Morphology and distribution of antennal sensilla in the pine wood nematode insect vectors Monochamus alternatus Hope and Monochamus saltuarius Gebler (Coleoptera: Cerambycidae)

As insect vectors of pine wood nematodes, Monochamus alternatus Hope and Monochamus saltuarius Gebler have different levels of attractiveness to semiochemicals. Although active use of chemical communication in both species is well known, there was no report on the differences in morphology and distribution of antennal sensilla between the two Monochamus species. The present study was carried out to explore the morphology, distribution, and ultrastructure of antennal sensilla of the two species using scanning and transmission electron microscopy. The overall shapes of the antennae were not different between M. alternatus and M. saltuarius. However, both M. alternatus and M. saltuarius exhibited sexual dimorphism overall. The antennae of each species were composed of the scape, pedicel, and nine flagellomeres, with four morphological types of sensilla: trichodea, basiconica, chaetica, and coeloconica. The four types occurred in varying numbers and distributions. The sensilla chaetica type was the most abundant in both species. Three types of sensilla (trichodea, basiconica, and chaetica) could be subdivided according to the two Monochamus species; sensilla trichodea could be divided into two subtypes, and sensilla basiconica and sensilla chaetica into three. All sensilla basiconica subtypes were multiporous, indicating that their primary function was olfactory. Sensilla trichodea subtype 2 was uniporous, indicating that the function of these sensilla might be gustatory. The morphological information obtained in our study provides a basis for future investigation of the sensory physiological function of each type of sensilla in the two species.     

Prevalence of laterally transferred Wolbachia genes in Japanese pine sawyer,Monochamus alternatus (Coleoptera: Cerambycidae)

Lateral gene transfer is any process in which an organism incorporates genetic material from a phylogenetically distant and reproductively isolated organism. A previous survey demonstrated that two Japanese populations of Monochamus alternatus Hope carried many Wolbachia genes that had been acquired by lateral gene transfer in their own genomes, but were not infected with Wolbachia. To understand the prevalence of Wolbachia infection and laterally transferred Wolbachia genes in this beetle, we performed a broader survey of natural populations covering two subspecies of M. alternatus from Japan (M. alternatus endai) and Taiwan (M. alternatus alternatus). We detected laterally transferred Wolbachia genes in all Japanese and Taiwanese populations of M. alternatus, but no Wolbachia infection in any population. In addition, we confirmed the absence of Wolbachia infection and of transferred Wolbachia genes in two Japanese populations of Monochamus saltuarius Gebler, which is a congeneric relative of M. alternatus. Our findings suggest that the Wolbachia endosymbiont as gene donor has disappeared from M. alternatus, and that the transfer of part of its genome to M. alternatus occurred in the ancestor of M. alternatus before the subspeciation event.     

Transmission of Bursaphelenchus xylophilus between Monochamus alternatus and Monochamus saltuarius through interspecific mating behaviour

Cerambycid adults of the genus Monochamus transmit the pine wood nematode (Bursaphelenchus xylophilus [Steiner et Buhrer] Nickle), the causative agent of pine wilt disease. To confirm the transmission of B. xylophilus between vector species, nematode‐infected Monochamus alternatus Hope and nematode‐free Monochamus saltuarius (Gebler) adults were paired and their behaviour was observed for 107–220 min. In three pairs that exhibited mounting without copulation, nematode transmission occurred, whereas it was not found in another pair without mountings. The effect of nematode transmission between different vector species on the invasion biology of B. xylophilus is discussed.     

Changes in spatial and temporal distributions of Monochamus beetles along the fire severity in burned Pinus densiflora forests

Wildfire is an important disturbance factor in forest ecosystem and could affect the distribution of insects. Because Monochamus beetles are known vector insects of pine wood nematodes in Korea and burnt pine trees can be used as oviposition habitats for Monochamus beetles, we investigated changes in the spatial (among fire severity classes) and temporal (between years) distributions of M. alternatus and M. saltuarius. From late May 2017 to early October 2018, four multi-funnel traps with pheromone lure were installed in each fire severity class (unburned, light, light-moderate edge, moderate-severe edge, and severe). All traps were replaced fortnightly from May to October for two years. The spatial distribution of the two Monochamus beetles was significantly affected by fire severity. In particular, M. alternatus showed higher catches in the severely burned sites and responded positively to the fire. A similar number of M. saltuarius individuals were observed between 2017 and 2018, while more M. alternatus were caught in 2018 compared to 2017. Consequently, it was confirmed that the dead wood of P. densiflora caused by the wildfire had a great influence on the density of insects, especially M. alternatus.     

Synergistic attraction of pine sawyer Monochamus saltuarius (Coleoptera: Cerambycidae) to monochamol and α‐pinene

Monochamus (Coleoptera: Cerambycidae) species are longhorn pine sawyers that serve as insect vectors of the pinewood nematode Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae), which are responsible for debilitating pine wilt disease. An aggregation pheromone, 2‐(1‐undecyloxy)‐1‐ethanol (hereafter referred to as monochamol), was shown to be effective at attracting Monochamus species. However, attraction of the pine sawyers to aggregation pheromones varied depending on semiochemicals, including host plant volatiles and kairomones. In this study, we investigated the abilities of monochamol and the host‐plant volatiles α‐pinene and ethanol to attract M. saltuarius in a pine forest in Cheongsong, Gyeongsangbuk‐do, Korea. A total of 91 M. saltuarius (28 males and 63 females) were captured. The combination of monochamol (700 mg) with α‐pinene and ethanol exhibited a synergistic effect on attracting M. saltuarius (11.0 beetles per trap), whereas monochamol alone and a mixture of α‐pinene and ethanol resulted in the capture of 3.2 beetles and 3.6 beetles per trap, respectively. Our results suggest that multi‐funnel traps baited with a blend of monochamol, α‐pinene and ethanol are highly effective for monitoring M. saltuarius and M. alternatus in pine forests.     

Trapping strategy for Monochamus sutor and Monochamus galloprovincialis: potential vectors of the pine wood nematode in Scandinavia

相似文献   

Evolutionary relationships within European Monochamus (Coleoptera: Cerambycidae) highlight the role of altitude in species delineation

Phylogenetic relationships within the European Monochamus (Coleoptera: Cerambycidae) remain understudied despite their increasing importance in the Pine Wood Nematode spread in Europe. To clarify the delimitation and the evolutionary history of the two main European Monochamus species, Monochamus galloprovincialis and Monochamus sutor, as well as their sub‐species, a comparative study using morphological, molecular, and biogeographical criterions was conducted. Four morphological characters, including a newly‐described morphological character on the male genitalia, separated the two species. Additionally, molecular data revealed twelve and two single nucleotide polymorphisms in cytochrome oxidase c subunit I and 28S, respectively, supporting species segregation. By contrast, incongruence between morphological and genetic results did not allow discriminating the sub‐species of M. galloprovincialis and M. sutor, even though mitochondrial DNA revealed intraspecific differentiation, mostly consenting to a multiple refugia origin. Within‐species variability was explained to a large extent by biogeography (i.e. altitude, climate). These different ecological adaptations within beetle species, together with potential climate change impact, increase the risk of spreading the nematode across Europe to novel conifer hosts and challenge the European biosecurity. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 354–376.     

First record of the family Bothrideridae (Coleoptera) in Korea represented by the wood-boring beetle ectoparasite,Dastarcus helophoroides

The ectoparasitic beetle, Dastarcus helophoroides (Fairmaire), was observed for the first time in Korea as a result of a study of the natural enemies of Monochamus alternatus Hope and M. saltuarius Gebler, the vector of the pine wood nematode (Bursaphelenchus xylophilus (Steiner & Buhner)). Diagnostic illustrations are provided and the biology and host range of D. helophoroides (Fairmaire) are reviewed.     

Effects of C10‐ and C12‐chain length alkyl analogs of monochamol on attraction of longhorn pine sawyer Monochamus saltuarius (Coleoptera: Cerambycidae)

The aggregation pheromone of Monochamus (Coleoptera: Cerambycidae) beetles, 2‐(undecyloxy) ethanol (hereafter referred to as monochamol), has gained considerable attention because of its usefulness in monitoring and population control of pine sawyer beetles. The hydroxyether structural motif is conserved in pheromones of the subfamily Lamiinae of the Cerambycidae. In this study, we investigated the effects of C10‐ and C12‐chain length alkyl analogs of monochamol, 2‐(decyloxy) ethanol and 2‐(dodecyloxy) ethanol, on attracting M. saltuairus in Andong, Gyeongsangbuk‐do, Korea. The C10 and C12 analogs attracted M. saltuarius when used in combination with α‐pinene and ethanol, but the responses of these alkyl chain analogs were lower than those of monochamol. Furthermore, the addition of either C10 or C12 analog to the use of monochamol with α‐pinene and ethanol had no effect on attraction of M. saltuarius, indicating high sensitivity of M. saltuarius to monochanol. Taken together, the results of this study suggest that chemical communication within a Monochamus species depends not only on monochamol, but also on other semiochemicals.     

The bimodal adult activity of Monochamus alternatus (Coleoptera: Cerambycidae) caught in pheromone traps in Jeju can be explained by the competitive attractiveness of dying pine trees

The Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae), is known to be the primary vector of pinewood nematode Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle that causes pine wilt disease. Adult activity of M. alternatus caught in a pheromone trap on Jeju Island of Korea showed a bimodal form with the first peak in mid to late June and the second peak in mid to late September. The two peaks were separated between mid and late August, showing a valley. Accumulated degree‐days predicted that the emergence of the second generation adults could be possible just before the second peak. But actually no adults of the second generation occurred in the field development experiments of M. alternatus in 2016 and 2017. Pine trees without oleoresin flow (namely dying trees by the infection of pinewood nematode) were abundant during early July to early August. The bimodal adult activity pattern of M. alternatus could be partially explained by the competitive attractiveness of dying trees against pheromone traps, when we accepted the assumption that dying pine trees attract strongly M. alternatus.     

松墨天牛成虫室内外种群肠道细菌的多样性及功能分析

[目的]为明确松墨天牛Monochamus alternatus成虫中、后肠细菌群落结构,探索肠道细菌的潜在功能.[方法]分别提取室外和室内饲养的松墨天牛成虫各15头(室内和室外各15个中肠、15个后肠)的肠道DNA,利用二代测序技术对松墨天牛成虫肠道细菌的16S rDNA V3-V4区序列进行测序,统计操作分类单元(...     

Physiological development and dispersal ability of newly emerged Monochamus galloprovincialis

Novel associations between exotic pathogens and native insects may result in major ecological and economical losses. In Europe, Monochamus galloprovincialis (Olivier) (Coleoptera: Cerambycidae) is the only known vector of the exotic pine wood nematode Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle (Nematoda: Aphelenchoididae), the causal agent of pine wilt disease (PWD). Transportation of goods containing nematode‐infested beetles is the main pathway for the spread of the disease. In this scenario, management actions involving early detection and eradication are critical to stop further spread by the vector. Although dispersal of mature M. galloprovincialis has been successfully tracked using commercial baits and traps, dispersal ability of immature individuals is poorly understood. Sexual maturation and other physiological traits related to dispersal were studied for newly emerged M. galloprovincialis after different shoot‐feeding spans. Sexual maturation was complete after on average 12 (males) or 13 (females) feeding days. Monochamus galloprovincialis adults emerged with an average of 10% lipid and 23.8% (males) or 29.9% (females) pterothorax muscle content, and these percentages did not change significantly during shoot feeding. Microtomography images of wing muscle structures at different maturation stages confirmed these results. Emerged adults that were kept unfed survived an average of 12 days in the lab. The ability of unfed immature insects to fly through hostless terrain was studied by marking and releasing newly emerged insects from a crop area located up to 3 km away from two small pine stands. The longest flown distance recorded was 2 km. Fitted regressions indicated that immature insects could have travelled up to 3 109 m to reach the experimental stands. We found that M. galloprovincialis emerge with well‐developed thoracic muscles and energy reserves that enable them to sustain long flights over non‐forested areas. These findings should aid managers and policy makers in devising sound procedures in areas where the risk of introducing PWD is high.     

Feeding and oviposition preference of the Sakhalin pine sawyer Monochamus saltuarius (Coleoptera: Cerambycidae) for various tree species

Monochamus saltuarius was recently identified as an important vector of Bursaphelenchus xylophilus, the cause of pine wilt disease. In this study, M. saltuarius adults preferred different species of tree based on the longevity, ingested amount and wounded area that were determined for 90 d. Among eight tree species, the longevity of feeding by M. saltuarius was not significantly different except when feeding in Sciadopitys verticillata. However, the highest ingested amounts with the largest wounded areas were associated with Pinus koraiensis. The highest oviposition preference was in P. densiflora for the first 20 d. However, after 40 d, the oviposition highest preference was noted in P. koraiensis. For oviposition activities, M. saltuarius preferred the tree species in the following order: P. densiflora > P. koraiensis > P. rigida > Larix leptolepis. Although many oviposition scars were observed, M. saltuarius laid fewer eggs in P. rigida than other species of pine, which was related to the bark thickness. The oviposition frequencies were highest with bark 2.0–2.5 mm thick and with tree diameters of 110–130 mm. The current study increased understanding of the ecology of M. saltuarius by identifying specific tree preferences.     

Combining pheromone and kairomones for effective trapping of the pine sawyer beetle Monochamus galloprovincialis

Monochamus galloprovincialis (Olivier) (Coleoptera: Cerambycidae) is a secondary wood borer that acquired primordial importance since it was identified as the European vector of Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD). An effective trapping method is needed as a tool for managing this insect vector and allowing early detection of nematode transportation. Among effective attractants identified in recent years are the specific M. galloprovincialis aggregation pheromone, host pine kairomones such as α‐pinene and bark beetle kairomones like ipsenol and methyl‐butenol. The main objective of this study was to optimize the combination of these volatiles to improve lure attractiveness and specificity. Based on ten complementary field experiments, we found a pheromone dose‐response of trap catches. The best combination of attractants was the aggregation pheromone plus two bark beetle kairomones, ipsenol and methyl‐butenol. Addition of pine terpenes, such as α‐pinene, did not significantly improve M. galloprovincialis trap capture, but did increase catch of non target species, including natural enemies. The use of pine terpenes would be advisable only if priorizing to maximize removal of vectors. While this research has lead to the development a new, highly attractive commercial lure for mature pine sawyers, none of the tested blends were successful in attracting immature pine sawyer adults. Further investigation is needed to develop attractants for these beetles.     

The stability of the pheromones of xylophagous insects to environmental factors: An evaluation by quantum chemical analysis

The ground and excited states of the pheromone molecules produced by xylophagous insects (the bark beetle Ips typographus L., the black fir sawyer beetle Monochamus urussovi Fisch., and the black pine sawyer M. galloprovincialis Oliv.) were modeled using a quantum chemical method utilizing DFT (density functional theory) with the B3LYP functional. The absorption wavelengths (energies) and dipole moments were calculated; the transitions of electrons from occupied to empty molecular orbitals were considered. The computed data were used to assess the stability of pheromone molecules exposed to environmental factors, such as solar radiation and humidity.     

Potential vector switching in the evolution of Bursaphelenchus xylophilus group nematodes (Nematoda: Aphelenchoididae)

To show the importance of vector switching of nematodes in the evolution of the Bursaphelenchus xylophilus group, we tested a hypothesis that “Bursaphelenchus doui (or its ancestor) was transferred by Acalolepta fraudatrix, Acalolepta sejuncta, and/or Monochamus subfasciatus (or their ancestral species) from broad‐leaved trees to conifers, switched vectors from these cerambycid beetles to Monochamus beetles in conifers, and then evolved into the common ancestor of Bursaphelenchus mucronatus and B. xylophilus.” We used a simple nematode‐loading method to beetles and produced 20 binary combinations of five B. xylophilus group species and four cerambycid beetle species in the tribe Lamiini. The affinity of the nematodes for the beetles was examined based on phoretic stage formation of the nematodes. Phoretic stages of B. doui appeared in all beetle species examined, namely Acalolepta luxuriosa, Psacothea hilaris, A. fraudatrix, and Monochamus alternatus, although the affinity of the nematode for M. alternatus was weak. This finding indicates that B. doui could switch vectors to conifer‐using Monochamus beetles after transfer by A. fraudatrix from broad‐leaved trees to conifers. We conclude that vector switching of nematodes could have potentially happened during the evolutionary history of the B. xylophilus group.     

Developmental stability is not disrupted by extensive hybridization and introgression among populations of the marine bivalve molluscs Mytilus edulis (L.) and M. galloprovincialis (Lmk.) from south-west England

The effects of hybridization and introzgression were assessed among two naturally hybridizing bivalve molluscs (the mussels Mytilus edulis and M. galloprovincialis) from western Europe to estimate how disruptive these processes are to developmental stability (measured in terms of morphological variability). Ten shell traits were measured for 392 mussels from four allopatric populations (two each of At. edulis and At. galloprovincialis) and two hybrid populations. An index of variability (defined as Z_i= |y_i–y_i where y_; is the population mean of the length-standardized trait, and y_i is the individualcar;s length-standardized trait value) was constructed for each trait, and for the sum of the traits. The hybrid populations did not exhibit greater mean variability than the allopatric populations for any of the indices. Upon pooling, the hybrid populations had significantly lower variability than the pooled M. edulis populations and the pooled M. galloprovincialis populations in two analyses, and had similar means in the remaining nine analyses. Where significant differences existed, the pooled M. galloprovincialis had lower levels of mean trait variability than the pooled M. edulis. Among the two hybrid populations, the putative Fl hybrids and backcross individuals exhibited means of trait variability which were similar to those of the parental types. Thus, extensive hybridization and introgression do not adversely affect developmental stability among these mussel populations. There was a strong significant correlation between the ranking of indices (based on the amount of variability) across all six populations, indicating that a large genetic component determines the measured morphological variability. It is concluded that the genes or gene complexes which control morphological development in M. edulis and M. galloprovincialis arc very similar, providing further evidence of the close evolutionary relatedness of these mussel taxa.     

Optimization of a solid culture medium based on Monochamus alternatus for Cordyceps militaris fruiting body formation

Monochamus alternatus (Coleoptera: Cerambycidae; M. alternatus), popularly known as the Japanese pine sawyer, is a vector of pinewood nematode (Bursaphelenchus xylophilus) that causes pine wilt disease. A solid medium culture with M. alternatus produced Cordyceps militaris fruiting bodies with the longest strips and the highest biological efficiency. Supplementing the original form of M. alternatus with oats resulted in slightly enhanced fruiting body production. The original form of M. alternatus showed higher production than its powder form. The solid culture medium was optimized using a response surface methodology, and the optimal medium contained the following: 8·5 g per bottle of M. alternatus and 11·5 g per bottle of oats mixed with 22·4 ml of water in a 300-ml cylindrical plastic bottle. The optimal culturing period for the fruiting body formation was 37·1 days. Under these conditions, a fruiting body dry weight of 38·0 g per bottle (actual value) was attained. The fruiting body produced using a solid culture medium based on M. alternatus had a cordycepin content of about 25 µg g⁻¹. The solid culture medium containing M. alternatus is highly efficient and eco-friendly, and its effectiveness in large-scale fruiting body production from C. militaris has been demonstrated.     

金龟子绿僵菌在森林土壤中的分布及对松墨天牛致病性测定

松墨天牛是重大森林植物检疫性病害——松材线虫病的主要媒介昆虫。本研究于2005年8月～2006年8月从福建、江西两省共110个林分样区(其中松林88个样区)采集土壤样品330份,采用选择性培养基分离土壤中的金龟子绿僵菌。从21个样区的26份土样中分离出的金龟子绿僵菌占采集样区的19．1％和样品的7．9％,成菌落数(CFU)500～72500CFU/g,表明金龟子绿僵菌在森林土壤中有较为广泛的分布。对分离到的9个产孢量高的菌株,采用浸渍法(1×10~7孢子/mL)接种3～4龄健康松墨天牛幼虫,采用跗节接种法接种2～15日龄健康成虫,测定其致病力。结果表明,MaYTTR-03、MaYTTR-04菌株对松墨天牛幼虫和成虫均有较高致病力,表现出良好的生防潜力。