Background Culex pipiens pallens and Culex pipiens quinquefasciatus are the dominant species of Culex mosquitoes in China and important disease vectors.Long-term use of insecticides can cause mutations in the voltage-...Background Culex pipiens pallens and Culex pipiens quinquefasciatus are the dominant species of Culex mosquitoes in China and important disease vectors.Long-term use of insecticides can cause mutations in the voltage-gated sodium channel(vgsc)gene of mosquitoes,but little is known about the current status and evolutionary origins of vgsc gene in different geographic populations.Therefore,this study aimed to determine the current status of vgsc genes in Cx.p.pallens and Cx.p.quinquefasciatus in China and to investigate the evolutionary inheritance of neighboring downstream introns of the vgsc gene to determine the impact of insecticides on long-term evolution.Methods Sampling was conducted from July to September 2021 in representative habitats of 22 provincial-level administrative divisions in China.Genomic DNA was extracted from 1308 mosquitoes,the IIS6 fragment of the vgsc gene on the nerve cell membrane was amplified using polymerase chain reaction,and the sequence was used to evaluate allele frequency and knockdown resistance(kdr)frequency.MEGA 11 was used to construct neighborjoining(NJ)tree.PopART was used to build a TCS network.Results There were 6 alleles and 6 genotypes at the L1014 locus,which included the wild-type alleles TTA/L and CTA/L and the mutant alleles TTT/F,TTC/F,TCT/S and TCA/S.The geographic populations with a kdr frequency less than 20.00%were mainly concentrated in the regions north of 38°N,and the geographic populations with a kdr frequency greater than 80.00%were concentrated in the regions south of 30°N.kdr frequency increased with decreasing latitude.And within the same latitude,the frequency of kdr in large cities is relatively high.Mutations were correlated with the number of introns.The mutant allele TCA/S has only one intron,the mutant allele TTT/F has three introns,and the wild-type allele TTA/L has 17 introns.Conclusions Cx.p.pallens and Cx.p.quinquefasciatus have developed resistance to insecticides in most regions of China.The neighboring downstream introns of the vgsc gene gradually decreased to one intron with the mutation of the vgsc gene.Mutations may originate from multiple mutation events rather than from a single origin,and populations lacking mutations may be genetically isolated.展开更多
Information on Culex mosquitoes (vectors of filarial worm and viral encephalitis) from northern Nigeria is scanty, hindering evidence-based control. Here, two Culex populations (Kano and Kaduna) were characterized. Cu...Information on Culex mosquitoes (vectors of filarial worm and viral encephalitis) from northern Nigeria is scanty, hindering evidence-based control. Here, two Culex populations (Kano and Kaduna) were characterized. Culex quinquefasciatus and Culex pipiens were found breeding in sympatry, with some hybrid individuals identified. Larval bioassays revealed high temephos resistance (LC<sub>50</sub>s = 1.34 mg/mL and 3.01 mg/mL for Kano and Kaduna, respectively). Larvae were more sensitive to α-cypermethrin (LC<sub>50</sub>s = 0.026 mg/mL and 0.067 mg/mL for Kano and Kaduna). WHO adult tube bioassays revealed high pyrethroid and DDT resistance, with mortalities of 44.01% ± 6.79%, 35.83% ± 12.58%, 29.69% ± 9.97% and 52.47% ± 4.34% for permethrin, deltamethrin, α-cypermethrin and DDT, respectively. Highest resistance was observed with bendiocarb (mortality = 13.58% ± 3.98%). High resistance was obtained with fenitrothion and malathion (mortalities = 21% ± 4.76% and 56.47% ± 8.67%, respectively), while a full susceptibility was observed with pirimiphos-methyl. Pre-exposure to piperonylbutoxide (PBO) significantly recovered α-cypermethrin susceptibility (mortality = 82% ± 5.16%, χ<sup>2</sup> = 50.99, p < 0.0001), compared with the conventional bioassay (mortality = 32 ± 7.30). Mortalities of <20% were obtained in cone bioassays with Yorkool, DuraNet and PermaNet3.0 (side panels) nets, suggesting a loss of efficacy of conventional long-lasting insecticidal nets. However, mortalities of 99% and 86% were obtained in Kano and Kaduna populations using the roof of PermaNet3.0 (containing PBO and deltamethrin). Despite the high frequency of the 1014F VGSC knockdown resistance mutation allele (0.90), no correlation was observed between the 1014F kdr genotype and resistance phenotype. Sequencing of fragments of the acetylcholinesterase-1 gene detected no G119S mutation, in malathion-alive and malathion-dead females. These suggest a preeminent role of metabolic resistance in these Culex populations.展开更多
目的探究蒙山地区地椒精油对淡色库蚊幼虫和成蚊的生物活性并对其成分进行分析,为植物源杀虫剂的研制提供理论依据。方法用挥发油提取器提取地椒精油,采用幼虫浸渍法测定地椒精油对淡色库蚊4龄幼虫的杀灭活性,采用密闭三角瓶熏蒸法测定...目的探究蒙山地区地椒精油对淡色库蚊幼虫和成蚊的生物活性并对其成分进行分析,为植物源杀虫剂的研制提供理论依据。方法用挥发油提取器提取地椒精油,采用幼虫浸渍法测定地椒精油对淡色库蚊4龄幼虫的杀灭活性,采用密闭三角瓶熏蒸法测定对成蚊的熏蒸活性,通过气相色谱-质谱法(GC-MS)分析地椒精油的化学成分。采用SPSS 25.0软件分析,计算半数致死浓度(LC50)、击倒中时(KT50)、毒力回归方程及95%置信限并进行卡方检验。结果幼虫杀灭活性测定显示地椒精油对淡色库蚊4龄幼虫的24 h LC50值为104.74μg/mL(χ^(2)=0.787,P=0.853);雌性成蚊熏蒸活性的KT_(50)值为20.73 min,差异有统计学意义。地椒精油中共检测出50种化合物,其中γ-松油烯的相对含量最高(12.18%),其次是左旋龙脑(8.56%)、3,4,5-三甲基甲苯(7.39%)和麝香草酚(6.04%)。结论蒙山地区地椒精油对淡色库蚊幼虫和成蚊均具有一定的杀虫活性,有望作为潜在的杀虫剂。展开更多
基金funded by the National Science and Technology Major Project of China(No.2018ZX10101002-002)
文摘Background Culex pipiens pallens and Culex pipiens quinquefasciatus are the dominant species of Culex mosquitoes in China and important disease vectors.Long-term use of insecticides can cause mutations in the voltage-gated sodium channel(vgsc)gene of mosquitoes,but little is known about the current status and evolutionary origins of vgsc gene in different geographic populations.Therefore,this study aimed to determine the current status of vgsc genes in Cx.p.pallens and Cx.p.quinquefasciatus in China and to investigate the evolutionary inheritance of neighboring downstream introns of the vgsc gene to determine the impact of insecticides on long-term evolution.Methods Sampling was conducted from July to September 2021 in representative habitats of 22 provincial-level administrative divisions in China.Genomic DNA was extracted from 1308 mosquitoes,the IIS6 fragment of the vgsc gene on the nerve cell membrane was amplified using polymerase chain reaction,and the sequence was used to evaluate allele frequency and knockdown resistance(kdr)frequency.MEGA 11 was used to construct neighborjoining(NJ)tree.PopART was used to build a TCS network.Results There were 6 alleles and 6 genotypes at the L1014 locus,which included the wild-type alleles TTA/L and CTA/L and the mutant alleles TTT/F,TTC/F,TCT/S and TCA/S.The geographic populations with a kdr frequency less than 20.00%were mainly concentrated in the regions north of 38°N,and the geographic populations with a kdr frequency greater than 80.00%were concentrated in the regions south of 30°N.kdr frequency increased with decreasing latitude.And within the same latitude,the frequency of kdr in large cities is relatively high.Mutations were correlated with the number of introns.The mutant allele TCA/S has only one intron,the mutant allele TTT/F has three introns,and the wild-type allele TTA/L has 17 introns.Conclusions Cx.p.pallens and Cx.p.quinquefasciatus have developed resistance to insecticides in most regions of China.The neighboring downstream introns of the vgsc gene gradually decreased to one intron with the mutation of the vgsc gene.Mutations may originate from multiple mutation events rather than from a single origin,and populations lacking mutations may be genetically isolated.
文摘Information on Culex mosquitoes (vectors of filarial worm and viral encephalitis) from northern Nigeria is scanty, hindering evidence-based control. Here, two Culex populations (Kano and Kaduna) were characterized. Culex quinquefasciatus and Culex pipiens were found breeding in sympatry, with some hybrid individuals identified. Larval bioassays revealed high temephos resistance (LC<sub>50</sub>s = 1.34 mg/mL and 3.01 mg/mL for Kano and Kaduna, respectively). Larvae were more sensitive to α-cypermethrin (LC<sub>50</sub>s = 0.026 mg/mL and 0.067 mg/mL for Kano and Kaduna). WHO adult tube bioassays revealed high pyrethroid and DDT resistance, with mortalities of 44.01% ± 6.79%, 35.83% ± 12.58%, 29.69% ± 9.97% and 52.47% ± 4.34% for permethrin, deltamethrin, α-cypermethrin and DDT, respectively. Highest resistance was observed with bendiocarb (mortality = 13.58% ± 3.98%). High resistance was obtained with fenitrothion and malathion (mortalities = 21% ± 4.76% and 56.47% ± 8.67%, respectively), while a full susceptibility was observed with pirimiphos-methyl. Pre-exposure to piperonylbutoxide (PBO) significantly recovered α-cypermethrin susceptibility (mortality = 82% ± 5.16%, χ<sup>2</sup> = 50.99, p < 0.0001), compared with the conventional bioassay (mortality = 32 ± 7.30). Mortalities of <20% were obtained in cone bioassays with Yorkool, DuraNet and PermaNet3.0 (side panels) nets, suggesting a loss of efficacy of conventional long-lasting insecticidal nets. However, mortalities of 99% and 86% were obtained in Kano and Kaduna populations using the roof of PermaNet3.0 (containing PBO and deltamethrin). Despite the high frequency of the 1014F VGSC knockdown resistance mutation allele (0.90), no correlation was observed between the 1014F kdr genotype and resistance phenotype. Sequencing of fragments of the acetylcholinesterase-1 gene detected no G119S mutation, in malathion-alive and malathion-dead females. These suggest a preeminent role of metabolic resistance in these Culex populations.
文摘目的探究蒙山地区地椒精油对淡色库蚊幼虫和成蚊的生物活性并对其成分进行分析,为植物源杀虫剂的研制提供理论依据。方法用挥发油提取器提取地椒精油,采用幼虫浸渍法测定地椒精油对淡色库蚊4龄幼虫的杀灭活性,采用密闭三角瓶熏蒸法测定对成蚊的熏蒸活性,通过气相色谱-质谱法(GC-MS)分析地椒精油的化学成分。采用SPSS 25.0软件分析,计算半数致死浓度(LC50)、击倒中时(KT50)、毒力回归方程及95%置信限并进行卡方检验。结果幼虫杀灭活性测定显示地椒精油对淡色库蚊4龄幼虫的24 h LC50值为104.74μg/mL(χ^(2)=0.787,P=0.853);雌性成蚊熏蒸活性的KT_(50)值为20.73 min,差异有统计学意义。地椒精油中共检测出50种化合物,其中γ-松油烯的相对含量最高(12.18%),其次是左旋龙脑(8.56%)、3,4,5-三甲基甲苯(7.39%)和麝香草酚(6.04%)。结论蒙山地区地椒精油对淡色库蚊幼虫和成蚊均具有一定的杀虫活性,有望作为潜在的杀虫剂。
