Culex tarsalis Coquillett(Diptera:Culicidae)mosquitoes are capable of vectoring numerous pathogens affecting public and animal health.Unfortunately,the probing behaviors of mosquitoes are poorly understood because the...Culex tarsalis Coquillett(Diptera:Culicidae)mosquitoes are capable of vectoring numerous pathogens affecting public and animal health.Unfortunately,the probing behaviors of mosquitoes are poorly understood because they occur in opaque tissues.Electropenetrography(EPG)has the potential to elucidate these behaviors by recording the electrical signals generated during probing.We used an AC–DC EPG with variable input resistors(Ri levels)to construct a waveform library for Cx.tarsalis feeding on human hands.Biological events associated with mosquito probing were used to characterize waveforms at four Ri levels and with two electrical current types.The optimal settings for EPG recordings of Cx.tarsalis probing on human hands was an Ri level of 10^(7)Ohms using an applied signal of 150 millivolts alternating current.Waveforms for Cx.tarsalis included those previously observed and associated with probing behaviors in Aedes aegypti L.(Diptera:Culicidae):waveform families J(surface salivation),K(stylet penetration through the skin),L(types 1 and 2,search for a blood vessel/ingestion site),M(types 1 and 2,ingestion),N(type 1,an unknown behavior which may be a resting and digestion phase),and W(withdrawal).However,we also observed variations in the waveforms not described in Ae.aegypti,which we named types L3,M3,M4,and N2.This investigation enhances our understanding of mosquito probing behaviors.It also provides a new tool for the automated calculation of peak frequency.This work will facilitate future pathogen acquisition and transmission studies and help identify new pest and disease management targets.展开更多
Sap-sucking insects often transmit plant viruses but also carry insect viruses,which infect insects but not plants.The impact of such insect viruses on insect host biology and ecology is largely unknown.Here,we identi...Sap-sucking insects often transmit plant viruses but also carry insect viruses,which infect insects but not plants.The impact of such insect viruses on insect host biology and ecology is largely unknown.Here,we identified a novel insect-specific virus carried by brown citrus aphid(Aphis citricidus),which we tentatively named Aphis citricidus picornavirus(AcPV).Phylogenetic analysis discovered a monophyletic cluster with AcPV and other unassigned viruses,suggesting that these viruses represent a new family in order Picornavirales.Systemic infection with AcPV triggered aphid antiviral immunity mediated by RNA interference,resulting in asymptomatic tolerance.Importantly,we found that AcPV was transmitted horizontally by secretion of the salivary gland into the feeding sites of plants.AcPV influenced aphid stylet behavior during feeding and increased the time required for intercellular penetration,thus promoting its transmission among aphids with plants as an intermediate site.The gene expression results suggested that this mechanism was linked with transcription of salivary protein genes and plant defense hormone signaling.Together,our results show that the horizontal transmission of AcPV in brown citrus aphids evolved in a manner similar to that of the circulative transmission of plant viruses by insect vectors,thus providing a new ecological perspective on the activity of insect-specific viruses found in aphids and improving the understanding of insect virus ecology.展开更多
基金supported by the USDA Research,Education,and Economics Workforce Development Agreement(#58-3022-0-002)the Hatch Multistate Project(NE1943)。
文摘Culex tarsalis Coquillett(Diptera:Culicidae)mosquitoes are capable of vectoring numerous pathogens affecting public and animal health.Unfortunately,the probing behaviors of mosquitoes are poorly understood because they occur in opaque tissues.Electropenetrography(EPG)has the potential to elucidate these behaviors by recording the electrical signals generated during probing.We used an AC–DC EPG with variable input resistors(Ri levels)to construct a waveform library for Cx.tarsalis feeding on human hands.Biological events associated with mosquito probing were used to characterize waveforms at four Ri levels and with two electrical current types.The optimal settings for EPG recordings of Cx.tarsalis probing on human hands was an Ri level of 10^(7)Ohms using an applied signal of 150 millivolts alternating current.Waveforms for Cx.tarsalis included those previously observed and associated with probing behaviors in Aedes aegypti L.(Diptera:Culicidae):waveform families J(surface salivation),K(stylet penetration through the skin),L(types 1 and 2,search for a blood vessel/ingestion site),M(types 1 and 2,ingestion),N(type 1,an unknown behavior which may be a resting and digestion phase),and W(withdrawal).However,we also observed variations in the waveforms not described in Ae.aegypti,which we named types L3,M3,M4,and N2.This investigation enhances our understanding of mosquito probing behaviors.It also provides a new tool for the automated calculation of peak frequency.This work will facilitate future pathogen acquisition and transmission studies and help identify new pest and disease management targets.
基金This research was supported by the National Natural Science Foundation of China(32072423).
文摘Sap-sucking insects often transmit plant viruses but also carry insect viruses,which infect insects but not plants.The impact of such insect viruses on insect host biology and ecology is largely unknown.Here,we identified a novel insect-specific virus carried by brown citrus aphid(Aphis citricidus),which we tentatively named Aphis citricidus picornavirus(AcPV).Phylogenetic analysis discovered a monophyletic cluster with AcPV and other unassigned viruses,suggesting that these viruses represent a new family in order Picornavirales.Systemic infection with AcPV triggered aphid antiviral immunity mediated by RNA interference,resulting in asymptomatic tolerance.Importantly,we found that AcPV was transmitted horizontally by secretion of the salivary gland into the feeding sites of plants.AcPV influenced aphid stylet behavior during feeding and increased the time required for intercellular penetration,thus promoting its transmission among aphids with plants as an intermediate site.The gene expression results suggested that this mechanism was linked with transcription of salivary protein genes and plant defense hormone signaling.Together,our results show that the horizontal transmission of AcPV in brown citrus aphids evolved in a manner similar to that of the circulative transmission of plant viruses by insect vectors,thus providing a new ecological perspective on the activity of insect-specific viruses found in aphids and improving the understanding of insect virus ecology.
