旱芹籽粗提取物对埃及伊蚊的效果评定

埃及伊蚊(Aedes aegypti)是众所周知的虫媒病毒性疾病--登革热的传播媒介,分布于东南亚、太平洋岛屿、非洲和美洲.它也是中美、南美和西非传播黄热病的媒介.登革热因报告的病例数逐年上升,尤其是因该病有多种类型--登革出血热、登革休克综合症和其他诸如侵犯中枢神经系统等少见类型,已成为当今社会严重的公共卫生问题.据2003年世界卫生组织的报告,全球受到登革热威胁的人口约占全球人口总数的40%.目前,减少该病发生的最有效措施是加强个人防护和控制埃及伊蚊.     

Oviposition preferences of Culex restuans and Culex pipiens (Diptera: Culicidae) for selected infusions in oviposition traps and gravid traps

Field studies were conducted in southwestern Virginia to determine the ovipositional preferences of Culex restuans and Culex pipiens by using ovitraps and gravid traps baited with selected infusions. For the ovitrap collections, 4 different infusions (manure, hay, grass, and rabbit chow) were used. Significant differences among infusions were detected on most sample dates for both species. For 3 of the first 4 wk of collections, the manure infusion collected significantly more Cx. restuans than all the other infusions. The hay and grass infusions collected the majority of the egg rafts during weeks 5-9. Cx. pipiens egg rafts were absent from the first 3 wk of collections. Of the remaining 6 wk, 4 showed significant differences in attractiveness of infusions, with the hay and grass infusions preferred by Cx. pipiens. Two infusions, manure and hay, were used for the gravid trap experiment and both Cx. restuans and Cx. pipiens data were combined for analysis. Only the first 2 wk showed significance, with manure being preferred over hay in both weeks. In later collections, the relative attractiveness of the hay infusion increased. A seasonal shift in infusion preference may be related to incubation temperature during preparation of the infusions. New infusions were prepared each week and incubation was done outside. Increased attractiveness of the hay infusion coincided with higher average temperatures in July and August. Hay infusion was very effective for trapping both Cx. pipiens and Cx. restuans in southwestern Virginia and is more convenient to use than manure. However, cool outside temperatures in the early season may interfere with the fermentation process and thus incubation should be done for a longer time or brought indoors.     

孑孓的龄期对武昌罗索线虫感染率的影响

在同一温度条件上，武昌罗索线虫寄生前期幼虫对致乏库蚊不同龄期幼虫的感染率均不相同。笔者分别对致乏库蚁Ⅰ、Ⅱ、Ⅲ、Ⅳ龄孑孓及蛹在２６±１℃条件下进行４８ｈ感染实验，感染率分别是５８．５％，７８％、６３．５％和１３．５％，以Ⅱ龄孑孓感染率最高，而蛹几乎不被感染。孑孓的龄期对寄生后期幼线虫雌、雄性比无明显规律性影响。     

Efficacy of encapsulated Lagenidium giganteum (Oomycetes: Lagenidiales) against Culex quinquefasciatus and Aedes aegypti larvae in artificial containers

Presporangial mycelia of Lagenidium giganteum cultured on sunflower seed extract were encapsulated in calcium alginate and added once (July 18) to outdoor (Raleigh, NC) caged tires, wood and concrete containers populated with first instars of Culex quinquefasciatus or Aedes aegypti. First instars were added twice weekly (for 10 wk) to simulate natural oviposition. The fungus persisted for 10 wk and recycled in the mosquito larvae of both species. The overall reductions of Cx. quinquefasciatus and Ae. aegypti immatures were higher in tires (55 and 45%, respectively) and wood (67 and 38%) than in concrete containers (17 and 14%). There were low correlations of the numbers of mosquito immatures with measurements of water quality (chemical oxygen demand, ammonia nitrogen and conductivity) in the containers.     

Gonotrophic cycle and survivorship of Culex quinquefasciatus (Diptera: Culicidae) using sticky ovitraps in Monterrey, northeastern Mexico

Mark-release-recapture experiments were conducted to determine the length of the gonotrophic cycle and rate of survivorship of Culex quinquefasciatus Say in Monterrey, northeastern Mexico. A total of 2,352 field-caught Cx. quinquefasciatus females were marked and released at 8-12 h postemergence in 2 field trials. Sticky ovitraps were used to recapture marked gravid females. One hundred and ten (4.6%) marked females were recaptured during a 12-day sampling period. Recapture rates for the 2 individual trials were 6.4% and 3.5%. The length of the gonotrophic cycle, calculated as the average time between the initial blood meal and the time of recapture of gravid females, was 2-3 days. The first blood-fed mosquitoes were recaptured on the 2nd day postrelease. Gravid egg-laying females were most commonly recaptured at 2-3 days postfeeding. Daily survival estimates for the 2 release dates were of 0.871 and 0.883, respectively.     

Response of Aedes aegypti (Diptera: Culicidae) larvae to three xenobiotic exposures: larval tolerance and detoxifying enzyme activities

The ability of mosquito larvae to tolerate toxic compounds (temephos, Bacillus thuringiensis var. israelensis, toxic vegetable leaf litter) was examined on a laboratory larval strain of Aedes aegypti L. Bioassays and detoxifying enzyme activity measurements were performed to compare tolerance/resistance capacities. The possibility of a functional plasticity of detoxifying equipment was investigated through experimental determination of the inductive effect of each xenobiotic within a given generation. In the same way, the selective effect of a toxic leaf litter was also investigated along successive generations. Results revealed that differential cytochrome P450 monooxygenase, esterase, and glutathione S-transferase activity levels correlated with the bioassay results. Both induction and selection increased larval tolerance to the xenobiotics used and increased the levels of larval detoxifying enzyme activities.     

茴香醛对蚊虫嗅觉行为的影响研究

目的 探讨茴香醛对蚊虫嗅觉行为的影响.方法 在风洞系统内测试茴香醛不同剂量诱导的白纹伊蚊行为反应及对宿主定向行为的影响;在密闭空间中,分别以0.013～0.250 μg/cm3剂量的茴香醛处理白纹伊蚊24～96 h后测定其感受、定向寄主的能力.结果 在风洞系统内,茴香醛单一化合物其剂量3.1％～99.0％对白纹伊蚊均有一定的引诱作用,而与宿主气味并存时,只有高剂量(99.0％)对宿主定向行为有较高的抑制率(85.4％).白纹伊蚊在0.050～0.250 μg/cm3剂量茴香醛气味空间处理24～96 h后对其正常感受宿主气味的能力有显著的抑制作用,随处理时间延长、剂量升高抑制效果增强,但低于此剂量则没有抑制作用.结论 茴香醛单一化合物对蚊虫具有引诱性,但与宿主气味并存时,对蚊虫正常感受宿主气味的能力具有一定的抑制作用.     

In vitro transmission of Wuchereria bancrofti L3-stage larvae by experimentally infected Culex pipiens L. (Diptera : Culicidae)

Females of Culex pipiens L. experimentally infected with Wuchereria bancrofti were tested for in vitro transmission of infective stage L3 larvae using a capillary tube technique. Of the females harbouring L3 larvae, 60.7% (34/56) transmitted a geometric mean of 2.84 L3 larvae (range 1-35). Transmitting Cx. pipiens contained significantly more L3 larvae than non-transmitters. Both the probability of transmission and the number of L3 larvae transmitted were related to the total number of loads larvae/mosquito. Almost all females with L3 loads > or = 10 transmitted larvae in vitro. The possibility is discussed that the detection of L3 larvae in field collected mosquitoes by dissection may overestimate the proportion capable of parasite transmission and the proportion of L3 larvae deposited on host skin by Ca. 40%.     

Peroral susceptibility of Aedes albifasciatus and Culex pipiens complex mosquitoes (Diptera: Culicidae) from Argentina to western equine encephalitis virus

The transmission cycle of western equine encephalitis (WEE) virus in South America is unknown. A WEE virus strain was isolated from Aedes albifasciatus in Argentina during the WEE epizootic of 1982-83. Also, Culex pipiens from Argentina was reported to be able to transmit WEE virus experimentally, but other results indicate that Cx. pipiens from the USA is refractory to this virus. We determined the susceptibility of Argentina strains of Ae. albifasciatus and Culex pipiens complex mosquitos to infection by WEE virus by the oral route. Adult females were fed on chicks infected with a WEE virus strain isolated in Cordoba Province, Argentina, or were fed on a blood/virus suspension. Each mosquito ingested between 10(1.6) to 10(6.4) vero cell plaque-forming units of virus. Each of 28 Ae. albifasciatus was positive for virus from the fourth day postfeeding, and there was evidence for virus replication. In contrast, 0/44 Cx. p. quinquefasciatus and only 1/15 Cx. p. pipiens was positive. Aedes albifasciatus is susceptible to infection by WEE virus and should be considered a potential vector of this virus in Argentina. Both subspecies of Cx. pipiens are refractory to peroral infection by WEE virus and probably do not play a role in the WEE virus cycle in Argentina.     

Susceptibility and Resistance of Field Populations of Anopheles sinensis (Diptera: Culicidae) Collected from Paju to 13 Insecticides

ObjectivesOver 20% of all malaria cases reported annually in the Republic of Korea (ROK) occur in Paju, Gyeonggi Province. Vector control for malaria management is essential, but the insecticide resistance of the vector, Anopheles mosquitoes, has been a major obstacle in implementing effective control. In this study, the insecticide resistance of the vector mosquitoes was evaluated and compared with that of vector mosquitoes collected from the same locality in 2001 and 2009.MethodsThe insecticide resistance of Anopheles sinensis s.s. collected from Paju, Gyeonggi Province in the ROK was evaluated under laboratory conditions with a micro-application method using 13 insecticides currently used by local public health centers and pest control operators in the ROK.ResultsBased on median lethal dose (LC₅₀) values, An. sinensis s.s. were most susceptible to the insecticides bifenthrin, cyfluthrin, and etofenprox in that order, and least susceptible to permethrin. An. sinensis showed higher susceptibility to pyrethroids than organophosphates, except for fenthion and permethrin. In a comparative resistance test, the resistance ratios (RRs) of An. sinensis collected in 2012 (AS12) to the 13 insecticides were compared to the RRs of two strains of An. sinensis collected from the same locality in 2001 (AS01) and 2008 (AS08). With some exceptions, AS12 demonstrated higher resistance to all tested insecticides compared to AS01 and AS08, and less resistance to bifenthrin, cyfluthrin, and cypermethrin compared to AS01.ConclusionThese results indicate that careful selection and rotation of these insecticides may result in continued satisfactory control of field populations of An. sinensis s.s. for effective malaria management in Paju.     

Wing geometry and genetic analyses reveal contrasting spatial structures between male and female Aedes aegypti (L.) (Diptera: Culicidae) populations in metropolitan Manila,Philippines

The population genetic structure of Aedes aegypti (Linnaeus, 1762) has been studied in order to understand its role as an efficient vector. Several studies utilized an integrative approach; to combine genetic and phenotypic data to determine its population structure but these studies have only focused on female populations. To address this particular gap, our study compared the population variability and structuring between its male and female populations using phenotypic and genetic data from a highly-urbanized and dengue-endemic region of the Philippines, Metropolitan Manila. Five mosquito populations comprised of female (n = 137) and male (n = 49) adult mosquitoes were used in this study. All mosquito individuals underwent geometric morphometric (26 landmarks), and genetic (11 microsatellite loci) analyses. Results revealed that F_ST estimates (genetic) were 0.055 and 0.009 while Q_ST estimates (phenotypic) were 0.318 and 0.309 in in male and female populations, respectively. Wing shape variation plots showed that male populations were distinctly separated from each other while female populations overlapped. Similarly, discriminant analysis of principal components using genetic data revealed that male populations were also distinctly separated from each other while female populations showed near-overlapping populations. Genetic and phenetic dendrograms showed the formation of two groups in male populations but no groups in female populations. Further analysis indicated a significant correlation (r = 0.68, p = 0.02) between the genetic and phenetic distances of male populations. Bayesian analysis using genetic data also detected multiple clusters in male (K = 3) and female (K = 2) populations, while no clusters were detected using the phenotypic data from both sexes. Our results revealed contrasting phenotypic and genetic patterns between male and female Ae. aegypti, indicating that male populations were more spatially structured than female populations.     

Detection of dengue viruses in field-caught Aedes aegypti (Diptera: Culicidae) in Maracay, Aragua state, Venezuela by type-specific polymerase chain reaction.

Virological surveillance of dengue viruses in Aedes aegypti populations constitutes a powerful tool for early prediction of dengue outbreaks. We have standardized a protocol for viral RNA extraction from individual and pools of mosquitoes that permits a sensitive detection of dengue virus without RNA degradation or PCR inhibition when we apply a semi-nested RT-PCR. The limit of detection for each dengue serotype was 0.1 PFU. In a prospective field study conducted from November 2000 to December 2001, adult female A. aegypti mosquitoes from several municipalities with high dengue transmission in Maracay, Aragua State, Venezuela were collected and screened for dengue viruses using RT-PCR. We analyzed a total of 296 A. aegypti pools (1,632 mosquitoes); of these, 154 pools (469 mosquitoes) were collected from houses with persons with clinical diagnosis of dengue (dengue houses), and 142 pools (1,163 mosquitoes) from adjacent residences (neighbour houses). From the dengue houses, eight mosquito pools (5.2%) were positive for DENV-1 (0.7%), DENV-3 (3.2%) and DENV-4 (1.3%) viruses. From the neighbour houses, 18 mosquito pools (12.7%) were positive for DENV-3 (12%) and DENV-4 (0.7%) viruses. From these 26 RT-PCR positive mosquito pools (containing 1-25 mosquitoes each), 22 pools (84.6%) were positive for DENV-3. The most prevalent serotype in the 2001 dengue outbreak was also DENV-3. The minimum infection rate in both A. aegypti collections, from dengue houses and neighbour houses was 17 and 15 per 1,000, respectively. The relevance of these results for dengue surveillance is discussed.     

Variation in tarsal claw morphology and the identification of Aedes (Stegomyia) demeilloni/segermanae and Aedes (Stegomyia) simpsoni/bromeliae (Diptera: Culicidae) in South Africa.

Individuals in families of Aedes (Stegomyia) mosquitoes reared from females collected at Kloof, KwaZulu-Natal, were identified as Aedes demeilloni or Aedes segermanae or were indeterminate because tarsal claw morphology, the distinguishing character, varied. Similarly, Aedes (Stegomyia) simpsoni and Aedes (Stegomyia) bromeliae reared from ovitraps exposed at Ndumu, northern KwaZulu-Natal, showed variation in tarsal claw morphology. Variation existed between tarsal claws on individual specimens, which made identification difficult at Ndumu, indicating that tarsal claws may not be taxonomically significant.     

保幼激素与光照对三带喙库蚊滞育发生与解除作用的研究

本文报告了经保幼激素（ＪＨＩ）处理对三带喙库蚊滞育发生与解除的影响。结果表明，用保幼激素吸入或点滴处理新羽化成蚊，对短光照诱导其发生滞育具有一定的抑制作用，而滞育蚊经吸入或点滴一定量的ＪＨＩ后，可以解除其滞育，解除率与用量有关。此外，ＪＨＩ处理滞育蚊亦可提高其吸血率。     

淡色库蚊越冬过程中体重、含水量及脂、蛋白质、碳水化合物含量的动态变化

郑州地区淡色库蚊越冬过程中,10～12月份单个蚊虫体重显著增加,以后逐渐下降。体液系数在11～1月份显著降低,以后明显升高。单个蚊虫及血淋巴内脂、蛋白及碳水化合物的动态变化,揭示了越冬过程中蚊虫体内代谢物质的蓄积与消耗过程。花蜜糖定性试验提示,越冬前期(9～10月份)蚊虫摄取大鼠植物糖类。本文结合蚊虫越冬的生理生态学,对上述指标的动态变化进行了分析讨论。     

The isolation of Leishmania tropica and L. aethiopica from Phlebotomus (Paraphlebotomus) species (Diptera: Psychodidae) in the Awash Valley, northeastern Ethiopia

In a survey of Leishmania infections in phlebotomine sandflies in a highly suspected focus of leishmaniasis in the Awash Valley (northeastern Ethiopia) between January 1994 and August 1997, a total of 3307 females of 11 Phlebotomus species (P. orientalis, P. fantalensis, P. saevus, P. sergenti, P. gemetchi, P. alexandri, P. bergeroti, P. duboscqi, P. arabicus, P. martini, and P. rodhaini) were dissected. Promastigotes were detected in 17 females of three species (11 P. saevus, 4 P. sergenti and 2 P. arabicus). Of these, only two P. saevus (one from Upper Awash and one from Middle Awash) and three P. sergenti (from Upper Awash) positives were successfully isolated in culture and were typed by isoenzyme analysis. Four isolates (two each from P. saevus and P. sergenti) were identified as new zymodemes (Z) of L. tropica and one isolate from P. sergenti was typed as a new zymodeme of L. aethiopica. This is the first finding of natural infections of P. saevus and P. arabicus and the first evidence for the former to be a vector of L. tropica. This is also the first time P. sergenti has been implicated in L. tropica transmission in Ethiopia; the isolation of L. aethiopica from a Paraphlebotomus species (P. sergenti) is also a new record. The possible presence of human cutaneous leishmaniasis (L. tropica and L. aethiopica), and wild reservoir host(s) of the parasites, especially rock hyrax (Procavia capensis) in the Upper and Middle Awash Valley remain to be determined.