The red turpentine beetle （RTB）, Dendroctonus valens LeConte, as a destructive invasive pest, has become one of the most economically important forest pest in China. Effective control measures are desperately needed...The red turpentine beetle （RTB）, Dendroctonus valens LeConte, as a destructive invasive pest, has become one of the most economically important forest pest in China. Effective control measures are desperately needed. Entomopathogenic fungi, such as Beauveria bassiana, have shown great potential for the management of some bark beetle species. In this study, 12 isolates of B. bassiana from bark beetle were examined for biological characteristics and virulence, to assess their potential as biocontrol agents for RTB. There were significant differences （at P = 0.05） in colony growth rate, conidial yield, conidial germination, tolerance to UV light and extracellular proteases activity among the tested B. bassiana isolates. Isolates, including Bbl801, Bb1906, Bb789 and Bb773, exhibited the best characteristics, because they have faster hyphal growth rate, higher spore production and faster spore germination, higher UV tolerance and protease （Prl） production. The results of a pathogenicity test ofB. bassiana on RTB larvae showed that most isolates of B. bassiana have demonstrated high efficacy and the highest virulent isolate was Bb 1801, which killed 100% of the treated insects and had a median lethal time （LT50） of 4.60 days at a concentration of 1 ×107 conidia/mL. Therefore, isolate Bb1801 has a great potential for sustainable control of RTB in the forest. The correlation between biological characteristics and virulence of the fungal isolates is discussed and the possibility of combination of entomopathogenic fungi with semiochemicals, as one of the promising strategy for RTB control, is considered.展开更多
Conifers respond to herbivore attack with defensive chemicals, which are toxic to both insects and their associated microorganisms. Microorganisms associated with insects have been widely reported to metabolize toxic ...Conifers respond to herbivore attack with defensive chemicals, which are toxic to both insects and their associated microorganisms. Microorganisms associated with insects have been widely reported to metabolize toxic chemicals, which may help both microorganisms and host insects overcome host conifer defense. Dendroctonus valens LeConte, an introduced exotic pest from North America to China, has killed millions of healthy pines. Alpha-pinene is the most abundant defensive monoterpene in Chinese Pinus tabuliformis. Although microorganisms associated with D. valens have already been investigated, little is known about their bioactivities when encountering host defensive monoterpenes. In this study, we evaluated the influences of different concentrations ofα- pinene to D. valens and the three most frequently isolated yeasts and bacteria ofD. valens, and further assayed microorganisms＇ capabilities to degrade α-pinene. Results showed that the gallery lengths and body weight changes of bark beetles were significantly affected by 6 mg/mL and 12 mg/mL of α-pinene applied in media compared to controls. The tolerance of experimental microorganisms to α-pinene varied depending on the microbial species. Two out of three yeast strains and all three bacterial strains degraded 20%-50% of α-pinene compared to controls in 24 h in vitro. The microorganisms capable of α-pinene degradation in vitro and their tolerance to high levels ofα-pinene suggested that D. valens- associated microorganisms may help both microorganisms and the bark beetle overcome host α-pinene defense.展开更多
The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to unde...The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle in order to develop an effective monitoring and management strategy. In this study, the effects of hillside exposure （south- and north-facing）, host-tree locations according to relief （valley, mid-slope, and ridge-top） and tree diameters on RTB colonization were investigated in one valley （3 sites）. The results showed that （i） RTB clearly preferred colonizing pines growing on south-facing hillsides, especially in the valley; （ii） RTB preferred to colonize the pines growing at the valley rather than pines growing at mid-slope or on ridge-top; （iii） RTB preferred to colonize trees with large diameter over small and medium-sized pines; （iv） the attack density of RTBs （measured by pitch tubes/pine） was obviously higher on larger trees standing in the valley than other trees standing at other places. We conclude from RTB colonization patterns, that RTB prefers to attack large trees in the valley, which may be useful in developing a pest-management strategy.展开更多
Bark beetles are an economically and ecologically important insect group,with aggregation behavior and thus host colonization success depends on pheromone-mediated communication.For some species,such as the major inva...Bark beetles are an economically and ecologically important insect group,with aggregation behavior and thus host colonization success depends on pheromone-mediated communication.For some species,such as the major invasive forest pest in China,red turpentine beetle(Dendroctonus valens),gut microbiota participates in pheromone production by converting tree monoterpenes into pheromone products.However,how variation in gut microenvironment,such as pH,affects the gut microbial composition,and consequently pheromone production,is unknown.In this study,we fed wild caught D.valens with 3 different pH media(main host diet with natural pH of 4.7;a mildly acidic diet with pH 6 mimicking the beetle gut pH;and highly acidic diet with pH 4),and measured their effects on the gut pH,bacterial community and production of the main aggregation and anti-aggregation pheromone(verbenone).We further tested the verbenone production capacity of 2 gut bacterial isolates in different pH environments(pH 6 and 4).Compared to natural state or main host diet,feeding on less acidic diet(pH 6)diluted the acidity of the gut,whereas feeding on highly acidic diet(pH 4)enhanced it.Both changes in gut pH reduced the abundance of dominant bacterial genera,resulting in decreased verbenone production.Similarly,the highest pheromone conversion rate of the bacterial isolates was observed in pH mimicking the acidity in beetle gut.Taken together,these results indicate that changes in gut pH can affect gut microbiota composition and pheromone production,and may therefore have the potential to affect host colonization behavior.展开更多
Red turpentine beetle （RTB）, Dendroctongs valens LeConte, is a destructive forest invasive species in China, it mainly attacks Pings tabuliformis and P. bungeana. So far it has spread rapidly to the provinces of Sha...Red turpentine beetle （RTB）, Dendroctongs valens LeConte, is a destructive forest invasive species in China, it mainly attacks Pings tabuliformis and P. bungeana. So far it has spread rapidly to the provinces of Shanxi, Hebei, Henan, Shanxi and Beijing since its first outbreak in Shanxi Province in 1998, and has caused extensive tree mortality. Space-time dynamics of D. valens population and spatial sampling technique based on its spatial distribution pattern were ana- lyzed using geostatistical methods in the pure P. tabuliforis forests and mixedwood stands which were at different damage levels. According to the spatial distribu- tion of D. valeas population, the specific spatial sampling technique was also studied, and then was compared with traditional sampling technique. The spatial sam- piing technique combined with sampling theory and the biological characteristics of D. valens population, which not only could calcnlate the error of the sampling, but also could discuss the optimal sampling number and the optimum size of plot according to different damage levels and different stand types. This helps to explain population expansion and colonization mechanism of D. valens, and to provide a good reference for adopting snitable control measures.展开更多
Background： In Western North America, increasing wildfire and outbreaks of native bark beetles have been mediated by warming climate conditions. Bioclimatic models forecast the loss of key high elevation species thro...Background： In Western North America, increasing wildfire and outbreaks of native bark beetles have been mediated by warming climate conditions. Bioclimatic models forecast the loss of key high elevation species throughout the region. This study uses retrospective vegetation and fire history data to reconstruct the drivers of past disturbance and environmental change. Understanding the relationship among climate, antecedent disturbances, and the legacy effects of settlement-era logging can help identify the patterns and processes that create landscapes susceptible to bark beetle epidemics. Methods： Our analysis uses data from lake sediment cores, stand inventories, and historical records. Sediment cores were dated with radiometric techniques （14C and 210pb/137Cs） and subsampled for pollen and charcoal to maximize the temporal resolution during the historical period （1800 CE to present） and to provide environmental baseline data （last 10,500 years）. Pollen data for spruce were calibrated to carbon biomass （C t/ha） using standard allometric equations and a transfer function. Charcoal samples were analyzed with statistical models to facilitate peak detection and determine fire recurrence intervals. Results： The Wasatch Plateau has been dominated by Engelmann spruce forests for the last ～10,500 years, with subalpine fir becoming more prominent since 6000 years ago. This landscape has experienced a dynamic fire regime, where burning events are more frequent and of higher magnitude during the last 3000 years. Two important disturbances have impacted Engelmann spruce in the historical period： 1） high-grade logging during the late 19th century; and （2） a high severity spruce beetle outbreak in the late 20th century that killed 〉90 % of mature spruce （〉10 cm dbh）. Conclusions： Our study shows that spruce-dominated forests in this region are resilient to a range of climate and disturbance regimes. Several lines of evidence suggest that 19th century logging promoted a legacy of simp展开更多
Semiochemical-based management strategies are important for controlling bark beetles,such as invasive Red Turpentine Beetle(Denroctonus valens),the causal agent for mass mortality of pine trees(Pinus spp.)in China.It ...Semiochemical-based management strategies are important for controlling bark beetles,such as invasive Red Turpentine Beetle(Denroctonus valens),the causal agent for mass mortality of pine trees(Pinus spp.)in China.It has been previously shown that the pheromone verbenone regulates the attack density of this beetle in a dose-dependent manner and that the gut bacteria of D.valens are involved in verbenone production.However,molecular functional verification of the role of gut bacteria in the pheromone production of D.valens is still lacking.To better understand the molecular function of gut bacterial verbenone production,we chose a facultative anaerobic gut bacterium(Enterobacter xiangfangensis)of D.valens based on its strong ability to convert cis-verbenol to verbenone,as shown in our previous study,and investigated its transcriptomics in the presence or absence of cis-verbenol under anaerobic conditions(simulating the anoxic environment in the beetle's gut).Based on this transcriptome analysis,aldehyde dehydrogenase(ALDH1)was identified as a putative key gene responsible for verbenone production and was knocked-down by homologous recombination to obtain a mutant E.xiangfangensis strain.Our results show that these mutants had significantly decreased the ability to convert the monoterpene precursor to verbenone compared with the wild-type bacteria,indicating that ALDH1 is primarily responsible for verbenone conversion for this bacterium species.These findings provide further mechanistic evidence of bacterially mediated pheromone production by D.valens,add new perspective for functional studies of gut bacteria in general,and may aid the development of new gene silencing-based pest management strategies.展开更多
Background:The epidemic Dendroctonus rufipennis(spruce beetle)outbreak in the subalpine forests of the Colorado Plateau in the 1990s killed most larger Picea engelmannii(Engelmann spruce)trees.One quarter century late...Background:The epidemic Dendroctonus rufipennis(spruce beetle)outbreak in the subalpine forests of the Colorado Plateau in the 1990s killed most larger Picea engelmannii(Engelmann spruce)trees.One quarter century later,the larger snags are beginning to fall,transitioning to deadwood(down woody debris)where they may influence fire behavior,regeneration,and habitat structure.Methods:We tracked all fallen trees≥1 cm in diameter at breast height(1.37-m high)and mapped all pieces of deadwood≥10-cm diameter and≥1 m in length within 13.64 ha of a high-elevation mixed-species forest in the Picea–Abies zone annually for 5 years from 2015 through 2019.We examined the relative contribution of Picea engelmannii to snag and deadwood pools relative to other species and the relative contributions of large-diameter trees(≥33.2 cm at this subalpine site).We compared spatially explicit mapping of deadwood to traditional measures of surface fuels and introduce a new method for approximating vertical distribution of deadwood.Results:In this mixed-species forest,there was relatively high density and basal area of live Picea engelmannii 20 years after the beetle outbreak(36 trees ha^(−1) and 1.94 m^(2) ha^(−1)≥10-cm diameter)contrasting with the near total mortality of mature Picea in forests nearby.Wood from tree boles≥10-cm diameter on the ground had biomass of 42 Mg ha^(−1),7 Mg ha^(−1) of Picea engelmannii,and 35 Mg ha^(−1) of other species.Total live aboveground biomass was 119 Mg ha^(−1),while snag biomass was 36 Mg ha^(−1).Mean total fuel loading measured with planar transects was 63 Mg ha^(−1) but varied more than three orders of magnitude(0.1 to 257 Mg ha^(−1)).Planar transects recorded 32 Mg ha^(−1) of wood≥7.62-cm diameter compared to the 42 Mg ha^(−1) of wood≥10-cm diameter recorded by explicit mapping.Multiple pieces of deadwood were often stacked,forming a vertical structure likely to contribute to active fire behavior.Conclusion:Bark beetle mortality in the 1990s has made Picea an展开更多
The behavioral strategies and mechanisms by which some insects maintain monogamous mating systems are not well understood.We investigated the mating system of the bark beetle Dendroctonus valens,and identified several...The behavioral strategies and mechanisms by which some insects maintain monogamous mating systems are not well understood.We investigated the mating system of the bark beetle Dendroctonus valens,and identified several contributing mechanisms.Field and laboratory observations suggest the adults commonly form permanent bonds during host colonization.Moreover,it showed mated females that remained paired with males produced more offspring than mated females that were alone in galleries.In bioassays,a second female commonly entered a gallery constructed by a prior female.Videos show she commonly reached the location of the first female,but they did not engage in actual fighting.Rather,the second female typically departs to form her own gallery.Acoustic signaling likewise does not appear to influence female-female encounters,based on controlled muting experiments.Instead the intruder appears to perceive the residents presence by physical contact.Both acoustic signals and volatiles released by females during gallery constructing were shown to attract males.After a male joined a female in a gallery,the male-produced aggressive sounds,which were shown by playback to deter other males from entering the gallery.Unlike female-female interactions,resident males use their head and rear to push intruders out of galleries.Additionally,volatiles released by males during feeding repelled intruding males,discouraging them from entering the gallery.Males also construct plugs that block the entrance,which may prevent subsequent males and predators from entering the gallery.Thus,D.valens has evolved multifaceted mechanisms contributing to single pairings that confer benefits to both sexes.展开更多
Accurate and reliable predictions of pest species distributions in forest ecosystems are urgently needed by forest managers to develop management plans and monitor new areas of potential establishment.Presence-only sp...Accurate and reliable predictions of pest species distributions in forest ecosystems are urgently needed by forest managers to develop management plans and monitor new areas of potential establishment.Presence-only species distribution models are commonly used in these evaluations.The maximum entropy algorithm(MaxEnt)has gained popularity for modelling species distribution.Here,MaxEnt was used to model the spatial distribution of the Mexican pine bark beetle(Dendroctonus mexicanus)in a daily fashion by using forecast data from the Weather Research and Forecasting model.This study aimed to exploit freely available geographic and environmental data and software and thus provide a pathway to overcome the lack of costly data and technical guidance that are a challenge to implementing national monitoring and management strategies in developing countries.Our results showed overall agreement values between 60 and 87%.The results of this research can be used for D.mexicanus monitoring and management and may aid as a model to monitor similar species.展开更多
Dendroctonus spp. is one of the most portable pests in imported and ex- ported timber and wooden packages, and it is an important object of the port quarantine. Making rapid and accurate identification of Dendroctonus...Dendroctonus spp. is one of the most portable pests in imported and ex- ported timber and wooden packages, and it is an important object of the port quarantine. Making rapid and accurate identification of Dendroctonus spp. is an im- portant method to reduce the invasion risk of Dendroctonus spp. for China. In this paper, Dendroctonus punctatus, which belongs to the Dendroctonus spp., is intro- duced in detail from the aspects of taxonomic status, biological characteristics, mor- phological characteristics and the invasion risk, providing reference for the identifica- tion of Dendroctonus punctatus in inspection and quarantine.展开更多
基金We would like to thank Stephen Clarke, USDA Forest Service, for a critical review of the manuscript. Mr Zhen-Wang Miao, the Forest Pest Control Station of Shanxi Province, Tulanchuan Forest Farm, Gujiao, Shanxi Province, who provided logistical support in collecting insects. This study was funded by the State Key Laboratory of Integrated Management of Pest Insects and Rodents （Grant Chinese IPM0702）, the Anhui Provin- cial Natural Science Foundation （070411012, 070411029, TD200708）, the Youth Foundation of Anhui Educational Committee （2008jq1046zd）, the grant of General Administration of Quality Supervision, Inspection and Quarantine of the People＇s Republic of China （2009IK268） and the grant of Anhui Entry-Exit Inspection and Quarantine Bureau （AHKT-04-2008）.
文摘The red turpentine beetle （RTB）, Dendroctonus valens LeConte, as a destructive invasive pest, has become one of the most economically important forest pest in China. Effective control measures are desperately needed. Entomopathogenic fungi, such as Beauveria bassiana, have shown great potential for the management of some bark beetle species. In this study, 12 isolates of B. bassiana from bark beetle were examined for biological characteristics and virulence, to assess their potential as biocontrol agents for RTB. There were significant differences （at P = 0.05） in colony growth rate, conidial yield, conidial germination, tolerance to UV light and extracellular proteases activity among the tested B. bassiana isolates. Isolates, including Bbl801, Bb1906, Bb789 and Bb773, exhibited the best characteristics, because they have faster hyphal growth rate, higher spore production and faster spore germination, higher UV tolerance and protease （Prl） production. The results of a pathogenicity test ofB. bassiana on RTB larvae showed that most isolates of B. bassiana have demonstrated high efficacy and the highest virulent isolate was Bb 1801, which killed 100% of the treated insects and had a median lethal time （LT50） of 4.60 days at a concentration of 1 ×107 conidia/mL. Therefore, isolate Bb1801 has a great potential for sustainable control of RTB in the forest. The correlation between biological characteristics and virulence of the fungal isolates is discussed and the possibility of combination of entomopathogenic fungi with semiochemicals, as one of the promising strategy for RTB control, is considered.
文摘Conifers respond to herbivore attack with defensive chemicals, which are toxic to both insects and their associated microorganisms. Microorganisms associated with insects have been widely reported to metabolize toxic chemicals, which may help both microorganisms and host insects overcome host conifer defense. Dendroctonus valens LeConte, an introduced exotic pest from North America to China, has killed millions of healthy pines. Alpha-pinene is the most abundant defensive monoterpene in Chinese Pinus tabuliformis. Although microorganisms associated with D. valens have already been investigated, little is known about their bioactivities when encountering host defensive monoterpenes. In this study, we evaluated the influences of different concentrations ofα- pinene to D. valens and the three most frequently isolated yeasts and bacteria ofD. valens, and further assayed microorganisms＇ capabilities to degrade α-pinene. Results showed that the gallery lengths and body weight changes of bark beetles were significantly affected by 6 mg/mL and 12 mg/mL of α-pinene applied in media compared to controls. The tolerance of experimental microorganisms to α-pinene varied depending on the microbial species. Two out of three yeast strains and all three bacterial strains degraded 20%-50% of α-pinene compared to controls in 24 h in vitro. The microorganisms capable of α-pinene degradation in vitro and their tolerance to high levels ofα-pinene suggested that D. valens- associated microorganisms may help both microorganisms and the bark beetle overcome host α-pinene defense.
基金This study was funded by the National Natural Science Foundation of China （Project 30525009 and 30621003） and Beijing Science and Technology Commission （D0705002040391）. Workers at Chakou Forest Farm, Gujiao, Shanxi Province, provided technical assistance in the field. We thank Emily Wheeler for editorial assistance.
文摘The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle in order to develop an effective monitoring and management strategy. In this study, the effects of hillside exposure （south- and north-facing）, host-tree locations according to relief （valley, mid-slope, and ridge-top） and tree diameters on RTB colonization were investigated in one valley （3 sites）. The results showed that （i） RTB clearly preferred colonizing pines growing on south-facing hillsides, especially in the valley; （ii） RTB preferred to colonize the pines growing at the valley rather than pines growing at mid-slope or on ridge-top; （iii） RTB preferred to colonize trees with large diameter over small and medium-sized pines; （iv） the attack density of RTBs （measured by pitch tubes/pine） was obviously higher on larger trees standing in the valley than other trees standing at other places. We conclude from RTB colonization patterns, that RTB prefers to attack large trees in the valley, which may be useful in developing a pest-management strategy.
基金This work was supported by the National Natural Science Foundation of China(32101529,32088102,and 32061123002)Open Project of the State Key Laboratory of the Institute of Zoology,Chinese Academy of Sciences(IPM2021)+1 种基金the Program of the Natural Science Foundation of Hebei Province of China(C2019204244)Hebei Agricultural University introduced talents scientific research project(YJ201917).
文摘Bark beetles are an economically and ecologically important insect group,with aggregation behavior and thus host colonization success depends on pheromone-mediated communication.For some species,such as the major invasive forest pest in China,red turpentine beetle(Dendroctonus valens),gut microbiota participates in pheromone production by converting tree monoterpenes into pheromone products.However,how variation in gut microenvironment,such as pH,affects the gut microbial composition,and consequently pheromone production,is unknown.In this study,we fed wild caught D.valens with 3 different pH media(main host diet with natural pH of 4.7;a mildly acidic diet with pH 6 mimicking the beetle gut pH;and highly acidic diet with pH 4),and measured their effects on the gut pH,bacterial community and production of the main aggregation and anti-aggregation pheromone(verbenone).We further tested the verbenone production capacity of 2 gut bacterial isolates in different pH environments(pH 6 and 4).Compared to natural state or main host diet,feeding on less acidic diet(pH 6)diluted the acidity of the gut,whereas feeding on highly acidic diet(pH 4)enhanced it.Both changes in gut pH reduced the abundance of dominant bacterial genera,resulting in decreased verbenone production.Similarly,the highest pheromone conversion rate of the bacterial isolates was observed in pH mimicking the acidity in beetle gut.Taken together,these results indicate that changes in gut pH can affect gut microbiota composition and pheromone production,and may therefore have the potential to affect host colonization behavior.
基金Supported by Research Project of Jiangsu Entry-Exit Inspection and Quarantine Bureau(2015KJ49)Project of Beijing Municipal Education Commission(JD100220888)+2 种基金Project of Beijing Excellent Talents Funding(D Class)Project of Beijing Municipal Education Commission(JD100220888)Beijing Excellent Talents Funding(D Class)Project "Study on Prevention and Control Technology of Dendroctonus valens"
文摘Red turpentine beetle （RTB）, Dendroctongs valens LeConte, is a destructive forest invasive species in China, it mainly attacks Pings tabuliformis and P. bungeana. So far it has spread rapidly to the provinces of Shanxi, Hebei, Henan, Shanxi and Beijing since its first outbreak in Shanxi Province in 1998, and has caused extensive tree mortality. Space-time dynamics of D. valens population and spatial sampling technique based on its spatial distribution pattern were ana- lyzed using geostatistical methods in the pure P. tabuliforis forests and mixedwood stands which were at different damage levels. According to the spatial distribu- tion of D. valeas population, the specific spatial sampling technique was also studied, and then was compared with traditional sampling technique. The spatial sam- piing technique combined with sampling theory and the biological characteristics of D. valens population, which not only could calcnlate the error of the sampling, but also could discuss the optimal sampling number and the optimum size of plot according to different damage levels and different stand types. This helps to explain population expansion and colonization mechanism of D. valens, and to provide a good reference for adopting snitable control measures.
文摘Background： In Western North America, increasing wildfire and outbreaks of native bark beetles have been mediated by warming climate conditions. Bioclimatic models forecast the loss of key high elevation species throughout the region. This study uses retrospective vegetation and fire history data to reconstruct the drivers of past disturbance and environmental change. Understanding the relationship among climate, antecedent disturbances, and the legacy effects of settlement-era logging can help identify the patterns and processes that create landscapes susceptible to bark beetle epidemics. Methods： Our analysis uses data from lake sediment cores, stand inventories, and historical records. Sediment cores were dated with radiometric techniques （14C and 210pb/137Cs） and subsampled for pollen and charcoal to maximize the temporal resolution during the historical period （1800 CE to present） and to provide environmental baseline data （last 10,500 years）. Pollen data for spruce were calibrated to carbon biomass （C t/ha） using standard allometric equations and a transfer function. Charcoal samples were analyzed with statistical models to facilitate peak detection and determine fire recurrence intervals. Results： The Wasatch Plateau has been dominated by Engelmann spruce forests for the last ～10,500 years, with subalpine fir becoming more prominent since 6000 years ago. This landscape has experienced a dynamic fire regime, where burning events are more frequent and of higher magnitude during the last 3000 years. Two important disturbances have impacted Engelmann spruce in the historical period： 1） high-grade logging during the late 19th century; and （2） a high severity spruce beetle outbreak in the late 20th century that killed 〉90 % of mature spruce （〉10 cm dbh）. Conclusions： Our study shows that spruce-dominated forests in this region are resilient to a range of climate and disturbance regimes. Several lines of evidence suggest that 19th century logging promoted a legacy of simp
基金supported by the National Natural Science Foundation of China(grant numbers:32088102,32061123002,and 32101529)National Key Research and Development Program of China(grant number:2021YFC2600100)the Program of the Natural Science Foundation of Hebei Province of China(grant number:C2019204244).
文摘Semiochemical-based management strategies are important for controlling bark beetles,such as invasive Red Turpentine Beetle(Denroctonus valens),the causal agent for mass mortality of pine trees(Pinus spp.)in China.It has been previously shown that the pheromone verbenone regulates the attack density of this beetle in a dose-dependent manner and that the gut bacteria of D.valens are involved in verbenone production.However,molecular functional verification of the role of gut bacteria in the pheromone production of D.valens is still lacking.To better understand the molecular function of gut bacterial verbenone production,we chose a facultative anaerobic gut bacterium(Enterobacter xiangfangensis)of D.valens based on its strong ability to convert cis-verbenol to verbenone,as shown in our previous study,and investigated its transcriptomics in the presence or absence of cis-verbenol under anaerobic conditions(simulating the anoxic environment in the beetle's gut).Based on this transcriptome analysis,aldehyde dehydrogenase(ALDH1)was identified as a putative key gene responsible for verbenone production and was knocked-down by homologous recombination to obtain a mutant E.xiangfangensis strain.Our results show that these mutants had significantly decreased the ability to convert the monoterpene precursor to verbenone compared with the wild-type bacteria,indicating that ALDH1 is primarily responsible for verbenone conversion for this bacterium species.These findings provide further mechanistic evidence of bacterially mediated pheromone production by D.valens,add new perspective for functional studies of gut bacteria in general,and may aid the development of new gene silencing-based pest management strategies.
基金Funding was received from the Utah Agricultural Experiment Station(projects 1153 and 1398 to JAL and 1423 to JAL,LLY,and DJM)and the Smithsonian Institution ForestGEO.Research was performed under the National Park Service research permits CEBR-2014-SCI-0001,CEBR-2015-SCI0001,CEBR-2016-SCI-0001,CEBR-2017-SCI-0001,CEBR-2018-SCI-0001,and CEBR-2019-SCI-0001 for study CEBR-00016.
文摘Background:The epidemic Dendroctonus rufipennis(spruce beetle)outbreak in the subalpine forests of the Colorado Plateau in the 1990s killed most larger Picea engelmannii(Engelmann spruce)trees.One quarter century later,the larger snags are beginning to fall,transitioning to deadwood(down woody debris)where they may influence fire behavior,regeneration,and habitat structure.Methods:We tracked all fallen trees≥1 cm in diameter at breast height(1.37-m high)and mapped all pieces of deadwood≥10-cm diameter and≥1 m in length within 13.64 ha of a high-elevation mixed-species forest in the Picea–Abies zone annually for 5 years from 2015 through 2019.We examined the relative contribution of Picea engelmannii to snag and deadwood pools relative to other species and the relative contributions of large-diameter trees(≥33.2 cm at this subalpine site).We compared spatially explicit mapping of deadwood to traditional measures of surface fuels and introduce a new method for approximating vertical distribution of deadwood.Results:In this mixed-species forest,there was relatively high density and basal area of live Picea engelmannii 20 years after the beetle outbreak(36 trees ha^(−1) and 1.94 m^(2) ha^(−1)≥10-cm diameter)contrasting with the near total mortality of mature Picea in forests nearby.Wood from tree boles≥10-cm diameter on the ground had biomass of 42 Mg ha^(−1),7 Mg ha^(−1) of Picea engelmannii,and 35 Mg ha^(−1) of other species.Total live aboveground biomass was 119 Mg ha^(−1),while snag biomass was 36 Mg ha^(−1).Mean total fuel loading measured with planar transects was 63 Mg ha^(−1) but varied more than three orders of magnitude(0.1 to 257 Mg ha^(−1)).Planar transects recorded 32 Mg ha^(−1) of wood≥7.62-cm diameter compared to the 42 Mg ha^(−1) of wood≥10-cm diameter recorded by explicit mapping.Multiple pieces of deadwood were often stacked,forming a vertical structure likely to contribute to active fire behavior.Conclusion:Bark beetle mortality in the 1990s has made Picea an
基金the Thirteenth Five-Year State Key Research Program of China(2018YFD0600204)the National Natural Science Foundation(31770690)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB11050000)the CAS Key Project of Frontier Science Program(QYZDJ-SSW-SMC024).
文摘The behavioral strategies and mechanisms by which some insects maintain monogamous mating systems are not well understood.We investigated the mating system of the bark beetle Dendroctonus valens,and identified several contributing mechanisms.Field and laboratory observations suggest the adults commonly form permanent bonds during host colonization.Moreover,it showed mated females that remained paired with males produced more offspring than mated females that were alone in galleries.In bioassays,a second female commonly entered a gallery constructed by a prior female.Videos show she commonly reached the location of the first female,but they did not engage in actual fighting.Rather,the second female typically departs to form her own gallery.Acoustic signaling likewise does not appear to influence female-female encounters,based on controlled muting experiments.Instead the intruder appears to perceive the residents presence by physical contact.Both acoustic signals and volatiles released by females during gallery constructing were shown to attract males.After a male joined a female in a gallery,the male-produced aggressive sounds,which were shown by playback to deter other males from entering the gallery.Unlike female-female interactions,resident males use their head and rear to push intruders out of galleries.Additionally,volatiles released by males during feeding repelled intruding males,discouraging them from entering the gallery.Males also construct plugs that block the entrance,which may prevent subsequent males and predators from entering the gallery.Thus,D.valens has evolved multifaceted mechanisms contributing to single pairings that confer benefits to both sexes.
文摘Accurate and reliable predictions of pest species distributions in forest ecosystems are urgently needed by forest managers to develop management plans and monitor new areas of potential establishment.Presence-only species distribution models are commonly used in these evaluations.The maximum entropy algorithm(MaxEnt)has gained popularity for modelling species distribution.Here,MaxEnt was used to model the spatial distribution of the Mexican pine bark beetle(Dendroctonus mexicanus)in a daily fashion by using forecast data from the Weather Research and Forecasting model.This study aimed to exploit freely available geographic and environmental data and software and thus provide a pathway to overcome the lack of costly data and technical guidance that are a challenge to implementing national monitoring and management strategies in developing countries.Our results showed overall agreement values between 60 and 87%.The results of this research can be used for D.mexicanus monitoring and management and may aid as a model to monitor similar species.
基金Supported by Quarantine Industry Research Special Funds for Public Welfare Projects(201310075-2)Research Project of General Administration of Quality Supervision,Inspection and Quarantine(2012IK276)Changzhou Science and Technology Project(CJ20120027,CJ20130036)~~
文摘Dendroctonus spp. is one of the most portable pests in imported and ex- ported timber and wooden packages, and it is an important object of the port quarantine. Making rapid and accurate identification of Dendroctonus spp. is an im- portant method to reduce the invasion risk of Dendroctonus spp. for China. In this paper, Dendroctonus punctatus, which belongs to the Dendroctonus spp., is intro- duced in detail from the aspects of taxonomic status, biological characteristics, mor- phological characteristics and the invasion risk, providing reference for the identifica- tion of Dendroctonus punctatus in inspection and quarantine.
