Seasonal and spatial ovipositional activity of Aedes albopictus (Skuse, 1894) was investigated in Split, South Croatia. During 2009 and 2010, 35 oviposition traps were used in this research. For studying oviposition behavior, mean egg density and Lloyd's mean crowding were used to define the dispersion of eggs into ovitraps and, together with Taylor's power law, to show aggregation degree. To show monthly distribution of egg density, Kriging interpolation was used. Oviposition activity started in April (week 13) and was completed at the beginning December (week 48). Mean egg density reaches the highest values from June to early September (week 25–35). Slope of regressions (mean crowding on mean density and log variance and log mean density) indicated a clumped distribution of eggs. Sampling sites were divided in four groups based on quartiles of median and maximum of mean density. There was no significant difference in measured abiotic factors (temperature, humidity, and rainfall) and measured mean egg density, total amount of eggs, and percentage of positive ovitraps between investigated years, except in mean egg density in some localities.

Laboratory studies have shown clear relationships between relative humidity (RH) and the activity and survival of Ixodes scapularis Say (blacklegged tick). However, field studies have produced conflicting results. We examined this relationship using weekly tick count totals and hourly RH observations at three field sites, stratified by latitude, within the state of Rhode Island. Records of nymphal tick abundance were compared with several RH-related variables (e.g., RH at time of sampling and mean weekly daytime RH). In total, 825 nymphs were sampled in 2009, a year of greater precipitation, with a weighted average leaf litter RH recorded at time of sampling of 85.22%. Alternatively, 649 nymphs were collected in 2010, a year of relatively low precipitation, and a weighted average RH recorded at time of sampling was 75.51%. Negative binomial regression analysis of tick count totals identified cumulative hours <82% RH threshold as a significant factor observed in both years (2009: P = 0.0037; 2010: P < 0.0001). Mean weekly daytime RH did not significantly predict tick activity in either year. However, mean weekly daytime RH recorded with 1-wk lag before sample date was a significant variable (P = 0.0016) in 2010. These results suggest a lag effect between moisture availability and patterns of tick activity and abundance. Differences in the relative importance of each RH variable between years may have been due to abnormally wet summer conditions in 2009.

White-tailed deer (Odocoileus virginianus Zimmerman), serve as the primary host for the adult blacklegged tick (Ixodes scapularis Say), the vector for Lyme disease, human babesiosis, and human granulocytic anaplasmosis. Our objective was to evaluate the degree of association between deer density, tick abundance, and human cases of Lyme disease in one Connecticut community over a 13-yr period. We surveyed 90–98% of all permanent residents in the community six times from 1995 to 2008 to document resident's exposure to tick-related disease and frequency and abundance of deer observations. After hunts were initiated, number and frequency of deer observations in the community were greatly reduced as were resident-reported cases of Lyme disease. Number of resident-reported cases of Lyme disease per 100 households was strongly correlated to deer density in the community. Reducing deer density to 5.1 deer per square kilometer resulted in a 76% reduction in tick abundance, 70% reduction in the entomological risk index, and 80% reduction in resident-reported cases of Lyme disease in the community from before to after a hunt was initiated.

Five types of long-lasting insecticidal nets (LNs), namely, Olyset, Netprotect, PermaNet, DuraNet, and Interceptor, were tested after 20 washes for efficacy in terms of mortality, deterrence effect, blood-feeding inhibition, and induced exophily of the malaria vector Anopheles fluviatilis in experimental huts in Malkangiri district of Odisha State, India. Efficacy of the three synthetic pyrethroids (SPs) used in the LNs was also analyzed. Use of LNs reduced the entry of An. fluviatilis into the huts by 73.3–83.2%, and the five LNs were comparable in terms of deterrence. The exit rate of An. fluviatilis from the huts with untreated net was 56.3%, and relative to this, Olyset followed by DuraNet induced significantly a higher exophily. In contrast, the exit rate was significantly lower with Interceptor. Among the three SPs, permethrin induced significantly greater exophily relative to the untreated control, and as a result of this, permethrin-treated Olyset produced a lower mortality. Blood-feeding rate of An. fluviatilis was significantly lower with all the five LNs than the control. Similarly, all the three SPs significantly inhibited blood feeding compared with the control. Interceptor and DuraNet, both alphacypermethrin-treated LNs, caused relatively a higher mortality of An. fluviatilis than the other LNs. The five brands of LNs and three SPs tested in the current study were equally effective in terms of deterrence and blood-feeding inhibition; only exiting and killing effect differed among them. Permethrin-treated LNs induced greater exophily, while, overall, alphacypermethrin-treated LNs killed more An. fluviatilis that entered the huts. Advantage of deterrence, excito-repellent, and killing effects of LNs and appropriate selection of SP for net treatment are discussed in this paper.

Many ticks of the genus Amblyomma are vectors of human pathogens, and the correct species identification is medically and epidemiologically important. Morphological identification is time-consuming and requires a high level of expertise. Identification of engorged, immature, or damaged ticks and the differentiation of closely related species remain problematic. Here, we report the development of a real-time TaqMan assay for the genomic identification and differentiation of Amblyomma americanum (L.), Amblyomma cajennense (F.), and Amblyomma maculatum (Koch), which are human-biting species found in the eastern United States. New species-specific sets of oligonucleotides for the multiplex reaction that detect and differentiate the ITS2 genomic regions of three target species were designed using Visual OMP; the previously published A. americanum oligonucleotide set was also incorporated into our assay. Specificity and sensitivity tests for two multiplex master mixes using different A. americanum sets were performed using individual and pooled samples of adult, nymphal, and larval ticks, and optimization procedures were applied. The multiplex assay successfully differentiates between genomes of three target species and does not cross-react with DNAs of ticks from other genera. Rare cases of nonspecific amplification occurred with DNAs of A. imitator and Amblyomma triste Koch misidentified as A. americanum and A. maculatum, respectively. However, this cross-reaction does not diminish the usefulness of the developed assay east of the 95th meridian, where neither A. imitator nor A. triste are found. Two master mixes incorporating the previously published or newly developed A. americanum sets are being recommended for identification of individual ticks or pooled samples, respectively.

An assessment was made of the toxicity of 12 insecticides and three essential oils as well as Bacillus thuringiensis subsp. israelensis (Bti) alone or in combination with the oil major constituents (E)-anethole (AN), (E)-cinnamaldehyde (CA), and eugenol (EU; 1:1 ratio) to third instars of bamboo forest-collected Aedes albopictus (Skuse) and rice paddy field-collected Anopheles sinensis Wiedemann. An. sinensis larvae were resistant to various groups of the tested insecticides. Based on 24-h LC₅₀ values, binary mixtures of Bti and CA, AN, or EU were significantly more toxic against Ae. albopictus larvae (0.0084, 0.0134, and 0.0237 mg/liter) and An. sinensis larvae (0.0159,0.0388, and 0.0541 mg/liter) than either Bti (1.7884 and 2.1681 mg/liter) or CA (11.46 and 18.56 mg/liter), AN (16.66 and 25.11 mg/liter), or EU (24.60 and 31.09 mg/liter) alone. As judged by cotoxicity coefficient (CC) and synergistic factor (SF), the three binary mixtures operated in a synergy pattern (CC, 140.7–368.3 and SF, 0.0007–0.0010 for Ae. albopictus; CC, 75.1–245.3 and SF, 0.0008–0.0017 for An. sinensis). Global efforts to reduce the level of highly toxic synthetic insecticides in the aquatic environment justify further studies on the binary mixtures of Bti and essential oil constituents described, in particular CA, as potential larvicides for the control of malaria vector mosquito populations.

The mosquito Aedes albopictus (Skuse, 1895) is a potent vector of several arboviral diseases, most notably chikungunya and dengue fever. In the context of the sterile insect technique (SIT), the sterilization of the male mosquitoes before their release can be achieved by gamma-ray irradiation. As gamma-ray irradiators are becoming increasingly problematic to purchase and transport, the suitability of an X-ray irradiator as an alternative for the sterilization of Ae. albopictus males was studied. The sterilization of up to 200,000 pupae at one time can be achieved with relative ease, and the sterility results obtained were comparable with those achieved by gamma irradiation, where 99% sterility is induced with a dose of 40 Gy. A significant reduction of longevity was observed in the latter stages of the males’ life after irradiation treatments, especially at doses >40 Gy, which is consistent with the negative effects on longevity induced by similar radiation doses using gamma rays. Females irradiated at 40 Gy were not only 100% sterile, but also failed to oviposit entirely, i.e., all of the females laid 0 eggs. Overall, it was found that the X-ray irradiator is generally suitable for the sterilization process for sterile insect technique programs, as it showed a high processing capacity, practicality, high effectiveness, and reproducibility.

Culex pipiens molestus Forskal (Diptera: Culicidae) is the dominant mosquito species in septic tanks in South Korea. An assessment was made of the biological control potential of mud loaches, Misgurnus mizolepis Günther (Cypriniformes: Cobitidae), toward Cx. p. molestus larvae in laboratory and septic tanks. Results were compared with those of temephos 20% emulsifiable concentrate. In laboratory tests, all mud loaches survived on sedimentation chamber- and effluent chamber-collected water of aerobic septic tanks (ASTs), whereas all mud loaches died within 3–12 h after introduction into sedimentation chamber- and effluent chamber-collected water of anaerobic septic tanks. Gill hyperplasia and hemorrhages at the bases of pectoral fins were detected in all dead mud loaches. These appeared to have been caused by bacterial disease, rather than the physical and chemical characteristics of the septic tank water. A mud loach consumed an average range of 1,072–1,058 larvae of Cx. p. molestus in the AST water at 24 h. At the manufacturer's recommended rate (10 ml/ton) in the AST water, the temephos formulation did not cause fish mortality. In the AST experiment, predation of mosquito larvae by mud loaches at a release rate of one fish per 900 mosquito larvae resulted in complete mosquito control from the third day after treatment throughout the 18-wk survey period, compared with temephos 20% emulsifiable concentrate-treated AST water (reduction rate, 40% at 28 days after treatment). Reasonable mosquito control in aerobic septic tanks can be achieved by mosquito breeding season stocking of a rate of one mud loach per 900 mosquito larvae.

Water-distilled essential oils from dried aerial parts of Tanacetum argenteum (Lam.) Willd. subsp. argenteum (Lam.) and T. argenteum (Lam.) Willd. subsp. canum (C. Koch) Grierson were analyzed by gas chromatography and gas chromatography-mass spectrometry. In total, 27 and 32 components were identified representing 97.2 and 98.7% of essential oils of subsp. argenteum and canum, respectively. Main compounds of T. argenteum subsp. argenteum were α-pinene (67.9%) and β-pinene (4.8%), whereas α-pinene (53.6%), 1, 8-cineole (14.8%), and camphor (4.7%) were the major constituents of subsp. canum. Essential oil of T. argenteum subsp. canum at 10 µg/cm² with Biting Deterrent Index (BDI) value of 0.73 showed activity similar to N,N-Diethyl-meta-toluamide (DEET) at 25 mol/cm², whereas the activity of essential oil of subsp. argenteum was lower (BDI = 0.47) than subsp. canum and DEET. Based on 95% CIs, activity of ß-caryophyllene (BDI value = 0.54) and caryophyllene oxide (BDI = 0.66) were significantly lower than DEET. In larval bioassays, essential oil of T. argenteum subsp. argenteum showed LC₅₀ value of 93.34 ppm, whereas T. argenteum subsp. canum killed only 40% of the larvae at the highest dose of 125 ppm. Among the pure compounds, β-caryophyllene (LC₅₀ = 26 ppm) was the most potent compound followed by caryophyllene oxide (LC₅₀ = 29 ppm), which was also similar to (-)-β-pinene (LC₅₀ = 35.9 ppm) against 1-d-old Ae. aegypti larvae at 24-h post treatment. Compounds (-)-α-pinene and ( )-β-pinene showed similar larvicidal activity. Activity of ( )-β-pinene with LC₅₀ value of was similar to the essential oil of T. argenteum subsp. argenteum.

Fecundity, bloodmeal size, and survival are among the most important parameters in the overall fitness of mosquitoes. Impact of an intervention that affects fecundity can be assessed by directly counting the eggs laid by exposed mosquitoes, which is usually done manually. We have developed a macroinstruction, which can be used to count thousands of Anopheles stephensi Liston eggs in a few minutes, to provide an alternative and adaptable method to egg counting as a measure of fecundity. The macro was developed using a scanner and a computer running AxioVision Rel. 4.8 software, a freely accessible software compatible with Windows XP/7/Vista. Using this semiautomated method, it is possible to reduce time, avoid human error and bias, and obtain improved consistency in studies measuring mosquito fecundity.

Spinosad consisting of spinosyn A and D is derived from a naturally occurring, soil-dwelling bacterium, Saccharopolyspora spinosa. Spinosyns are neurotoxins that activate postsynaptic nicotinic acetylcholine and gamma-aminobutyric acid receptors and cause rapid excitation of the insect nervous system and ultimately exhaustion and death of the targets. During the past 30 yr, numerous spinosad-based formulations have been developed and applied to control various arthropod pests of agricultural importance. Natular T-30 is a new slow-release formulation containing 8.33% spinosad for use in mosquito larval control programs. High-level larvicidal activity, as indicated by low LC₅₀ and LC₉₀ levels, was demonstrated against Culex quinquefasciatus Say in the laboratory. Larvicidal efficacy was evaluated in semifield microcosms, field mesocosms, and underground storm drains. Fair performance against larval populations of Culex spp. and other mosquito species was achieved, although low efficacy during the initial few days posttreatment was encountered. This slow-release formulation will play an important role in controlling mosquitoes in persistent breeding sources.

Control of the mosquito vector, Aedes aegypti (L.), inside human habitations must be performed quickly and efficiently to reduce the risk of transmission during dengue outbreaks. As part of a broad study to assess the efficacy of dengue vector control tools for the U.S. Military, two pesticide delivery systems (ultra-low volume [ULV] and thermal fog) were evaluated for their ability to provide immediate control of Ae. aegypti mosquitoes with a contact insecticide inside simulated urban structures. An insect growth regulator was also applied to determine how well each sprayer delivered lethal doses of active ingredient to indoor water containers for pupal control. Mortality of caged Ae. aegypti, pesticide droplet size, and droplet deposition were recorded after applications. In addition, larval and pupal mortality was measured from treated water samples for 4 wk after the applications. The ULV and the thermal fogger performed equally well in delivering lethal doses of adulticide throughout the structures. The ULV resulted in greater larval mortality and adult emergence inhibition in the water containers for a longer period than the thermal fogger. Therefore, the ULV technology is expected to be a better tool for sustained vector suppression when combined with an effective insect growth regulator. However, during a dengue outbreak, either delivery system should provide an immediate knockdown of vector populations that may lower the risk of infection and allow other suppression strategies to be implemented.

Rickettsia parkeri Luckman (Rickettsiales: Rickettsiaceae), a member of the spotted fever group of Rickettsia, is the tick-borne causative agent of a newly recognized, eschar-associated rickettsiosis. Because of its relatively recent designation as a pathogen, few studies have examined the pathogenesis of transmission of R. parkeri to the vertebrate host. To further elucidate the role of tick feeding in rickettsial infection of vertebrates, nymphal Amblyomma maculatum Koch (Acari: Ixodidae) were fed on C3H/HeJ mice intraderm ally inoculated with R. parkeri (Portsmouth strain). The ticks were allowed to feed to repletion, at which time samples were taken for histopathology, immunohistochemistry (IHC), quantitative polymerase chain reaction (qPCR) for rickettsial quantification, and reverse transcriptase polymerase chain reaction (RT-PCR) for expression of Itgax, Mcpl, and Il1β. The group of mice that received intradermal inoculation of R. parkeri with tick feeding displayed significant increases in rickettsial load and IHC staining, but not in cytokine expression, when compared with the group of mice that received intradermal inoculation of R. parkeri without tick feeding. Tick feeding alone was associated with histopathologic changes in the skin, but these changes, and particularly vascular pathology, were more pronounced in the skin of mice inoculated previously with R. parkeri and followed by tick feeding. The marked differences in IHC staining and qPCR for the R. parkeri with tick feeding group strongly suggest an important role for tick feeding in the early establishment of rickettsial infection in the skin.

Birds are the specific hosts of many tick species and may contribute to the dissemination of ticks and tick-borne pathogens throughout the world. Determination of ticks infesting birds and their pathogens are important for the detection of natural foci of human pathogens. Unfortunately, there is very limited information about the occurrence of ticks on birds and associated pathogens in Turkey. We performed a tick survey on three passerine bird species; Parus major, Sylvia atricapilla, and Turdus merula. Ticks collected from these birds were identified to species and tested for the presence of Borrelia, Ehrlichia, and Rickettsia species. Ixodes arboricola Schulze & Schlottke, Ixodes frontalis Panzer, and Ixodes ricinus L. were found on the birds. This is the first study reporting the presence of I. frontalis and I. arboricola on S. atricapilla and P. major, respectively, in Turkey. In addition, the results of polymerase chain reaction (PCR) with primers specific for gltA and ompA genes and DNA sequence analysis of positive PCR products indicated the presence of Candidatus Rickettsia vini in I. arboricola ticks. In conclusion, this is the first record of both I. arboricola and Candidatus Rickettsia vini in Turkey. Therefore, future studies needed to be conducted on the ticks infesting birds and their pathogens to elucidate the role of birds in the dispersal of tick species and tick-borne pathogens in Turkey.

Amblyomma americanum, the lone star tick, is the most common and most aggressive human biting tick in the Southeastern United States. It is known to transmit the agents of human ehrlichioses, Ehrlichia chaffeensis and Ehrlichia ewingii. In addition, it carries agents of unspecified pathogenicity to humans, including Rickettsia amblyommii, Borrelia lonestari, and the newly emerging Panola Mountain Ehrlichia (PME). Surveillance of these ticks for recognized or emerging pathogens is necessary for assessing the risk of human infection. From 2005 to 2009, we surveyed A. americanum ticks from four locations in the state of Georgia. Ticks (1,183 adults, 2,954 nymphs, and 99 larval batches) were tested using a multiplex real-time polymerase chain reaction (PCR) assay designed to detect and discriminate DNA from Rickettsia spp., E. chaffeensis, and E. ewingii, This assay was capable of detecting as few as 10 gene copies of the aforementioned agents. Ticks were also tested for PME and B. lonestari by nested PCR. The prevalence of infection ranged from 0 to 2.5% for E. chaffeensis, 0 to 3.9% for E. ewingii, 0 to 2.2% for PME, 17 to 83.1% for R. amblyommii, and 0 to 3.1% for B. lonestari. There were 46 (4.1%) individual adults positive for two agents, and two females that were each positive for three agents. Two larval batches were positive for both B. lonestari and R. amblyommii, indicating the potential for transovarial transmission of both agents from a single female. Although infrequent in occurrence, the dynamics of coinfections in individual ticks should be explored further, given the potential implications for differential diagnosis and severity of human illness.

Two rates (0.4 mg/kg body weight/d and 0.6 mg/kg body weight/d) of a daily feed-through formulation of novaluron (Novaluron 0.67% active ingredient Cattle Mix), a newer benzoylphenyl urea insecticide, were evaluated for efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.), house flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.), developing in cow manure. Both rates of feed-through novaluron, delivered consecutively for 10 d, reduced adult emergence of all three species when compared with the untreated control. The presence of deformed puparia indicated that novaluron had an insect growth regulator effect on the developing fly larvae. Both of the feed-through rates evaluated resulted in 100% reduction of adult stable fly emergence after the second day of feed-through treatment. The level of control efficacy observed against these three fly species make this feed-through formulation a candidate for use in an integrated livestock pest management program, particularly in confined cattle production situations where a feed-through product could be easily administered.

We describe a simple silicone membrane for in vitro feeding of Ixodes scapularis (Say), the main tick vector of Lyme borreliosis in the United States. Membranes are prepared using regenerated cellulose lens paper, which is coated with a controlled layer of silicone by submerging and removing the paper in a defined solution of silicone glue dissolved in toluene. Median engorged weight obtained by I. scapularis fed on defibrinated bovine blood using these membranes was 109 mg (32–198 mg). These ticks laid eggs in the laboratory and larvae hatched 6 wk later. This method simplifies artificial membranes for in vitro feeding of ixodid ticks, which have long required a considerable amount of skill and experience to prepare.

Aedes albopictus (Skuse) is a competent vector of arboviruses of public health importance, including dengue virus (DENV) and chikungunya virus viruses. Ae. albopictus is the primary vector of chikungunya virus in Singapore. However, despite being ubiquitous, it plays a secondary role in DENV transmission. The vectorial capacity of Ae. albopictus for DENV in field settings appears to be weak because dengue primarily occurs in Aedes aegypti (L.)-dominated, urban settings of the country. As host-seeking behavior is one of the determinants of vectorial capacity, we screened 6,762 female Ae. albopictus from rural, semiurban, and urban locations in Singapore for avian and nonavian bloodmeals using two polymerase chain reaction-sequencing assays developed in-house. The majority (83.2%, n = 79) of bloodmeals from rural and semiurban areas were from humans. However, Ae. albopictus was also found to feed on shrews, swine, dogs, cats, turtles, and multiple hosts in rural settings. In urban areas, all positive bloodmeals were from humans. There were no avian bloodmeals. Our findings testify that Ae. albopictus is highly anthropophagic even in rural settings, but become opportunistic in extremely low human abundance. This opportunistic feeding behavior warrants further investigations into the vectorial capacity of Ae. albopictus to assess its role in arbovirus transmission in endemic habitats.

Surveillance of dengue virus (DENV) in Aedes (Stegomyia) aegypti (L.) females is of potential interest because human DENV infections are commonly asymptomatic, which decreases the effectiveness of dengue case surveillance to provide early warning of building outbreaks. Our primary aim was to examine if mosquito-based virological measures—monthly percentages of examined Ae. aegypti females infected with DENV or examined homes from which at least one DENV-infected Ae. aegypti female was collected—are correlated with reported dengue cases in the same or subsequent months within study neighborhoods in Mérida City, México. The study encompassed ≈30 neighborhoods in the southern and eastern parts of the city. Mosquitoes were collected monthly over a 15-mo period within study homes (average of 145 homes examined per month); this produced ≈5,800 Ae. aegypti females subsequently examined for DENV RNA. Although monthly dengue case numbers in the study neighborhoods varied >100-fold during the study period, we did not find statistically significant positive correlations between monthly data for mosquito-based DENV surveillance measures and reported dengue cases in the same or subsequent months. Monthly average temperature, rainfall, and indoor abundance of Ae. aegypti females were positively correlated (P ≤ 0.001) with dengue case numbers in subsequent months with lag times of 3–5, 2, and 1–2 mo, respectively. However, because dengue outbreak risk is strongly influenced by serotype-specific susceptibility of the human population to DENV, the value of weather conditions and entomological indices to predict outbreaks is very limited. Potential ways to improve the sensitivity of mosquito-based DENV surveillance are discussed.

The effects of azadirachtin A added to the sucrose diet of the adult females on the mortality, oviposition, and hatching of the sand fly vector of American visceral leishmaniasis Lutzomyia longipalpis (Lutz & Neiva, 1912) were investigated. Concentrations of 0.1, 1.0, and 10.0 μg/mg of azadirachtin significantly increased insect mortality in comparison with control insects. The same dose also significantly reduced oviposition but not hatching. After a long development period, significantly fewer adult insects were obtained from eggs hatching by azadirachtin-treated females in a doseresponse manner. These results indicate that azadirachtin is a potent sterilizer that could be used against the development of Lu. longipalpis populations and as a tool for studying physiological and biochemical processes in phlebotomine species.

The effect of spraying a mixture of the insect growth regulator (IGR) pyriproxyfen (1 mg/liter) and either 1% boric acid sugar bait or eugenol sugar bait on croton petra plants (Codiaeum variegatum L.) was evaluated against the container-inhabiting mosquito, Aedes albopictus (Skuse). Treatments were applied to plants and evaluated against adult and larval Ae. albopictus in the laboratory through contact and wash off experiments, respectively. The control treatment lacked an active ingredient and were treated with an attractive sugar bait. The plants treated with attractive toxic sugar baits plus the IGR resulted in 60–100% mortality of laboratory-reared adult Ae. albopictus. The pyriproxyfen solutions collected from the plant wash experiment resulted in 80–100% emergence inhibition to the exposed third- and fourth-instar larvae, compared with the untreated control. Attractive toxic sugar baits mixed with the IGR not only provide effective control of adult mosquitoes, but also provide additional control of larval mosquitoes after being washed off from the treated plants.

Strains of Culex flavivirus (CxFV), an insect virus isolated initially from Japan, were isolated from different species of Culex sp. mosquitoes collected in Corrientes province, Argentina, during 2009. CxFV was detected by reverse transcription polymerase chain reaction and by isolation in C6/36 cell culture. Phylogenetic analysis of nucleotide sequences showed that these strains are related closely to a CxFV strain isolated from Trinidad. Our study represents the first report of CxFV isolation and characterization in Argentina from the same geographic area where West Nile Virus has been detected. Further evaluation and viral competition studies will be necessary to determine the impact of this insect flavivirus on an infection caused by other pathogenic flaviviruses.