Phylogeography of spruce beetles (Dendroctonus rufipennis Kirby) (Curculionidae: Scolytinae) in North America

Tree-feeding insects that are widespread in north temperate regions are excellent models for studying how past glaciations have impacted differentiation and speciation. We used mitochondrial DNA (mtDNA) sequences and allele frequencies at nine microsatellite loci to examine genetic population structure across the current range of the spruce beetle (Dendroctonus rufipennis), an economically important insect in North America. Two major haplotype groups occur across northern North America, from Newfoundland to Alaska, on white spruce (Picea glauca), and a third distinctive haplotype group occurs throughout the Rocky Mountains on Engelmann spruce (Picea engelmannii). The two mtDNA lineages found in northern populations are 3-4% divergent from each other and from the lineages found in the Rocky Mountains. Analyses of microsatellite data also suggest the existence of major population groupings associated with different geographical regions. In the Pacific Northwest, concordant contact zones for genetically distinct populations of spruce beetles and their principal hosts appear to reflect recent secondary contact. Although we could detect no evidence of historical mtDNA gene flow between allopatric population groups, patterns of variation in the Pacific Northwest suggest recent hybridization and introgression. Together with the pollen record for spruce, they also suggest that beetles have spread from at least three glacial refugia. A minimum estimate of divergence time between the Rocky Mountain and northern populations was 1.7 Myr (million years), presumably reflecting the combined effects of isolation during multiple glacial cycles.     

DNA条形码试剂盒检测技术在大小蠹属种类鉴定中的应用

[目的]DNA条形码技术已成为生物分类鉴定的有力工具.DNA条形码技术的相关问题,如物种种内和种间的遗传距离出现重叠区域,将直接影响到物种鉴定的准确性.我们应用DNA条形码试剂盒检测技术来快速、准确地鉴定口岸截获的检疫性大小蠹属种类.[方法]针对大小蠹昆虫设计引物以提高PCR扩增效率.运用自主研发的基因条码分析软件找出基因片段上区分每个物种的多态位点规律,作为该物种的鉴定特征并建立数据库,应用于物种鉴定.[结果]使用针对大小蠹属昆虫设计的引物成功扩增出325 bp的COI基因片段.将大小蠹属12种昆虫的COI基因片段上的核苷酸诊断位点的组合作为物种的鉴定特征,可以准确地区分近似种.通过比对植物检疫鉴定系统数据库里的鉴定特征,将6个大小蠹属的未知样品成功鉴定到种(核苷酸序列一致性为100％),与形态鉴定结果一致.[结论]结果表明DNA条形码试剂盒检测技术可以准确鉴定大小蠹属的种类.该检测技术可以应用于其他经济重要性有害生物的检测鉴定.     

Five new species of Triotemnus (Coleoptera, Curculionidae, Scolytinae) from Morocco and Yemen

Fivenew species of the genus Triotemnus from Morocco and Yemen are described. Triotemnus is a new genus of Scolytinae for the Yemen region. External morphology of the new species and all morphologically related species of the genus were studied. While the new species from Morocco are morphologically similar to the known species from the corresponding region, all three newly described species from Yemen, mainly two of them living in Socotra, are morphologically very different from all other known species of the genus. Geographical distribution and the probability of endemicity are discussed.     

Influence of temperature on spring flight initiation for southwestern ponderosa pine bark beetles (Coleoptera: Curculionidae, Scolytinae)

Determination of temperature requirements for many economically important insects is a cornerstone of pest management. For bark beetles (Coleoptera: Curculionidae, Scolytinae), this information can facilitate timing of management strategies. Our goals were to determine temperature predictors for flight initiation of three species of Ips bark beetles, five species of Dendroctonus bark beetles, and two genera of bark beetle predators, Enoclerus spp. (Coleoptera: Cleridae) and Temnochila chlorodia (Mannerheim) (Coleoptera: Ostomidae), in ponderosa pine forests of northcentral Arizona. We quantified beetle flight activity using data loggers and pheromone-baited funnel traps at 18 sites over 4 yr. Ambient air temperature was monitored using temperature data loggers located in close proximity to funnel traps. We analyzed degree-day accumulation and differences between minimum, average, and maximum ambient temperature for the week before and week of first beetle capture to calculate flight temperature thresholds. Degree-day accumulation was not a good predictor for initiation of beetle flight. For all species analyzed other than D. adjunctus Blandford, beetles were captured in traps only when springtime temperatures exceeded 15.0 degrees C. D. adjunctus was collected when maximum temperatures reached only 14.5 degrees C. Once initial flights had begun, beetles were often captured when maximum ambient air temperatures were below initial threshold temperatures. Maximum and average air temperatures were a better predictor for beetle flight initiation than minimum temperature. We establish a temperature range for effective monitoring of bark beetles and their predators, and we discuss the implications of our results under climate change scenarios.     

100 million years of morphological conservation in bark beetles (Coleoptera: Curculionidae: Scolytinae)

Abstract Scolytine weevils (bark and ambrosia beetles) have a unique ecological significance in forest ecosystems, which equates to major effects on landscape ecology and to monetary losses. Fossilized galleries of scolytines have been reported in Late Mesozoic wood, but here we describe a well‐preserved body fossil from the Cretaceous, c. 100 Ma, preserved in amber from northern Myanmar. Moreover, the specimen is remarkably similar to Recent species of the genus Microborus, revealing stasis unexpected within scolytines and thus highlighting the antiquity of the group. Stratigraphic dating and comparison of insect palaeofaunas included in other well‐dated ambers from multiple sites support the age estimate of the Burmese amber. A minimum age for one clade of scolytines is thus established, indicating an early divergence of scolytines from other weevils in the Late Jurassic or Early Cretaceous and challenging the current perspective of weevil evolution.     

Genetic diversity of aboriginal and invasive populations of four‐eyed fir bark beetle Polygraphus proximus Blandford (Coleoptera,Curculionidae, Scolytinae)

相似文献   

Distribution of Norway spruce bark and wood‐boring beetles along Alpine elevational gradients

相似文献   

Gut-associated yeast in bark beetles of the genus Dendroctonus Erichson (Coleoptera: Curculionidae: Scolytinae)

Scolytine bark beetles are the most destructive pests of conifers; they sometimes aggregate in such large numbers that they actually kill their hosts. They maintain close relationships with yeasts and fungi, in particular those that are assumed to aid in digestive, detoxification processes and pheromone production. In this study, 403 yeast strains were isolated from the guts, ovaries, eggs and frass of nine bark beetle species in the genus Dendroctonus Erichson. The beetles were collected from 10 conifer species at 34 locations in Mexico, Guatemala and the USA. Yeast identification was based on partial DNA sequences from 18S rDNA, 26S rDNA and internal transcribed spacer (ITS1), as well as morphological and physiological characteristics. A combined phylogenetic analysis delimited 11 clades with sequences similar to Candida arabinofermentans , C. ernobii , C. membranifaciens (including C. lessepsii , Pichia mexicana and P. scolyti ), C. oregonensis , C. piceae , Kuraishia capsulata (including K. capsulata and K. cf. molischiana ), Pichia americana , P. canadensis , P. glucozyma , P. guilliermondii and an undescribed species of Candida . Nucleotide divergences between the major clades were at least 5% while, with the exception of 30 isolates, yeasts within clades differed from named reference species at fewer than 1% of the nucleotide sites. There do not appear to be obligate relationships between particular yeasts and specific anatomical partitions, nor between particular yeasts and bark beetle species. Some yeasts do appear to be preferentially associated with bark beetles feeding on different conifer genera and therefore host plant defences may limit yeast community diversity in Dendroctonus .  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 325–342.     

Pathogens of bark beetles (Curculionidae: Scolytinae) and other beetles in Bulgaria

The presence and diversity of beetle pathogens associated with different tree species in Bulgaria was investigated. In total, 818 specimens belonging to 22 beetle species were examined. Pathogens occurred in 9 host species. The infections were found in the gut (virus, nematodes, protozoans, microsporidia) and haemolymph (nematodes) of the infected insects. The following pathogen species: ItEPV, Beauveria bassiana, B. brongniartii, Isaria farinosa, Gregarina typographi, Gregarina spp., Chytridiopsis typographi, Chytridiopsis sp., and nematodes were revealed. Insects with mycoses were mummified and filled up with fungal structures, formed pseudosclerotium. Most pathogens were established in bark beetles (Scolytinae). For the first time, the fungus B. bassiana was reported in Tomicus piniperda, Orthotomicus longicollis, O. erosus, X. spinole, Taphrorychus villifrons and Phylobius sp. in Bulgaria. We also present the first records of gregarines in O. longicollis, Acanthocinus aedilis, Rhagium inquisitor, Pyrochroa coccinea, and of the microsporidium Chytridiopsis sp. in O. longicollis.     

Temperature-dependent parameters of stridulatory signals in the four-eyed fir bark beetle,Polygraphus proximus (Coleoptera: Curculionidae: Scolytinae)

Acoustic signals are an essential part of the multi-modal systems of conspecific communication among insects. The patterns of abiotic factors effects on their communication parameters are of great interest for prognostic purposes in current climatic instability and for practical application in order to manage their populations.The aim of this study was to reveal the dependence of the parameters of acoustic signals produced by bark beetle Polygraphus proximus, an aggressive alien stem pest on the environmental temperature. Male stridulatory signals were recorded in seven temperature settings (5–35 °C), and changes in their temporal parameters were evaluated under laboratory conditions.The obtained results allowed us to reveal the pattern of temperature dependence of signals produced by P. proximus. More than half of the insects were found to actively stridulate at 5 °C. Raising temperature caused an increment in chirp rate that continued to increase up to 30 °C. Further temperature increase led to suppression of signaling in most of the tested males. The obtained results showed a number of patterns of temperature effect on the parameters of acoustic signals which might be universal for representatives of different bark beetles genera with various stridulatory apparatus types.     

Phylogeny of Dendroctonus bark beetles (Coleoptera: Curculionidae: Scolytinae) inferred from morphological and molecular data

Bark beetles in the genus Dendroctonus may attack and kill several species of coniferous trees, some of them causing major economic losses in temperate forests throughout North and Central America. For this reason, they have been widely studied. However, various aspects of the taxonomy and evolutionary history of the group remain contentious. The genus has been subdivided in species groups according to morphological, biological, karyological or molecular attributes, but the evolutionary affinities among species and species groups within the genus remain uncertain. In this study, phylogenetic relationships among Dendroctonus species were reassessed through parsimony‐based cladistic analysis of morphological and DNA sequence data. Phylogenetic inference was based on 36 morphological characters and on mitochondrial DNA sequences of the cytochrome oxidase I (COI) gene. Analyses were carried out for each dataset, as well as for the combined data analysed simultaneously, under equal and implied weights. According to the combined analysis, the genus Dendroctonus is a monophyletic group defined by at least three synapomorphic characters and there are four main lineages of varied composition and diversity within the genus. Within these lineages, several monophyletic groups match, to some extent, species groups defined by previous authors, but certain groups proposed by those authors are polyphyletic or paraphyletic.     

Prepupal diapause and instar IV developmental rates of the spruce beetle, Dendroctonus rufipennis (Coleoptera: Curculionidae, Scolytinae)

The spruce beetle, Dendroctonus rufipennis (Kirby), is an important mortality agent of native spruces throughout North America. The life-cycle duration of this species varies from 1 to 3 years depending temperature. The univoltine cycle (one generation per year) is thought to maximize outbreak risk and accelerate host mortality in established outbreaks. Prepupal diapause is associated with the semivoltine cycle (one generation per 2 years) and we investigated thermal conditions that result in diapause induction. Preliminary experiments used respirometry in an attempt to distinguish the diapause state of experimental insects but the technique was apparently confounded by low respiration before and during pupation, regardless of diapause status. Therefore, diapause induction was deduced using developmental delays. The observed developmental response was not a “switch”, with developmental delay either present or absent, but instead varied continuously. We found that temperatures <15 °C from instar III through mid-instar IV were associated with developmental delays beyond that expected from cool temperatures. Moreover, the duration of exposure to cool temperatures was important in determining the degree of developmental delay. Small, if any, delays were observed if the cumulative exposure to <15 °C was <20 d whereas >40 d cumulative exposure was associated with distinct developmental suppression. Intermediate exposure to cool temperatures resulted in minor developmental delays. We used our results to parameterize a maximum likelihood estimation model of temperature-dependent instar IV developmental rates, including the effect of diapause. This model can be included as part of a spruce beetle phenology model for predicting population dynamics.     

Lack of genetic differentiation in aggressive and secondary bark beetles (Coleoptera: Curculionidae, Scolytinae) from Arizona

Bark beetles (Coleoptera: Curculionidae, Scolytinae) play an important role as disturbance agents in ponderosa pine (Pinus ponderosa Douglas ex Lawson) forests of Arizona. However, from 2001 to 2003, elevated bark beetle activity caused unprecedented levels of ponderosa pine mortality. A better understanding of the population structure of these species will facilitate analysis of their dispersal patterns and improve management strategies. Here, we use fluorescently labeled amplified fragment length polymorphism (fAFLP) analysis to resolve genetic variation among and within sampling locations in northcentral Arizona of Ips pini (Say), Dendroctonus brevicomis LeConte, and D. frontalis Zimmermann. We generated genetic fingerprints for >500 beetle specimens and analyzed genetic diversity. For all species, gene flow estimates among sampling locations were high, and significant population subdivision was not discernible across a large portion of ponderosa pine forests in Arizona. However, a weak relationship was detected with I. pini population structure and elevation. Because of the lack of genetic differentiation detected throughout the large study area, our findings suggest these insects are capable of long distance dispersal and exhibit a high degree of gene flow across a broad region. We conclude that our results are consistent with strong dispersal patterns and large population sizes of all three species.     

Variations in bark acidity and conductivity over the trunk length of silver fir and Norway spruce

 Before using bark to determine the degree of acidity in the environment due to atmospheric pollution, a better understanding of the internal factors which are involved in the evolution of the physico-chemical characteristics of bark is necessary. In this paper, variation of acidity and bark conductivity over the trunk length of silver fir and Norway spruce are examined. First, we show that it is more accurate to measure average bark pH and conductivity in each 2 m section of a tree by starting at the top than by starting at the base of the tree. A positive pH and conductivity gradient is observed over the trunk length; bark thickness decreases towards the top of the trunk. In the upper part of both silver fir and Norway spruce there are good correlations between acidity, conductivity, bark thickness and height, but in the lower part of the trees, silver fir and Norway spruce show contradictory behaviour. In silver fir, pH is linked with bark thickness and distance from the ground, while conductivity is not correlated with these two criteria. In Norway spruce we observe opposite results. It appears that conductivity measured on the external part of bark is directly influenced by the proximity of internal tissues, which are rich in ions, while acidity depends on the length of exposure to leaching due to water flowing down the trunk. Received: 15 June 1993/Accepted: 30 January 1995     

Influence of elevation on bark beetle (Coleoptera: Curculionidae, Scolytinae) community structure and flight periodicity in ponderosa pine forests of Arizona

We examined abundance and flight periodicity of five Ips and six Dendroctonus species (Coleoptera: Curculionidae, Scolytinae) among three different elevation bands in ponderosa pine (Pinus ponderosa Douglas ex. Lawson) forests of northcentral Arizona. Bark beetle populations were monitored at 10 sites in each of three elevation bands (low: 1,600-1,736 m; middle: 2,058-2,230 m; high: 2,505-2,651 m) for 3 yr (2004-2006) using pheromone-baited Lindgren funnel traps. Trap contents were collected weekly from March to December. We also studied temperature differences among the elevation bands and what role this may play in beetle flight behavior. Bark beetles, regardless of species, showed no consistent elevational trend in abundance among the three bands. The higher abundances of Ips lecontei Swaine, I. calligraphus ponderosae Swaine, Dendroctonus frontalis Zimmerman, and D. brevicomis LeConte at low and middle elevations offset the greater abundance of I. knausi Swaine, D. adjunctus Blandford, D. approximatus Dietz, and D. valens LeConte at high elevations. I. pini (Say) and I. latidens LeConte were found in similar numbers across the three bands. Flight periodicity of several species varied among elevation bands. In general, the flight period shortened as elevation increased; flight initiated later and terminated earlier in the year. The timing, number, and magnitude of peaks in flight activity also varied among the elevation bands. These results suggest that abundance and flight seasonality of several bark beetles are related to elevation and the associated temperature differences. The implications of these results are discussed in relation to bark beetle management and population dynamics.     

Association of Geosmithia fungi (Ascomycota: Hypocreales) with pine- and spruce-infesting bark beetles in Poland

Bark beetles (Coleoptera, Scolytinae) are known to be associated with fungi, particularly species of the orders Ophiostomatales and Microascales. However, very little is known about other ectosymbionts of phloeophagous bark beetles on Pinaceae. In this study, we examined the Geosmithia species associated with eight bark beetle species infesting Picea abies and Pinus sylvestris branches in Poland. Fungi were isolated from 1 731 samples collected from 14 study sites. We identified a total of 653 isolates that were sorted into nine taxa based on their phenotypic similarity and phylogeny of their ITS-LSU regions of rDNA, β-tubulin, elongation factor 1α and the second-largest subunit of the RNA polymerase II gene. They represented nine species without formal names. There were large quantitative and qualitative differences in the composition of Geosmithia communities between P. sylvestris and P. abies trees. The proportion of samples infested with Geosmithia species suggests that this association is more widespread among bark beetles infesting branches of P. sylvestris. In addition, these beetles were vectors of different Geosmithia species compared with than the beetles that colonize P. abies. In mixed-conifer forests, the Geosmithia communities were more diverse and richer than in pure spruce or pine stands, where the insects Pityogenes chalcographus and Pityophthorus pityographus with low host-specificity play a distributing role for various Geosmithia species. Among eight bark beetle species examined, only P. bidentatus, P. pityographus, P. chalcographus and Polygraphus poligraphus acted as effective vectors for Geosmithia species. The following hypothesis emerges from these studies: changes in the composition of ectosymbionts of pine- and spruce-infesting bark beetles in Central Europe run along a gradient of thickness of the wood substrata preferred by insects.     

Additions to the check list of bark beetles (Coleoptera,Curculionidae: Scolytinae) from Leningrad Province,Russia

The field work of the authors during the last 16 years in both the western and the eastern parts of Leningrad Province, Russia, has resulted in the addition of 7 species to the regional list of bark beetles, namely: Hylurgus ligniperda F., Crypturgus subcribrosus Egg., Pityogenes irkutensis Egg., Scolytus mali Bechst., S. scolytus F., S. pygmaeus F., and Xyleborinus attenuatus Blandf. Of these species, P. irkutensis occurs only in the eastern districts of Leningrad Province, C. subcribrosus, over the whole territory, and the remaining species, only in the western districts. We suggest excluding Polygraphus proximus Blandf. from the regional faunal list. As a result, the updated list of the bark beetle species of Leningrad Province comprises 75 taxa. New data on findings of rare species in the region are considered.     

Phylogeography of the bark beetle Dendroctonus mexicanus Hopkins (Coleoptera: Curculionidae: Scolytinae)

Dendroctonus mexicanus is polyphagous within the Pinus genus and has a wide geographical distribution in Mexico and Guatemala. We examined the pattern of genetic variation across the range of this species to explore its demographic history and its phylogeographic pattern. Analysis of the mtDNA sequences of 173 individuals from 25 Mexican populations allowed to us identify 53 geographically structured haplotypes. High haplotype and low nucleotide diversities and Tajima’s D indicate that D. mexicanus experienced rapid population expansion during its dispersal across mountain systems within its current range. The nested clade phylogeographic analysis indicates that the phylogeographic pattern of D. mexicanus is explained by continuous dispersion among lineages from the Sierra Madre Occidental, the Sierra Madre Oriental and the Trans-Mexican Volcanic Belt. However, we also observed isolation events among haplotypes from the Cofre de Perote/Trans-Mexican Volcanic Belt/Sierra Madre Oriental and the Trans-Mexican Volcanic Belt/Sierra Madre del Sur, which is consistent with the present conformation of mountain systems in Mexico and the emergence of geographical barriers during the Pleistocene.     

Temperature‐dependent development of the great European spruce bark beetle Dendroctonus micans (Kug.) (Coleoptera: Curculionidae: Scolytinae) and its predator Rhizophagus grandis Gyll. (Coleoptera: Monotomidae: Rhizophaginae)

相似文献   

Integration of visual and olfactory cues of hosts and non-hosts by three bark beetles (Coleoptera: Scolytidae)

Abstract.  1. There has been a long-standing pre-occupation with how phytophagous insects use olfactory cues to discriminate hosts from non-hosts. Foragers, however, should use whatever cues are accurate and easily assessed, including visual cues.
2. It was hypothesised that three bark beetles, the mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, the Douglas-fir beetle (DFB), D. pseudotsugae Hopkins, and the western balsam bark beetle (WBBB), Dryocoetes confusus Swaine, integrate visual and olfactory information to avoid non-host angiosperms (e.g. paper birch, trembling aspen), that differ in visual and semiochemical profile from their respective host conifers (lodgepole pine, Douglas-fir, interior fir), and tested this hypothesis in a series of field trapping experiments.
3. All three species avoided attractant-baited, white (non-host simulating) multiple-funnel traps, and preferred attractant-baited black (host-simulating) traps. In experiments combining white, non-host traps with non-host angiosperm volatiles, bark beetles were repelled by these stimuli in an additive or redundant manner, confirming that these species could integrate visual and olfactory information to avoid non-host angiosperms while flying.
4. When antiaggregation pheromones were released from white traps, the DFB and MPB were repelled in an additive-redundant manner, suggesting that beetles can integrate diverse and potentially anomalous stimuli.
5. The MPB demonstrated the most consistent visual preferences, suggesting that it may be more of a 'visual specialist' than the DFB or WBBB, for which visual responses may be more contingent on olfactory inputs.