Insecticide resistance in Panonychus citri is a major obstacle to mite control in citrus orchards.Pyrethroid insecticides are continually used to control mites in China,although resistance to pyrethroids has evolved i...Insecticide resistance in Panonychus citri is a major obstacle to mite control in citrus orchards.Pyrethroid insecticides are continually used to control mites in China,although resistance to pyrethroids has evolved in some populations.Here,the resistance to the pyrethroid fenpropathrin was investigated and 7 out of 8 field-collected populations of P citri exhibited a high level of resistance,ranging from 171-fold to 15391-fold higher than the susceptible(SS)comparison strain.Three voltage-gated sodium channel(VGSC)mutations were identified in the tested populations:L1031V,F1747L,and F17511.Amplicon sequencing was used to evaluate the frequency of these mutations in the 19 field populations.L1031V and F1751I were present in all populations at frequencies of 11.6%-82.1%and 0.5%-31.8%,respectively,whereas the F1747L mutation was only present in 12 populations from Chongqing,Sichuan,Guangxi,and Yunnan provinces.Introduction of these mutations singly or in combination into transgenic flies significantly increased their resistance to fenpropathrin and these flies also exhibited reduced mortality after exposure to the pyrethroids permethrin andβ-cypermethrin.Panonychus citri VGSC homology modeling and ligand docking indicate that F1747 and F1751 form direct binding contacts with pyrethroids,which are lost with mutation,whereas L1031 mutation may diminish pyrethroid effects through an allosteric mechanism.Overall,the results provide molecular markers for monitoring pest resistance to pyrethroids and offer new insights into the basis of pyrethroid actions on sodium channels.展开更多
Context: The resistance to pyrethroids in malaria vectors continues to grow in Africa and could therefore compromise or reduce substantially the effectiveness of LLINs in preventing malaria. It is therefore of paramou...Context: The resistance to pyrethroids in malaria vectors continues to grow in Africa and could therefore compromise or reduce substantially the effectiveness of LLINs in preventing malaria. It is therefore of paramount importance to evaluate the protective efficacy of LLINs in children sleeping in areas of vector resistance to insecticides in order to draw lessons for future interventions. This study assesses the effect of the use of LLINs on malaria morbidity in clusters of low and high resistance of vectors to pyrethroids. Methods: This is a cross-sectional case-control study with one control for one case that was conducted in the communes of Kétou, Ifangni, Kétou, and Pobè in the Plateau department of southern Benin. The use of LLINs and malaria morbidity was measured and compared in children from clusters of low and high vector resistance to insecticides. In each commune, 30 cases and 30 controls were recruited for a total of 240 children under 5 years of age from villages with low and high insecticide resistance. Results: According to the localities of origin of the children, of all parents of children surveyed, 169 (70.4%) asserted the children slept under an LLIN the day before they arrived at the health center. This rate represents 70.8% (85 children) among the cases and 70.0% (84 children) among the controls without significant difference (p = 0.8). The use of LLINs the day before the survey, the frequency of their use during the two weeks preceding the day of the survey, their availability at the household level, the use of other tools for protection against mosquito bites are the same in the two groups of children (cases and controls) (p > 0.05) as well in low and high resistance villages. On the other hand, the parasite prevalence, the splenomegaly and the geometric means of the parasite densities, are significantly higher in the cases than in the controls (p Conclusion: The evaluation of epidemiological indicators in children under five years old at the level of health centers did not enable demonstrating the impact of resistance on the operational effectiveness of the LLINs. The information collected within the four health facilities only reflects the situation that should normally be seen in the population under the real conditions of use of LLINs in high and low resistance areas.展开更多
The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that in...The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that incorporate synergistic components, such as piperonyl butoxide (PBO). The purpose of this study is to provide entomological evidence for the efficacy of a PBO-based ITN brand at the village level, serving as a basis for decision-making before large-scale net deployment. During the high malaria transmission period, ITNs were distributed in each group and vector sampling was conducted biweekly in selected households. Bionomic data were collected to assess the resistance of wild An. gambiae populations to various chemical insecticides. There was a significant disparity in total An. gambiae sl. collected between the ITN arms, the intervention arm (ITN arms), and the control arm (P = 0.003). An. coluzzi was identified as the predominant species in the study area, as confirmed by PCR analysis. Analysis of the blood-feeding inhibition rate revealed that 100% permethrin + PBO ITN exhibited significantly greater inhibition than 66.81% permethrin only ITN. According to the log-time probit regression analysis, permethrin exhibited a knockdown time of 256 min without synergists, while it decreased to 139 min (P = 0.001) when pre-exposed to PBO. The evidence from this trial supports the use of PBO ITNs over standard ITNs for pyrethroids to combat pyrethroid resistance and improve protection against malaria for both individuals and communities, particularly in areas with high pyrethroid resistance.展开更多
The widespread use of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. While coverage of LLINs has increased, there is a need for information on the operational effectiveness ...The widespread use of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. While coverage of LLINs has increased, there is a need for information on the operational effectiveness of nets deployed in the field in the context of malaria vector resistance to insecticides used for impregnation. The development of specific anti-malarial biomarkers to assess exposure to mosquito bites is an important development in evaluations. The aim of this study was to characterize the human IgG antibody response to Anopheles gSG6-P1 saliva, a salivary peptide antigen previously shown to be a relevant biomarker of human exposure to Anopheles bites, in order to assess the LLINs under field conditions in areas of low and high vector resistance to insecticides. We analyzed data from 240 randomly selected children ( 0.05). Furthermore, the same finding was observed for antibody expression in children whether or not they used LLINs on the day before the survey (p = 0.7724). Similarly, gender and especially age, major factors of variation in the adaptive immune response, did not have a significant effect on IgG expression.展开更多
MicroRNAs(miRNAs)are small non-coding RNAs,which play a critical role in many biological processes such as apoptosis,differentiation and innate immunity.Anopheles sinensis is the most widespread malaria vector in Chin...MicroRNAs(miRNAs)are small non-coding RNAs,which play a critical role in many biological processes such as apoptosis,differentiation and innate immunity.Anopheles sinensis is the most widespread malaria vector in China and Southeast Asian countries.In present study,the miRNAs from the genome sequences of An.sinensis were annotated by bioinformatics analyses,and sequenced and identified the miRNAs using seven samples from one pyrethroid-susceptible laboratory strain,three field pyrethroid-resistant populations,and three field pyrethroid-susceptible populations in An.sinensis.A total of 272 miRNAs were identified from genome sequences with a total length of 24978 bp and accounting up 0.009%of genome.A total of 62 known miRNAs and 432 novel miRNAs were identified from the small RNA sequencing of these seven samples.There is no distinct difference in the number of known miRNAs among these samples,which suggests that these known miRNAs be quite popular and be the most abundant in expression.The numbers of novel miRNAs do not distinctly vary between laboratory and field samples and between resistant and susceptible samples.This study provides the information frame of miRNAs in An.sinensis.However,further research is necessary to reveal the relationships of miRNA species between miRNA species in these samples and the regulatory mechanism of pyrethroid resistance of these miRNA to pyrethroid in different samples.展开更多
Due to rapidly developed resistance,pest management relies less on pyrethroids to control economically damaging infestations of the tarnished plant bug(TPB),Lygus lineolaris(Palisot de Beauvois)in cotton fields of Mis...Due to rapidly developed resistance,pest management relies less on pyrethroids to control economically damaging infestations of the tarnished plant bug(TPB),Lygus lineolaris(Palisot de Beauvois)in cotton fields of Mississippi.Yet,pyrethroid resistance remains prevalent in TPB populations.This study assessed the resistance levels in adult TPB to six common pyrethroids and acephate.Resistant TBPs were collected from wild host plants in late October after harvest in the Mississippi Delta region of the United States.Based on LCso values,the field-resistant TPBs displayed higher resistance to permethrin,esfenvalerate,and bifenthrin(approximately 30 fold)and moderate resistance toα-cyhalothrin,β-cyfluthrin,5-cypermethrin,and acephate(approximately 15 fold).Further investigations showed that the inhibitors of three detoxification enzyme,triphenyl phosphate(TPP),diethyl maleate(DEM),and piperonyl butoxide(PBO)had synergistic effects on permethrin,γ-cyhalothrin,and bifenthrin in resistant TPBs.Furthermore,elevated esterase,GST,and P450 activities were significantly expressed in fieldresistant TPBs.Additionally,GST and esterase were reduced after 48 h exposure to certain pyrethroids at LCso dose.The synergistic and biochemical assays consistently indicated that P450 and esterase were involved in pyrethroid detoxification in TPBs.This study provides valuable information for the continued use of pyrethroids and acephate in controlling TPBs in cotton fields in the Mississippi Delta region of the United States.展开更多
基金supported by the Science and Technology Basic Resources Investigation Program of China(2018FY101105)the National Natural Science Foundation of China(31972272,31871969)+1 种基金the Fundamental Research Funds for the Central Universities(SWU-XDPY22001)of Chinathe China Agricultural Research System of MOA and MARA.
文摘Insecticide resistance in Panonychus citri is a major obstacle to mite control in citrus orchards.Pyrethroid insecticides are continually used to control mites in China,although resistance to pyrethroids has evolved in some populations.Here,the resistance to the pyrethroid fenpropathrin was investigated and 7 out of 8 field-collected populations of P citri exhibited a high level of resistance,ranging from 171-fold to 15391-fold higher than the susceptible(SS)comparison strain.Three voltage-gated sodium channel(VGSC)mutations were identified in the tested populations:L1031V,F1747L,and F17511.Amplicon sequencing was used to evaluate the frequency of these mutations in the 19 field populations.L1031V and F1751I were present in all populations at frequencies of 11.6%-82.1%and 0.5%-31.8%,respectively,whereas the F1747L mutation was only present in 12 populations from Chongqing,Sichuan,Guangxi,and Yunnan provinces.Introduction of these mutations singly or in combination into transgenic flies significantly increased their resistance to fenpropathrin and these flies also exhibited reduced mortality after exposure to the pyrethroids permethrin andβ-cypermethrin.Panonychus citri VGSC homology modeling and ligand docking indicate that F1747 and F1751 form direct binding contacts with pyrethroids,which are lost with mutation,whereas L1031 mutation may diminish pyrethroid effects through an allosteric mechanism.Overall,the results provide molecular markers for monitoring pest resistance to pyrethroids and offer new insights into the basis of pyrethroid actions on sodium channels.
文摘Context: The resistance to pyrethroids in malaria vectors continues to grow in Africa and could therefore compromise or reduce substantially the effectiveness of LLINs in preventing malaria. It is therefore of paramount importance to evaluate the protective efficacy of LLINs in children sleeping in areas of vector resistance to insecticides in order to draw lessons for future interventions. This study assesses the effect of the use of LLINs on malaria morbidity in clusters of low and high resistance of vectors to pyrethroids. Methods: This is a cross-sectional case-control study with one control for one case that was conducted in the communes of Kétou, Ifangni, Kétou, and Pobè in the Plateau department of southern Benin. The use of LLINs and malaria morbidity was measured and compared in children from clusters of low and high vector resistance to insecticides. In each commune, 30 cases and 30 controls were recruited for a total of 240 children under 5 years of age from villages with low and high insecticide resistance. Results: According to the localities of origin of the children, of all parents of children surveyed, 169 (70.4%) asserted the children slept under an LLIN the day before they arrived at the health center. This rate represents 70.8% (85 children) among the cases and 70.0% (84 children) among the controls without significant difference (p = 0.8). The use of LLINs the day before the survey, the frequency of their use during the two weeks preceding the day of the survey, their availability at the household level, the use of other tools for protection against mosquito bites are the same in the two groups of children (cases and controls) (p > 0.05) as well in low and high resistance villages. On the other hand, the parasite prevalence, the splenomegaly and the geometric means of the parasite densities, are significantly higher in the cases than in the controls (p Conclusion: The evaluation of epidemiological indicators in children under five years old at the level of health centers did not enable demonstrating the impact of resistance on the operational effectiveness of the LLINs. The information collected within the four health facilities only reflects the situation that should normally be seen in the population under the real conditions of use of LLINs in high and low resistance areas.
文摘The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that incorporate synergistic components, such as piperonyl butoxide (PBO). The purpose of this study is to provide entomological evidence for the efficacy of a PBO-based ITN brand at the village level, serving as a basis for decision-making before large-scale net deployment. During the high malaria transmission period, ITNs were distributed in each group and vector sampling was conducted biweekly in selected households. Bionomic data were collected to assess the resistance of wild An. gambiae populations to various chemical insecticides. There was a significant disparity in total An. gambiae sl. collected between the ITN arms, the intervention arm (ITN arms), and the control arm (P = 0.003). An. coluzzi was identified as the predominant species in the study area, as confirmed by PCR analysis. Analysis of the blood-feeding inhibition rate revealed that 100% permethrin + PBO ITN exhibited significantly greater inhibition than 66.81% permethrin only ITN. According to the log-time probit regression analysis, permethrin exhibited a knockdown time of 256 min without synergists, while it decreased to 139 min (P = 0.001) when pre-exposed to PBO. The evidence from this trial supports the use of PBO ITNs over standard ITNs for pyrethroids to combat pyrethroid resistance and improve protection against malaria for both individuals and communities, particularly in areas with high pyrethroid resistance.
文摘The widespread use of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. While coverage of LLINs has increased, there is a need for information on the operational effectiveness of nets deployed in the field in the context of malaria vector resistance to insecticides used for impregnation. The development of specific anti-malarial biomarkers to assess exposure to mosquito bites is an important development in evaluations. The aim of this study was to characterize the human IgG antibody response to Anopheles gSG6-P1 saliva, a salivary peptide antigen previously shown to be a relevant biomarker of human exposure to Anopheles bites, in order to assess the LLINs under field conditions in areas of low and high vector resistance to insecticides. We analyzed data from 240 randomly selected children ( 0.05). Furthermore, the same finding was observed for antibody expression in children whether or not they used LLINs on the day before the survey (p = 0.7724). Similarly, gender and especially age, major factors of variation in the adaptive immune response, did not have a significant effect on IgG expression.
文摘MicroRNAs(miRNAs)are small non-coding RNAs,which play a critical role in many biological processes such as apoptosis,differentiation and innate immunity.Anopheles sinensis is the most widespread malaria vector in China and Southeast Asian countries.In present study,the miRNAs from the genome sequences of An.sinensis were annotated by bioinformatics analyses,and sequenced and identified the miRNAs using seven samples from one pyrethroid-susceptible laboratory strain,three field pyrethroid-resistant populations,and three field pyrethroid-susceptible populations in An.sinensis.A total of 272 miRNAs were identified from genome sequences with a total length of 24978 bp and accounting up 0.009%of genome.A total of 62 known miRNAs and 432 novel miRNAs were identified from the small RNA sequencing of these seven samples.There is no distinct difference in the number of known miRNAs among these samples,which suggests that these known miRNAs be quite popular and be the most abundant in expression.The numbers of novel miRNAs do not distinctly vary between laboratory and field samples and between resistant and susceptible samples.This study provides the information frame of miRNAs in An.sinensis.However,further research is necessary to reveal the relationships of miRNA species between miRNA species in these samples and the regulatory mechanism of pyrethroid resistance of these miRNA to pyrethroid in different samples.
文摘Due to rapidly developed resistance,pest management relies less on pyrethroids to control economically damaging infestations of the tarnished plant bug(TPB),Lygus lineolaris(Palisot de Beauvois)in cotton fields of Mississippi.Yet,pyrethroid resistance remains prevalent in TPB populations.This study assessed the resistance levels in adult TPB to six common pyrethroids and acephate.Resistant TBPs were collected from wild host plants in late October after harvest in the Mississippi Delta region of the United States.Based on LCso values,the field-resistant TPBs displayed higher resistance to permethrin,esfenvalerate,and bifenthrin(approximately 30 fold)and moderate resistance toα-cyhalothrin,β-cyfluthrin,5-cypermethrin,and acephate(approximately 15 fold).Further investigations showed that the inhibitors of three detoxification enzyme,triphenyl phosphate(TPP),diethyl maleate(DEM),and piperonyl butoxide(PBO)had synergistic effects on permethrin,γ-cyhalothrin,and bifenthrin in resistant TPBs.Furthermore,elevated esterase,GST,and P450 activities were significantly expressed in fieldresistant TPBs.Additionally,GST and esterase were reduced after 48 h exposure to certain pyrethroids at LCso dose.The synergistic and biochemical assays consistently indicated that P450 and esterase were involved in pyrethroid detoxification in TPBs.This study provides valuable information for the continued use of pyrethroids and acephate in controlling TPBs in cotton fields in the Mississippi Delta region of the United States.
