Tsetse flies are the sole cyclic vectors of African trypanosomes,which cause human and animal African trypanosomiases in Africa.Tsetse fly control remains a promising option for disease management.The sterile insect t...Tsetse flies are the sole cyclic vectors of African trypanosomes,which cause human and animal African trypanosomiases in Africa.Tsetse fly control remains a promising option for disease management.The sterile insect technique(SIT)stands as an environmentally friendly tool to control tsetse populations.SIT requires the mass-rearing of competent sterile males to mate with wild females.However,long-term colonization might affect the genetic structure of the reared flies.This study investigated the genetic structure of four Glossina palpalis gambiensis colonies of different ages:two originating from Senegal(SEN and ICIRSEN)and two from Burkina Faso(CIR and IBD).Samples from these colonies were genotyped at ten microsatellite loci,followed by downstream population genetic analyses.The results show that the two colonies from Burkina Faso collected from close sites(~20 km apart)over 45-year interval retained the same genetic background(FsT cIR~IBD≈0,P-value=0.47).These flies were however,genetically different from those from the Senegal colonies(FsT cIR~SEN≈0.047;FsT IBD~SEN≈0.058,P-value=10-4).Moreover,no significant difference was detected in the gene diversity of the CIR and IBD colonies,with Hs values of 0.650 and 0.665,respectively.Theinbreeding coefficient showed that all four colonies where under Hardy—Weinberg equilibrium,with FIs values of 0.026,0.012,-0.064,and 0.001,for CIR,IBD,ICIRSEN,and SEN.respectively.Furthermore,no sign of a recent bottleneck was identified in tsetse samples from any of the four colonies.The results suggest that long-term mass-rearing of tsetse flies has no significant impact on their genetic background and diversity.展开更多
Background:Changes of land cover modify the characteristics of habitat,host-vector interaction and consequently infection rates of disease causing agents.In this paper,we report variations in tsetse distribution patte...Background:Changes of land cover modify the characteristics of habitat,host-vector interaction and consequently infection rates of disease causing agents.In this paper,we report variations in tsetse distribution patterns,abundance and infection rates in relation to habitat types and age in the Maasai Steppe of northern Tanzania.In Africa,Tsetse-transmitted trypanosomiasis negatively impacted human life where about 40 million people are at risk of contracting the disease with dramatic socio-economical consequences,for instance,loss of livestock,animal productivity,and manpower.Methods:We trapped tsetse flies in dry and wet seasons between October 2014 and May 2015 in selected habitats across four villages:Emboreet,Loiborsireet,Kimotorok and Oltukai adjacent to protected areas.Data collected include number and species of tsetse flies caught in baited traps,PCR identification of trypanosome species and extraction of monitored Normalized Difference Vegetation Index(NDVI)data from Moderate Resolution Imaging Spectrometer(MODIS).Results:Our findings demonstrate the variation of tsetse fly species abundance and infection rates among habitats in surveyed villages in relation to NDVI and host abundance.Results have shown higher tsetse fly abundance in Acacia-swampy ecotone and riverine habitats for Emboreet and other villages,respectively.Tsetse abundance was inconsistent among habitats in different villages.Emboreet was highly infested with Glossina swynnertoni(68%)in ecotone and swampy habitats followed by G.morsitans(28%)and G.pallidipes(4%)in riverine habitat.In the remaining villages,the dominant tsetse fly species by 95%was G.pallidipes in all habitats.Trypanosoma vivax was the most prevalent species in all infected flies(95%)with few observations of co-infections(with T.congolense or T.brucei).Conclusions:The findings of this study provide a framework to mapping hotspots of tsetse infestation and trypanosomiasis infection and enhance the communities to plan for effective control of trypanosomiasis.展开更多
Tsetse flies are insects of significant public health and zoonotic importance as they are the main vectors of African trypanosomes.To date,an effective vaccine is unavailable and efforts to limit the spread of the dis...Tsetse flies are insects of significant public health and zoonotic importance as they are the main vectors of African trypanosomes.To date,an effective vaccine is unavailable and efforts to limit the spread of the disease primarily rely on controlling the tsetse populations.The discovery of Spiroplasma(class Mollicutes)in Glossina fuscipes fuscipes(Gff)(palpalis subgroup),offers promising insights into its potential use as a biological control agent to hinder trypanosomes infection in tsetse flies.Indeed,a negative correlation between Spiroplasma and trypanosome co-infection has been observed.Using a laboratory strain of Gff,we provide fundamental biological insights into the effects of Spiroplasma infection on the mating behavior of the fly.We found a sex-biased Spiroplasma infection,with males exhibiting a higher infection rate.Mass mating experiments revealed a higher mating propensity in Spiroplasma-infected flies.Additionally,the presence of Spiroplasma influenced premating isolation,leading to nonrandom mating patterns that favored the pairing of individuals with matching infection statuses.Moreover,we present evidence of Spiroplasma vertical paternal transmission.By analyzing female reproductive tissues at 2 and 24 h postmating,we confirmed that an infected male can transfer Spiroplasma to the female via the spermatophore,which can subsequently migrate to the spermathecae.This study provides foundational insights into the role of Spiroplasma in tsetse fly mating behavior and provides supporting evidence for vertical transmission from infected males.展开更多
Sterile Insect Technique (SIT) applications against major insect pests and disease vectors rely on the cost-effective production of high-quality sterile males. This largely depends on the optimal management of target ...Sterile Insect Technique (SIT) applications against major insect pests and disease vectors rely on the cost-effective production of high-quality sterile males. This largely depends on the optimal management of target pest colonies by maximizing the benefits provided by a genetically rich and pathogen-free mother colony, the presence of symbiotic microorganisms, and efficient domestication, mass-rearing, irradiation, and release processes. At the same time microbial (bacteria, fungi, microsporidia, and viruses) pathogen outbreaks should be minimized or eliminated, and the use of hazardous chemicals restricted. The optimization of the colony management strategies for different SIT target insects will ensure a standardized high-quality mass-rearing process and the cost-effective production of sterile males with enhanced field performance and male mating competitiveness. The aims of the Coordinated Research Project (CRP) were to develop best practices for insect colony management for the cost-effective production of high-quality sterile males for SIT applications against major insect pests and disease vectors through a multidisciplinary approach involving entomologists, geneticists, ecologists, microbiologists, pathologists, virologists, and mass-rearing experts.展开更多
Tsetse flies(Glossina spp.)can vector the parasites(Trypanosoma spp.)that cause the socioeconomically devastating neglected tropical diseases human and animal African trypanosomoses.In addition to this parasite,tsetse...Tsetse flies(Glossina spp.)can vector the parasites(Trypanosoma spp.)that cause the socioeconomically devastating neglected tropical diseases human and animal African trypanosomoses.In addition to this parasite,tsetse can harbor four genera of endosymbiotic bacteria,including Wigglesworthia,Sodalis,Wolbachia,and Spiroplasma,which are functionally crucial for the fly's physiological homeostasis and/or are potentially useful for the development of disease control strategies.Recent discoveries indicate that Spiroplasma infection negatively impacts tsetse fecundity.Conversely,housing the bacterium can benefit its fly host by making it unusually refractory to infection with parasitic African trypanosomes.In this study,we assessed the physiological impact of Spiroplasma infection on a laboratory colony of Glossina fuscipes fuscipes(Gff).For this purpose,two distinct Gff colonies were established:a Spi–colony that harbors a low Spiroplasma infection prevalence and a Spi+colony that harbors a high Spiroplasma infection prevalence.Fitness parameters for both colonies revealed no significant differences in the length of larval development,adult eclosion rate,and flight propensity.However,flies from the Spi+colony presented with lower fecundity and higher overall mortality than did individuals from the Spi–colony.Furthermore,males from the Spi–colony exhibited a competitive mating advantage over their Spi+counterparts in a field cage setting.These findings have potential implications for the improvement of mass-rearing of Gff for sterile insect technique(SIT)applications.展开更多
Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This ...Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This study investigates paratransgenesis,a novel strategy to engineer symbiotic bacteria in tsetse flies,Sodalis glossinidius,to deliver anti-trypanosome compounds.Disrupting the trypanosome life cycle within the fly and reducing parasite transmission could offer a sustainable solution for trypanosomiasis control.In this context,we tested the effect of cecropin,reported to be lethal for Trypanosoma cruzi(Chagas disease)and TbgTCTP(Translationally Controlled Tumor Protein from Trypanosoma brucei gambiense),previously reported to modulate the growth of bacteria isolated from the fly microbiome,to delay the first peak of parasitemia and the death of trypanosome-infected mice.We have successfully cloned and transfected the genes encoding the two proteins into Sodalis strains.These Sodalis recombinant strains(recSodalisTbgTCTP and recSodaliscecropin)have been then microinjected into the L3 larval stage of Glossina palpalis gambiensis flies.The stability of the cloned genes was checked up to the 20th day after microinjection of recSodalis.The rate of fly emergence from untreated pupae was 95%;it was reduced by nearly 50%due to the mechanical injury caused by microinjection.It decreased to nearly 7%when larvae were injected with recSodalisTbgTCTP,which suggests TCTP could have a lethal impact to larvae development.When challenged with T.brucei gambiense,a slightly lower,but statistically non-significant,infection rate was recorded in flies harboring recSodaliscecropin compared to control flies.The effect of recSodalisTbgTCTP could not be measured due to the very low rate of fly emergence after corresponding treatment of the larvae.The results do not allow to conclude on the effect of cecropin or TCTP,delivered by para-transgenesis into the fly's gut,on the fly infection by the trypanosome.Nevertheless,the results are encouraging insofar as the technical approach works on the couple G.p.gambiensis/T.brucei gambiense.The next step will be to optimize the system and test other targets chosen among the ESPs(Excreted-Secreted Proteins)of the trypanosome secretum,or the differentially expressed genes associated with the sensitivity/resistance of the fly to trypanosome infection.展开更多
基金funded by the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture,IAEA(CRP No.:D4.20.17),Vienna,Austria.
文摘Tsetse flies are the sole cyclic vectors of African trypanosomes,which cause human and animal African trypanosomiases in Africa.Tsetse fly control remains a promising option for disease management.The sterile insect technique(SIT)stands as an environmentally friendly tool to control tsetse populations.SIT requires the mass-rearing of competent sterile males to mate with wild females.However,long-term colonization might affect the genetic structure of the reared flies.This study investigated the genetic structure of four Glossina palpalis gambiensis colonies of different ages:two originating from Senegal(SEN and ICIRSEN)and two from Burkina Faso(CIR and IBD).Samples from these colonies were genotyped at ten microsatellite loci,followed by downstream population genetic analyses.The results show that the two colonies from Burkina Faso collected from close sites(~20 km apart)over 45-year interval retained the same genetic background(FsT cIR~IBD≈0,P-value=0.47).These flies were however,genetically different from those from the Senegal colonies(FsT cIR~SEN≈0.047;FsT IBD~SEN≈0.058,P-value=10-4).Moreover,no significant difference was detected in the gene diversity of the CIR and IBD colonies,with Hs values of 0.650 and 0.665,respectively.Theinbreeding coefficient showed that all four colonies where under Hardy—Weinberg equilibrium,with FIs values of 0.026,0.012,-0.064,and 0.001,for CIR,IBD,ICIRSEN,and SEN.respectively.Furthermore,no sign of a recent bottleneck was identified in tsetse samples from any of the four colonies.The results suggest that long-term mass-rearing of tsetse flies has no significant impact on their genetic background and diversity.
基金This research received financial support from the project“Predicting vulnerability and improving resilience of the Maasai communities to vector borne infections:An Eco-health approach in Maasai steppe ecosystem,based at Nelson Mandela African Institute of Science and Technology(NM-AIST)”.
文摘Background:Changes of land cover modify the characteristics of habitat,host-vector interaction and consequently infection rates of disease causing agents.In this paper,we report variations in tsetse distribution patterns,abundance and infection rates in relation to habitat types and age in the Maasai Steppe of northern Tanzania.In Africa,Tsetse-transmitted trypanosomiasis negatively impacted human life where about 40 million people are at risk of contracting the disease with dramatic socio-economical consequences,for instance,loss of livestock,animal productivity,and manpower.Methods:We trapped tsetse flies in dry and wet seasons between October 2014 and May 2015 in selected habitats across four villages:Emboreet,Loiborsireet,Kimotorok and Oltukai adjacent to protected areas.Data collected include number and species of tsetse flies caught in baited traps,PCR identification of trypanosome species and extraction of monitored Normalized Difference Vegetation Index(NDVI)data from Moderate Resolution Imaging Spectrometer(MODIS).Results:Our findings demonstrate the variation of tsetse fly species abundance and infection rates among habitats in surveyed villages in relation to NDVI and host abundance.Results have shown higher tsetse fly abundance in Acacia-swampy ecotone and riverine habitats for Emboreet and other villages,respectively.Tsetse abundance was inconsistent among habitats in different villages.Emboreet was highly infested with Glossina swynnertoni(68%)in ecotone and swampy habitats followed by G.morsitans(28%)and G.pallidipes(4%)in riverine habitat.In the remaining villages,the dominant tsetse fly species by 95%was G.pallidipes in all habitats.Trypanosoma vivax was the most prevalent species in all infected flies(95%)with few observations of co-infections(with T.congolense or T.brucei).Conclusions:The findings of this study provide a framework to mapping hotspots of tsetse infestation and trypanosomiasis infection and enhance the communities to plan for effective control of trypanosomiasis.
文摘Tsetse flies are insects of significant public health and zoonotic importance as they are the main vectors of African trypanosomes.To date,an effective vaccine is unavailable and efforts to limit the spread of the disease primarily rely on controlling the tsetse populations.The discovery of Spiroplasma(class Mollicutes)in Glossina fuscipes fuscipes(Gff)(palpalis subgroup),offers promising insights into its potential use as a biological control agent to hinder trypanosomes infection in tsetse flies.Indeed,a negative correlation between Spiroplasma and trypanosome co-infection has been observed.Using a laboratory strain of Gff,we provide fundamental biological insights into the effects of Spiroplasma infection on the mating behavior of the fly.We found a sex-biased Spiroplasma infection,with males exhibiting a higher infection rate.Mass mating experiments revealed a higher mating propensity in Spiroplasma-infected flies.Additionally,the presence of Spiroplasma influenced premating isolation,leading to nonrandom mating patterns that favored the pairing of individuals with matching infection statuses.Moreover,we present evidence of Spiroplasma vertical paternal transmission.By analyzing female reproductive tissues at 2 and 24 h postmating,we confirmed that an infected male can transfer Spiroplasma to the female via the spermatophore,which can subsequently migrate to the spermathecae.This study provides foundational insights into the role of Spiroplasma in tsetse fly mating behavior and provides supporting evidence for vertical transmission from infected males.
文摘Sterile Insect Technique (SIT) applications against major insect pests and disease vectors rely on the cost-effective production of high-quality sterile males. This largely depends on the optimal management of target pest colonies by maximizing the benefits provided by a genetically rich and pathogen-free mother colony, the presence of symbiotic microorganisms, and efficient domestication, mass-rearing, irradiation, and release processes. At the same time microbial (bacteria, fungi, microsporidia, and viruses) pathogen outbreaks should be minimized or eliminated, and the use of hazardous chemicals restricted. The optimization of the colony management strategies for different SIT target insects will ensure a standardized high-quality mass-rearing process and the cost-effective production of sterile males with enhanced field performance and male mating competitiveness. The aims of the Coordinated Research Project (CRP) were to develop best practices for insect colony management for the cost-effective production of high-quality sterile males for SIT applications against major insect pests and disease vectors through a multidisciplinary approach involving entomologists, geneticists, ecologists, microbiologists, pathologists, virologists, and mass-rearing experts.
文摘Tsetse flies(Glossina spp.)can vector the parasites(Trypanosoma spp.)that cause the socioeconomically devastating neglected tropical diseases human and animal African trypanosomoses.In addition to this parasite,tsetse can harbor four genera of endosymbiotic bacteria,including Wigglesworthia,Sodalis,Wolbachia,and Spiroplasma,which are functionally crucial for the fly's physiological homeostasis and/or are potentially useful for the development of disease control strategies.Recent discoveries indicate that Spiroplasma infection negatively impacts tsetse fecundity.Conversely,housing the bacterium can benefit its fly host by making it unusually refractory to infection with parasitic African trypanosomes.In this study,we assessed the physiological impact of Spiroplasma infection on a laboratory colony of Glossina fuscipes fuscipes(Gff).For this purpose,two distinct Gff colonies were established:a Spi–colony that harbors a low Spiroplasma infection prevalence and a Spi+colony that harbors a high Spiroplasma infection prevalence.Fitness parameters for both colonies revealed no significant differences in the length of larval development,adult eclosion rate,and flight propensity.However,flies from the Spi+colony presented with lower fecundity and higher overall mortality than did individuals from the Spi–colony.Furthermore,males from the Spi–colony exhibited a competitive mating advantage over their Spi+counterparts in a field cage setting.These findings have potential implications for the improvement of mass-rearing of Gff for sterile insect technique(SIT)applications.
文摘Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This study investigates paratransgenesis,a novel strategy to engineer symbiotic bacteria in tsetse flies,Sodalis glossinidius,to deliver anti-trypanosome compounds.Disrupting the trypanosome life cycle within the fly and reducing parasite transmission could offer a sustainable solution for trypanosomiasis control.In this context,we tested the effect of cecropin,reported to be lethal for Trypanosoma cruzi(Chagas disease)and TbgTCTP(Translationally Controlled Tumor Protein from Trypanosoma brucei gambiense),previously reported to modulate the growth of bacteria isolated from the fly microbiome,to delay the first peak of parasitemia and the death of trypanosome-infected mice.We have successfully cloned and transfected the genes encoding the two proteins into Sodalis strains.These Sodalis recombinant strains(recSodalisTbgTCTP and recSodaliscecropin)have been then microinjected into the L3 larval stage of Glossina palpalis gambiensis flies.The stability of the cloned genes was checked up to the 20th day after microinjection of recSodalis.The rate of fly emergence from untreated pupae was 95%;it was reduced by nearly 50%due to the mechanical injury caused by microinjection.It decreased to nearly 7%when larvae were injected with recSodalisTbgTCTP,which suggests TCTP could have a lethal impact to larvae development.When challenged with T.brucei gambiense,a slightly lower,but statistically non-significant,infection rate was recorded in flies harboring recSodaliscecropin compared to control flies.The effect of recSodalisTbgTCTP could not be measured due to the very low rate of fly emergence after corresponding treatment of the larvae.The results do not allow to conclude on the effect of cecropin or TCTP,delivered by para-transgenesis into the fly's gut,on the fly infection by the trypanosome.Nevertheless,the results are encouraging insofar as the technical approach works on the couple G.p.gambiensis/T.brucei gambiense.The next step will be to optimize the system and test other targets chosen among the ESPs(Excreted-Secreted Proteins)of the trypanosome secretum,or the differentially expressed genes associated with the sensitivity/resistance of the fly to trypanosome infection.
