Ochlerotatus Caspius Research Articles

Interactive effects of salinity and a predator on mosquito oviposition and larval performance

Oviposition habitat selection (OHS) is increasingly being recognized as playing a large role in explaining mosquito distributions and community assemblages. Most studies have assessed the role of single factors affecting OHS, while in nature, oviposition patterns are most likely explained by multiple, interacting biotic and abiotic factors. Determining how various factors interact to affect OHS is important for understanding metapopulation and metacommunity dynamics. We investigated the individual and interactive effects of three water salinities (0, 15 and 30 p.p.t. NaCl added) and the aquatic predator Anisops debilis Perplexa (Hemiptera: Notonectidae) on OHS and larval performance of the mosquitoes Ochlerotatus caspius Pallas and Culiseta longiareolata Macquart (Diptera: Culicidae) in outdoor-artificial-pool and laboratory experiments. C. longiareolata inhabited only freshwater pools, strongly avoided pools containing A. debilis, and larvae experienced lower survival in the presence of A. debilis. Salinity concentration interacted strongly with the predator in affecting OHS and larval survival of O. caspius; oviposition increased with increasing salinity in the absence of the predator and decreased with increasing salinity in the presence of the predator. O. caspius larval survival in predator-free pools was lowest in freshwater and highest at intermediate salinity. In predator pools, survival was highest at high salinity, where predation rate was shown to be lowest in the laboratory. Our results highlight that assessing the role of single factors in affecting mosquito distributions can be misleading. Instead, multiple factors may interact to affect oviposition patterns and larval performance.

Species-Specific Non-Physical Interference Competition among Mosquito Larvae

Individuals of different sex, size or developmental stage can compete differently and hence contribute distinctively to population dynamics. In species with complex life cycles such as insects, competitive ability is often positively correlated with larval developmental stage. Yet, little is known on how the development and survival of early-instars is influenced by interference from late-instar larvae, especially at low densities when exploitative competition is expected to be negligible. Furthermore, the specificity and mechanisms by which interference competition operates are largely unknown. We performed two complementary experiments aiming to quantify the competitive effects of late instar Ochlerotatus caspius on early instar larvae at low densities and under high resource supply rate. The first experiment examined the net effect of interference by 4th on 1st instar O. caspius larvae, relative to the effect of 1st instars on themselves. The second experiment examined the effect of species-specific, non-physical interference competition (i.e., cage larvae) by 4th on 1st instar O. caspius larvae at low or high densities. Specifically, we compared the responses of O. caspius larvae raised in the presence of caged con- or hetero-specific, Culiseta longiareolata, with that of larvae in the empty-cage control group. As expected, interference from late instar larvae had a net negative effect on the development rate of first instars. In contrast, the presence of caged con-specifics (non-physical interference) accelerated the development rate of O. caspius, however, this pattern was only evident at the low density. Notably, no such pattern was detected in the presence of caged hetero-specifics. These results strongly suggest the existence of species-specific growth regulating semiochemicals.

How entomological studies can help the control of mosquito-borne diseases: a five-years experience in north-eastern Italy

North-eastern Italy is particularly suitable for mosquito survival, due to its climate, landscape and abundance of wild/domestic animals. After the emergence of West Nile Virus (WNV) in 2008, entomological studies were implemented. Here we describe how entomological data were managed to optimize surveillance and control of mosquito-borne pathogens. CDC-CO2 traps were used (May-October, 2009-2013). In one site, captures with CDC and gravid traps were organized every 2hrs for 24hrs. In other three sites pre- and post-disinfestation captures were done. The mosquitoes were screened by RT-PCR for Flaviviridae and a sub-sample for Bunyaviridae. Host preference of Culex pipiens was assessed by PCR blood meal analysis. Mapping, modelling and spatial analyses were done using entomological data to identify correlations with climate, landscape, animal and human infections. More than 700,000 mosquitoes were collected, with Cx.pipiens the most abundant (80%) and the only vector of WNV and USUV. Tahyna virus was isolated once in Ochlerotatus caspius. Cx.pipiens fed preferentially on birds (76%), mainly blackbird, sparrow, magpie and collared dove, but not on humans. Diel activity showed that Cx.pipiens changed its host searching activity according to the season and defined the favorite period for oviposition. The success of disinfestation measures in reducing Cx.pipiens density varied according to the methods used. The contribution of density-dependence in regulating vector population growth resulted greater than any environmental factor on its own. Overall the most significant predictors of Cx.pipiens dynamics included length of daylight, population density and temperature in the 15 days prior to sampling. Precipitation, number of rainy days and humidity had limited importance. Linear models detected significant relationships between WNV in humans and mosquitoes. Spatial analysis detected clusters of WNV occurrences for all the hosts, identifying an area where to focus surveillance and promptly detect WNV re-activation. In long term studies the mosquito species composition, seasonality, distribution, abundance and pathogen rate of infections were assessed. The blood-meal analyses indicated possible bird targets for surveillance. The control of the efficacy of disinfestations highlighted the need for harmonic guidelines. Modelling indicated the need to incorporate density dependence in combination with key environmental factors for robust prediction of Cx.pipiens population expansion, helping to identify when and where an increase in vector population size and WNV transmission risk should be expected. The results stressed also the necessity to improve the density and the frequency of mosquito captures.

Physico-chemical characteristics of the mosquito breeding water in two urban areas of Cairo Governorate, Egypt

Certain physico-chemical characteristics of mosquito breeding habitats [temperature, pH, salinity, turbidity, dissolved oxygen (DO) and nitrite] were examined relative to the distribution of mosquito larval species in two urban areas of Cairo Governorate namely El- Muqattam (M) and Abu-Seir (A). Mean values and ranges of such characteristics for the reported mosquito species (<em>Culex pipiens</em>, <em>Cx. perexiguus</em>, <em>Ochlerotatus caspius</em>, <em>Cx. pusillus</em> and <em>Culiseta longiareolata</em>) were reported. In conclusion, based on the significant correlations of the different characteristics with the abundance of the two common larval species (<em>Culex pipiens</em> and <em>Cx. perexiguus</em>), salinity and DO may be considered the predictor variables associated with the immature abundance. Considering altogether mosquitoes, there is an increasing presence from planned safe (M) to unplanned unsafe (A) habitats mainly due to turbidity and nitrite.

Novel Virus Discovery and Genome Reconstruction from Field RNA Samples Reveals Highly Divergent Viruses in Dipteran Hosts

We investigated whether small RNA (sRNA) sequenced from field-collected mosquitoes and chironomids (Diptera) can be used as a proxy signature of viral prevalence within a range of species and viral groups, using sRNAs sequenced from wild-caught specimens, to inform total RNA deep sequencing of samples of particular interest. Using this strategy, we sequenced from adult Anopheles maculipennis s.l. mosquitoes the apparently nearly complete genome of one previously undescribed virus related to chronic bee paralysis virus, and, from a pool of Ochlerotatus caspius and Oc. detritus mosquitoes, a nearly complete entomobirnavirus genome. We also reconstructed long sequences (1503-6557 nt) related to at least nine other viruses. Crucially, several of the sequences detected were reconstructed from host organisms highly divergent from those in which related viruses have been previously isolated or discovered. It is clear that viral transmission and maintenance cycles in nature are likely to be significantly more complex and taxonomically diverse than previously expected.

Ecological Niche Modelling of Potential West Nile Virus Vector Mosquito Species and Their Geographical Association with Equine Epizootics in Italy

In Italy, West Nile virus (WNV) equine outbreaks have occurred annually since 2008. Characterizing WNV vector habitat requirements allows for the identification of areas at risk of viral amplification and transmission. Maxent-based ecological niche models were developed using literature records of 13 potential WNV Italian vector mosquito species to predict their habitat suitability range and to investigate possible geographical associations with WNV equine outbreak occurrence in Italy from 2008 to 2010. The contribution of different environmental variables to the niche models was also assessed. Suitable habitats for Culex pipiens, Aedes albopictus, and Anopheles maculipennis were widely distributed; Culex modestus, Ochlerotatus geniculatus, Ochlerotatus caspius, Coquillettidia richiardii, Aedes vexans, and Anopheles plumbeus were concentrated in north-central Italy; Aedes cinereus, Culex theileri, Ochlerotatus dorsalis, and Culiseta longiareolata were restricted to coastal/southern areas. Elevation, temperature, and precipitation variables showed the highest predictive power. Host population and landscape variables provided minor contributions. WNV equine outbreaks had a significantly higher probability to occur in habitats suitable for Cx. modestus and Cx. pipiens, providing circumstantial evidence that the potential distribution of these two species coincides geographically with the observed distribution of the disease in equines.

Characterization of the Mosquito Breeding Habitats in Two Urban Localities of Cairo Governorate, Egypt

The knowledge of the natural characteristics of the mosquito breeding habitats is important for implementing effective larval control program. For this, the association of six mosquito species ( Culex pipiens , Cx. perexiguus , Cx. pusillus , Ochlerotatus caspius , Anopheles multicolor and Culiseta longiareolata ) with the physical characteristics of their breeding habitats was examined in El-Muqattam and Abu-Seir; of the urban areas in Cairo Governorate. Based on the highest frequency of occurrence (P 10m perimeter), mud bottoms, presence of aquatic vegetations and absence of predators. The study concluded that the environmental control measures based on modifying habitat characteristics can be effective in controlling targeted mosquito species specially those vectors of diseases.

Morphological and molecular characterization of a microsporidian parasite, Takaokaspora nipponicus n. gen., n. sp. from the invasive rock pool mosquito, Ochlerotatus japonicus japonicus

A new genus and species of Microsporidia, Takaokaspora nipponicus n. gen., n. sp. is described from Ochlerotatus japonicus japonicus (Theobald) and Ochlerotatus hatorii (Yamada) based on light microscope and ultrastructural morphology, developmental features, transmission cycles and comparative sequence analyses of the small subunit ribosomal DNA (SSU rDNA). The microsporidium is both vertically and horizontally transmitted, exhibits dimorphic development alternating between diplokaryotic and monokaryotic stages and produces two morphologically distinct spores, one in larvae and another in adult females. Horizontal transmission of infection to larval mosquitoes occurs via direct oral ingestion of uninucleate spores that are produced in vertically-infected larval hosts. Development in horizontally-infected hosts is diplokaryotic following karyokinesis of uninucleate schizonts and binary fission to produce small (4.3μm×2.0μm) membrane free, ovoid, binucleate spores that are confined to adult female reproductive tissues (ovariole sheath and oviducts). Vertical transmission of the microsporidium from adult females to larval progeny takes place via surface contamination of the egg (transovum). Microsporidian development in vertically-infected larvae is haplophasic with unpaired nuclei throughout, producing rosette-shaped sporogonial plasmodia contained within a thin non-persistent sporophorous vesicle and culminating in the formation of membrane free, uninucleate, conical spores (7.0μm×2.8μm). Development is confined to host fat body tissue which appears as swollen white masses in the thorax and selected segments of the abdomen causing larvae to appear abnormally distorted and results in death during the third and fourth instar stages. The SSU rDNA sequences obtained from the two morphologically identical microsporidia isolated from Oc. j. japonicus and Oc. hatorii were nearly identical and unique when compared with GenBank entries of all other mosquito-parasitic species. Phylogenetic trees constructed by Maximum Parsimony, Maximum Likelihood and bootstrap analyses using the Neighbor Joining search parameter yielded similar typologies. In each case, the novel microsporidium was the sister group to the clade containing Parathelohania species from Anopheles mosquitoes and the monotypic Novothelohania ovalae from Ochlerotatus caspius showing approximately 10–13% sequence divergence to those two genera providing strong support for establishment as a separate genus.

Arboviral Surveillance of Field-Collected Mosquitoes Reveals Circulation of West Nile Virus Lineage 1 Strains in Eastern Thrace, Turkey

Arbovirus screening in invertebrate vectors is an important component of the vector-borne disease surveillance programs. Turkey has been shown to harbor medically important mosquito-borne arboviruses such as West Nile Virus (WNV). However, limited information about infections in vectors are currently available. This study was performed to provide preliminary data from Eastern Thrace region, Turkey, where no arbovirus vector surveillance has previously been performed. Mosquito sampling was undertaken at 23 sites in Edirne province during July, 2012. All specimens were identified morphologically, and selected individuals were subjected to DNA barcoding via cytochrome c oxidase I (COI) sequencing. Consensus PCR for Flavivirus, Alphavirus, and Phlebovirus genera and WNV-specific nested and real-time reverse transcription PCR were employed for mosquito pool screening and/or confirmation. Viral sequences detected in pools were characterized via sequencing. A total of 9261 mosquitoes were captured and distributed into 232 pools from the following species: Ochlerotatus caspius (90.9%), Culex pipiens sensu lato (s.l.) (4.7%), Anopheles pseudopictus (3%), and Anopheles maculipennis s.l. (1.3%). Specimens morphologically classified as Cx. pipiens s.l. were identified as Cx. pipiens pipiens via barcoding. Thirty-seven mosquito pools (15.9%) were positive in pan-flavivirus and WNV-specific assays. Viral sequences in positive pools were characterized as WNV lineage 1 clade 1a and demonstrated 1-4% divergence. No flavivirus sequences other than WNV were detected in the mosquito pools. WNV infection rates in Oc. caspius and Cx. pipiens s.l. pools were 15.6% and 36.3%, respectively. Comparison of current and previously identified WNV sequences from Turkey revealed 94.00-96.34% similarity. WNV RNA was identified for the first time in Cx. pipiens s.l. and Oc. caspius mosquitoes in Eastern Thrace, Turkey. Our findings indicate the circulation of WNV lineage 1 strains in potential vector species and provide an epidemiological link between WNV activity in mosquitoes and vertebrate infections.

A divergent insect-specific flavivirus that causes overt cytopathic effect in a mosquito cell-line

The genus Flavivirus (Flaviviridae) includes over seven dozen known enveloped viruses with ssRNA genomes, the evolution, geographic dispersion and epidemiology of which seems to have been shaped both by environmental constraints (involving ecological factors and human activities), and by their replication in vertebrate and invertebrate hosts. Most bona-fide flaviviruses have been classified as mosquito or tick-borne viruses, although for some no known invertebrate vector has yet been found. Over time, a divergent cluster including viral agents that seem to be specific of insect (Insect-Specific Flaviviruses-ISF) has been associated with the genus. The classification of ISF as flaviviruses is supported by their genomic organization, protein hydropathy plots, conserved polyprotein cleavage sites and enzyme domains, which are similar to those of classical flaviviruses. However, they are antigenically distinct, and share approximately the same level of nucleotide sequence identity with other members of the genus, as when compared to the members of the two other genera in the Flaviviridae family.This work reports the initial characterization, including near full-length sequence analysis, of an ISF which seems to form a divergent lineage within the ISF radiation (Figure 1), as indicated by phylogenetic analysis based on ac multiple sequence alignment of the NS5 flavivirus coding sequence. This virus, tentatively designated OCFV (Ochlerotatus caspius flavivirus) was isolated from clarified macerates of a pool of Aedes (Ochlerotatus) caspius (Pallas, 1771) adult mosquitoes (lab code number 174) using the Ae. albopictus-derived C6/36 cell line. The mosquitoes from which OCFV was isolated were collected using CDC-traps baited with CO2, and are amongst those found in high densities in the coastal, and estuarine, districts of Setúbal and Faro. Detection of viral genomes by RT-PCR using RNA directly extracted from supernatants of C6/36 infected cultures, collected 24h post-infection, indicated that the virus replicates rapidly in these cells. Nevertheless, but as expected for an ISF, it does not replicate in Vero cells. Unexpectedly, unlike most ISF OCFV seems to cause overt cytopathic effect in C6/36 cells, which rapidly detach from a solid support and round-up soon (24-48h) after infection. Electron-microscope analysis of thin-sections of C6/36 cells at 48h post-infection with OCFV revealed nuclear hyperplasy, and an evident enlargement of the intracisternal space of the nuclear envelope, which is filled by multiple sized vesicles. In some cells, a complex network of apparent membrane trabeculae was also clearly evident (Figure 2A). Viral particles seem to assemble at the endoplasmatic reticulum, from which viruses reach the cell surface by vesicular transport (Figure 2B). Unexpectedly for a flavivirus, but as previously observed, viral particles also seem to gemulate directly from the cytoplasmic membrane (Figure 2C).

Characterization of an insect-specific flavivirus (OCFVPT) co-isolated from Ochlerotatus caspius collected in southern Portugal along with a putative new Negev-like virus

We describe the isolation and characterization of an insect-specific flavivirus (ISF) from Ochlerotatus caspius (Pallas, 1771) mosquitoes collected in southern Portugal. The RNA genome of this virus, tentatively designated OCFVPT, for O. caspius flavivirus from Portugal, encodes a polyprotein showing all the features expected for a flavivirus. As frequently observed for ISF, the viral genomes seems to encode a putative Fairly Interesting Flavivirus ORF (FIFO)-like product, the synthesis of which would occur as a result of a -1 translation frameshift event. OCFVPT was isolated in the C6/36 Stegomyia albopicta (=Aedes albopictus) cell line where it replicates rapidly, but failed to replicate in Vero cells in common with other ISFs. Unlike some of the latter, however, the OCFVPT genome does not seem to be integrated in the mosquito cells we tested. Phylogenetic analyses based on partial ISF NS5 nucleotide sequences placed OCFVPT among recently published viral strains documented from mosquitoes collected in the Iberian Peninsula, while analyses of ORF/E/NS3/or NS5 amino acid sequences cluster OCFVPT with HANKV (Hanko virus), an ISF recently isolated from O. caspius mosquitoes collected in Finland. Taking into account the genetic relatedness with this virus, OCFVPT is not expected to be overtly cytopathic to C6/36 cells. The cytopathic effects associated with its presence in culture supernatants are postulated to be the result of the replication of a co-isolated putative new Negev-like virus.

Dirofilaria repens microfilariae in Aedes vexans mosquitoes in Slovakia

In this study, we screened field-caught mosquitoes for presence of Dirofilaria spp. by using a polymerase chain reaction (PCR) assay. Potential occurrence of Dirofilaria repens and Dirofilaria immitis microfilariae was examined in 3,600 mosquitoes of eight species (Aedes vexans, Aedes cinereus, Aedes rossicus, Culex pipiens, Culiseta annulata, Ochlerotatus sticticus, Ochlerotatus cantans and Ochlerotatus caspius) collected from five locations in two districts (Kosice and Trebisov) of Eastern Slovakia, endemic region of canine dirofilariasis. Collection of mosquitoes was performed between May and August 2012 in premises known to be inhabited by Dirofilaria-infected dogs. PCR assays were performed on 72 pools, each pool containing 50 mosquitoes of the same species, collected on the same location. Each pool was examined separately for the presence of D. immitis and D. repens, respectively. A positive finding of D. repens was recorded in one pool of A. vexans mosquitoes collected in Košické Olšany village. Minimum infection rate in A. vexans was 1:1,750, i.e. 0.57 per 1,000 mosquitoes. The identity of D. repens was confirmed by direct sequencing of PCR product which has shown 100 % homology with sequence attributed to D. repens (GenBank accession number AJ271614). This study represents the first molecular evidence of D. repens microfilariae in mosquitoes in Slovakia and highlights a need for better surveillance of zoonotic dirofilariasis in central Europe.

Avian Plasmodium in Culex and Ochlerotatus Mosquitoes from Southern Spain: Effects of Season and Host-Feeding Source on Parasite Dynamics

Haemosporidians, a group of vector-borne parasites that include Plasmodium, infect vertebrates including birds. Although mosquitoes are crucial elements in the transmission of avian malaria parasites, little is known of their ecology as vectors. We examined the presence of Plasmodium and Haemoproteus lineages in five mosquito species belonging to the genera Culex and Ochlerotatus to test for the effect of vector species, season and host-feeding source on the transmission dynamics of these pathogens. We analyzed 166 blood-fed individually and 5,579 unfed mosquitoes (grouped in 197 pools) from a locality in southern Spain. In all, 15 Plasmodium and two Haemoproteus lineages were identified on the basis of a fragment of 478 bp of the mitochondrial cytochrome b gene. Infection prevalence of blood parasites in unfed mosquitoes varied between species (range: 0–3.2%) and seasons. The feeding source was identified in 91 mosquitoes where 78% were identified as bird. We found that i) several Plasmodium lineages are shared among different Culex species and one Plasmodium lineage is shared between Culex and Ochlerotatus genera; ii) mosquitoes harboured Haemoproteus parasites; iii) pools of unfed females of mostly ornithophilic Culex species had a higher Plasmodium prevalence than the only mammophylic Culex species studied. However, the mammophylic Ochlerotatus caspius had in pool samples the greatest Plasmodium prevalence. This relative high prevalence may be determined by inter-specific differences in vector survival, susceptibility to infection but also the possibility that this species feeds on birds more frequently than previously thought. Finally, iv) infection rate of mosquitoes varies between seasons and reaches its maximum prevalence during autumn and minimum prevalence in spring.

Effect of blood meal digestion and DNA extraction protocol on the success of blood meal source determination in the malaria vector Anopheles atroparvus

BackgroundHost identification is an essential step in studies on the transmission dynamics of vector-borne disease. Nowadays, molecular tools allow the identification of vertebrate hosts to the species level. However, the proportion of successful identifications is variable and may be affected by the quality of the samples and the laboratory protocols. Here, the effect of two of these factors, namely the digestion status of mosquito blood meal and the DNA extraction procedure, on the success of host identification by amplification and sequencing of a fragment of the cytochrome oxidase 1 gene were tested.MethodsMosquitoes collected both outdoors and indoors during 2012 in southern Spain were identified to species level and their blood meal digestion status recorded using the Sella score, a visual estimation of the digestion status of mosquito blood meals. Each mosquito was assigned randomly to one of two DNA extraction procedures: the quick and cheap HotSHOT procedure or the QIAGEN DNeasy Blood and Tissue® kit and their hosts identified by a molecular method.ResultsThree hundred and forty-seven blood-fed mosquitoes belonging to Anopheles atroparvus (n=171), Culex perexiguus (n=84), Culex pipiens (n=43), Culex theileri (n=39), Culex modestus (n=5), Ochlerotatus caspius (n=4), Culiseta sp. (n=1) were included in this study. Overall, hosts were identified from 234 blood meals compromising at least 25 species including mammals, birds and a single reptile. The success of host identification was lower in mosquitoes with an advanced stage of blood meal digestion and for blood meals extracted using the HotSHOT procedure.ConclusionsThe success of host identification decreases with the advanced stage of mosquito blood meal digestion, from 84.5% for recent blood meals to 25.0% for more digested ones. Using the QIAGEN kit, the identification success improved by 17.6%, with larger increases at more advanced stages of blood meal digestion. Availability of blood-fed females used to be very limited for studies of vector ecology, and these results may help to increase the efficiency of blood meal analyses. In addition, results obtained in this study clearly support that the potential malaria vector An. atroparvus feeds on animals located outdoors but use human-made shelters for resting after feeding.

Risk of canine and human exposure to Dirofilaria immitis infected mosquitoes in endemic areas of Italy

BackgroundThe occurrence of infections by Dirofilaria immitis in canine and human populations depends on several factors linked to both the definitive and intermediate hosts. Little data are available on the risk of human and dog exposure to D. immitis in endemic areas. Data collected on dog- and human-bait traps in endemic areas of north-eastern Italy were used to estimate the likelihood of a receptive host coming into contact with an infected vector.MethodsFrom 1997 to 1999, mosquitoes were collected from three sampling sites of north-eastern Italy on D. immitis microfilaraemic dogs and on human baits. The bite/night/host rates were determined based on the number of feeding and probing mosquitoes on dogs and humans, respectively. The survival/mortality rates of different species of mosquitoes following the blood meal, and the rate of natural Dirofilaria infection in unfed specimens were estimated. The risk of exposure of dogs and humans to infected mosquito species was determined by combining the bite/host/night and the mosquito infection rates.ResultsA total of 1,165 mosquitoes were collected on human (n = 815) and dog (n = 350) baits with varying species composition (i.e., Culex pipiens, 87.3% and Ochlerotatus caspius, 11.6%). Overall, dogs were more attractive to Cx pipiens than humans (feeding rate 70.2% vs probing rate 25.9%). The highest bite/night/host rate was 84.0 for dogs and 26.5 for humans. Cx pipiens displayed a mortality rate of 76.3% within 13 days and Oc. caspius of 100% within two days following the infective blood meal. In addition, D. immitis DNA was detected in unfed Cx pipiens (infection rate of 0.26%-2.07%). The infection rate adjusted for mosquito mortality was 0.38%. Based on data collected, the contact between an infected mosquito and a host can occur as often as every four nights for D. immitis infected-mosquitoes in dogs and within two weeks for humans.ConclusionsCx pipiens was confirmed as the most efficient natural vector of D. immitis in the studied area. In endemic areas, the risk of transmission can be very high for dogs and relevant for humans. Despite the increased awareness of veterinarians and owners on canine dirofilarioses, dogs from rural areas still maintain the natural life cycle of Dirofilaria spp., therefore acting as a source of infection to humans through vector bites.

The fauna and ecology of mosquito larvae (Diptera: Culicidae) in western Iran

Ecological data are important in integrated vector management. There are few published documents about the ecology of mosquitoes (Diptera: Culicidae) in western Iran. To study the fauna and ecology of the mosquito larvae of Kurdistan Province, the samples were collected by the dipping method during June-October 2005 and June-August 2006. Larval habitat characteristics were recorded according to habitat type, water conditions (stagnant or running, clear or turbid), water temperature, vegetation (with or without vegetation), and sunlight exposure (full or partial sunlight or shaded). A total of 2096 third- and fourth-instar larvae were collected. Four genera and 11 species were identified: Anopheles claviger (1%), An. maculipennis sensu lato (s.l.) (17.4%), An. superpictus (57.7%), Culex hortensis (1.5%), Cx. mimeticus (2.7%), Cx. perexiguus (0.2%), Cx. pipiens (0.8%), Cx. theileri (12.2%), Culiseta longiareolata (6.1%), Cs. subochrea (0.3%), and Ochlerotatus caspius s.l. (0.1%). Anopheles superpictus, An. maculipennis s.l., and Cx. theileri were the most abundant and widely distributed species. All larvae were collected from natural habitats (river edges or ground pools). There was no significant difference among the mean water temperatures (17.7-26 °C) of the habitats of different species (P = 0.098). The larval habitat characteristics, association occasions, and percentages of each species are discussed.

Comparison of fatty acid contents and composition in major lipid classes of larvae and adults of mosquitoes (Diptera: Culicidae) from a steppe region

Emerging aquatic insects, including mosquitoes, are known to transfer to terrestrial ecosystems specific essential biochemicals, such as polyunsaturated fatty acids (PUFA). We studied fatty acid (FA) composition and contents of dominant mosquito populations (Diptera: Culicidae), that is, Anopheles messeae, Ochlerotatus caspius, Oc. flavescens, Oc. euedes, Oc. subdiversus, Oc. cataphylla, and Aedes cinereus, inhabited a steppe wetland of a temperate climate zone to fill up the gap in their lipid knowledge. The polar lipid and triacylglycerol fractions of larvae and adults were compared. In most studied mosquito species, we first found and identified a number of short-chain PUFA, for example, prominent 14:2n-6 and 14:3n-3, which were not earlier documented in living organisms. These PUFA, although occurred in low levels in adult mosquitoes, can be potentially used as markers of mosquito biomass in terrestrial food webs. We hypothesize that these acids might be synthesized (or retroconverted) by the mosquitoes. Using FA trophic markers accumulated in triacylglycerols, trophic relations of the mosquitoes were accessed. The larval diet comprised green algae, cryptophytes, and dinoflagellates and provided the mosquitoes with essential n-3 PUFA, linolenic, and eicosapentaenoic acids. As a result, both larvae and adults of the studied mosquitoes had comparatively high content of the essential PUFA. Comparison of FA proportions in polar lipids versus storage lipids shown that during mosquito metamorphosis transfer of essential eicosapentaenoic and arachidonic acids from the reserve in storage lipids of larvae to functional polar lipids in adults occurred.

The Identification of Culicine Mosquitoes in the Shadegan Wetland in Southwestern Iran

In order to study the culicine mosquito fauna (Diptera: Culicidae: Culicinae) of the Shadegan wetland in southern Khouzestan Province of Iran, sampling was carried out using hand catch, total catch, and New Jersy light traps, from October 2008 to March 2009. A total of 2664 culicine mosquitoes were captured. Three genera and five species were identified, including Culex pipiens L., Cx. tritaeniorhynchus Giles, Cx. sinaiticus Kirkpatrik, Cx. modestus Ficalbi, Ochlerotatus caspius Pallas and a Culiseta species. All of these species, reported for the first time, were from the Shadegan wetland and Khouzestan Province, and some are medically important.

Mosquito fauna (Diptera: Culicidae) of the Iranian islands in the Persian Gulf II. Greater Tonb, Lesser Tonb and Kish Islands

Mosquitoes of five Iranian islands in the Persian Gulf (Abu-Musa, Greater Tonb, Lesser Tonb, Kish and Qeshm), Hormozgan Province of southern Iran, were studied during 2009 (February and March) and 2010 (April, May and November). Adult mosquitoes were obtained by hand catch, total catch and night landing catch using aspirators and light traps. Larvae were collected by dipping with a 350-ml dipper. In total, 963 adults and 114 third-instar and fourth-instar larvae representing seven species belonging to four genera were collected and identified, including Anopheles stephensi Liston, Culex perexiguus Theobald, Cx. quinquefasciatus Say, Cx. sitiens Wiedemann, Cx. tritaeniorhynchus Giles, Culiseta longiareolata (Macquart) and Ochlerotatus caspius (Pallas) s.l. This is the first record of mosquitoes on the Greater Tonb, Lesser Tonb and Kish Islands.

Host-Feeding Patterns ofCulex pipiensand Other Potential Mosquito Vectors (Diptera: Culicidae) of West Nile Virus (Flaviviridae) Collected in Portugal

The host blood-feeding patterns of mosquito vectors affects the likelihood of human exposure to zoonotic pathogens, including West Nile Virus (family Flaviviridae, genus Flavivirus, WNV). In Portugal, data are unavailable regarding the blood-feeding habits of common mosquito species, including Culex pipiens L., considered the primary vector of WNV to humans. The sources of bloodmeals in 203 blood-fed mosquitoes of nine species collected from June 2007 to November 2010 in 34 Portuguese counties were analyzed by sequencing cytochrome-b partial fragments. Cx. pipiens was the most common species collected and successfully analyzed (n = 135/78). In addition, blood-fed females of the following species were analyzed: Ochlerotatus caspius Pallas (n = 20), Culex theileri Theobald (n = 16), Anopheles maculipennis s.l. Meigen (n = 10), Culiseta longiareolata Macquart (n = 7), Aedes aegypti L. (n = 6), Culex perexiguus Theobald (n = 3), Culiseta annulata Schrank (n = 3), and Ochlerotatus detritus Haliday (n = 3). The Cx. pipiens mosquitoes fed predominantly on birds (n = 55/78, 70.5%), with a high diversity of avian species used as hosts, although human blood was identified in 18 specimens (18/78, 23.1%). No significant differences were found between the host-feeding patterns of blood-fed Cx. pipiens collected in residential and nonresidential habitats. The occurrence of human derived blood meals and the presence of a mix avian-human bloodmeal accordingly suggest this species as a potential vector of WNV. Therefore, in Portugal, Cx. pipiens may play a role both in the avian-to-avian enzootic WNV cycle and in the avian-to-mammal transmission. In this context, the identity of Cx. pipiens (considering the forms molestus and pipiens) and the potential consequence on feeding behavior and WNV transmission are discussed.