetle Platypus quercivorus causes mass mortality of Fagaceae trees in Japan, and tree species differ in their susceptibility to P. quercivorus. We hypothesized that interspecific differences in susceptibility are caused by differences in beetle infestation patterns, that is, how many beetles fly to a tree and how many of those arriving bore holes. To examine how tree susceptibility is related to these parameters, two tree species with different degrees of susceptibility were studied (highly susceptible Quercus crispula and less susceptible Q. salicina). Specifically, we measured the number of male beetles per unit area that flew to the host trees (NFM) and the density of holes bored by male beetles (DH). From these two values, we calculated the proportion of male beetles flying to a host tree that bored holes (PBM). These parameters were compared for the two Quercus species. Although the two species did not differ in NFM in 2003, PBM was markedly lower for Q. salicina than for Q. crispula and DH was significantly lower for Q. salicina than for Q. crispula. Thus, the lower susceptibility of Q. salicina is partly explained by its low PBM.     

Comparison of lure-baited insecticide-treated tripod trap logs and lure-baited traps for control of Ips duplicatus (Coleoptera: Curculionidae)

Two methods were compared for capturing the bark beetle Ips duplicatus Sahlberg (Coleoptera: Curculionidae, Scolytinae): lure-baited, insecticide-treated tripod trap logs (TRIPODs) versus Theysohn pheromone traps (TPTs). In 2008 and 2011 and at each of three clearcuts, five TPTs and five TRIPODs baited with ID Ecolure pheromone evaporators were installed with 10 m spacing. The pheromone evaporators were renewed every 8 weeks. The TRIPODs were treated with the insecticide Vaztak 10 EC in mid-April and then every 5 weeks thereafter. Trap logs and traps were inspected weekly during the entire period of I. duplicatus flight activity (April–September). Two to three times more beetles were trapped by the TPTs than by the TRIPODs. The TPTs captured more females than males, while TRIPODs captured equivalent numbers of males and females or more males than females on some dates. The TPTs and TRIPODs trapped approximately the same numbers of males, but the TPTs captured more females than the TRIPODs. Both traps captured more adults in spring than in summer. The higher numbers of entomophagous arthropods, including the predacious beetles Thanasimus formicarius L. and T. femoralis, were captured in the TRIPODs than in the TPTs.     

Relationships between mass mortality of two oak species (Quercus mongolica Turcz. var.grosseserrata Rehd. et Wils. andQ. serrata Thunb.) and infestation by and reproduction ofPlatypus quercivorus (Murayama) (coleoptera: Platypodidae)

This study investigated the number of adults ofPlatypus quercivorus (Murayama) captured on host oak (Quercus spp.) trees, the attack density (the number of entry holes per 100 cm²), and the number of emerging adults to clarify the relationships between the beetle’s colonization on trees in oak stands and tree mortality. The initial attack ofP. quercivorus, which was the most intense attack, was observed on most living trees simultaneously. Although some attacked trees died within the year of the attack or in the next year, a high density of attack did not usually cause the death of host trees. Surviving trees suffered low levels of consecutive attack after the initial attack. BecauseP. quercivorus successfully produced broods only in the dead trees, the population of the insect seems to be maintained only in stands where oak mortality occurs. However, the adults that landed on most of the surviving trees appeared unable to reproduce probably due to degradation of host quality. Thus, oak mortality probably ceases within 3 or 4 years after the start of infestation in a stand, with subsequent reductions in population density of the borer.     

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.     

Predation of lowbush blueberry insect pests by ground beetles (Coleoptera: Carabidae) in the laboratory

Agriculture relies on ecosystem services, such as biological control of pests, for economic success and sustainability. Commercially managed lowbush blueberries are an important crop in eastern North America, but pest control by natural enemies has not been well studied. In this paper we address questions about consumption of two blueberry pests by ground beetles (Carabidae) that are common in blueberry fields. In the first experiment, a Poecilus l. lucublandus, Carabus nemoralis, or Pterostichus mutus beetle was placed with two blueberry spanworm larvae, Itame argillacearia, in a simple (cup only or cup + soil) or more complex (cup + soil + blueberry sprigs) treatment arena. In most cases, probability of spanworm consumption reached 100 % in simple arenas by the end of the experiment (48 h) but was 25–50 % lower in more complex arenas. In a second experiment, a male or female Pterostichus melanarius or Harpalus rufipes beetle was placed in a plastic container with saturated or dry soil into which mature blueberry maggots, Rhagoletis mendax, dropped from blueberries to pupate. Approximately 40–80 and 35 % fewer pupae were recovered when a P. melanarius and H. rufipes beetle was present, respectively, but soil moisture and beetle sex were not significant factors. Our results demonstrate that ground beetles can prey upon important blueberry pests, but suggest that consumption may be influenced by microhabitat structure.     

天牛成虫胸部的发音和行为（鞘翅目：天牛科）

本文研究了15种天牛成虫的发音及其有关的行为。天牛两性对外界不同强度的刺激能作出反应,并借助胸部发音器的摩擦而发音。波形照片显示:天牛的声波信号因种不同差异极大,其频率范围约3000—10000Hz。楝星天牛可借助鞘翅的运动而发出强烈的声音以恐吓敌害,其胸部摩擦发音器则趋于退化。某些天牛雄虫在争夺雌虫、交配前和交配中,可发出不同的声波,这类声波的生物学意义尚待进一步研究。     

Horizontal niche differentiation of ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) within the standing trunk of <Emphasis Type="Italic">Quercus serrata</Emphasis>

Niche differentiation, in terms of time and space, has been reported within a community of ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) in a tree trunk. Two platypodid ambrosia beetles, Platypus quercivorus (Murray) and Platypus calamus Blandford, utilize a similar height range with respect to the Quercus serrata Murray (Fagaceae) trunk. The sapwood and heartwood (i.e., wood types) are known to differ in their physical and chemical characteristics. The objective of this study was to determine the differences among ambrosia beetles, in terms of wood type preferences, in a Q. serrata tree trunk. We analyzed the horizontal distribution patterns of ambrosia beetles within two mature Q. serrata tree trunks. Platypus calamus and the other ambrosia beetles [P. quercivorus, Ambrosiodmus lewisi (Blandford), Ambrosiophilus atratus Eichhoff, and Xyleborus sp.] showed different horizontal distribution patterns within the wood. The former tended to utilize the heartwood, whereas the latter utilized the sapwood. These results suggest that the wood type can be regarded as one of the niche dimensions of ambrosia beetles in a Q. serrata trunk.     

Discoloration induced by Raffaelea quercivora isolates in Quercus serrata logs and its relation to phylogeny: a comparison among isolates with and without the Japanese oak wilt incidence including outside of Japan

Japanese oak wilt (JOW) has been prevalent in Japan since the late 1980s. Infections of the fungus, Raffaelea quercivora Kubono et Shin. Ito, which is transmitted by an ambrosia beetle [Platypus quercivorus (Murayama)], can cause JOW. Although R. quercivora, P. quercivorus, and oak trees are distributed in other Asia–Pacific countries, the incidence of JOW has not been reported outside Japan. In this study, we collected R. quercivora isolates from 5 Asian countries, including Japan, and compared their ability to induce sapwood discoloration by inoculating Q. serrata logs. The tangential widths of the discoloration in sapwoods inoculated with non-Japanese isolates were equivalent to or greater than those of the 2 Japanese isolates. This indicates that a lack of JOW incidence outside Japan is not because of the lowered ability of R. quercivora to spread discoloration compared with the Japanese isolates. Statistical analyses of the relationship between discoloration and phylogeny based on DNA sequences of actin and chitin synthase showed that the discoloration width was independent of phylogenetic relatedness among the isolates. To discuss why the occurrence of JOW has not been reported outside Japan, further studies (e.g., on host susceptibility and P. quercivorus aggression) throughout Asia are needed.     

Eine verbesserte Technik zur Gewinnung eines höheren Weibchenanteils beim Parasitoiden Bracon brevicornis Wesm. (Hym., Braconidae)

The effect on sex ratio ofBracon brevicornis progeny when male, female, and host larva (Sesamia cretica) were placed together in different time sequences, was investigated. Placing a parasitoid female first, a male after 3 hours, and a host larva after 24 hours, yielded significantly the highest proportion of females (48%). In this case female/male sex ratio was 1∶1 approximately, while other manipulations, they ranged from 1∶4 to 1∶20 (with preponderance to males).     

Mating behaviour of female Tuta absoluta (Lepidoptera: Gelechiidae): polyandry increases reproductive output

Tuta absoluta (Meyrick) is an important pest of tomato. Mass trapping of males has seldom proved an effective control measure, probably due to the pest’s reproductive biology. There are few studies on female mating behaviour. For this reason, this study aimed to determine female mating frequency and its effects on reproductive output and female longevity; the effects of male mating status on female reproductive output and longevity and the fate of the spermatophore inside the bursa copulatrix. The studied population of T. absoluta mated only once a day at the beginning of the photophase, females remated frequently and can be classified as polyandrous. The refractory period of both T. absoluta males and females was very short and was not observed in many cases. The lack of refractory period could be due to the female’s rapid metabolism of the spermatophore thus allowing the female to reduce the intermating interval and mate again. Remating had direct benefits for T. absoluta females increasing their fecundity, fertility and longevity. These benefits were greater when females could remate to virgin males instead of to the same male. In this species, therefore, polyandry has direct benefits for the female. The occurrence of polyandry together with other known or unknown reasons can explain the failure of control methods based on pheromones in the open greenhouses in some tomato-growing areas.     

Bark beetle (Coleoptera: Scolytidae) diversity in spaced and unmanaged mature lodgepole pine (Pinaceae) in southeastern British Columbia

Variation in the number and diversity of bark beetles in spaced mature lodgepole pine stands in the East Kootenay region of British Columbia was analyzed in relation to location (site), spacing treatment and years following treatment. We analyzed the number of bark beetles and the number of bark beetle species that emerged from stumps or were captured in flight traps in the first five years following spacing. We also investigated the incidence of bark beetle attacks on the remaining trees and the mean dates of emergence from stumps and of capture in flight traps for the common species. Observations were made on three sites, each having three treatments: 4 m × 4 m spacing, 5 m × 5 m spacing, and an untreated control. The mean density of bark beetles emerged from stumps was different among sites and years but not between spacing treatments. There was no statistically significant variation in the number of bark beetle species captured in flight traps by site, spacing treatment, years, or spacing treatment and years. Significantly more bark beetles were captured in the 4 m × 4 m spacing treatment than in the control. The number of bark beetles captured was the highest in the first 2 years following treatment. Up to 26 species of bark beetles, excluding ambrosia beetles, were captured in flight barrier traps. There was no difference in species diversity by site or treatment indicating that species diversity in mature lodgepole pine is relatively stable over large areas. Of the 213 trees that sustained at least 10 attacks by bark beetles on the lower 2 m of the bole, 59.1% occurred in the spaced plots but only 18.2% of those were successful, versus 74.7% success in the infested trees in the control plots. The majority of infested trees contained Ips sp., Dendroctonus valens and D. murrayanae. Of the seven trees attacked by mountain pine beetle (D. ponderosae) only one tree was located in a spaced plot.     

Transfer of inoculum of Metarhizium anisopliae between adult Glossina morsitans morsitans and effects of fungal infection on blood feeding and mating behaviors

The transfer of conidia of Metarhizium anisopliae between tsetse flies Glossina morsitans and the effects of fungal inoculation on mating and blood meal feeding behaviors were investigated in the laboratory. Male or female flies were inoculated with fungal conidia (“donors“) and allowed to pair with fungus-free mate of opposite sex (“recipients”) at 1-day-interval up to three mates. Fungus-treated male or female “donor” flies as well as their mates “recipients” died from fungal infection. However, mortality in male “recipient” flies declined with successive mating, from 82.5 to 32.5 %. Fungus-treated males readily located female flies and mating was successful in most cases comparable to the controls. There were no significant differences (P > 0.05) in mean duration of mating, number of jerking movements between fungus-treated and fungus-free males for all the mating lines, except in the number of jerking movements when male flies mated with the 3rd line female flies. Fungus-treated and fungus-free female flies previously mated with treated and non-treated males showed refractoriness during subsequent pairings. The number of fertile female flies was higher (P < 0.05) in fungus-free than in fungus-treated treatments, thus producing more pupae. High concentration of fungus (3.0 × 10⁶ conidia ml^?1) significantly (P < 0.05) reduced blood meal intake of flies. This study has shown that fungal infection does not affect the mating behavior of tsetse flies and fly-to-fly contamination does occur during matings. These are important attributes if entomopathogenic fungi have to be used in auto-dissemination strategy and be integrated into sterile insect technique.     

Habitat associations of saproxylic beetles in the southeastern United States: A comparison of forest types,tree species and wood postures

Saproxylic beetles are highly sensitive to forest management practices that reduce the abundance and variety of dead wood. However, this diverse fauna continues to receive little attention in the southeastern United States even though this region supports some of the most diverse, productive and intensively managed forests in North America. In this replicated three-way factorial experiment, we investigated the habitat associations of saproxylic beetles on the coastal plain of South Carolina. The factors of interest were forest type (upland pine-dominated vs. bottomland hardwood), tree species (Quercus nigra L., Pinus taeda L. and Liquidambar styraciflua L.) and wood posture (standing and downed dead wood, i.e., snags and logs). Wood samples were taken at four positions along each log and snag (lower bole, middle bole, upper bole and crown) ∼11 months after the trees were killed and placed in rearing bags to collect emerging beetles. Overall, 33,457 specimens from 52 families and ≥250 species emerged. Based on an analysis of covariance, with surface area and bark coverage as covariates, saproxylic beetle species richness differed significantly between forest types as well as between wood postures. There were no significant interactions. Species richness was significantly higher in the upland pine-dominated stand than the bottomland hardwood forest, possibly due to higher light exposure and temperature in upland forests. Although L. styraciflua yielded more beetle species (152) than either Q. nigra (122) or P. taeda (125), there were no significant differences in species richness among tree species. There were also no relationships evident between relative tree abundance and observed or expected beetle species richness. Significantly more beetle species emerged from logs than from snags. However snags had a distinct fauna including several potential canopy specialists. Our results suggest that conservation practices that retain or create entire snags as opposed to high stumps or logs alone will most greatly benefit saproxylic beetles in southeastern forests.     

Effect of aging in adult Monochamus alternatus (Coleoptera: Cerambycidae) on the susceptibility of the beetle to Beauveria bassiana (Ascomycota: Hypocreales)

To clarify the effect of aging in adult Monochamus alternatus on the susceptibility of the beetle to Beauveria bassiana, we inoculated the fungus into adult beetles 0, 3, 7, 14, and 28 days after emergence. The number of days from B. bassiana inoculation to M. alternatus death increased with the number of days from beetle emergence to inoculation up to 14 days after emergence. This indicated that the susceptibility of adult beetles to the fungus decreased with aging. However, B. bassiana-inoculated beetles 28 days after emergence died earlier after inoculation than those inoculated with the fungus 14 days after emergence; i.e., the beetle’s susceptibility to the fungus increased again. We considered this phenomenon to be the result of senescence of adult beetles. We concluded that the susceptibility of M. alternatus to B. bassiana decreased first and then increased again with aging.     

Beetles (Coleoptera) caught with pheromones of Gnathotrichus retusus and G. sulcatus (Col., Scolytidae) in southern Finland

The ambrosia beetle Gnathotrichus materiarius, which originally came from North America, was discovered in southern Finland in 1996. In 1997, using Norwegian drainpipe traps baited with pheromones of Gnathotrichus retusus and G. sulcatus, we collected beetles in the region where the first specimen had been caught in order to determine whether this potential pest species had become established in the area. Samples from a total of 16 traps included 79 species of beetles and 719 individuals, but no specimens of G. materiarius. The most abundant species in the samples were the ambrosia beetles Xyleborus dispar and Trypodendron lineatum. Several predators and other associates of bark beetles were also captured. The majority of the beetles caught were saproxylic species.