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
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
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
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
The volatile compositions of Chinese Pine (Pinus tabulaeformis) are analyzed. The main turpentine volatiles are (R)-(+)-α-pinene, (S)-(-)-β-pinene, (S)-(+)-3-carene (the largest) which occupy more than 97% of the to...The volatile compositions of Chinese Pine (Pinus tabulaeformis) are analyzed. The main turpentine volatiles are (R)-(+)-α-pinene, (S)-(-)-β-pinene, (S)-(+)-3-carene (the largest) which occupy more than 97% of the total. There are also myrcene, (+)-limonene, camphene, terpinen and phellandrene. In the experiment of Electroantennograms(EAG), the male of red turpentine beetles are sensitive to (S)-(-)-α-pinene、limonene and (S)-(+)-3-carene; while the female of the red turpentine beetles are sensitive to (S)-(+)-3-carene、limonene、(S)-(-)-α-pinene and myrcene. The female are more sensitive to the volatiles than the male. There is much difference in response of Dendroctonus valens in Chinese pine compared to that in USA in ponderosa pine. The volatile difference of the two pine species and the environment condition may contribute to this change. Further study on the mechanism of the change is needed.展开更多
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.
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 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The volatile compositions of Chinese Pine (Pinus tabulaeformis) are analyzed. The main turpentine volatiles are (R)-(+)-α-pinene, (S)-(-)-β-pinene, (S)-(+)-3-carene (the largest) which occupy more than 97% of the total. There are also myrcene, (+)-limonene, camphene, terpinen and phellandrene. In the experiment of Electroantennograms(EAG), the male of red turpentine beetles are sensitive to (S)-(-)-α-pinene、limonene and (S)-(+)-3-carene; while the female of the red turpentine beetles are sensitive to (S)-(+)-3-carene、limonene、(S)-(-)-α-pinene and myrcene. The female are more sensitive to the volatiles than the male. There is much difference in response of Dendroctonus valens in Chinese pine compared to that in USA in ponderosa pine. The volatile difference of the two pine species and the environment condition may contribute to this change. Further study on the mechanism of the change is needed.
