House flies are carriers of > 100 devastating diseases that have severe consequences for human and animal health. Despite the fact that it is a passive vector, a key bottleneck to progress in controlling the human diseases transmitted by house flies is lack of knowledge of the basic molecular biology of this species. Sequencing of the house fly genome will provide important inroads to the discovery of novel target sites for house fly control, understanding of the house fly immune response, rapid elucidation of insecticide resistance genes, and understanding of numerous aspects of the basic biology of this insect pest. The ability of the house fly to prosper in a remarkably septic environment motivates analysis of its innate immune system. Its polymorphic sex determination system, with male-determining factors on either the autosomes or the Y chromosome, is ripe for agenomic analysis. Sequencing of the house fly genome would allow the first opportunity to study the interactions between a pest insect and its parasitoid (Nasonia vitripennis) at the whole genome level. In addition, the house fly is well placed phylogenetically to leverage analysis of the multiple Dipteran genomes that have been sequenced (including several mosquito and Drosophila species). The community of researchers investigating Musca domestica are well prepared and highly motivated to apply genomic analyses to their widely varied research programs.

Five new quill mite species of the genus Torotrogla Kethley, 1970 (Acari: Syringophilidae) are described from North American passerines: T. aphelocoma sp.n. from Aphelocoma californica (Corvidae) and T. cardinalis sp.n. from Cardinalis cardinalis (Cardinalidae) in Texas; and T. coccothraustessp.n. from Coccothraustes vespertinus (Fringillidae), T. cyanocitta sp.n. from Cyanocitta stelleri (Corvidae), and T. piranga sp.n. from Piranga ludoviciana (Thraupidae) in California. A key to females of all known Torotrogla spp. and a table with their host associations and distributions are given.

Biological invasions generally induce profound effects on the structure of resident communities. In Mayotte, where Aedes aegypti and Ae. lilii were already present, the recent introduction of Ae. albopictus raises public health concerns because it may affect the risk of arbovirus transmission. Entomological surveys were carried out in six locations on the island following a transect defined by a gradient from urban to rural habitats during a dry and a wet season. A total of 438 larval habitats containing Aedes spp. immature stages were surveyed. We evaluated the characteristics of larval habitats and analyzed the field distribution of Aedes spp. throughout Mayotte using generalized linear models. Artificial containers used for water storage were significantly more productive for Ae. albopictus immature stages than for Ae. aegypti ones. Most of natural larval habitats collected were colonized by Ae. aegypti, and it was also the most common Aedes species encountered in rural habitats. Conversely, Ae. albopictus greatly predominated in urban and suburban habitats and during the dry season. Ae. lilii was uncommon and occurred preferentially in leaf axillae and dead leaves on the ground. Ae. albopictus has rapidly colonized the inhabited areas of Mayotte. A displacement of Ae. aegypti populations by Ae. albopictus populations in urban areas might be happening. The increasing urbanization seems to greatly favor the presence of the invasive species. Thus, arbovirus surveillance programs should focus, as a priority, on areas where this vector is present because of a higher risk of emergence of an epidemic source of arboviruses.

The Scottish biting midge, Culicoides impunctatus (Diptera: Ceratopogonidae), is a major pest in Scotland, causing a significant impact to the Scottish tourist and forestry industries. C. impunctatus is a generalist feeder, preferring to feed on large mammals, and is notorious for its attacks on humans. Until now, there was anecdotal evidence for differential attraction of female host-seeking C. impunctatus to individual human hosts, and the mechanism for this phenomenon was unknown. Using extracts of human odor collected by air entrainment, electroantennogram recordings to identify the physiologically active components, followed by behavioral assays, we show, for the first time, the differential attraction of female C. impunctatus to human odors and the chemical basis for this phenomenon. Certain chemicals, found in greater amounts in extracts that cause low attractiveness to midges, elicit a repellent effect in laboratory assays and repellency trials in the field. Differences in the production of these natural human-derived compounds could help to explain differential “attractiveness” between different human hosts. A mixture of two compounds in particular, 6-methyl-5-hepten-2-one and geranylacetone [(E)-6,10-dimethylundeca-5,9-dien-2-one], showed significant repellency (87, 77.4, 74.2, and 31.6% at hours 0, 1, 2, and 3, respectively) in the field and have the potential to be developed as novel repellents.

Ecosystem changes caused by anthropogenic activities have modified the environment in ways that at times promote the emergence of vector-borne diseases. Here, we study the effects of combined sewage overflows (CSOs) from urban streams in Atlanta, GA, on oviposition site selection by Culex quinquefasciatus under seminatural field conditions. Counting egg rafts was a reliable indicator of oviposition preferences, and CSO water quality, especially when enriched, was a more attractive oviposition substrate than nonenriched water. Therefore, environmentally sound management of municipal waste water systems has the potential to diminish the risk of Culex-borne diseases in urban areas.

Mosquito swarms are poorly understood mating aggregations. In the malaria vector Anopheles gambiae Giles, they are known to depend on environmental conditions, such as the presence of a marker on the ground, and they may be highly relevant to reproductive isolation. We present quantitative measurements of in dividual An. gambiae positions within swarms from Donéguébougou, Mali, estimated by stereoscopic video image analysis. Results indicate that swarms in this species are approximately spherical, with an unexpectedly high density of individuals close to the swarm centroid. This high density may be the result of individual males maximizing their probability of encountering afemale or aproduct of mosquito orientation through cues within the swarm. Our analysis also suggests a difference in swarm organization between putative incipient species of An. gambiae with increasing numbers of males. This may be related to a difference in marker use between these groups, supporting the hypothesis that swarming behavior is a mechanism of mate recognition and ultimately reproductive isolation.

Mosquitoes in the Culex pipiens complex, Cx. p. pipiens L. and Cx. p. quinquefasciatus Say are morphologically similar and important vectors of West Nile and St. Louis Encephalitis viruses in the United States. The subspecies differ with respect to overwintering strategies, with Cx. p. pipiens entering diapause in response to winter conditions and Cx. p. quinquefasciatus lacking this ability, yet they hybridize when found in sympatry. Specimens (n = 646) were collected using gravid traps set along a transect from New Orleans, LA, to Chicago, IL. Microsatellite markers were used to: genetically characterize subspecies and hybrids, determine the degree and extent of hybridization to better define the hybrid zone, and examine the efficacy of hybrid detection between microsatellites and a singlegene assay based on the acetylcholinesterase.2 gene (HotAce.2). The results support the presence of two distinct genetic entities, with abroad, stable hybrid zone in between. Admixture analyses classified >40% of individuals as hybrids. Allelic richness was markedly different at the northern and southern ends of the transect, and there was a significant isolation by distance effect. The hybrid zone seems to be wider and extends further to the south than previous work indicated, and as a result, we propose new boundaries compared with those indicated by a previous study. Microsatellites detected more hybrids than the HotAce.2 assay, although the latter assay remains useful as a screening tool. We suggest that the parental subspecies and the hybrid zone are maintained by heterosis combined with selection for diapause at northern latitudes.

Forcipomyia taiwana (Shiraki), a biting midge, is one of the most annoying bloodsucking pests in Taiwan. In this study, partial DNA sequences of cytochrome c oxidase II from 113 individuals collected from 11 locations around the island were analyzed to delineate the differentiation pattern and possible dispersal processes of F. taiwana in Taiwan. The uncorrected nucleotide divergences, composed of mostly transition substitutions, were high (up to 2.7%) among the samples. Average comparable variations (≈0.7%) were found within and between populations. Phylogenetic analysis suggested that several distinct lineages exist and some can be found simultaneously in some populations. A relationship between sequence divergences among populations and their relative geographical distances was observed. Moreover, haplotype diversity was high in all populations, and low to middle levels (F_st = 0.004–0.288) of genetic differentiation were found among populations. Linearized calibration from sequence divergences and phylogenetic analysis showed that different ancestral lineages of F. taiwana possibly emerged as early as 0.6 million years ago. Taken together, genetic exchanges among these divergently ancestral lineages, likely caused by recent artificial events, have possibly led to the similarly diversified compositions of F. taiwana populations all around Taiwan nowadays.

The horn fly, Haematobia irritans L., is an obligate blood-feeding parasite of cattle, and control of this pest is a continuing problem because the fly is becoming resistant to pesticides. Dominant conditional lethal gene systems are being studied as population control technologies against agricultural pests. One of the components of these systems is a female-specific gene promoter that drives expression of a lethality-inducing gene. To identify candidate genes to supply this promoter, microarrays were designed from a horn fly expressed sequence tag (EST) database and probed to identify female-specific and larval-specific gene expression. Analysis of dye swap experiments found 432 and 417 transcripts whose expression levels were higher or lower in adult female flies, respectively, compared with adult male flies. Additionally, 419 and 871 transcripts were identified whose expression levels were higher or lower in first-instar larvae compared with adult flies, respectively. Three transcripts were expressed more highly in adult females flies compared with adult males and also higher in the first-instar larval lifestage compared with adult flies. One of these transcripts, a putative nanos ortholog, has a high female-to-male expression ratio, a moderate expression level in first-instar larvae, and has been well characterized in Drosophila. melanogaster (Meigen). In conclusion, we used microarray technology, verified by reverse transcriptase-polymerase chain reaction and massively parallel pyrosequencing, to study life stage- and sex-specific gene expression in the horn fly and identified three gene candidates for detailed evaluation as agene promoter source for the development of a female-specific conditional lethality system.

Insect odorant-binding proteins (OBPs) are a diverse gene family that encode proteins thought to function as molecular chaperones by binding semiochemicals and transporting them through the aqueous lymph of insect sensilla. Between 66 and 68 genes have been classified as OBPs in both Anopheles gambiae (Giles) and Aedes aegypti L. based on bioninformatics criteria. We have cloned and sequenced from a subtracted cDNA library three OBPs in Aedes albopcitus (Skuse). BLASTP and phylogenetic analysis of deduced amino acid sequences identified a unique putative ortholog in Ae. aegypti for each Ae. albopictus OBP. Comparison of these putative Ae. aegypti orthologs with the results of previous bioinformatics analyses of OBP genes in Ae. aegypti highlight the potential variability of bioinformatics analyses and suggest that the OBP gene family of Culicids is even more diverse than previously described. Alignment of deduced amino acid sequences and phylogenetic analysis identified the N-terminal region of Culicid OBPs that is associated with aedine-specific diversification. Analysis of tissue-specific expression indicates that two of the Ae. albopictus OBPs are expressed both in preadult stages and in the hemolymph of adults, suggesting that the proteins encoded by these genes may be involved in the transport of hydrophobic ligands in the hemolymph. The other Ae. albopictus OBP is expressed exclusively in antennae and leg, suggesting a chemosensory function. These results are discussed within the context of the evolution and functional diversification of OBPs in mosquitoes.

The toxicity of tetrahydrofuran lignan grandisin was evaluated against larvae of Chry somya megacephala F. (Diptera: Calliphoridae). The bioassay involved topical treatment on larvae topical treatment on egg masses, and incorporation in the larval diet. Grandisin showed inhibition o postembryonic development by ovicidal (30%) and larvicidal (38%) effects and reduced larval weigh (4 mg), when topically applied on egg masses and starving larvae (L1) at a concentration of 100 µg/ µl. These findings elucidated the effect of grandisin on the C. megacephala life cycle and its potential to control C. megacephala populations.

Previously undiscovered isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycetes: Clavicipitaceae) able to control Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae) were obtained for the first time in Argentina. The isolates were selected from three sources: 1) soil samples from the provinces of Corrientes, Formosa, and Chaco, where ticks are endemic; 2) dead female ticks; and 3) the fungal collection from the Entomopathogenic Fungi Laboratory of IMYZA-INTA Castelar. To select the isolates, population parameters were estimated, LC₅₀ values of the most virulent isolates were calculated, and fungi-acaricides compatibility assays carried out. Isolates B. bassiana 259 and 98 were the most virulent and effective to reduce the number of eggs, the percentage of larval hatching, and parameters r_m (natural intrinsic growth rate) and λ (infinite growth rate) of Rh. (Bo.) microplus populations. The values of LC₅₀were 1 × 10⁷ and 1.15 × 10⁷, respectively, when applied to Rh. (Bo.) microplus eggs. In addition, they were compatible with acaricides. A novel methodology to evaluate the entomopathogenic activity of fungi on Rh. (Bo.) microplus ticks is introduced.

Mosquitoes from three genera, Aedes aegypti L., Anopheles quadrimaculatus Say, and Culex quinquefasciatus Say, were tested for facultative landing and resting behavior on pyrethroidtreated surfaces paired with adjacent untreated surfaces. The three pyrethroids tested were bifenthrin, deltamethrin, and lambda-cyhalothrin. Landing and resting behavior was video recorded and quantified using Observer XT software. Untreated control treatments were tested to show behavior in the absence of insecticides. In controls, the three species had different activity levels, with An. quadrimaculatus being the most active and Cx. quinquefasciatus being the least active. The three species had unique responses to different compounds tested. Landing frequency on adjacent untreated and treated filter papers did not differ for any compound or species at any time during the experiment. However, landing frequencies did differ between treatments and over time. Differences between treated and untreated sides were largely caused by changes in the length of time mosquitoes rested on each side. An. quadrimaculatus had a unique response to the presence of deltamethrin compared with the other species or compounds in which it spent an increased amount of time in contact with both treated and adjacent untreated surfaces. Cx. quinquefasciatus avoided all three compounds by the end of the experiment and rested longer on untreated sides. In most cases, modification of landing and resting behaviors occurred only after mosquitoes had the opportunity to come into contact and acquire a dose of pyrethroid. Bifenthrin had the fastest TK₅₀ for all species. Other differences between compounds for each species are described. The term excito-repellency has produced confusion in the literature, and it is revisited and discussed with respect to the results, which justify the use of alternative terminology. The term “locomotive stimulant” is offered as an acceptable alternative.

To provide information for public health policy on mosquito nets in the Amazon region of Colombia, we conducted landing catches to estimate Anopheles species composition and biting activity. Two hundred twenty person-nights of catches were done in seven locations over a period of 14 mo. A total of 1,780 Anopheles mosquitoes were caught (8.1 per person-night). Among the nine species found, An. oswaldoi Peryassú was the most common (776 mosquitoes, 44%), followed by An. darlingi Root s.l. (498, 28%). An. oswaldoi was the most common species collected outdoors, where its biting rate dropped steadily from a peak of >15 bites/person-night at the start of the night (1800–1900 hours) to ≈2 bites/person-night before dawn. An. darlingi was the most common species collected indoors, with a biting rate of ≈3–4 bites/person-night until about midnight, when the rate dropped below 1 bite/person-night, before showing a secondary peak before dawn. Sixty-four mosquito nets were analyzed by the technique of high-performance liquid chromatography (HPLC) for levels of deltamethrin (DM). Allbuttwo (62) of these were reported by their owners to have been impregnated with insecticide, and 53 were found by HPLC to have deltamethrin. However, one half (32) of the nets had concentrations <4 mg/m² and therefore were likely to have been inadequately protective. An inverse association was found between the reported time between washes and deltamethrin concentration. These findings show a need for additional protection from mosquitoes when not inside nets, as well as for more effective impregnation, possibly through wash-resistant insecticide formulation.

Certain forms of Anopheles gambiae s.s. actively maintain malaria transmission in the driest areas and months of the year because of considerable drought tolerance. We monitored desiccation resistance of F₁ offspring of both the M and S forms of field-collected An. gambiae s.s. Our results indicate that the geographic cline in the distribution of the two forms, as observed in Mali, corresponds to a physiological difference in response to arid environments. In addition, female mosquitoes survived significantly longer than males, enhancing the vector competence for the malaria parasite. Our study supports a genetic link to the drought tolerance phenotype, a phenotype with important consequences to malaria transmission in many places in Africa.

West Nile virus (WNV) has emerged as a health threat to the North American population since its initial outbreak in New York City in 1999. Culex (Culex) pipiens complex mosquitoes have been considered to play the primary role in the enzootic maintenance and transmission of WNV in North America. The voltage-gated sodium channel (NaCh) gene contains pyrethroid resistance-associated mutations in the coding region in many insect species. However, the knowledge of potential NaCh mutations was minimal in Culex. Seeking pyrethroid resistance alleles in Culex, we evaluated a transect along the east coast of the United States with an NaCh-based genotyping tool that amplified a portion of the transcribed sequence containing kdr mutations and the intron immediately downstream of the mutation site. Three genotypes that are typically associated with pyrethroid resistance in insects have been identified in Culex pipiens complex mosquitoes in this study: susceptible wild type kds, the classical knock-down resistance Leu → Phe mutation (Phe/kdr), and a second resistance mechanism, a Leu → Ser mutation (Ser/kdr). Moreover, we observed heterozygotic individual mosquitoes possessing both kdr alleles. Results of this study advance our knowledge of the potential for pyrethroid insecticide resistance among the populations of Cx. pipiens complex in the United States.

This research studied 31 volatile compounds for indoor control of the medically important mosquitoes Aedes aegypti L. and Culex quinquefasciatus Say. Only adult female mosquitoes were tested. The test compounds were from six families that included five heterobicyclics, eight formate esters, formic acid (a hydrolyzed metabolite of formate esters), eight acetate esters, four propionate esters, three butyrate esters, and two valerate esters. Also, the organophosphate compound dichlorvos (DDVP) was tested as a positive control. Cx. quinquefasciatus was generally more susceptible than Ae. aegypti. Cx. quinquefasciatus was most susceptible to a subset of heterobicyclics and formate esters (rank: n-butyl formate > hexyl formate = dihydrobenzofuran = menthofuran = heptyl formate = ethyl formate). Ae. aegypti was most susceptible to a subset of formate esters (rank: methyl > n-butyl > propyl = ethyl = hexyl). The most active materials against both species had LC₅₀s of 0.4–1 mg active ingredient per 0.5 liter of air volume (0.8–2 mg/liter), which is 50- to 60-fold less toxic than dichlorvos (an organophosphate insecticide that is being phased out from indoor use). In relation to Drosophila melanogaster Meigen, both mosquito species were generally more susceptible to formate esters but more tolerant of heterobicyclics. Generally, the most toxic compound against all dipterans tested to date is n-butyl formate, whereas menthofuran is additionally toxic against Cx. quinquefasciatus and D. melanogaster. Finally, the toxicity differences between species point to the potential for differential toxicity among mosquito genera/species, suggesting that further studies of a number of mosquito species might be warranted.

Mosquitoes that transmit human diseases are of major importance to the international public health community. Pesticides remain a major component of integrated programs to control these medically important species. However, very few types of pesticides are currently registered for mosquito control. A high-throughput screening method using first-instar larvae of Aedes aegypti was created and evaluated in our laboratory to quickly screen large numbers of chemicals for activity against mosquitoes. LC₅₀ values of a representative group of compounds were determined using this high-throughput screening method and compared with LD₅₀ values determined by topical application against female adults of Ae. aegypti. Our results show that this high-throughput screening method is suitable for screening large numbers of candidate chemicals quickly to identify effective compounds.

A village-scale trial was conducted on the efficacy of Olyset nets: a long-lasting insecticidal net (LLIN) factory treated with 2% wt:wt permethrin against malaria vectors Anopheles culicifacies Giles and Anopheles fluviatilis James, in Sundargarh District, Orissa, India. The study area comprised 22 villages that were randomized into three clusters and designated as Olyset net, untreated net, and no net clusters. Baseline studies showed that both vector species were 100% susceptible to permethrin. Results of wash resistance and bioefficacy of Olyset nets showed 100% mortality in An culicifacies up to 11 washings, whereas 100% mortality was observed in An. fluviatilis even after 20 washings. The median knock-down time for these species ranged between 4.55–6.00 and 4.45–5.45 min, respectively, during 1 yr of intervention. In the Olyset net study area, there was a significant reduction of 80.6, 94.1, and 76.7% in the entry rate of An. culicifacies, An. fluviatilis, and other anopheline species, respectively, with an overall reduction of 63.5% in total mosquitoes. Floor sheet collections in houses with Olyset nets indicated 39% immediate mortality in total mosquitoes. The overall feeding success rate of mosquitoes in the trial village was only 18.0% in comparison to 44.2 and 79.1% in villages with untreated nets and no nets, respectively. A significant reduction was also recorded in parity rate and human blood index of vector species in the Olyset net area. This study showed that Olyset nets are an effective personal protection tool that can be used in a community-based intervention program.

Thrombostasin (TS) is a previously characterized anticlotting protein with multiple isoforms found in the saliva of horn flies. In this report, the effect of TS isoforms on blood feeding was assessed using individual flies that carried corresponding ts allelles. Laboratory studies of horn fly blood feeding were conducted using colony-reared flies fed on New Zealand White (NZW) rabbits. After timed 20-min feeding periods, each fly was characterized for gender, blood volume uptake, and ts genotype. The results showed that mean blood volumes obtained by individual flies were not related to fly gender but were correlated to the ts genotype(s) carried by each fly. A fly having one or both fe alleles coding for the TS9 isoform took less blood than those possessing one or both fe alleles coding for the TS10 isoform. These results confirm the significant role that TS plays in horn fly feeding and highlight the differential impact of TS protein isoforms that vary by as few as three amino acids.

Cattle exposed to a paralyzing strain of Dermacentor andersoni (Stiles) were all paralyzed during an initial exposure, but the incidence of paralysis decreased to 17 and 0% after two subsequent exposures to virulent flat ticks. Cattle with a single exposure to paralyzing ticks became paralyzed when challenged with ticks that had been prefed on cattle. Western blots indicated that cattle developed antibody responses to 13 antigens in paralyzing tick saliva. The likelihood of paralysis was inversely related to the number of saliva proteins that cattle developed antibody responses to. Cattle challenged with prefed ticks developed antibody response to fewer saliva antigens than cattle challenged with flat ticks. Variation in tick dose did not influence the expression of paralysis. Daily survival of ticks was similar on all groups of cattle, and tick weight was not reduced on previously challenged cattle, indicating immunity developed to the paralysis toxin rather than tick feeding. Four saliva antigens (molecular weights ranging from 36.9 to 42.2 kDa) were associated with the development of immunity to paralysis.

Recently there has been an increasing interest in studying arthropods that live close to humans, such as cockroaches and mites, for their potential as vectors. Gregarines observed under light microscopy in intestinal extracts of house dust mites (Dermatophagoides spp.) are described for the first time in scientific literature.

Ticks are vectors of a variety of pathogens, including Francisella tularensis. Bacteria in the genus Francisella have been identified mostly in the Northern Hemisphere and include tick endosymbionts. Francisella has never been described in Brazil, where Amblyomma spp. ticks are known as the vector of many bacterial zoonotic pathogens. In the present work, we have identified bacterial DNA sequences with identity to Francisella genes in Amblyomma dubitatum Neumann Dermacentor nitens (Neumann), and Rhipicephalus microplus (Canestrini) in Brazil. DNA fragments with homology to Francisella spp. 16S rDNA and the tul4 gene were polymerase chain reaction amplified from tick DNA samples collected in Minas Gerais and Mato Grosso states. These sequences were 96–99% identical to the reported sequences for Franeisella-like tick endosymbionts (FLEs). Sequences similar to the tularemia agent F. tularensis pathogenicity island gene iglC and its regulatory gene mglA also were identified in FLEs.

Alphaviruses (Togaviridae) rarely have been found to be vertically transmitted from female arthropods to their progeny. We report two isolations of Buggy Creek virus (BCRV), an ecologically unusual alphavirus related to western equine encephalomyelitis virus, from field-collected eggs of cimicid swallow bugs (Oeciacus vicarius Horvath), the principal vector for BCRV. Ten percent of egg pools were positive for BCRV, and we estimated minimum infection rates to be 1.03 infected eggs per 1,000 tested. The results show potential vertical transmission of BCRV, represent one of the few isolations of any alphavirus from eggs or larvae of insects in the field, and are the first report of any virus in the eggs of cimicid bedbugs. The specialized ecological niche of BCRV in swallow bugs and at cliff swallow (Petrochelidon pyrrhonota Vieillot) nesting sites may promote vertical transmission of this virus.

Studies on Culex tarsalis Coquillett in Colorado have shown marked seasonal variation in the proportion of blood meals from birds and mammals. However, limitations in the specificity of antibodies used in the precipitin test and lack of vertebrate host availability data warrant revisiting Cx. tarsalis blood feeding behavior in the context of West Nile virus (WNV) transmission. We characterized the host preference of Cx. tarsalis during peak WNV transmission season in eastern Colorado and estimated the relative contribution of different avian species to WNV transmission. Cx. tarsalis preferred birds to mammals each month, although the proportion of blood meals from mammals increased in July and August. The distribution of blood meals differed significantly across months, in part because of changes in the proportion of blood meals from American robins, a preferred host. The estimated proportion of WNV-infectious vectors derived from American robins declined from 60 to 1% between June and August. The majority of avian blood meals came from doves, preferred hosts that contributed 25–40% of the WNV-infectious mosquitoes each month. Active WNV transmission was observed in association with a large house sparrow communal roost. These data show how seasonal patterns in Cx. tarsalis blood feeding behavior relate to WNV transmission in eastern Colorado, with the American robin contributing greatly to early-season virus transmission and a communal roost of sparrows serving as a focus for late-season amplification.

Arboviruses have seldom been found overwintering in adult vectors at northern latitudes in North America. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an ecologically unusual arbovirus vectored principally by the cimicid swallow bug (Oeciacus vicarius Horvath). The ectoparasitic bugs reside year-round in the mud nests of their host, the cliff swallow (Petrochelidon pyrrhonota Vieillot). We report successful overwintering of infectious BCRV in bugs at a field site in western North Dakota, where mid-winter temperatures routinely reach -11 to -15°C. Approximately 21% of bug pools were positive for virus in early spring just before the cliff swallows' return to their nesting colonies; this proportion did not differ significantly from that in summer at active cliff swallow nesting colonies in the same study area. Fewer of the isolates in early spring were cytopathic on Vero cells, and those that were infectious showed less plaque formation than did summer samples. The results show that infectious BCRV commonly overwinters in the adult stages of its vector at northern latitudes in North America.

Chikungunya virus (CHIKV) is an arbovirus (genus Alphavirus, family Togaviridae) that has recently caused disease outbreaks in the Indian Ocean basin and southern Europe. These outbreaks could be associated with a possible shift in primary vector from Aedes aegypti to Ae. albopictus. To evaluate vector competence differences in possible CHIKV vectors, we evaluated the dose-dependant susceptibility of Florida strains of Ae. albopictus and Ae. aegypti for infection with a La Réunion island strain of CHIKV. Pledget and water-jacketed membrane feeding systems were also evaluated. We show that both Aedes spp. were susceptible to the highest CHIKV doses, whereas only Ae. albopictus developed disseminated infections after exposure to the two lowest doses. Infection rates for both mosquito species were significantly affected by the bloodmeal delivery method used. This information is important in assessing risk of an outbreak of imported CHIKV in the United States, in determining differences in vectorial capacity of these two vector species, and in evaluating arbovirus delivery methods in the laboratory.

The geographical distribution of Phlebotomus papatasi Scopoli, vector of Leishmania major Yakimoff and Schokhor (Kinetoplastida: Trypanosomatidae), the etiologic agent of zoonotic cutaneous leishmaniasis (ZCL), was assessed during September 2006 through a transect from the north to the south of Tunisia using CDC light traps. P. papatasi was found to be abundant in the arid and Saharan bioclimatic zones and rare in the humid, subhumid, and semiarid bioclimatic zones. Similarly, the highest incidence of ZCL was observed in the arid and Saharan bioclimatic zones and the lowest in the humid, subhumid, and semiarid bioclimatic zones. Our overall findings confirm the close spatial association between the abundance of P. papatasi and the incidence of ZCL.

Species of Neomelaniconion (Neo.) are aggressive toward humans and domestic animals. Some of these species play a role in the transmission of arbovirus. In Madagascar, separation of these arbovirus vectors was based on doubtful morphological features. Sequence variation of the ribosomal DNA internal transcribed spacer 2 from morphological Neomelaniconion species of the Neomelaniconion subgenus from Madagascar was investigated to assess the validity of morphologically defined taxa. Both methods showed two taxonomic groups: the Circumluteolus Group that includes Aedes (Neo.) belleci (Le Goff, Bousses, and Brunhes, 2007), Ae. (Neo.) nigropterum (Le Goff, Bousses, and Brunhes, 2007), and Ae. (Neo.) circumluteolus (Theobald, 1908); and the Sylvaticum Group that includes Ae. (Neo.) sylvaticum (Le Goff, Bousses,and Brunhes, 2007), Ae. (Neo.) fontenillei (Le Goff, Bousses, and Brunhes, 2007), and Ae. (Neo.) albiradius (Le Goff, Bousses, and Brunhes, 2007). Although sequence analysis failed to completely resolve each group, four distinct patterns of sequence variation supported by several fixed mutations were shown from specimens in Madagascar.