Comparison of the microbiota diversity between autogenous and anautogenous Culex pipiens pallens / 中国血吸虫病防治杂志

Objective To investigate the microbiota composition and diversity between autogenous and anautogenous Culex pipiens pallens, so as to provide insights into unraveling the pathogenesis of autogeny in Cx. pipiens pallens. Methods Autogenous and anautogenous adult Cx. pipiens pallens samples were collected at 25 ℃, and the hypervariable regions of the microbial 16S ribosomal RNA (16S rRNA) gene was sequenced on the Illumina NovaSeq 6000 sequencing platform. The microbiota abundance and diversity were evaluated using the alpha diversity index, and the difference in the microbiota structure was examined using the beta diversity index. The microbiota with significant differences in the abundance between autogenous and anautogenous adult Cx. pipiens pallens samples was identified using the linear discriminant analysis effect size (LEfSe). Results The microbiota in autogenous and anautogenous Cx. pipiens pallens samples belonged to 18 phyla, 28 classes, 70 orders, 113 families, and 170 genera, and the dominant phyla included Proteobacteria, Bacteroidetes, and so on. At the genus level, Wolbachia was a common dominant genus, and the relative abundance was (77.6 ± 11.3)% in autogenous Cx. pipiens pallens samples and (47.5 ± 8.5)% in anautogenous mosquito samples, while Faecalibaculum (0.4% ± 0.1%), Dubosiella (0.5% ± 0.0%) and Massilia (0.5% ± 0.1%) were specific species in autogenous Cx. pipiens pallens samples. Alpha diversity analysis showed that higher Chao1 index and ACE index in autogenous Cx. pipiens pallens samples than in anautogenous samples (both P values > 0.05), and lower Shannon index (P > 0.05) and Simpson index (P < 0.05) in autogenous Cx. pipiens pallens samples than in anautogenous samples. LEfSe analysis showed a total of 48 significantly different taxa between autogenous and anautogenous Cx. pipiens pallens samples (all P values < 0.05). Conclusion There is a significant difference in the microbiota diversity between autogenous and anautogenous Cx. pipiens pallens.

Attraction of different concentrations of glucose solution to Aedes albopictus, Culex pipiens pallens and their egg-laying behaviors / 预防医学

Objective@#To explore the effects of different concentrations of glucose solution on the survival of Aedes albopictus and Culex pipiens pallens larvae, the attraction to mosquitoes and egg-laying behaviors, so as to provide the reference for developing mosquito control technology based on sugar bait.@*Methods@#White porcelain bowls were filled with 100 mL of 3%, 5%, 8%, 10% and 15% glucose solutions. Ten of fourth instar larvae of Aedes albopictus or Culex pipiens pallens were added to each bowl, and the survival of larvae was recorded after 2, 4, 6, 24, 48 and 72 hours. Egg-laying cups containing 5%, 8% and 15% glucose solution were put in mosquito cages containing fully blooded female mosquitoes of Aedes albopictus and Culex pipiens pallens (50 mosquitoes each), and the total number of eggs laid in 72 hours was observed. The analogous site room was filled with fully blooded and starved female mosquitoes of Aedes albopictus and Culex pipiens pallens (100 mosquitoes each), and simple mosquito control buckets containing 5% and 8% glucose solution and black sticky insect plates. The number of mosquitoes and eggs was observed after 6 days. All the above experiments were repeated 3 times using dechlorinated water as the control.@*Results@#The 72 hour corrected mortality rates of Aedes albopictus and Culex pipiens pallens larvae gradually increased with the increase of glucose concentration. The glucose solution with 5% and higher concentrations was not suitable for mosquito larvae to survive. The attraction of egg-laying behaviors to Aedes albopictus and Culex pipiens pallens gradually decreased with the increase of glucose concentration. The effects were similar between 5% and 8% glucose solution, with the averages of 686.67 and 682.33 eggs for Aedes albopictus, and 3.00 and 2.33 egg rafts for Culex pipiens pallens. In analogous site room, there were 93.33, 105.00 and 130.33 adult mosquitoes captured on average in the control group, 5% and 8% glucose solution groups, respectively, with 8% glucose solution group more attractive to adult mosquitoes than the control group (F=3.283, P=0.030); there were 70.33, 55.33 and 63.00 Aedes albopictus eggs (eggs counts+larvae counts) on average, respectively, with statistically significant differences among the three groups (H=6.761, P=0.034).@*Conclusion@#Glucose solution with concentration of 5% or higher can effectively inhibit the survival of Aedes albopictus and Culex pipiens pallens larvae, and attractive to adult mosquitoes and egg-laying behavoirs.

Effects of angiotensin-converting enzyme on reproduction of Culex pipiens pallens / 中国血吸虫病防治杂志

Objective To investigate the role of angiotensin-converting enzyme (ACE) in the reproduction of Culex pipiens pallens, so as to provide insights into selection of targets for controlling mosquito vector populations. Methods Cx. pipiens pallens was collected from Tangkou County, Shandong Province in 2009. Female and male mosquitoes were selected at 72 hours post-eclosion, and quantitative real-time reverse transcription PCR (qPCR) assay was used to detect the expression of ACE gene in the whole body and reproductive tissues of male mosquitoes and fertilized female mosquitoes before (0 h) and after blood meals (24, 48, 72 h), respectively. Then, 150 female and 150 male mosquitoes at 0 to 4 hours post-eclosion were selected and divided into the wild-type group (WT group), small interfering RNA-negative control group (siNC group) and small interfering RNA-ACE group (siACE group), of 50 mosquitoes in each group. Mosquitoes in the WT group were given no treatment, and mosquitoes in the siNC and siACE groups were given microinjection of siNC and siACE into the hemolymph at a dose of 0.3 μg per mosquito. The knockdown efficiency was checked using qPCR assay, and the reproductive phenotype of mosquitoes was observed. Results The relative ACE gene expression was higher in the whole body of male mosquitoes (5.467 ± 1.006) relative to females (1.199 ± 0.241) (t = 5.835, P = 0.004) at 72 h post-eclosion, and the highest ACE expression was seen in reproductive tissues of male mosquitoes (199.100 ± 24.429), which was 188.3 times higher than in remaining tissues (1.057 ± 0.340) (t = 6.602, P = 0.002). Blood meal induced high ACE expression in all body tissues of fertilized female mosquitoes, with peak expression at 24 h after blood meals (14.957 ± 2.815), which was 14.8 times higher than that before blood meals (1.009 ± 0.139) (P = 0.002). The transcriptional level of ACEs continued to increase in the ovaries of female mosquitoes after blood meals during the vitellogenesis phase, peaking at 48 h after blood meals (5.500 ± 0.734), which was 5.1 times higher than that before blood meals (1.072 ± 0.178) (P = 0.002). Small RNA interference targeting ACE resulted in a 57.2% reduction in ACE expression in female mosquitoes in the siACE group (0.430 ± 0.070) relative to the siNC group (1.002 ± 0.070) (P = 0.001), and a 41.1% reduction in male mosquitoes in the siACE group (0.588 ± 0.067) relative to the siNC group (1.008 ± 0.131) (P = 0.016). Knockdown of ACE expression resulted in a 48.0% decrease in the number of eggs laid by female mosquitoes in the siACE group [(94.000 ± 27.386) eggs] relative to the siNC group [(180.800 ± 27.386)] (P < 0.001), and a 45.0% decrease in the number of eggs laid by wild female mosquitoes mated with males in the siACE group [(104.500 ± 20.965) eggs] relative to the siNC group [(190.050 ± 10.698) eggs] (P < 0.001). Conclusions Reduced ACE expression may inhibit the fecundity of male and female mosquitoes, and ACE may be as a potential target for mosquito vector population suppression.

Insecticidal activity and physiopathological effects of Cotula cinerea crude extract against Culex pipiens

@#The development of new alternatives strategies to synthetic insecticides aimed at reducing pest populations by developing pesticides based on plant extracts without negative effects in non target organisms and environment. The present study was undertaken in order to assess the insecticidal activity of the crude methanolic extract of the Algerian Asteraceae Cotula cinerea, against the larval and the pupal stage of Culex pipiens (Diptera: Culicidae). It is also to determine the chemical composition of the used extract, and to understand the mechanism of toxic action of the tested extract. Based on the preliminary tests, five concentrations of the crude methanolic extract of C. cinerea (0.62, 1.25, 2.50, 3.75, and 5 mg/mL) were tested for their insecticidal activity according to the protocol recommended by the World Health Organization. The chemical profile of the extract was also obtained by high performance liquid chromatography (HPLC). Histopathological effects and inhibition of acetylcholinesterase activity in treated mosquitoes with LC90 were examined to elucidate the mechanism of the toxic effect of the tested extract (48 h post treatment). Eight compounds have been identified by HPLC. That includes four flavonoids (rutin, quercetin, myrcetin and cathechin), three phenolic acids (benzoic acid, vanillic acid, p-coumaric acid) and one alkaloid (berberine). C. cinerea methanolic extract showed good larvicidal and pupicidal activities with LC50 and LC90 values of 1.10 and 4.37 mg/mL respectively against pupae, 24h post treatment and 1.26, 2.35 mg/mL respectively against the fourth instar larvae. Data of enzymatic assay performed on LC50 and LC90 pupae and larvae revealed prominent neurotoxic effects. C. cinerea extract reduced the activity of acetylcholinesterase (AChE) enzyme in a concentration dependent manner. Obtained inhibition percentages, 48 h after treatment, were 35.11 ± 7.44 and 51.83 ± 4.04% for pupal stage and 30.98 ± 2.97 % and 48.77 ± 4.72% for the fourth instar larvae for LC50 and LC90 values respectively. Treated larvae and pupae showed also histopathological damages in the pupal cuticle and larval midgut. The results of this study showed that C. cinerea crude methanolic extract could be considered as an eco-friendly alternative for mosquito control.

Monitoring density of mosquitoes and resistance of major vector mosquitoes to insecticides in Zigong, Sichuan / 中国热带医学

@#Abstract: Objective 　To investigate the population densities composition and seasonal change of mosquitoes, and resistance of Culex pipiens quinquefasciatus and Aedes albopictus several commonly used insecticides in Zigong, so as to provide a theoretical basis for guiding the scientific rational selection and use of chemical insecticides, as well as the prevention and control of mosquito-borne diseases. Methods　The surveillance data on mosquitoes by traps were collected from 2018 to 2020 in Zigong. The wild Culex pipiens quinquefasciatus and Aedes albopictus were collected throughout the city and reared to F1 generation in lab. The resistance of adult Culex pipiens quinquefasciatus and Aedes albopictus to these commonly insecticides was detected by contact tube method recommended. The statistical analysis on the monitoring results was used by Excel 2010. Results　The annual average mosquito densities of monitoring sites were 1.11, 10.71, and 4.81 mosquitoes/(lamp·h), respectively from 2018 to 2020. The seasonal density of mosquitoes showed a single peak curve distribution throughout the year from 2018 to 2020 in Zigong, with the highest in July. There were obvious differences in mosquito density between different habitats, with the highest density of mosquitoes in barn. The 24 h mortality of Aedes albopictus and Culex pipiens quinquefasciatus to beta-cypermethrin, lambda-cyhalothrin, deltamethrin, permethrin, malathion, fenitrothion, chlorpyrifos, propoxur, and bendiocarb were 70.71% and 3.85%, 26.53% and 1.68%, 19.79% and 1.94%, 40.80% and 0.81%, 97.98% and 3.85%, 100.00% and 7.52%, 100.00% and 66.34%, 96.15% and 33.60%, 100.00% and 71.43%, respectively. The adult Aedes albopictus larvae in Zigong was sensitive to fenitrothion, chlorpyrifos, bendiocarb, showed resistance to beta-cypermethrin, lambda-cyhalothrin, deltamethrin, permethrin, and showed resistance dubiously to malathion and propoxur. The adult Culex pipiens quinquefasciatus larvae in Zigong have developed certain resistance to these commonly insecticides. Conclusion　Both Culex pipiens quinquefasciatus and Aedes albopictus had high resistance to pyrethroid insecticides, which suggested that we should strengthen the patriotic hygiene campaigns, reduce pyrethroid insecticides, use alternately different types of insecticides for delay the development of resistance and better mosquito prevention and control.

Chemical composition and insecticidal activity of Origanum floribundum Munby essential oil endemic plant from Algeria

@#Among strategies for decreasing diseases, the use of larvicidal plant extracts against mosquito larvae gain an important place in vector control. The aim of the present study was to reveal the insecticidal effectiveness of an endemic medicinal plant on Mosquito-Borne Diseases. The chemical composition of the dried aerial part from Origanum floribundum Essential oil, obtained by hydrodistillation, was characterized by Fourier-transform infrared (FTIR) spectroscopy and gas chromatography-mass spectrometer (GC-MS) system. The potential larvicidal activity of this extract as bioinsecticide was assessed against Culex pipiens. Results showed many functional groups such as phenols and alcohols, besides, the chemical composition by GC-MS identified thymol (86.9%) and p-Cymene (5.1%) as major components. A significant larvicidal effect against the target mosquito species was noted, with values of LC50 at 21.19 mg/l and LC90 at 68.37 mg/l. The results obtained showed that the essential oil of Origanum floribundum with chemotype thymol possess a potent larvicidal activity and could be considered as an eco-friendly alternative for vector control.

Distribution of mosquito species and associated viruses in Hami City of Xinjiang Uygur Autonomous Region from 2019 to 2020 / 中国血吸虫病防治杂志

Objective To investigate the distribution of mosquito species and their associated viruses, and identify Culex pipiens subspecies in Hami City, Xinjiang Uygur Autonomous Region. Methods Mosquitoes were captured using mosquito trapping lamps method in Yizhou District, Yiwu County, and Balikun County of Hami City in mi-July, 2019 and 2020. The species and subspecies of all captured mosquitoes were characterized. In addition, the flavivirus, alphavirus, bunyavirus, Japanese encephalitis virus, Liaoning virus, Tahyna virus, tick-borne encephalitis virus and West Nile virus were detected using reverse-transcription PCR assay in captured mosquitoes. Results A total of 1 496 mosquitoes were captured from Yizhou District, Yiwu County, and Balikun County of Hami City, belonging to 3 genus and 3 species. Cx. pipiens was the dominant mosquito species (986 mosquitoes, 65.91%), followed by Aedes caspius (457 mosquitoes, 30.55%), while Culiseta alaskaensis had the lowest number (53 mosquitoes, 3.54%). All captured Cx. pipiens mosquitoes were identified as Cx. pipiens pipiens based on the terminalia of male mosquitoes. RT-PCR assay tested negative for flavivirus, alphavirus, bunyavirus, Japanese encephalitis virus, Liaoning virus, Tahyna virus, tick-borne encephalitis or West Nile virus in captured Cx. pipiens mosquitoes. Conclusions There were 3 species of mosquitoes in Hami City from 2019 to 2020, including Cx. pipiens, Ae. Caspius and C. alaskaensis, with Cx. pipiens as the dominant mosquito species, and all captured Cx. pipiens mosquitoes were Cx. pipiens pipiens; however, no arboviruses were detected.

Phytochemical composition of almond oil from Melia azedarach L. and its larvicidal, ovicidal, repellent and enzyme activities in Culex pipiens L

@#Melia azedarach L. (Meliaceae) is a botanical species with focal point of global research for its biological properties. The Melia azedarach tree is distinguished by its rapid growth, its adaptation to different temperate zones, as well as its insecticidal properties. All this made us think of exploiting it in biological control against different stages of mosquitoes. To this end, we aim, through the present work, to evaluate the effectiveness of Melia azedarach extracts against Culex pipiens mosquito. More specifically, our study focuses on determining the chemical composition of Melia almond oil, as well as the larvicidal, ovicidal and repellent activities on Culex pipiens L. mosquito as well as the activities of acetylcholinesterase (AChE) and glutathione-S-transferase (GST). Almond oil was extracted by a Soxhlet and subjected to gas chromatography–mass spectrometry (GC/MS). The yield was found to be 35.17%. The chemical composition revealed the presence of various phytoconstituents. A total of 7 compounds were identified, the main ones being 9,11-Octadecadienoic acid, methyl ester, (E,E)- (79.32%), 9-octadecenoic acid (Z)-, methyl ester (13.24%), hexadecanoic acid and methyl ester (3.69%). The larvicidal bioassays were performed according to the protocol recommended by the World Health Organization with concentrations varying from 20 to 80 mg/L depending on the exposure time (24, 48 and 72 hours). The almond oil exhibited remarkable larvicidal activity against fourth instar larvae and the lethal concentrations were determined (LC25= 23.70 mg/L, LC50=35.49 mg/L, LC90=79.61 mg/L). The results also showed that the oil caused an ovicidal activity with a significant effect on egg hatch. The recorded hatching percentages were respectively 88.79% and 72.40% for the LC25 and LC50, and this compared to the control series. Moreover, this oil exhibited significant repellency against adult mosquitoes. Furthermore, the enzymatic measurements performed on LC50 and LC90 treated larvae revealed a neurotoxic activity and a stimulation of the detoxification system as evidenced, respectively, by an inhibition of AChE and induction in GST activity. Overall, our data proved that Melia azedarach almond oil could be considered as a potent biorational alternative to synthetic insecticides for mosquito control.

Effects of Peganum harmala L Seed Extract on Culex pipiens (Diptera: Culicidae) / Efeitos do extrato de semente de Peganum harmala L em Culex pipiens (Diptera: Culicidae)

Mosquito-borne diseases result in the loss of life and economy, primarily in subtropical and tropical countries, and the emerging resistance to insecticides is increasing this threat. Botanical insecticides are promising substitutes for synthetic insecticides. This study evaluated the larvicidal and growth index of Culex pipiens of four solvent extracts of Terminalia chebula, Aloe perryi, and Peganum harmala against Cx. pipiens. None of the 12 extracts exhibited larvicidal potential against third instars except the ethyl acetate extract of P. harmala. After 24 h of exposure, the LC50 value was 314.88 ppm, and the LC90 value was 464.19 ppm. At 320 ppm, the hatchability was 25.83%, and it resulted in 100% mortality. In addition, the eggs treated with the EtOAc extract of P. Harmala exhibited a long larval period compared with the control. The larval period continued for 12 days, and the pupal period took three days in the treatment groups. The growth index data also exhibited a decrease (0.00–7.53) in the treated groups compare with 8.5 in the control. The transformation of eggs into adults decreased with increasing concentrations. This paper is the first report on the development and growth index of Cx. pipiens potential using P. harmala seeds.

As doenças transmitidas por mosquitos resultam na perda de vidas e economia, principalmente em países subtropicais e tropicais, e a resistência emergente aos inseticidas está aumentando essa ameaça. Os inseticidas botânicos são substitutos promissores dos inseticidas sintéticos. Este estudo avaliou o índice larvicida e de crescimento de Culex pipiens de quatro extratos solventes de Terminalia chebula, Aloe perryi e Peganum harmala contra Cx. pipiens. Nenhum dos 12 extratos exibiu potencial larvicida contra o terceiro ínstar, exceto o extrato de acetato de etila de P. harmala. Após 24 horas de exposição, o valor LC50 era 314,88 ppm e o valor LC90 era 464,19 ppm. A 320 ppm, a eclodibilidade foi de 25,83% e resultou em 100% de mortalidade. Além disso, os ovos tratados com o extrato de EtOAc de P. harmala exibiram um longo período larval em comparação com o controle. O período larval continuou por 12 dias, e o período pupal durou três dias nos grupos de tratamento. Os dados do índice de crescimento também exibiram uma diminuição (0,00-7,53) nos grupos tratados em comparação com 8,5 no controle. A transformação de ovos em adultos diminuiu com o aumento das concentrações. Este artigo é o primeiro relatório sobre o índice de desenvolvimento e crescimento de Cx. potencial de pipiens usando sementes de P. harmala.

Effects of Peganum harmala L. Seed Extract on Culex pipiens (Diptera: Culicidae)

Abstract Mosquito-borne diseases result in the loss of life and economy, primarily in subtropical and tropical countries, and the emerging resistance to insecticides is increasing this threat. Botanical insecticides are promising substitutes for synthetic insecticides. This study evaluated the larvicidal and growth index of Culex pipiens of four solvent extracts of Terminalia chebula, Aloe perryi, and Peganum harmala against Cx. pipiens. None of the 12 extracts exhibited larvicidal potential against third instars except the ethyl acetate extract of P. harmala. After 24 h of exposure, the LC50 value was 314.88 ppm, and the LC90 value was 464.19 ppm. At 320 ppm, the hatchability was 25.83%, and it resulted in 100% mortality. In addition, the eggs treated with the EtOAc extract of P. Harmala exhibited a long larval period compared with the control. The larval period continued for 12 days, and the pupal period took three days in the treatment groups. The growth index data also exhibited a decrease (0.007.53) in the treated groups compare with 8.5 in the control. The transformation of eggs into adults decreased with increasing concentrations. This paper is the first report on the development and growth index of Cx. pipiens potential using P. harmala seeds.

Resumo As doenças transmitidas por mosquitos resultam na perda de vidas e economia, principalmente em países subtropicais e tropicais, e a resistência emergente aos inseticidas está aumentando essa ameaça. Os inseticidas botânicos são substitutos promissores dos inseticidas sintéticos. Este estudo avaliou o índice larvicida e de crescimento de Culex pipiens de quatro extratos solventes de Terminalia chebula, Aloe perryi e Peganum harmala contra Cx. pipiens. Nenhum dos 12 extratos exibiu potencial larvicida contra o terceiro ínstar, exceto o extrato de acetato de etila de P. harmala. Após 24 horas de exposição, o valor LC50 era 314,88 ppm e o valor LC90 era 464,19 ppm. A 320 ppm, a eclodibilidade foi de 25,83% e resultou em 100% de mortalidade. Além disso, os ovos tratados com o extrato de EtOAc de P. harmala exibiram um longo período larval em comparação com o controle. O período larval continuou por 12 dias, e o período pupal durou três dias nos grupos de tratamento. Os dados do índice de crescimento também exibiram uma diminuição (0,00-7,53) nos grupos tratados em comparação com 8,5 no controle. A transformação de ovos em adultos diminuiu com o aumento das concentrações. Este artigo é o primeiro relatório sobre o índice de desenvolvimento e crescimento de Cx. potencial de pipiens usando sementes de P. harmala.

Effects of Peganum harmala L. Seed Extract on Culex pipiens (Diptera: Culicidae) / Efeitos do extrato de semente de Peganum harmala L. em Culex pipiens (Diptera: Culicidae)

Mosquito-borne diseases result in the loss of life and economy, primarily in subtropical and tropical countries, and the emerging resistance to insecticides is increasing this threat. Botanical insecticides are promising substitutes for synthetic insecticides. This study evaluated the larvicidal and growth index of Culex pipiens of four solvent extracts of Terminalia chebula, Aloe perryi, and Peganum harmala against Cx. pipiens. None of the 12 extracts exhibited larvicidal potential against third instars except the ethyl acetate extract of P. harmala. After 24 h of exposure, the LC50 value was 314.88 ppm, and the LC90 value was 464.19 ppm. At 320 ppm, the hatchability was 25.83%, and it resulted in 100% mortality. In addition, the eggs treated with the EtOAc extract of P. Harmala exhibited a long larval period compared with the control. The larval period continued for 12 days, and the pupal period took three days in the treatment groups. The growth index data also exhibited a decrease (0.00­7.53) in the treated groups compare with 8.5 in the control. The transformation of eggs into adults decreased with increasing concentrations. This paper is the first report on the development and growth index of Cx. pipiens potential using P. harmala seeds.

As doenças transmitidas por mosquitos resultam na perda de vidas e economia, principalmente em países subtropicais e tropicais, e a resistência emergente aos inseticidas está aumentando essa ameaça. Os inseticidas botânicos são substitutos promissores dos inseticidas sintéticos. Este estudo avaliou o índice larvicida e de crescimento de Culex pipiens de quatro extratos solventes de Terminalia chebula, Aloe perryi e Peganum harmala contra Cx. pipiens. Nenhum dos 12 extratos exibiu potencial larvicida contra o terceiro ínstar, exceto o extrato de acetato de etila de P. harmala. Após 24 horas de exposição, o valor LC50 era 314,88 ppm e o valor LC90 era 464,19 ppm. A 320 ppm, a eclodibilidade foi de 25,83% e resultou em 100% de mortalidade. Além disso, os ovos tratados com o extrato de EtOAc de P. harmala exibiram um longo período larval em comparação com o controle. O período larval continuou por 12 dias, e o período pupal durou três dias nos grupos de tratamento. Os dados do índice de crescimento também exibiram uma diminuição (0,00-7,53) nos grupos tratados em comparação com 8,5 no controle. A transformação de ovos em adultos diminuiu com o aumento das concentrações. Este artigo é o primeiro relatório sobre o índice de desenvolvimento e crescimento de Cx. potencial de pipiens usando sementes de P. harmala.

Study on the mechanism of resistance to cypermethrin in Culex pipiens pallens using proteomics / 中国血吸虫病防治杂志

Objective To compare the differentially expressed proteins between cypermethrin-resistant and -sensitive Culex pipiens pallens, so as to unravel the mechanism underlying the resistance to cypermethrin in Cx. p. pallens. Methods A quantitative proteomic analysis was performed among cypermethrin-sensitive and -resistant isolates of Cx. p. pallens using isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results A total of 164 differentially expressed proteins were identified between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens, including 54 up-regulated proteins and 110 down-regulated proteins. A large number of cuticular proteins, larval cuticular proteins, pupal cuticular proteins and cuticular structural constituent proteins, which are associated with cytoskeletal structure and components, were differentially expressed between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens. Thirteen proteins, which were involved in energy production and conversion, translation, ribosomal structure and biogenesis, lipid transport and metabolism, post-translational modification, protein turnover, chaperones, cytoskeleton and intracellular transportation, were validated to be differentially expressed between cypermethrin-sensitive and -resistant isolates of Cx. p. pallens, which may serve as potential markers of cypermethrin resistance. Conclusion Multiple insecticide resistance mechanisms contribute to the resistance to cypermethrin in Cx. p. pallens, including cuticular resistance and metabolic resistance, and the cuticular protein genes and cytochrome P450 enzymes may play an important role in the resistance of Cx. p. pallens to cypermethrin.

Genes associated with Wolbachia-induced cytoplasmic incompatibility in natural populations of Culex pipiens pallens: a preliminary study / 中国血吸虫病防治杂志

Objective To investigate the genes involved in Wolbachia-induced cytoplasmic incompatibility among three natural populations of Culex pipiens pallens in eastern China, so as to provide insights into the development of preventive and control measures for mosquito-borne diseases based on Wolbachia. Methods The cytoplasmic incompatibility was tested among three natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province using reciprocal crosses. Wolbachia infection was detected in C. pipiens pallens using a PCR assay, and the expression of Wolbachia wsp and WD0513 genes was quantified using a fluorescent quantitative real-time PCR (qPCR) assay. Results Bidirectional compatibility was found between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (t = 0.57 and 0.15, both P values > 0.05), while bidirectional incompatibility was seen between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (t = 63.81 and 43.51, both P values < 0.01), and between the natural populations of C. pipiens pallens collected from Nanjing of Jiangsu Province and Tangkou of Shandong Province (t = 39.62 and 43.12, both P values < 0.01). Wolbachia wsp gene was amplified in all three natural populations of C. pipiens pallens, and qPCR assay detected no significant difference in the Wolbachia wsp gene expression among the three natural populations of C. pipiens pallens (F = 2.15, P > 0.05). In addition, there was no significant difference in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Nanjing of Jiangsu Province (q = 8.42, P < 0.05) or between the natural populations of C. pipiens pallens collected from Tangkou of Shandong Province and Wuxi of Jiangsu Province (q = 7.84, P < 0.05); however, there was a significant difference detected in the WD0513 gene expression between the natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province (q = 0.40, P > 0.05). Conclusions Different Wolbachia numbers are detected in natural populations of C. pipiens pallens collected from Nanjing and Wuxi of Jiangsu Province and Tangkou of Shandong Province, and WD0513 gene may be involved in the Wolbachia-induced cytoplasmic incompatibility among three natural populations of C. pipiens pallens.

Assessment of Culex pipiens bioforms in the world's southernmost distribution limit

The mosquito Culex pipiens s.s. L. occurs as two bioforms that differ in physiology and behaviour affecting virus transmission cycles. To assess the occurrence of Cx. pipiens bioforms in the southernmost limit of its distribution, specimens were collected aboveground in southern Buenos Aires Province and east Patagonia, Argentina. Ten larvae and 25 adults were individually processed and identified by polymerase chain reaction (PCR) amplification of Ace-2 and CQ11 loci. Culex quinquefasciatus Say (one larva, two adults), Cx. pipiens f. molestus (one larva, one adult) and one adult of hybrid origin were identified in Buenos Aires Province; only Cx. pipiens f. molestus was recorded in Patagonia (eight larvae, 21 adults). The potential absence of bioform pipiens and its implications in arbovirus enzootic cycles is discussed.

Effect of several human metabolic compounds for trapping Culex pipiens quinquefasciatus / 中国血吸虫病防治杂志

Objective To evaluate the indoor effect of six human metabolic compounds for trapping adult Culex pipiens quinquefasciatus. Methods The effects of six human metabolic compounds alone (acetic acid, propionic acid, octanoic acid, lactic acid, 1-octene-3-alcohol and urea alone), liquid lactic acid, acetic acid, propionic acid, octanoic acid, lactic acid or 1-octene-3-alcohol in combination with urea at an equal mass ratio, and lactic acid-urea combinations at various mass ratios, for trapping Cx. p. quinquefasciatus were examined using the trapping method, while the dechlorinated water served as a control. Results The indoor mosquito-trapping efficacy of the six human metabolic compounds was all superior to the dechlorinated water. Acetic acid, propionic acid, octanoic acid, or 1-octene-3-alcohol combined with urea at a mass ratio of 1∶1 had a comparable mosquito-trapping efficacy with acetic acid, propionic acid, octanoic acid, or 1-octene-3-alcohol alone (all P values > 0.05). The lactic acidurea combination at a mass ratio of 1∶1 had a significantly higher mean cumulative trapping capacity [(35.60 ± 8.11) mosquitoes] than lactic acid [(20.80 ± 8.53) mosquitoes], urea [(17.00 ± 7.18) mosquitoes] or dechlorinated water alone (7.20 ± 2.68) (all P values < 0.05). In addition, the lactic acid-urea combinations at mass ratios of 1∶1, 1∶2, 1∶3, 1∶4 or 1∶5 all had significantly greater mosquito-trapping efficacies than lactic acid, urea or dechlorinated water alone (all P values < 0.05), and the optimal combination (lactic acid-urea at a 1∶4 mass ratio) had a mean cumulative trapping capacity of (56.20 ± 9.88) mosquitoes, which was significantly superior to lactic acid [(17.00 ± 3.94) mosquitoes], urea [(16.40 ± 3.78) mosquitoes] or dechlorinated water alone [(7.40 ± 3.44) mosquitoes] (all P values < 0.05). Conclusions The lactic acid-urea combination remarkably increases the indoor trapping capability of Cx. p. quinquefasciatus, and this combination has a weak smell, which is suitable to be used at home and office environments.

Study on insecticide resistance of Culex pipiens pallens in southwest region of Shandong Province / 中国血吸虫病防治杂志

Objective To explore the sensitivity of Culex pipiens pallens to common chemical insecticides in the southwestern region of Shandong Province, so as to provide a theoretical basis for the development of reasonable and effective mosquito control measures. Methods The resistance of Cx. pipiens pallens larvae to 5 chemical insecticides, such as cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate were tested by using the WHO biological test method in 2018, and the co-toxicity coefficients after compounding the above-mentioned insecticides were tested by using a drug compounding method. Results The resistance indexes of Cx. pipiens pallens to cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate in 3 cities were 144.43–557.54, 118.17–445.33, 6.44–19.00, 2.37–8.10, and 0.88–2.98, respectively, and expect the difference between the DDVP resistances of Cx. pipiens pallens in Jining City and Heze City was not statistically significant (P > 0.05), all the other differences were statistically significant (all P < 0.05). The synergistic coefficients of cypermethrin + DDVP, cypermethrin + propoxur, DDVP + acetofenate, and propoxur + acetofenate were 199.58 – 456.95, 190.56 – 292.37, 123.32 – 319.24, and 192.31 – 367.32, respectively. The lower synergism was observed by using the mixture of DDVP + propoxur (synergistic coefficient: 99.87–108.36) . Conclusions After decades of chemical control, Cx. pipiens pallens in the southwestern region of Shandong Province has produced different degrees of resistance to common chemical insecticides. Therefore, comprehensive control measures should be taken to control mosquito breeding and prevent the development of insecticide resistance.

Effects of low temperature on trehalose and trehalase contents in Culex pipiens pallens / 中国血吸虫病防治杂志

Objective To examine the effect of low temperature on trehalose and trehalase levels in Culex pipiens pallens. Methods The fourth instar larvae and female adult mosquitoes of Cx. pipiens pallens were exposed at 4 ℃ for 0, 1, 3, 6, 12, 18, 24 h and 0, 1, 3, 6, 12, 18, 24, 36, 48, 72 h, respectively. Then, the trehalose and trehalase contents were detected by enzyme-linked immunosorbent assay (ELISA) in mosquitoes. Results The contents of trehalose and trehalase significantly increased in the larval and female adult mosquitoes post-exposure to low temperature. The changing trend of trehalose levels was consistent in the larval and female adult mosquitoes, and the highest levels were (2.458 8 ± 0.379 2) mg/g and (2.825 7 ± 0.211 1) mg/g 3 h post-exposure to low temperature, respectively. The trehalose and trehalase levels fluctuated greatly within the first 6 h post-exposure to low temperature. Following adaptation for a period of time, the trehalose and trehalase levels remained at a relatively high level. Conclusion Low temperature may induce the production of trehalose and trehalase in Cx. pipiens pallens, and the trehalose and trehalase may play an important role in the improvement of the cold resistance.

Study on kdr allele mutation of Culex pipiens pallens in Zichuan District, Zibo City, Shandong Province / 中国血吸虫病防治杂志

Objective To study the seasonal dynamics of Culex pipiens pallens and the distribution of knockdown resistance (kdr) gene related sodium channel gene polymorphism in Zichuan District, Zibo City, Shandong Province. Methods Cx. pipiens pallens mosquitoes were collected in Zichuan District during the peak period of mosquito vector activity from 2017 to 2018. The DNA from Cx. pipiens pallens was extracted, and the genotypes and frequencies of kdr allele mutation were detected by polymerase chain reaction. Results Totally 830 mosquitoes belonging to six species, including Cx. pipiens pallens, Armigeres subalbatus, Aedes albopictus, Ae. vexans, Anopheles sinensis, and Cx. tritaeniorhchus were collected in this study. The number of Cx. pipiens pallens accounted for 83.13% in total, with the density of 12.32 per lamp per night. The annual density monitoring curve of Cx. pipiens pallens showed a bimodal trend, and the peaks were observed in June and September respectively. In this study, five kdr alleles were detected at the 1 014 locus of kdr gene, with TTA (75.71%), TTT (10.00%), CTA (5.71%), TCA (4.29%), and TTC (4.29%). Two nonsynonymous nucleotide mutations were detected at site 1 014 of kdr gene, namely leucine (L1014) mutated to phenylalanine (L1014F) and serine (L1014S). The kdr gene mutation frequency (%) of Cx. pipiens pallens in Luochun Town and Taihe Town was 10.53% and 40.63%, respectively, and the difference was statistically significant ( χ2 = 8.559, P = 0.003). Conclusions Cx. pipiens pallens is the dominant mosquito species in Zichuan District. In addition, two novel mutations, CTA and TTC, are identified in the voltage-dependent sodium channel gene of Cx. pipiens pallens. The kdr genotype of Cx. pipiens pallens in Zichuan area was polymorphic.

Study on the mechanisms underlying overwintering of Culex pipiens pallens using iTRAQ-based quantitative proteomic analysis / 中国血吸虫病防治杂志

Objective To compare the difference of protein expression between the post-overwintering stage and the diapauses preparation stage in Culex pipiens pallens, so as to reveal the mechanisms underlying the overwintering diapause of Cx. pipienspallens. Methods A quantitative proteomic analysis was performed in Cx. pipiens pallens before and after overwintering diapause by using isobaric tags for relative and absolute quantification (iTRAQ) labeling. Results A total of 244 differentially expressed proteins were identified in Cx. pipiens pallens before and after overwintering diapause, including 126 up-regulated proteins and 118 down-regulated proteins. iTRAQ-based quantitative proteomic analysis revealed that these differentially expressed proteins were linked to function and energy production and conversion, lipid metabolism, remodeling of cytoskeleton, carbohydrate metabolism, protein transport, molecular chaperones, stress tolerance and metabolic enzymes. Conclusions This is the first study to identify the overwintering diapause-related proteins in Cx. pipiens pallens using proteomics tools, which reveals KEGG pathways and GO terms associated with the overwintering diapauses of Cx. pipiens pallens. Our findings provide additional understandings pertaining to the mechanisms underlying the overwintering diapauses of Cx. pipiens pallens.

Study on kdr allele mutation of Culex pipiens pallens in Zichuan District, Zibo City, Shandong Province / 中国血吸虫病防治杂志

Objective To study the seasonal dynamics of Culex pipiens pallens and the distribution of knockdown resistance (kdr) gene related sodium channel gene polymorphism in Zichuan District, Zibo City, Shandong Province. Methods Cx. pipiens pallens mosquitoes were collected in Zichuan District during the peak period of mosquito vector activity from 2017 to 2018. The DNA from Cx. pipiens pallens was extracted, and the genotypes and frequencies of kdr allele mutation were detected by polymerase chain reaction. Results Totally 830 mosquitoes belonging to six species, including Cx. pipiens pallens, Armigeres subalbatus, Aedes albopictus, Ae. vexans, Anopheles sinensis, and Cx. tritaeniorhchus were collected in this study. The number of Cx. pipiens pallens accounted for 83.13% in total, with the density of 12.32 per lamp per night. The annual density monitoring curve of Cx. pipiens pallens showed a bimodal trend, and the peaks were observed in June and September respectively. In this study, five kdr alleles were detected at the 1 014 locus of kdr gene, with TTA (75.71%), TTT (10.00%), CTA (5.71%), TCA (4.29%), and TTC (4.29%). Two nonsynonymous nucleotide mutations were detected at site 1 014 of kdr gene, namely leucine (L1014) mutated to phenylalanine (L1014F) and serine (L1014S). The kdr gene mutation frequency (%) of Cx. pipiens pallens in Luochun Town and Taihe Town was 10.53% and 40.63%, respectively, and the difference was statistically significant ( χ2 = 8.559, P = 0.003). Conclusions Cx. pipiens pallens is the dominant mosquito species in Zichuan District. In addition, two novel mutations, CTA and TTC, are identified in the voltage-dependent sodium channel gene of Cx. pipiens pallens. The kdr genotype of Cx. pipiens pallens in Zichuan area was polymorphic.