Diversity and molecular characterization of insect-specific flaviviruses in mosquitoes (Diptera: Culicidae) collected in central and northern Argentina.

The genus Flavivirus comprises approximately 80 different viruses. Phylogenetic relationships among its members indicate a clear ecological separation between those viruses transmitted by mosquitoes, ticks, with no known vector, and insect-specific Flaviviruses. The diversity and phylogenetic relationships among insect-specific flaviviruses circulating in the central and northern regions of Argentina were studied by performing molecular detection and characterization of the NS5 protein gene in mosquitoes collected in Córdoba, Chaco and Tucumán provinces. Overall, 68 out of 1776 pools were positive. CxFV, KRV and CFAV circulate in the 3 studied provinces. Several mosquito species (Aedes aegypti, Culex bidens, Cx. dolosus, Cx. interfor, Cx. quinquefasciatus, Cx. saltanensis, Haemagogus spegazzini) were found infected. A wide circulation of CxFV was observed in the central-northern region of Argentina. CxFV strains detected in our study clustered with strains circulating in Santa Fe and Buenos Aires provinces (Argentina), and other countries such as Indonesia, Mexico, Uganda and Taiwan. The presence of these viruses in mosquitoes could play an important role from the public health perspective, because it has been shown that previous CxFV infection can increase or block the infection of the mosquito by other pathogenic flaviviruses.

Updated Anopheles mosquitos abundance and distribution in north-eastern malaria-free area of Argentina.

Malaria is the most important parasitic disease worldwide. In 2019, more than 679,441 cases of malaria were reported in the American region. During this study, Argentina was in malaria pre-elimination autochthonous transmission phase with the aim of being declared as malaria-free country. The aim of this work was to assess the influence of remote sensing spectral indices (NDVI, NDWI) and climatic variables (temperature, relative humidity and precipitation) on the distribution and abundance of Anopheles mosquitoes, in four localities with different degrees of anthropogenic disturbance and with previous malaria cases records located , in a historical malarious area in northeastern of Argentina. Between June 2012 and July 2014, mosquitoes were collected. We collected 535 Anopheles adult mosquitoes. Anopheles strodei s.l. was the most abundant species. The greatest richness, diversity and abundance of species were registered in wild and semi-urban environments. The abundance of Anopheles presented a negative association with relative humidity and mean temperature, but positive with mean maximum temperature. The most important variables determining Anopheles total abundance and distribution were NDWI Index and distance to vegetation. The abundance of An. strodei s.l., was positive associated with water areas whereas the NDVI Index was negatively associated.

Satellite observation to assess dengue risk due to Aedes aegypti and Aedes albopictus in a subtropical city of Argentina.

Earth observation environmental features measured through remote sensing and models of vector mosquitoes species Aedes aegypti and Ae. albopictus provide an advancement with regards to dengue risk in urban environments of subtropical areas of Argentina. The authors aim to estimate the effect of landscape coverage and spectral indices (Normalized Difference Vegetation Index [NDVI], Normalized Difference Water Index [NDWI] and Normalized Difference Built-up Index [NDBI]) on the larvae abundance of Ae. aegypti and Ae. albopictus in Eldorado, Misiones, Argentina using remote satellite sensors. Larvae of these species were collected monthly (June 2016 to April 2018), in four environments: tire repair shops, cemeteries, dwellings and an urban natural park. The proportion of landscape coverage (water, urban areas, bare soil, low vegetation and high vegetation) was determined from the supervised classification of Sentinel-2 images and spectral indices, calculated. The authors developed spatial models of both vector species by generalized linear mixed models. The model's results showed that Ae. aegypti larvae abundance was better modelled by NDVI minimum values, NDBI maximum values and the interaction between them. For Ae. albopictus proportion of bare soil, low vegetation and the interaction between both variables explained better the abundance.

Abiotic factors affecting the prevalence of Wolbachia (Rickettsiaceae) in immature Aedes albopictus (Skuse) (Culicidae).

Wolbachia is a genus of gram-negative endosymbiotic bacterium of maternal transmission, located mainly in the gonads of arthropods, including mosquitoes such as Aedes albopictus. The current distribution of Ae. albopictus in Argentina is restricted to the subtropical northeastern region of the country. Here, we studied the seasonal prevalence of Wolbachia detected in Ae. albopictus larvae and the relationship between the abiotic factors of the larval microhabitat and the infection status, in Eldorado city, Misiones province, subtropical region. The prevalence of Wolbachia infection found was 76.89% (n = 312). From the total samples examined, 52.80% (n = 214) showed double infection with the wAlbA/wAlbB strains, 23.84% (n = 97) infection only with wAlbB, and 0.25% (n = 1) only with wAlbA. The prevalence of double infection did not present statistically significant differences between the sites studied. For single infection, the lowest prevalence value of the wAlbB strain (13.33%) was found in the natural park, whereas the highest was found in the family dwellings and cemeteries. Tire repair shops showed an intermediate value. The wAlbA single infection was identified once. Our results also showed an association between temperature and slightly turbid waters with exposure to the sun in the larval habitats and the probability of infection by Wolbachia.

Presence of Ascogregarina culicis and Ascogregarina sp. in natural sympatric populations of Aedes aegypti and Ae. albopictus (Diptera: Culicidae) in Argentina.

Aedes aegypti is the main vector of the four arboviruses in America which have the greatest impact on human health. The introduction of Aedes albopictus in South America and Argentina acquires importance given the possibility that this species may be a new vector of arboviruses in this region. For this reason, the studies of the biology of their parasites, such as Ascogregarina spp., should be important for the knowledge of the invasive behavior of these vectors. We reported the finding of Ascogregarina culicis in Aedes aegypti and Ascogregarina sp. in Ae. albopictus populations in subtropical Argentina. The prevalence of parasitism by A. culicis in Ae. aegypti and Ascogregrarina sp. in Ae. albopictus was 34.81% (n = 464) and 37.23% (n = 70), respectively, differing between the seasons and habitats. The infection intensity caused by A. culicis and Ascogregarina sp. varied between 1 to 250 and 1 to 327 trophozoites respectively. Ascogregarina culicis was found throughout the all sampling period of Ae. aegypti (June 2016-April 2018). However the presence of Ascogregarina sp. in the midgut of Ae. albopictus was not recorded throughout the whole sampling period despite the presence of the host.

Environmental effects on phlebotominae sand flies (Diptera:Phychodidae) and implications for sand fly vector disease transmission in Corrientes city, northern Argentina.

We evaluated species richness, abundance, alpha diversity, and true diversity of Phlebotominae sand flies temporal changes in domiciles within the northern Argentina city of Corrientes. A total of 16 sampling nights were conducted seasonally throughout the years 2012-2014 through light traps supplemented with CO2. Meteorological and remote sensing environmental factors were used to assessed for vectors implications in disease transmission through Generalized Mixt Models. Lutzomyia longipalpis was the most abundant and common species, followed by Nyssomyia neivai and Migonemyia migonei. Lutzomyia longipalpis was more abundant in urban areas, Ny. neivai was associated with vegetation in periurban areas, both were found all sampling years with higher abundance during the rainy season. Positive association of Lu. longipalpis with precipitation and relative humidity and negative association with temperature were observed. Models showed humidity and vegetation as making effects on Lu. longipalpis abundance. Precipitation was significant for Mg. migonei models, with higher abundance in periurban and periurban-rural environments. For Ny. neivai models, relative humidity was the most important variable, followed by precipitation frequency. Our findings led to identify high risk areas and develop predictive models. These are useful for public health stakeholders giving tolls to optimized resources aim to prevent leshmaniasis transmission on the area.

Cold Season Mortality Under Natural Conditions and Subsequent Hatching Response of Aedes (Stegomyia) aegypti (Diptera: Culicidae) Eggs in a Subtropical City of Argentina.

In temperate and subtropical regions, populations of Aedes (Stegomyia) aegypti (L.) survive unfavorable winter conditions in the egg stage. Knowing their survival rates can be of great interest for the health authorities in charge of control activities. In this study, we analyzed the mortality of Ae. aegypti eggs exposed to the cold season as well as their hatching patterns under laboratory conditions in the city of Resistencia, Chaco, Argentina. The mortality rate was 48.6%. No statistically significant differences were observed in the mortality of eggs exposed at different sites. Hatching response differed significantly among the successive postexposure immersions, with the highest proportion of hatched eggs during the first immersion. These results show that the mortality rate of Ae. aegypti eggs exposed to the cold season in a subtropical city of Argentina was higher than those from temperate climate region. The additional mortality of eggs in our study might be related to fungal development (an unexpected event), which was not observed in research in temperate climate. The hatching pattern observed in this study ensures a rapid increase of the population at the beginning of the favorable breeding season, but it also maintains a batch with delayed hatching eggs, posing a risk for the community.

A genotyping array for the globally invasive vector mosquito, Aedes albopictus.

BACKGROUND: Although whole-genome sequencing (WGS) is the preferred genotyping method for most genomic analyses, limitations are often experienced when studying genomes characterized by a high percentage of repetitive elements, high linkage, and recombination deserts. The Asian tiger mosquito (Aedes albopictus), for example, has a genome comprising up to 72% repetitive elements, and therefore we set out to develop a single-nucleotide polymorphism (SNP) chip to be more cost-effective. Aedes albopictus is an invasive species originating from Southeast Asia that has recently spread around the world and is a vector for many human diseases. Developing an accessible genotyping platform is essential in advancing biological control methods and understanding the population dynamics of this pest species, with significant implications for public health. METHODS: We designed a SNP chip for Ae. albopictus (Aealbo chip) based on approximately 2.7 million SNPs identified using WGS data from 819 worldwide samples. We validated the chip using laboratory single-pair crosses, comparing technical replicates, and comparing genotypes of samples genotyped by WGS and the SNP chip. We then used the chip for a population genomic analysis of 237 samples from 28 sites in the native range to evaluate its usefulness in describing patterns of genomic variation and tracing the origins of invasions. RESULTS: Probes on the Aealbo chip targeted 175,396 SNPs in coding and non-coding regions across all three chromosomes, with a density of 102 SNPs per 1 Mb window, and at least one SNP in each of the 17,461 protein-coding genes. Overall, 70% of the probes captured the genetic variation. Segregation analysis found that 98% of the SNPs followed expectations of single-copy Mendelian genes. Comparisons with WGS indicated that sites with genotype disagreements were mostly heterozygotes at loci with WGS read depth < 20, while there was near complete agreement with WGS read depths > 20, indicating that the chip more accurately detects heterozygotes than low-coverage WGS. Sample sizes did not affect the accuracy of the SNP chip genotype calls. Ancestry analyses identified four to five genetic clusters in the native range with various levels of admixture. CONCLUSIONS: The Aealbo chip is highly accurate, is concordant with genotypes from WGS with high sequence coverage, and may be more accurate than low-coverage WGS.

Culicidae (Diptera) selection of humans, chickens and rabbits in three different environments in the province of Chaco, Argentina.

Studies were conducted to determine the selection of humans, chickens and rabbits by Culicidae in three different environments in the province of Chaco, Argentina. Mosquitoes were collected fortnightly using cylindrical metal traps containing animal bait (chickens and rabbits). The mosquitoes were collected between June 2001-May 2002. During the same period and with the same frequency, mosquitoes biting the human operators of the traps were collected during the first 15 min of exposure within different time intervals: from 09:00 am-11:00 am, 01:00 pm-03:00 pm, 05:00 pm-07:00 pm and 09:00 pm-10:00 pm. A total of 19,430 mosquitoes of 49 species belonging to 10 genera were collected. Culex species mainly selected chicken bait and Wyeomyia species selected rabbit bait. Ochlerotatus and Psorophora species were more abundant in rabbit-baited traps. Anopheles triannulatus, Coquillettidia nigricans, Ochlerotatus scapularis, Mansonia titillans and Psorophora albigenu showed a strong attraction for human bait. The Anopheles, Coquillettidia, Culex and Mansonia species were more active between 05:00 pm-09:00 pm, while Ochlerotatus, Psorophora, Haemagogus and Wyeomyia were most active from 09:00 am-07:00 pm. This study provides additional information about the biology and ecology of arbovirus vectors in Chaco.

Description of male, pupa and larva of Psorophora (Grabhamia) paulli and redescription of the female (Diptera: Culicidae).

The female of Psorophora (Grabhamia) paulli Paterson & Shannon is redescribed, and the pupa, fourth-instar larva and male genitalia are described and illustrated for the first time. Information about the distribution, bionomics and taxonomy is also included. Adults of Ps. paulli can be separated from the other species of the genus and subgenus by its small size. The larva of Ps. paulli is similar to that of Ps. varinervis Edwards and Ps. discolor (Coquillett) but can be separated based on the development of setae 1-X and 5-VIII, the length of the anal papillae and the comb on a sclerotized area.

New records of mosquito species in the provinces of Chaco and Formosa, Argentina.

Seven mosquito species are recorded for the 1st time for northeastern Argentina: Culex (Melanoconion) albinensis, Cx. (Mel.) elevator, Cx. (Mel.) intrincatus, and Cx. (Mel.) serratimarge for Formosa Province, and Sabethes (Peytonulus) undosus, Sa. (Sabethinus) melanoninphe, and Toxorhynchites (Lynchiella) theobaldi for Chaco Province. The geographical distribution of these species is extended to northeastern Argentina, and the number of species increases to 97 and 75 for the provinces of Chaco and Formosa, respectively.

New records of mosquitoes from northwestern Argentina.

Eleven mosquito species, namely Aedes hastatus, Ae. fulvus, Coquillettidia albicosta, Cq. juxtamansonia, Culex aliciae, Cx. delpontei, Cx. oedipus, Cx. pedroi, Mansonia flaveola, Uranotaenia leucoptera, and Wyeomyia oblita, are recorded for the first time from northwestern Argentina. In addition, 3 species, Cx. brethesi, Limatus durhami, and Ur. nataliae, are reported for the first time from Salta Province. These records extend the geographical distribution of these 3 species to Salta Province. This study also extends the geographical distributions of Cq. nigricans, Cx. chidesteri, and Ma. humeralis to Jujuy Province and of Ae. meprai, Ae. milleri, Ae. oligopistus, Cx. brethesi, Cx. fernandezi, and Cx. tatoi to Tucumán Province.

Morphological Description of the Female, Pupa, and Fourth-Instar Larva and Redescription of the Male of Culex (Melanoconion) aliciae (Diptera: Culicidae).

The female, pupa, and fourth-instar larva of Culex (Melanoconion) aliciae are described for the first time, and the male is redescribed. The cibarium, female and male genitalia, pupa, and fourth-instar larva are illustrated. Information on distribution, bionomics, and taxonomy is also included. Males of Cx. aliciae Duret and Cx. martinezi Casal & Garcia are indistinguishable, except for the appearance of the ninth tergal lobes. The female of Culex martinezi has not been described before. The females of Culex aliciae can be recognized by characteristics of the occipital scales, cibarium, and genitalia. The larva of Cx. aliciae and Cx. martinezi can be distinguished from characters of the thorax and abdomen.

Description of Larva and Pupa of Psorophora (Grabhamia) dimidiata (Diptera: Culicidae) and Redescription of the Adult Female and Male.

Psorophora (Grabhamia) dimidiata Cerqueira (1943) was described based on the adult female and male. Later, descriptions of the male and female genitalia were published by Lane (in Neotropical Culicidae, vols. I & II. Editora da Universidade de São Paulo, S. P., Brazil, 1953) and Guedes et al. (in Catalogo ilustrado dos mosquitos da coleção do Instituto Nacional de Endemias Rurais. I. Gênero Psorophora Robineau-Desvoidy, 1827. Rev. Bras. Malariol. Doencas Trop. 12: 3-24; 1965), respectively. Here we describe the pupa and fourth-instar larva and redescribe the adult male and female genitalia and female cibarium. All stages (except the egg) are illustrated. Unambiguous recognition is provided. Distinctions from Ps. cingulata (Fabricius) and possible phylogenetic relationships are discussed.

New Records of Mosquitoes in Bolivia and Northwestern Argentina.

Two mosquito species, Culex (Culex) hepperi and Culex (Culex) maxi are reported for the first time for Bolivia, in Tarija department. Aedes (Ochlerotatus) stigmaticus and Mansonia (Mansonia) indubitans are the first records in Aniceto Arce province, in Tarija department, southern Bolivia. In addition, Aedes (Protomacleaya) alboapicus and Culex (Phytotelmatomyia) renatoi are reported for the first time in the northwestern region of Argentina. Anopheles (Nyssorrhynchus) nuneztovari s.l. is reported for the first time in Jujuy and Tucumán provinces, and Aedes (Ochlerotatus) raymundi and Anopheles (Anopheles) neomaculipalpus are the first reports in Tucumán province. The 3 species are extending their geographical distribution in these provinces. Data on the collection localities and comments about the medical relevance of some species are also presented.

Classification of immature mosquito species according to characteristics of the larval habitat in the subtropical province of Chaco, Argentina.

To classify mosquito species based on common features of their habitats, samples were obtained fortnightly between June 2001-October 2003 in the subtropical province of Chaco, Argentina. Data on the type of larval habitat, nature of the habitat (artificial or natural), size, depth, location related to sunlight, distance to the neighbouring houses, type of substrate, organic material, vegetation and algae type and their presence were collected. Data on the permanence, temperature, pH, turbidity, colour, odour and movement of the larval habitat's water were also collected. From the cluster analysis, three groups of species associated by their degree of habitat similarity were obtained and are listed below. Group 1 consisted of Aedes aegypti. Group 2 consisted of Culex imitator, Culex davisi, Wyeomyia muehlensi and Toxorhynchites haemorrhoidalis separatus. Within group 3, two subgroups are distinguished: A (Psorophora ferox, Psorophora cyanescens, Psorophora varinervis, Psorophora confinnis, Psorophora cingulata, Ochlerotatus hastatus-oligopistus, Ochlerotatus serratus, Ochlerotatus scapularis, Culex intrincatus, Culex quinquefasciatus, Culex pilosus, Ochlerotatus albifasciatus, Culex bidens) and B (Culex maxi, Culex eduardoi, Culex chidesteri, Uranotaenia lowii, Uranotaenia pulcherrima, Anopheles neomaculipalpus, Anopheles triannulatus, Anopheles albitarsis, Uranotaenia apicalis, Mansonia humeralis and Aedeomyia squamipennis). Principal component analysis indicates that the size of the larval habitats and the presence of aquatic vegetation are the main characteristics that explain the variation among different species. In contrast, water permanence is second in importance. Water temperature, pH and the type of larval habitat are less important in explaining the clustering of species.

New records of mosquito species in the province of Formosa, northeastern region of Argentina.

Six species are recorded for the 1st time in Formosa province, northeast region of Argentina: Culex delpontei, Cx. eduardoi, Cx. maxi, [corrected] and Toxorhynchites theobaldi, increasing the number of species of that province to 73.

Hatching pattern and coexistence of Aedes aegypti and Aedes albopictus (Culicidae) in a subtropical city, Argentina, after three decades of coexistence.

Aedes aegypti and Aedes albopictus are mosquito vectors of numerous arboviruses of sanitary importance. Presently in Argentina, neither Ae. aegypti nor Ae. albopictus, have displaced the other species in the places where they coexist, since the introduction of the latter in 1998. In this study, we evaluated whether these species coexist at different scales (ovitrap, microhabitat and habitat) in the city of Eldorado, Misiones province, northeast Argentina. We also analyzed the seasonal variation and climate variables related to the delay in egg hatching of both species. Mosquitoes were collected weekly, from June 2017 to May 2018, using ovitraps placed in urban areas. We conclude that Ae. aegypti and Ae. albopictus coexist in the study area, at the ovitrap, microhabitat and habitat scales. Furthermore, no pronounced pattern of delayed hatching has been observed for either species; however, eggs of Ae. albopictus laid during colder weeks and less rainfall needed a greater number of immersions to hatch, while for Ae. aegypti those laid during weeks with low rainfall and high temperatures showed the longest delay in hatching response.

Two new mosquito species and six new provincial records in Argentina.

ABSTRACT. The geographical distribution of Aedes pennai, Anopheles galvaoi, Coquillettidia albicosta, Cq. nigricans, Culex usquatissimus, Cx. apicinus, Cx. chidesteri, Cx. coronator s.l., Cx. interfor, Cx. maxi, Cx. pipiens, Cx. saltanensis, Cx. educator, Cx. serratimarge, Cx. theobaldi, Psorophora cyanescens, Ps. cilipes, Ps. cingulata, Ps. pallescens, Uranotaenia lanei, Ur. nataliae, Wyeomyia diabolica, and Wy. melanocephala is extended, including new records for 6 provinces and 2 new records for the country, increasing the number of species in Argentina from 226 to 228.

Meteorological variables associated with the temporal oviposition rate of Aedes aegypti (Diptera: Culicidae) in Resistencia city, Chaco province, Northeastern Argentina.

Aedes aegypti is the main vector of dengue virus in South America. In the last fifteen years, Argentina has suffered three large dengue outbreaks: one in 2009, another one in 2016 and the current 2020 outbreak, with 26,000, 66,000 and more than 43,000 confirmed cases, respectively. These outbreaks are associated with the circulation of the virus in neighboring countries due to the constant movement of people across the frontier. In 2009, the main province affected was Chaco province, with 11,037 confirmed cases (50% of total cases). Thus, the aim of this study was to characterize the temporal oviposition rate of Aedes aegypti in Resistencia, the capital city of this province, in relation to meteorological variables. Mosquitoes were sampled weekly, from April 2015 to March 2017, using ovitraps located in houses randomly selected within the urban area. Oviposition rate was evaluated by means of the total number of eggs collected per week and the proportion of positive ovitraps per week. The coefficient of variation for these two indicators was estimated for the whole study period and then compared using the Wilcoxon Pair test. A generalized linear model (GLM) was performed to infer association between meteorological variables and oviposition rate without time lag and with a time lag of 1 to 4 weeks, considering the biology of this mosquito species. Comparisons between the coefficient of variation of egg number versus the proportion of positive ovitraps showed significant differences, being the former more variable than the latter. The most significant time lag was 2 weeks for the minimum temperature. The number of Ae. aegypti eggs increased 4.05 times when the minimum temperature increased 1°C two weeks before, and decreased 0.69 times with an increase of 1 unit in relative humidity. No eggs were collected when the temperature was below 8°C. The oviposition rate was associated with the increase in the critical minimum temperature (over 8°C) and the weekly frequency of precipitation and dissociated with relative humidity. The maximum oviposition rate was recorded between November and January of both years. The GLM could not explain the relation between meteorological variables and the proportion of positive ovitraps. The peaks of Ae. aegypti egg abundance occurred simultaneously with dengue autochthonous cases recorded in Chaco province, resulting in a good indicative of the period of greatest epidemiological risk.