41种植物精油对淡色库蚊的熏蒸活性

为发现具有较高杀蚊活性的精油, 推动植物精油类卫生杀虫剂的创制, 本研究采用三角瓶熏蒸法测定了17科41种植物精油对淡色库蚊Culex pipiens pallens雌成蚊的熏蒸活性, 并进一步采用密闭圆筒法验证其杀虫毒力大小。三角瓶熏蒸法测定表明, 在12 μL/L浓度下, 留兰香油（spearmint oil）、 薰衣草油（lavender oil）、 山苍子油（Litsea cubeba oil）等26种精油均有较强的熏蒸作用, KT₅₀小于15 min。该26种精油用密闭圆筒熏蒸法进一步测定表明, 在浓度为10 μL/L时, 冬青油（wintergreen oil）、 艾叶油（blumea oil）、 薄荷油（peppermint oil）、 桉叶油（Eucalyptus robusta oil）和蓝桉油（E. globulus oil）等植物精油熏蒸活性较强, 其KT₅₀分别为16.91, 21.20, 22.57, 18.43和19.48 min。结果证明冬青油、 艾叶油、 薄荷油、 桉叶油和蓝桉油等5种精油对淡色库蚊具有较强的熏蒸活性, 具备作为淡色库蚊防控剂开发的潜力, 值得进一步研究。     

Effect of body size on energy reserves in Culex pipiens pallens females (Diptera: Culicidae)

We examined the relationship between body size and energy reserves of female Culex pipiens pallens under laboratory conditions. Small and large‐sized adult mosquitoes were obtained from larvae reared at different densities. There was a significantly positive relationship between pupal body weight and adult wing length depending on body sizes. Studies showed large females contained significantly higher contents of glycogen and lipid but lower protein stores in comparison to small females. Large sized mosquitoes accumulated higher percentages of glycogen (21.2% vs 15.9%) and lipid (45.8% vs 30.7%) but lower levels of protein (33.0% vs 53.4%) than small females. This result suggests that larval‐derived glycogen and lipid stores may be important in determining the body size of female Cx. pipiens pallens.     

冬青油与肉桂油对淡色库蚊的生物活性

为进一步明确冬青油（wintergreen oil）与肉桂油（cinnamon oil）对蚊虫的生物活性, 本研究采用浸液法、 “Y”型嗅觉仪法和密闭三角瓶熏蒸法, 分别测定了两种精油对淡色库蚊Culex pipiens pallens幼虫的毒杀作用以及对成虫的驱避和熏杀活性。结果显示： 肉桂油和冬青油对淡色库蚊幼虫均具有较强的毒杀作用, 处理24 h的LC₅₀分别为71.87 mg/L和 102.83 mg/L。在0.5 μL的供试剂量下, 冬青油与肉桂油在20 min内对淡色库蚊的驱避率均在80%以上, 显示了较好的驱蚊活性。冬青油对淡色库蚊具有明显的熏蒸击倒作用, 12 μL/L浓度下的KT₅₀为3.97 min; 而肉桂油则具有较好的熏蒸致死活性, 熏蒸5 h的LC₅₀ 为0.31 μL/L。冬青油与肉桂油按1∶1体积比混配后对淡色库蚊表现出较好的击倒和致死效果。冬青油和肉桂油既对淡色库蚊幼虫具有较强的毒杀作用, 又对淡色库蚊雌成虫表现出较好的驱避和熏杀活性, 具有开发成为植物源蚊虫防控剂的潜力。     

Cultivation of the mosquito Culex pipiens pipiens f. molestus (Diptera, Culicidae) without blood feeding

Optimal photoperiod and temperature conditions for rearing of the mosquito Culex pipiens pipiens f. molestus without blood feeding (through autogenous eggs) were experimentally substantiated. This method may be used in order to obtain relatively small quantities of mosquitoes or for preservation of a laboratory colony. Optimal conditions of rearing are the short-day photoperiod (12 h of light per day) at 20 degrees C, when 87 % of the females produce autogenous eggs rafts consisting of 52 eggs on the average. It should be emphasized that larval food must be adequate and abundant, because the quality and quantity of it has a pronounced effect on the autogeny rate.     

Sympatric occurrence of Culex pipiens (Diptera,Culicidae) biotypes pipiens,molestus and their hybrids in Portugal,Western Europe: feeding patterns and habitat determinants

Culex (Culex) pipiens (Diptera: Culicidae) has two recognized biotypes, pipiens and molestus, which differ in physiology and behaviour; this difference may influence vectorial capacity for West Nile virus (WNV). Our goal was first to determine the presence of Cx. pipiens populations in 31 locations in Portugal and to subsequently analyse their host‐feeding preferences and habitat determinants. Molecular identification of Cx. pipiens forms and their hybrids was performed in 97 females; bloodmeal sources were identified in 59 engorged specimens. Overall, 61.9% of specimens were identified as Cx. pipiens f. pipiens, 20.6% as Cx. pipiens f. molestus, and 17.5% as hybrid forms. Culex pipiens f. pipiens fed preferentially on birds, and Cx. pipiens f. molestus on humans. Hybrid forms fed mostly on birds, but human bloodmeals were common. With reference to habitat, Cx. pipiens f. pipiens and hybrid forms were positively correlated with peri‐urban habitats. Our results confirm the sympatric presence of different Cx. pipiens biotypes in 14 of the 31 locations studied. Peri‐urban areas were a common habitat of all biotypes and may represent zones of hybridization. The feeding preferences and sympatric distribution of the Cx. pipiens biotypes observed in Portugal favour the epizootic circulation of WNV and the occurrence of disease outbreaks of WNV.     

Repellent efficacy of wood vinegar against Culex pipiens pallens and Aedes togoi (Diptera: Culicidae) under laboratory and semi-field conditions

The repellent efficacy of wood vinegar was assessed against mosquitoes under laboratory conditions at 1, 5, 10, 20, 40, 60 and 80% concentrations. The study evaluated whether wood vinegar is able to repel Culex pipiens pallens Coquillet and Aedes togoi (Theobald) from the human body and if so at what concentrations. The tests were conducted using the arm-in-cage method in 80 × 40 × 40 cm screened mosquito cages. The data were analyzed and compared with those of N,N-Diethyl-3-methylbenzamide (deet) at 10.3% concentration. The results showed that wood vinegar provided mosquito repellence of varying degree depending on the concentration used. The observed repellence averaged from as low as 39.6% at 5.0% concentration to as high as 100% at 80% concentration against Ae. togoi. Repellence against Cx. pipiens pallens was high being 90.3% at 20% concentration, 92.2% at 40% concentration, 93.9% at 60% concentration and 100% at 80% concentration. The duration of protection time tests showed that the 40% and 60% concentrations of the wood vinegar give protection from landing of Ae. togoi for a period of up to 7 h, though the lower concentration gave lower protection after the first five hours. The results indicated that wood vinegar has mosquito repellent characteristics that tend to vary with the concentration used and the species of mosquitoes. Wood vinegar in this case was very effective in repelling Cx. pipiens pallens, even at lower concentrations while higher concentrations were required to repel Ae. togoi.     

香芹酮和薄荷醇手性异构体对淡色库蚊熏蒸及驱避活性

【目的】比较香芹酮和薄荷醇各手性异构体对淡色库蚊Culex pipiens pallens成蚊的熏蒸及驱避活性,为其应用提供理论依据。【方法】以3日龄淡色库蚊雌成蚊为供试昆虫,采用三角瓶熏蒸法比较测定香芹酮和薄荷醇的5种手性异构体的击倒与熏蒸致死活性;用Y-型嗅觉仪法比较测定驱避作用;将活性较好单体制成电热蚊香片,用方箱法进一步评价药效。【结果】5种异构体对淡色库蚊均具有一定的击倒和致死作用,其中L-香芹酮的击倒速度最快,KT50为9.75 min;D-香芹酮的致死作用最强,LC50为0.26μL/L。L-香芹酮和D-香芹酮对淡色库蚊均具较好的驱避作用,在0.5μL剂量下,处理30 min后的驱避率仍达100%。方箱法实验表明,以200μL的L-香芹酮和D-香芹酮为有效成分的电热蚊香片加热1 h后,对淡色库蚊雌成蚊的KT50分别为13.70和17.90 min。【结论】香芹酮对淡色库蚊雌成蚊的熏杀活性优于薄荷醇,且不同异构体的活性存在显著差异,L-香芹酮具备被开发为植物源卫生害虫防控剂的潜力。     

Existence of Two Acetylcholinesterases in the Mosquito Culex pipiens (Diptera: Culicidae)

Abstract: Two acetylcholinesterases (AChEs), AChE1 and AChE2, differing in substrate specificity and in some aspects of inhibitor sensitivity, have been characterized in the mosquito Culex pipiens . The results of ultracentrifugation in sucrose gradients and nondenaturing gel electrophoresis of AChE activity peak fractions show that each AChE is present as two molecular forms: one amphiphilic dimer possessing a glycolipid anchor and one hydrophilic dimer that does not interact with nondenaturing detergents. Treatment by phosphatidylinositol-specific phospholipase C converts each type of amphiphilic dimer into the corresponding hydrophilic dimer. Molecular forms of AChE1 have a lower electrophoretic mobility than those of AChE2. However, amphiphilic dimers and hydrophilic dimers have similar sedimentation coefficients (5.5S and 6.5S, respectively). AChE1 and AChE2 dimers, amphiphilic or hydrophilic, resist dithiothreitol reduction under conditions that allow reduction of Drosophila AChE dimers. In the insecticide-susceptible strain S-LAB, AChE1 is inhibited by 5 × 10⁻⁴ M propoxur (a carbamate insecticide), whereas AChE2 is resistant. All animals are killed by this concentration of propoxur, indicating that only AChE1 fulfills the physiological function of neurotransmitter hydrolysis at synapses. In the insecticide-resistant strain, MSE, there is no mortality after exposure to 5 × 10⁻⁴ M propoxur: AChE2 sensitivity to propoxur is unchanged, whereas AChE1 is now resistant to 5 × 10⁻⁴ M propoxur. The possibility that AChE1 and AChE2 are products of tissue-specific posttranslational modifications of a single gene is discussed, but we suggest, based on recent results obtained at the molecular level in mosquitoes, that they are encoded by two different genes.     

一个致倦库蚊杀虫剂敏感品系的筛选

化学防治是控制蚊虫传播疾病的主要方法, 抗性监测表明我国蚊虫已对有机磷、 有机氯、 氨基甲酸酯和拟除虫菊酯类杀虫剂产生了不同程度的抗性。蚊虫抗药性的分子机制主要包括靶标抗性和三大解毒酶家族带来的代谢抗性。筛选对杀虫剂敏感的品系是抗性监测和抗性机理研究必不可少的材料。本研究通过从一个致倦库蚊Culex pipiens quinquefasciatus野生种群筛选无乙酰胆碱酯酶G119S突变且具有低活性羧酸酯酶、 P450单加氧酶和谷胱甘肽-S-转移酶的单雌系, 建立了一个对杀虫剂敏感的致倦库蚊品系。该品系的羧酸酯酶活性是敏感品系S-lab的2.5倍, P450单加氧酶和谷胱甘肽-S-转移酶的活性与S-lab相当。生物测定表明, 与S-lab相比, 该品系对有机磷杀虫剂有低于2倍的抗性, 对氨基甲酸酯和拟除虫菊酯类杀虫剂没有抗性, 可以作为相对敏感品系用于抗性监测。     

The distribution of the urban mosquitoes, Culex pipiens pipiens f. molestus (Diptera: Culicidae) in Petrozavodsk City

The distribution of the urban mosquitoes, Culex pipiens pipiens f. molestus in Petrozavodsk city was studied for the first time. Immature mosquito stages were found in 21 of 68 basements flooded with polluted waters, the occurrence of the mosquitoes varied in different districts of the sity. The mean siphonal index of the mosquito larvae from 6 underground populations varied from 3.8 up to 4.2, i. e. within the range typical for C. p. p. f. molestus.     

Molecular genetic methods for the identification of the urban mosquito Culex pipiens pipiens F. molestus (Diptera, Culicidae)

Molecular genetic methods for the identification of two ecotypes, or forms (pipiens and molestus) of the Culex pipiens pipiens mosquitoes, which are known as active bloodsuckers and vectors of various agents of diseases, are proposed. For the DNA analysis, two populations of the urban mosquitoes (the molestus ecotype) from St. Petersburg and Moscow and two populations from the overground reservoirs in the Leningrad Province and neighboring areas of Moscow (the pipiens ecotype) have been studied. These ecotypes differ by six transitions among 247 nucleotide sequences of 3' part of the cytochrome oxidase subunit I (COI) gene of mitochondrial DNA (mtDNA), by the mtDNA fragments resulted from the restriction analysis and by the lengths of second internal transcribed spacer (ITS2) sequences in the ribosomal DNA.     

Asymmetric introgression between sympatric molestus and pipiens forms of Culex pipiens (Diptera: Culicidae) in the Comporta region, Portugal

Background  

Culex pipiens L. is the most widespread mosquito vector in temperate regions. This species consists of two forms, denoted molestus and pipiens, that exhibit important behavioural and physiological differences. The evolutionary relationships and taxonomic status of these forms remain unclear. In northern European latitudes molestus and pipiens populations occupy different habitats (underground vs. aboveground), a separation that most likely promotes genetic isolation between forms. However, the same does not hold in southern Europe where both forms occur aboveground in sympatry. In these southern habitats, the extent of hybridisation and its impact on the extent of genetic divergence between forms under sympatric conditions has not been clarified. For this purpose, we have used phenotypic and genetic data to characterise Cx. pipiens collected aboveground in Portugal. Our aims were to determine levels of genetic differentiation and the degree of hybridisation between forms occurring in sympatry, and to relate these with both evolutionary and epidemiological tenets of this biological group.     

Effects of blood meal source on the reproduction of Culex pipiens quinquefasciatus (Diptera: Culicidae)

Culex pipiens quinquefasciatus were fed blood meals from a live chicken (LC), chicken blood in Alsever's (AC) solution, defibrinated bovine blood (DB), or bovine blood in citrate (CB) and incubated at 28° C. The effects of different blood meal sources were evaluated with respect to rates of blood feeding and reproduction (i.e., fecundity and fertility) over two gonotrophic cycles. Mosquitoes that fed on the first blood meal were subjected to a second blood meal as follows (first blood meal / second blood meal): LC/LC, LC/DB, DB/DB, CB/CB, AC/AC. Fecundity and fertility of Cx. p. quinquefasciatus were significantly (P < 0.05) greater in mosquitoes fed LC blood; however, fecundity and fertility in different treatment groups varied by gonotrophic cycle. These results contribute to our understanding of the impact of blood meal source on feeding and reproduction in Cx. p. quinquefasciatus. The potential impacts of blood meal source on virus transmission experiments are discussed.     

Population of the mosquitoes Culex pipiens molestus (Diptera: Culicidae) in dwellings of Lensk city

Culex pipiens molestus has been distributed in Siberia and the Russian Far East since 80s of XX century. In early 90s, C. p. molestus reached South Yakutia (Nerungri city), and nowadays it occurs in South-West Yakutia (Lensk city). The number of breeding places with larvae and pupae of mosquitoes was not numerous in Lensk; among 56 examined houses, the places with larvae and pupae mosquitoes were registered in seven houses, while the adult mosquitoes occurred in the majority of the houses. The occurrence of larvae varied from 12.5 to 33.3%, occurrence of adults-from 12.5 to 100%. The coefficient of variation of larvae in the samples was equal to 0.92, and adults had the following coefficients: 0.84 in the houses without basement; 0.92 in the houses with dry basements; 1.05 in the houses with pools in basements. This data are referred to the casual type, it means that the distribution of mosquitoes in space is dispersed. Imago spread actively in stone house of Lensk that provides mosquitoes with new places of breeding, and supports the stability of population in new areas.     

Monitoring of Insecticide Resistance in Field-Collected Populations of Culex pipiens pallens (Diptera: Culicidae)

A susceptible strain and six field populations of the northern house mosquito, Culex pipiens pallens Coquillett, were collected in Seoul, Paju, Daejeon, Heongseong, Jinhae, and Buan, and tested for their susceptibility to seven insecticides by topical application. In tests with female Cx. pipiens pallens, marked regional variations of insecticide susceptibility were observed. Five field-collected populations of Cx. pipiens pallens, except for the Seoul colony, exhibitedhightoveryhighlevelsofresistanceto cyfluthrin [resistance ratio (RR), 96–554] and deltamethrin (RR, 192–959). Low to moderate levels of resistance were observed in bendiocarb (RR, 14–46), chlorpyrifos [RR, 7–38; exceptions: Buan (RR, 63) and Jinhae (RR, 80) colonies], λ-cyhalothrin (RR, 5–23), S-bioallethrin (RR, 1–47), and permethrin [RR, 2–27; exception: Jinhae colony (RR, 247)]. These results indicate that careful selection and rotational use of these insecticides should result in continued satisfactory control against field populations of Cx. pipiens pallens.     

Chromosome-level genome assembly and characterization of Sophora Japonica

Sophora japonica is a medium-size deciduous tree belonging to Leguminosae family and famous for its high ecological, economic and medicinal value. Here, we reveal a draft genome of S. japonica, which was ∼511.49 Mb long (contig N50 size of 17.34 Mb) based on Illumina, Nanopore and Hi-C data. We reliably assembled 110 contigs into 14 chromosomes, representing 91.62% of the total genome, with an improved N50 size of 31.32 Mb based on Hi-C data. Further investigation identified 271.76 Mb (53.13%) of repetitive sequences and 31,000 protein-coding genes, of which 30,721 (99.1%) were functionally annotated. Phylogenetic analysis indicates that S. japonica separated from Arabidopsis thaliana and Glycine max ∼107.53 and 61.24 million years ago, respectively. We detected evidence of species-specific and common-legume whole-genome duplication events in S. japonica. We further found that multiple TF families (e.g. BBX and PAL) have expanded in S. japonica, which might have led to its enhanced tolerance to abiotic stress. In addition, S. japonica harbours more genes involved in the lignin and cellulose biosynthesis pathways than the other two species. Finally, population genomic analyses revealed no obvious differentiation among geographical groups and the effective population size continuously declined since 2 Ma. Our genomic data provide a powerful comparative framework to study the adaptation, evolution and active ingredients biosynthesis in S. japonica. More importantly, our high-quality S. japonica genome is important for elucidating the biosynthesis of its main bioactive components, and improving its production and/or processing.     

单宁酸对淡色库蚊抗氰戊菊酯品系和敏感品系幼虫生长发育的影响

单宁酸是一种植物次生代谢物, 为探索其用于蚊幼虫防治的可能性,在室内测定了其对淡色库蚊Culex pipiens pallens抗氰戊菊酯品系和敏感品系1～4龄幼虫的毒性,并观察了其对存活幼虫生长发育的影响。结果表明,淡色库蚊敏感品系幼虫对单宁酸的敏感性比抗氰戊菊酯品系的要高,1～4龄幼虫分别高6.4、4.9、4.7和2.0倍。4个龄期幼虫中,无论是敏感品系还是抗氰戊菊酯品系,均是1龄幼虫对单宁酸的敏感性最高,3龄幼虫最低。在1 000 mg/L单宁酸持续作用下,敏感品系和抗氰戊菊酯品系各龄幼虫的存活率,均随处理时间延长而降低。与对照相比,饲养在100 mg/L～500 mg/L单宁酸溶液中的存活幼虫发育历期延长,敏感品系和抗氰戊菊酯品系发育历期分别延长了34.5～38.3 h和59.2～93.4 h。其中,125 mg/L浓度处理的敏感品系1～4龄幼虫,其发育历期与对照的差异达到了显著水平(P<0.05);抗性品系则在250 mg/L作用下也达到了差异显著水平(P<0.05)。但100～250 mg/L单宁酸处理淡色库蚊抗氰戊菊酯品系和敏感品系1龄幼虫,对其存活幼虫的化蛹率、羽化率和成虫性比均无显著影响。表明单宁酸对淡色库蚊幼虫的影响主要是延迟其生长发育,且影响程度与蚊虫对氰戊菊酯的敏感性有关。     

Larvicidal potency of selected xerophytic plant extracts on Culex pipiens (Diptera: Culicidae)

Chemical insecticides released into the environment may have adverse biological effects. Therefore, there is a need for ecofriendly insecticides for mosquito control. Xerophytic plant extracts that may provide more ecofriendly active component were evaluated against Culex pipiens 4th instars. Plant extracts prepared using different solvents with a Soxhlet apparatus and different concentrations were tested against Culex pipiens larvae. The effects were observed at 24 h and 72 h intervals and LD₅₀ and LD₉₀ values determined. Chloroform (CHCl₃) and ethyl acetate (EtOAc) extracts of Althaea ludwigii were the most effective against Cx. pipiens 4^th instars, but were highly dependent on extract concentrations and exposure time. Results suggest that A. ludwigii extracts contain bioactive compounds, such as phenols and saponins, that may provide effective Cx. pipiens larval control. However, the extract was found to be toxic to zebrafish larvae, and may be toxic to other aquatic fauna. Further studies to determine the active components and toxicity to other fauna are needed.     

Differentiation between the urban mosquito Culex pipiens pipiens F. molestus and Culex torrentium (Diptera: Culicidae) by the molecular genetic methods

The molecular characters suitable for the differentiation between the autogenous form of Culex pipiens pipiens (the urban mosquito) and the species Culex torrentium, which was previously identified erroneously as an anautogenous form of C. pipiens pipiens (Shaikevich, Vinogradova, 2004), are given. These mosquitoes differ in the infection by the endosymbiotic bacteria Wolbachia pipientis, 6 transitions among 247 nucleotide sequences of 3' part of the cytochrome oxidase subunit I (COI) gene of mitochondrial DNA (mtDNA), in the mtDNA fragments resulted from the restriction analysis, and in the lengths of second internal transcribed spacer (ITS2) sequences in the ribosomal DNA.     

致倦库蚊对登革Ⅱ型病毒的中肠感染屏障作用

为探讨致倦库蚊对登革Ⅱ型病毒的中肠感染屏障作用,通过病毒分离、逆转录聚合酶链反应、透射电镜等技术进行了相关研究。结果表明：吸食感染性血液后,登革Ⅱ型病毒能侵染白纹伊蚊中肠上皮细胞并大量复制,但不能侵染致倦库蚊中肠上皮细胞。以上研究证明致倦库蚊对登革Ⅱ型病毒存在中肠感染屏障。