Seed pods of the carob tree Ceratonia siliqua are a favored sugar source for the mosquito Aedes albopictus in coastal Israel

The sugar feeding of Aedes albopictus was studied. In outdoor cages they fed avidly on carob (Ceratonia siliqua L., Caesalpiniaceae) seed pods soiled with sugary exudates. Feeding was either from the surface or by piercing the tissue which is indicated by the presence of plant tissue residues in the gut. More than 90% were sugar positive and about a third had plant tissue residues in the gut after overnight exposure. Similar exposure to clean undamaged seed pods resulted in about two thirds sugar positive mosquitoes and all of these had plant-tissue residues in the gut.In an irrigated, field site, with abundance of sugar sources in the summer 68% of the females and 75% of the males were sugar positive whereas, 1.2% of the females and no males had plant tissue in the gut. The proportion of sugar positive mosquitoes was similar in the autumn and plant tissue was not found in 150 females and 13 males. In the dry site in the summer 42% females and 33% males were sugar positive while 22% females and 33% males contained plant tissue. In the autumn 73% females and 80% males were sugar positive while 2% females and none of the males contained plant tissue.     

Geomapping generalized eigenvalue frequency distributions for predicting prolific Aedes albopictus and Culex quinquefasciatus habitats based on spatiotemporal field-sampled count data

Marked spatiotemporal variabilities in mosquito infection of arboviruses require adaptive strategies for determining optimal field-sampling timeframes, pool screening, and data analyses. In particular, the error distribution and aggregation patterns of adult arboviral mosquitoes can vary significantly by species, which can statistically bias analyses of spatiotemporal-sampled predictor variables generating misinterpretation of prolific habitat surveillance locations. Currently, there is a lack of reliable and consistent measures of risk exposure based on field-sampled georeferenced explanatory covariates which can compromise quantitative predictions generated from arboviral mosquito surveillance models for implementing larval control strategies targeting productive habitats. In this research we used spatial statistics and QuickBird visible and near-infra-red data for determining trapping sites that were related to Culex quinquefasciatus and Aedes albopictus species abundance and distribution in Birmingham, Alabama. Initially, a Land Use Land Cover (LULC) model was constructed from multiple spatiotemporal-sampled georeferenced predictors and the QuickBird data. A Poisson regression model with a non-homogenous, gamma-distributed mean then decomposed the data into positive and negative spatial filter eigenvectors. An autoregressive process in the error term then was used to derive the sample distribution of the Moran's I statistic for determining latent autocorrelation components in the model. Spatial filter algorithms established means, variances, distributional functions, and pairwise correlations for the predictor variables. In doing so, the eigenfunction spatial filter quantified the residual autocorrelation error in the mean response term of the model as a linear combination of various distinct Cx. quinquefasciatus and Ae. albopictus habitat map patterns. The analyses revealed 18–27% redundant information in the data. Prolific habitats of Cx. quinquefasciatus and Ae. albopictus can be accurately spatially targeted based on georeferenced field-sampled count data using QuickBird data, LULC explanatory covariates, robust negative binomial regression estimates and space–time eigenfunctions.     

Infection of adult Aedes aegypti and Ae. albopictus mosquitoes with the entomopathogenic fungus Metarhizium anisopliae

This study describes a laboratory investigation on the use of the insect-pathogenic fungus Metarhizium anisopliae against adult Aedes aegypti and Ae. albopictus mosquitoes. At a dosage of 1.6 x 10(10)conidia/m(2), applied on material that served as a mosquito resting site, an average of 87.1+/-2.65% of Ae. aegypti and 89.3+/-2.2% of Ae. albopictus became infected with the fungus. The life span of fungus-contaminated mosquitoes of both species was significantly reduced compared to uninfected mosquitoes. LT(50)-values of fungus-contaminated mosquitoes ranged between 3.1+/-0.2 days (male Ae. aegypti) and 4.1+/-0.3 days (female Ae. aegypti). LT(50)-values of uncontaminated mosquitoes ranged from 17.7+/-0.4 days (female Ae. albopictus) to 19.7+/-0.6 days (male Ae. albopictus). These results indicate that both mosquito species are highly susceptible to infection with this entomopathogen. Requirements for developing and incorporating this biological control method into current strategies to control major diseases vectored by these species, such as dengue fever, are discussed.     

Chikungunya Virus Replication in Salivary Glands of the Mosquito Aedes albopictus

Chikungunya virus (CHIKV) is an emerging arbovirus transmitted to humans by mosquitoes such as Aedes albopictus. To be transmitted, CHIKV must replicate in the mosquito midgut, then disseminate in the hemocele and infect the salivary glands before being released in saliva. We have developed a standardized protocol to visualize viral particles in the mosquito salivary glands using transmission electron microscopy. Here we provide direct evidence for CHIKV replication and storage in Ae. albopictus salivary glands.     

Molecular characterization of the invasive Asian tiger mosquito, Aedes (Stegomyia) albopictus (Diptera: Culicidae) in Corsica

The Asian tiger mosquito Aedes albopictus, vector of various human viruses and parasites, has recently spread and established in many temperate regions including European countries. In the present study, we developed a simple PCR-based assay (the amplification of the internal transcribed spacer ITS2 within nuclear ribosomal rDNA) for molecular identification of A. albopictus and confirmed its presence in Corsica island. This assay may (i) facilitate future large scale studies and avoid misidentifications, especially because of the presence of co-occurring close species in this island and (ii) contribute to the monitoring of A. albopictus populations required for targeted control programs.     

Insecticide resistance status of Aedes aegypti in 10 localities in Colombia

Insecticide resistance is one of the major threats to the effectiveness of vector control programs. In order to establish a baseline susceptibility profile of Aedes aegypti in the southwest of Colombia, 10 localities in four Departments (States) were evaluated. Standardized WHO bioassay, CDC bottle bioassay and microplate biochemical assays of non-specific β-esterase (NSE), mixed function oxidases (MFO) and acetylcholinesterase were used. Cross resistance was evaluated with field collected mosquitoes that underwent selection pressure in the laboratory from DDT, propoxur and lambdacyhalothrin during three alternate generations. Mosquitoes with mortality rates below 80% in bioassays were considered resistant. Insecticide resistance varied geographically. Insecticide resistance was observed in 100% of localities in which mosquitoes were exposed to DDT, bendiocarb and temephos using both assays. WHO bioassays showed susceptibility to pyrethroids in all the localities evaluated, however CDC bottle bioassays showed decreases in susceptibility especially with lambdacyhalothrin. All localities showed susceptibility to the organophosphate malathion. Mosquitoes from eight regions with evidence of resistance to any of the insecticide evaluated were also evaluated biochemically. Mosquitoes from five of these regions had increased levels of NSE and two regions had increased levels of MFO. Increase levels of NSE explain partially the low susceptibility to temephos found in all the localities. However, the biochemical mechanisms evaluated do not explain all the resistance observed. Cross resistance was observed between the DDT-selected strain and lambdacyhalothrin, and between the lambdacyhalothrin-selected strain and propoxur and vice versa. The selected strains do not show changes in the biochemical assays evaluated, therefore the observed cross-resistance suggests different biochemical mechanisms. This study shows that Ae. aegypti from Colombia can develop resistance to most of the insecticide classes in the market. Periodic surveillance of insecticide resistance is necessary in order to maintain effective interventions. This study helped to establish the National Network for the surveillance of the insecticide resistance in Colombia.     

Effects of culture medium and formulation on the larvicidal activity of the mosquito pathogen Lagenidium giganteum (Oomycetes: Lagenidiales) against Aedes aegypti

In this work, we examined the production of infective zoospores of Lagenidium giganteum in four culture media, and the larvicidal activity of the cultures was determined against Aedes aegypti larvae, as well as the effect of polymer encapsulation. Medium containing sunflower seed extract showed the greatest production of zoospores, 5.92 × 10⁶ zoospores/ml after six days of fermentation at 25 ± 2 °C and 150 rpm shaking. This culture tested against A. aegypti 1st stage larvae caused different mortality rates at 24, 48 and 72 h posttreatment. The LC₅₀ obtained was 43.9, 41.1 and 42.9 μl of total culture/ml, at 24, 48 and 72 h posttreatment respectively, while the culture grown in medium with soybean meal showed 3–5 times higher LC₅₀ values. Finally, the total culture including mycelium, zoospores and presporangia formulated with 2.5% pectin showed significantly higher mortality rates, around 100% more than the unformulated culture, whose values were from 40 to 1% at 3, 6, 9, and 12 d posttreatment in the bioassays carried out in the laboratory to determine residual activity.     

中山市白纹伊蚊现场种群击倒抗性基因检测分析

目的 检测广东省中山市不同生境白纹伊蚊现场种群的击倒抗性(kdr)基因突变,了解其抗药性水平,探讨kdr基因突变与性别间抗药性差异的关系,为蚊虫的抗性机制研究以及科学防制提供依据.方法 2019年8-11月在中山市选择5个生境采集白纹伊蚊幼虫和蛹569只,实验室饲养至成虫,提取单只成蚊基因组DNA,扩增并测序分析kdr...     

五株白纹伊蚊对溴氰菊酯抗性生物测定和生化检测的研究

目的检测采自野外株和实验室驯化株白纹伊蚊对溴氰菊酯的抗性水平,探讨实验室抗性株(R-lab)的抗性机理。方法以采自深圳、广州龙洞和东莞庄的三株白纹伊蚊(SZ,LD和DW)和两株实验室驯化白纹伊蚊(S-lab和R-lab)为研究对象,采用WHO推荐的幼虫浸渍法分别测定它们的抗药性水平,并采用PBO增效实验和生化检测方法测定R-lab株代谢酶活性。结果与S-lab株相比,R-lab株抗性倍数最高(RR50:480),而采自野外的三株抗性倍数较低(LD:6.6;DW:8.5;SZ:2.0)。对R-lab株活体增效实验和离体解毒酶实验结果表明PBO增效作用显著,增效倍数为120倍,GST酶活性上升1.29倍,EST酶活性没有改变。结论R-lab株和野外的三个种群对溴氰菊酯均有一定的抗性水平,以R-lab株抗性水平最高;代谢抗性是R-lab株抗药性形成的主要机理之一,其中细胞色素P450单加氧酶活性升高占据主导地位。     

Effects of different temperature regimens on the development of Aedes aegypti (L.) (Diptera: Culicidae) mosquitoes

This study was conducted to determine the effects of increased water temperatures on the development of Aedes aegypti immatures under laboratory conditions in Trinidad, West Indies using temperature regulated water baths to cover a range of temperatures from 24–25 °C to 34–35 °C at a relative humidity of 80%. Two experiments were designed: (1) at constant temperature regimens and (2) under diurnal temperature regimens ranging from 24–25 °C to 34–35 °C. At 24–25 °C egg hatching success was 98% at 48 h, however at 34–35 °C egg hatching rates declined to 1.6% after 48 h. Ae. aegypti larvae reared under constant temperature regimens showed pupation on day 4 with highest pupation occurring at 30 °C (78.4%) However, under diurnal temperature regimens, pupation began on day 4 but only at the higher temperatures of 30–35 °C. Under diurnal temperature regimens ranging from 24 °C to 35 °C significantly more females emerged at higher temperatures, than males. In contrast, at constant temperatures of 24–35 °C no significant difference in M/F ratios were observed. The body size of Ae. aegypti reared at constant temperature regimens was significantly larger than males and females larvae reared under diurnal temperature regimens of 25–30 °C. The results of this study are discussed in the context of changing or increasing water temperatures, seasonal changes in vector populations and vector competence. Using these key factors control strategies are recommended to manage vector populations as expected increases in temperatures impact the Caribbean region.     

南昌市登革热传播媒介白纹伊蚊密度、抗药性及病原体携带监测研究

目的 掌握南昌地区白纹伊蚊密度、季节消长规律、登革热病毒携带以及对常用杀虫剂的抗药性程度,为合理选择和使用杀虫剂,科学防控登革热提供科学依据。方法 采用WHO推荐的幼虫浸渍法和成蚊接触筒法分别测定白纹伊蚊幼虫和成蚊的抗药性;密度监测:成蚊采用双层叠帐法,幼虫分别采用布雷图指数法(BI)、勺舀法和路径指数法;白纹伊蚊登革热病毒携带检测采用RT-PCR核酸检测。结果 2018年南昌地区白纹伊蚊成蚊呈单峰活动趋势,活动最高峰为6月份,全年平均帐诱指数为2.76只/(顶·h),平均布雷图指数(BI)为6.18,平均路径指数为4.67处/km,居民区帐诱指数、BI和路径指数远高于工地和公园生境。白纹伊蚊成蚊对溴氰菊酯和高效氯氰菊酯产生抗性,对马拉硫磷、氯菊酯、杀螟硫磷和残杀威表现敏感;白纹伊蚊幼虫除对溴氰菊酯表现为敏感外,对DDVP等其他6种杀虫剂分别表现出不同的抗性,抗性倍数处于9.09~76.19之间。南昌地区野外品系白纹伊蚊未检测到登革热病毒。结论 一旦有登革热病例的输入,南昌地区存在登革热传播风险, 应停用已产生高度抗药性的氯氰菊酯、残杀威等杀虫剂,重点清除居民区生境内白纹伊蚊孳生地,及时根据监测结果评估登革热发生或流行的风险,可为南昌地区登革热疫情的预测预警提供科学依据。     

Human glutathione S-transferase A1, T1, M1, and P1 polymorphisms and susceptibility to prostate cancer in the Japanese population

Purpose: The incidence of prostate cancer is increasing in low-risk populations such as Japanese. One of the causes of this increase is considered to be associated with the Western diet, especially the high intake of red meat and fat. Glutathione S-transferase (GST) A1, T1, M1, and P1 are phase II enzymes that are important for activation and detoxification of chemical carcinogens.Methods: In this study, 190 Japanese male patients with prostate cancer and 294 healthy controls, frequency-matched for age, were compared for frequencies of GSTA1, GSTT1, GSTM1, and GSTP1 genotypes.Results: Among smokers, the frequency of the GSTA1*A/*B or *B/*B genotype in patients with prostate cancer (27.8%) showed a statistically significant increase compared with the control group frequency (18.2%; odds ratio [OR] =1.72; 95% CI, 1.01–2.94). In addition, the frequency of GSTT1 nondeletion genotype was associated with prostate cancer among smokers (OR =1.68; 95% CI, 1.06–2.68). The OR of carrying the combined genotyping of GSTA1*A/*B or *B/*B and GSTT1 nondeletion was 2.08 (95% CI, 1.14–3.80) with the combined genotyping of GSTA1*A/*A and GSTT1 null as a reference. On the other hand, no significant associations were observed for genotypes of GSTM1 and GSTP1 I105V.Conclusions: These findings suggest that the GSTA1 and GSTT1 polymorphisms are associated with prostate cancer susceptibility, especially among smokers.     

Development and application of a simple colorimetric assay reveals widespread distribution of sodium channel mutations in Thai populations of Aedes aegypti

Dengue fever and its more serious complications dengue haemorrhagic fever and dengue shock syndrome are growing public health problems in tropical and subtropical countries. In the absence of a vaccine, most dengue control programmes rely heavily on the use of insecticides to target the Aedes mosquito vectors. As a limited number of insecticides are routinely used in control, monitoring for the presence of resistance is an essential component of dengue prevention programmes. The pyrethroid insecticides target the voltage-gated sodium channel on the insects’ neurons. Substitutions at residue 1016 of this protein have been associated with pyrethroid and DDT resistance in Aedes aegypti populations from Latin America and Asia. Here we report on the development of a simple colorimetric assay to detect these mutations in individual mosquitoes. Evaluation of this diagnostic assay on 180 Ae. aegypti individuals from Thailand revealed the presence of high frequencies of the Val1016Gly mutation throughout the country. The assay requires no specialised equipment and will enable monitoring for insecticide resistance associated alleles to be routinely incorporated into dengue surveillance operations.     

Canine Leishmania infantum enzymatic polymorphism: a review including 1023 strains of the Mediterranean area, with special reference to Algeria

This bibliographic review reports the isoenzyme polymorphism of 1023 Leishmania infantum strains isolated from dogs that have been characterized by multilocus enzyme electrophoresis in the Leishmania Reference Centre of Montpellier, or in other laboratories, to which this typification technique has already been transferred. Between 1981 and 2010, a total of 12 zymodemes were identified around the Mediterranean basin: MON-1, MON-24, MON-34, MON-72, MON-77, MON-80, MON-98, MON-105, MON-108, MON-199, MON-199 var NP1130 and MON-281, of which 6 were present in Algeria. The zymodeme MON-1 was predominant (86.5% of the strains). The dog was confirmed as the main reservoir of L. infantum MON-1, while the reservoir of the other zymodemes has not yet been identified. The enzymatic polymorphism is relatively high in Algeria and in Spain in contrast to other Mediterranean countries. The reasons for this polymorphism are discussed.     

Laboratory and field evaluation of Teknar HP-D, a biolarvicidal formulation of Bacillus thuringiensis ssp. israelensis, against mosquito vectors

Larvicidal efficacy of Teknar HP-D, an improved biolarvicidal formulation of Bacillus thuringiensis ssp. israelensis (Bti), against Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti was determined in the laboratory, and in field the efficacy of the formulation was tested against Cx. quinquefasciatus breeding in cesspits, unused wells and drains. The toxicity of the formulation to Gambusia affinis (larvivorous fish), Notonecta sp. and Diplonychus indicus (water bugs) was also evaluated in the laboratory. Teknar HP-D was field tested at three recommended dosages, 1, 1.5 and 2l/ha, selecting five habitats for each dosage. Another five habitats were kept untreated as controls. Ae. aegypti showed greatest susceptibility to the Bti toxin in the laboratory. In cesspits, all the three dosages caused >80% reduction of pupal recruitment up to day 6 post-treatment, indicating that a weekly application at the lowest would be necessary for sustained control. The residual activity of the formulation was longer in unused wells, causing >80% reduction of pupal recruitment for 17 days from the day of treatment. In controlling pupal recruitment the three dosages produced equal effect. Application of Teknar HP-D at 1 l/ha once in three weeks is therefore recommended to control Cx. quinquefasciatus in unused wells. However, in drains, >80% reduction of pupal recruitment was observed for only 3 days and hence, application of Teknar HP-D at 2 l/ha that caused significantly higher level of reduction twice in a week at 3-day interval is necessary. At dosages from 0.032 to 3.2 mg/l (ppm), Teknar HP-D was non-toxic to Gambusia fish. The two predatory water bugs, Notonecta sp. and Diplonychus indicus that fed on the surviving larvae of Cx. quinquefasciatus exposed to the sub-lethal doses (LC(50) and LC(80)) of Teknar HP-D were safe with out having any mortality.     

Detailed assessment of microhabitat suitability for Aedes aegypti (Diptera: Culicidae) in Buenos Aires, Argentina

Little information is available on the ecology of Aedes aegypti Linnaeus at the southern extreme of its distribution (Buenos Aires, Argentina), particularly on microhabitat suitability. The aim of our study was to identify at a detailed scale, microhabitat factors that correlate with the presence of preimaginal stages of the mosquito. In March 2001, we performed a spatial census of all containers located in a 1 ha patch within a cemetery in Buenos Aires City. On a reference map (1:700) we plotted the position of graves and surrounding corridors, the location of containers, the shade projected by each plant between 10:00 and 16:00 h and vegetation cover. We classified vegetation by height, substrate by composition and shadow by level of exposure to sunlight. We performed univariate and multivariate logistic regression analyses with nine constructed independent variables, some of them at scales of 0.5, 1, 2, 3, and 10 m. Of 850 receptacles examined, 101 contained preimaginal stages of Ae. aegypti. Level of exposure to sunlight, type of substratum, vegetation height and distance of containers to vegetation were significantly associated with the presence of breeding sites at the studied scales. Final multivariate models were significant at scales of 2 m (chi(3)2=25.693, p<0.001) and 3m (chi(3)2=26.440, p<0.001), and 65.9 and 66.8% of our data were correctly classified, respectively, for each scale. Our results suggest that sites less exposed to sunlight, with taller and closer vegetation, and in shaded and vegetated neighbourhoods were the most favourable microhabitats for Ae. aegypti breeding.     

Surveillance of dengue fever cases using a novel Aedes aegypti population sampling method in Trinidad, West Indies: the cardinal points approach

A novel dengue surveillance method is described and used to evaluate 100 suspected dengue fever (DF) cases in county St. Patrick, Trinidad, West Indies. From the 30 confirmed DF cases fully investigated within 48 h of diagnosis, 63% (19/30 houses) of their homes were found harboring Aedes aegypti immature stages. Only houses at the four cardinal points of the index case rather than the entire neighborhood were investigated. The results showed significantly (P<0.001) more Ae. aegypti positive houses were observed to the east (P<0.04) and west (P<0.01) than to the north and south (P>0.9). In addition, from the 150 houses inspected a total of 474 artificial containers were inspected and treated, of which 20.8% (99) were infested with Ae. aegypti immature stages. More than 49% of the containers inspected were small miscellaneous containers, but they only produced 4.0% of the Ae. aegypti immatures, of which only 0.4% were pupae. Water tanks (41.7%), drums (40.4%) and buckets (24.2%) produced over 98% of the pupae. The results of this study imply that dengue vector control programs in Trinidad could increase their efficiency by applying the cardinal points surveillance approach during DF case investigations and concentrating their vector control measures on the most productive containers located at the east and west of the index cases.