Volatiles from female Asian longhorned beetle （ ALB ）, Anoplophora glabripenhis, were evaluated as candidate sex pheromone components. Previous studies on ALB have revealed several antennally active compounds from v...Volatiles from female Asian longhorned beetle （ ALB ）, Anoplophora glabripenhis, were evaluated as candidate sex pheromone components. Previous studies on ALB have revealed several antennally active compounds from virgin females; however the origins and activity of these compounds were not apparent and require further investigation. We tested the hypothesis that one or more of the ALB contact sex pheromones is a precursor that undergoes abiotic oxidation to yield volatile pheromone components, and evaluated the activity of these compounds using laboratory and field bioassays. Gas chromatogra- phy coupled electroantennography detection （GC-EAD） analysis indicated the presence of three antennally active aldehydes （heptanal, nonanal, and hexadecanal） in female cuticular extracts exposed to ozone or UV and visible light. In laboratory bioassays using a Y-tube olfactometer, males were preferentially attracted to ozonized female body washes over crude body washes. Similarly, synthetic formulations of these compounds were preferred over controls in the olfactometer. Field trapping experiments conducted from 2006 to 2008 in Ningxia, China showed that synthetic lures of the three aldehydes formulated in a ratio simulating that of virgin females attracted more beetles compared to controls, and that combinations of these aldehydes, linalool oxide, and host kairomones captured more beetles than controls, and captured significantly more males.展开更多
Symbiotic microbes play a crucial role in regulating parasite–host interactions;however,the role of bacterial associates in parasite–host interactions requires elucidation.In this study,we showed that,instead of int...Symbiotic microbes play a crucial role in regulating parasite–host interactions;however,the role of bacterial associates in parasite–host interactions requires elucidation.In this study,we showed that,instead of introducing numerous symbiotic bacteria,dispersal of 4th-stage juvenile(JIV)pinewood nematodes(PWNs),Bursaphelenchus xylophilus,only introduced few bacteria to its vector beetle,Monochamus alternatus(Ma).JIV showed weak binding ability to five dominant bacteria species isolated from the beetles’pupal chamber.This was especially the case for binding to the opportunistic pathogenic species Serratia marcescens;the nematodes’bacteria binding ability at this critical stage when it infiltrates Ma for dispersal was much weaker compared with Caenorhabditis elegans,Diplogasteroides asiaticus,and propagative-stage PWN.The associated bacterium S.marcescens,which was isolated from the beetles’pupal chambers,was unfavorable to Ma,because it caused a higher mortality rate upon injection into tracheae.In addition,S.marcescens in the tracheae caused more immune effector disorders compared with PWN alone.Ma_Galectin2(MaGal2),a pattern-recognition receptor,was up-regulated following PWN loading.Recombinant MaGal2 protein formed aggregates with five dominant associated bacteria in vitro.Moreover,MaGal2 knockdown beetles had up-regulated prophenoloxidase gene expression,increased phenoloxidase activity,and decreased PWN loading.Our study revealed a previously unknown strategy for immune evasion of this plant pathogen inside its vector,and provides novel insights into the role of bacteria in parasite–host interactions.展开更多
Intrasexual selection occurs in male-male competition over access to females and usually results in the larger male winning.While much research has documented that size matters,little is known about how the larger mal...Intrasexual selection occurs in male-male competition over access to females and usually results in the larger male winning.While much research has documented that size matters,little is known about how the larger male wins.Dendroctonus vale ns is an aggregating monogamous bark beetle in which males have large variation in body size and display intense competition over females.Behavioral observation showed two males fight each other within the gallery by pushing/shoving and stridulated more when two males encountered each other.Experiments using two different-sized males synchronously competing showed that larger males won 95%of contests.Reciprocal displacement experiments using muted and intact males of different or equal size were used to simulate male-male competition.Larger males displaced the smaller resident male in 90%of contests,while smaller males prevailed over larger residents in 6.7%of contests.With both males silenced,larger males displaced smaller males in 80%of con tests,while smaller males prevailed in 8%of con tests.Further experiments using equal-sized males showed aggressive soundemitting males displaced muted males in 67%of contests,yet intact males displaced other intact males in only 37.5%of con tests.Sound analysis showed sound pressure level is an honest signal of body size and males chose soft sounds over loud aggressive sounds in assays.Therefore,D.valens males have evolved dual behaviors,fighting and aggressive sounds associated with body size,to assess rivals to compete for a partner,gaining insights in male-male competition for this species and for other animals.展开更多
Pheromones are communication chemicals and regulatory signals used by animals and represent unique tools for organisms to mediate behaviors and make“decisions”to maximize their fitness.Phenotypic plasticity refers t...Pheromones are communication chemicals and regulatory signals used by animals and represent unique tools for organisms to mediate behaviors and make“decisions”to maximize their fitness.Phenotypic plasticity refers to the innate capacity of a species to tolerate a greater breadth of environmental conditions across which it adapts to improve its survival,reproduction,and fitness.The pinewood nematode,Bursaphelenchus xylophilus,an invasive nematode species,was accidentally introduced from North America into Japan,China,and Europe;however,few studies have investigated its pheromones and phenotypic plasticity as a natural model.Here,we demonstrated a novel phenomenon,in which nematodes under the condition of pheromone presence triggered increased reproduction in invasive strains(JP1,JP2,CN1,CN2,EU1,and EU2),while it simultaneously decreased reproduction in native strains(US1 and US2).The bidirectional effect on fecundity,mediated by presence/absence of pheromones,is henceforth termed pheromone-regulative reproductive plasticity(PRRP).We further found that synthetic ascaroside asc-C5(ascr#9),the major pheromone component,plays a leading role in PRRP and identified 2 candidate receptor genes,Bxydaf-38 and Bxysrd-10,involved in perceiving asc-C5.These results suggest that plasticity of reproductive responses to pheromones in pinewood nematode may increase its fitness in novel environments following introduction.This opens up a new perspective for invasion biology and presents a novel strategy of invasion,suggesting that pheromones,in addition to their traditional roles in chemical signaling,can influence the reproductive phenotype among native and invasive isolates.In addition,this novel mechanism could broadly explain,through comparative studies of native and invasive populations of animals,a potential underlying factor behind of the success of other biological invasions.展开更多
基金Acknowledgments We thank Y. Luo, Beijing Forestry University, V. Mas- tro, D. Lance, and B. Wang, USDA-APHIS-PPQ, and Li Shunping of the Qingtongxia City Forestry Bureau （postal code 751600）, for access to field sites and logistical sup- port in China the students of Beijing Forestry University, W. Xu, and M. Nehme for technical support during field studies+1 种基金 E Webster SUNY-ESF for access to the ozone generator in his laboratory and two anonymous reviewers for their helpful comments on the manuscript. We thank J. Francese, USDA APHIS-PPQ, and A. Hajek, SARL ＆ Cornell University for supplying male ALB. This work was supported by a grant from the Alphawood Founda- tion to SAT and by the National Science Foundation East Asia and South Pacific Summer Institute （NSF-EAPSI） under Grant No. OISE-0813023 to JDW. All experiments were done in China and USA according to the rules of the ethical boards for animal experiments and abided with the current laws of both countries.
文摘Volatiles from female Asian longhorned beetle （ ALB ）, Anoplophora glabripenhis, were evaluated as candidate sex pheromone components. Previous studies on ALB have revealed several antennally active compounds from virgin females; however the origins and activity of these compounds were not apparent and require further investigation. We tested the hypothesis that one or more of the ALB contact sex pheromones is a precursor that undergoes abiotic oxidation to yield volatile pheromone components, and evaluated the activity of these compounds using laboratory and field bioassays. Gas chromatogra- phy coupled electroantennography detection （GC-EAD） analysis indicated the presence of three antennally active aldehydes （heptanal, nonanal, and hexadecanal） in female cuticular extracts exposed to ozone or UV and visible light. In laboratory bioassays using a Y-tube olfactometer, males were preferentially attracted to ozonized female body washes over crude body washes. Similarly, synthetic formulations of these compounds were preferred over controls in the olfactometer. Field trapping experiments conducted from 2006 to 2008 in Ningxia, China showed that synthetic lures of the three aldehydes formulated in a ratio simulating that of virgin females attracted more beetles compared to controls, and that combinations of these aldehydes, linalool oxide, and host kairomones captured more beetles than controls, and captured significantly more males.
基金This work was funded by the National Natural Science Foundation of China(31630013)Frontier Science Key Project of the Chinese Academy of Sciences(QYZDJ-SSW-SMC024).
文摘Symbiotic microbes play a crucial role in regulating parasite–host interactions;however,the role of bacterial associates in parasite–host interactions requires elucidation.In this study,we showed that,instead of introducing numerous symbiotic bacteria,dispersal of 4th-stage juvenile(JIV)pinewood nematodes(PWNs),Bursaphelenchus xylophilus,only introduced few bacteria to its vector beetle,Monochamus alternatus(Ma).JIV showed weak binding ability to five dominant bacteria species isolated from the beetles’pupal chamber.This was especially the case for binding to the opportunistic pathogenic species Serratia marcescens;the nematodes’bacteria binding ability at this critical stage when it infiltrates Ma for dispersal was much weaker compared with Caenorhabditis elegans,Diplogasteroides asiaticus,and propagative-stage PWN.The associated bacterium S.marcescens,which was isolated from the beetles’pupal chambers,was unfavorable to Ma,because it caused a higher mortality rate upon injection into tracheae.In addition,S.marcescens in the tracheae caused more immune effector disorders compared with PWN alone.Ma_Galectin2(MaGal2),a pattern-recognition receptor,was up-regulated following PWN loading.Recombinant MaGal2 protein formed aggregates with five dominant associated bacteria in vitro.Moreover,MaGal2 knockdown beetles had up-regulated prophenoloxidase gene expression,increased phenoloxidase activity,and decreased PWN loading.Our study revealed a previously unknown strategy for immune evasion of this plant pathogen inside its vector,and provides novel insights into the role of bacteria in parasite–host interactions.
基金the National Natural Science Foundation(31770690)the National Key R&D Program of China(2018YFD0600204)the CAS Key Project of Frontier Science Program(QYZDJSSW-SMC024).
文摘Intrasexual selection occurs in male-male competition over access to females and usually results in the larger male winning.While much research has documented that size matters,little is known about how the larger male wins.Dendroctonus vale ns is an aggregating monogamous bark beetle in which males have large variation in body size and display intense competition over females.Behavioral observation showed two males fight each other within the gallery by pushing/shoving and stridulated more when two males encountered each other.Experiments using two different-sized males synchronously competing showed that larger males won 95%of contests.Reciprocal displacement experiments using muted and intact males of different or equal size were used to simulate male-male competition.Larger males displaced the smaller resident male in 90%of contests,while smaller males prevailed over larger residents in 6.7%of contests.With both males silenced,larger males displaced smaller males in 80%of con tests,while smaller males prevailed in 8%of con tests.Further experiments using equal-sized males showed aggressive soundemitting males displaced muted males in 67%of contests,yet intact males displaced other intact males in only 37.5%of con tests.Sound analysis showed sound pressure level is an honest signal of body size and males chose soft sounds over loud aggressive sounds in assays.Therefore,D.valens males have evolved dual behaviors,fighting and aggressive sounds associated with body size,to assess rivals to compete for a partner,gaining insights in male-male competition for this species and for other animals.
基金This work was funded by the National key R&D Program of China(2018YFC1200400)the Natural Science Foundation of China(31630013,31572272)the Frontier Science Key Project of the Chinese Academy of Sciences(QYZDJ-SSW-SMC024).
文摘Pheromones are communication chemicals and regulatory signals used by animals and represent unique tools for organisms to mediate behaviors and make“decisions”to maximize their fitness.Phenotypic plasticity refers to the innate capacity of a species to tolerate a greater breadth of environmental conditions across which it adapts to improve its survival,reproduction,and fitness.The pinewood nematode,Bursaphelenchus xylophilus,an invasive nematode species,was accidentally introduced from North America into Japan,China,and Europe;however,few studies have investigated its pheromones and phenotypic plasticity as a natural model.Here,we demonstrated a novel phenomenon,in which nematodes under the condition of pheromone presence triggered increased reproduction in invasive strains(JP1,JP2,CN1,CN2,EU1,and EU2),while it simultaneously decreased reproduction in native strains(US1 and US2).The bidirectional effect on fecundity,mediated by presence/absence of pheromones,is henceforth termed pheromone-regulative reproductive plasticity(PRRP).We further found that synthetic ascaroside asc-C5(ascr#9),the major pheromone component,plays a leading role in PRRP and identified 2 candidate receptor genes,Bxydaf-38 and Bxysrd-10,involved in perceiving asc-C5.These results suggest that plasticity of reproductive responses to pheromones in pinewood nematode may increase its fitness in novel environments following introduction.This opens up a new perspective for invasion biology and presents a novel strategy of invasion,suggesting that pheromones,in addition to their traditional roles in chemical signaling,can influence the reproductive phenotype among native and invasive isolates.In addition,this novel mechanism could broadly explain,through comparative studies of native and invasive populations of animals,a potential underlying factor behind of the success of other biological invasions.
