Seasonal Dynamics of Mosquito-Borne Viruses in the Southwestern Florida Everglades, 2016, 2017

Mosquitoes were collected for 12 consecutive months beginning June 2016, from 11 locations in the Florida Everglades, Collier County, and tested for viruses by isolation in Vero cells and subsequent identification. One species complex and 31 species of mosquitoes were identified from 668,809 specimens. Ochlerotatus taeniorhynchus comprised 72.2% of the collection. Other notable species were Anopheles crucians complex, Culex nigripalpus, Cx. erraticus, and Cx. cedecei. Seven species of virus were identified from 110 isolations: Everglades, Gumbo Limbo, Mahogany Hammock, Pahayokee, Shark River, Tensaw, and West Nile viruses. Everglades, West Nile, Tensaw, and Mahogany Hammock viruses were most frequently isolated. Largest numbers of viruses were identified from Cx. cedecei, Cx. nigripalpus, and An. crucians complex. Five species of virus were isolated from Cx. cedecei. Viruses were isolated from mangrove, cypress swamp, hardwood hammock, and sawgrass habitats. West Nile virus was isolated August through October when Cx. nigripalpus was most abundant. Everglades virus was the most frequently isolated virus from nine species of mosquitoes collected from June through August. Tensaw virus was isolated primarily from Anopheles species. Isolations were made in July, August, January, February, and April, suggesting that this virus may be present in host-seeking mosquitoes throughout the year. Mahogany Hammock, Shark River, Gumbo Limbo, and Pahayokee viruses were isolated primarily from Cx. cedecei from June through December. Shotgun metagenomic sequencing was used to document that seven pools of Cx. cedecei were infected with two arboviruses. As communities expand into the Everglades, more humans will become exposed to arboviruses.

Molecular phylogeny of heritable symbionts and microbiota diversity analysis in phlebotominae sand flies and Culex nigripalpus from Colombia

Background Secondary symbionts of insects include a range of bacteria and fungi that perform various functional roles on their hosts, such as fitness, tolerance to heat stress, susceptibility to insecticides, reproduction. These endosymbionts could have the potential to shape microbial communites and high potential to develop strategies for mosquito-borne disease control. Methodology/Principal findings The relative frequency and molecular phylogeny of Wolbachia, Microsporidia and Cardinium were determined of phlebotomine sand flies and mosquitoes in two regions from Colombia. Illumina Miseq using the 16S rRNA gene as a biomarker was conducted to examine the microbiota. Different percentages of natural infection by Wolbachia, Cardinium, and Microsporidia in phlebotomines and mosquitoes were detected. Phylogenetic analysis of Wolbachia shows putative new strains of Lutzomyia gomezi (wLgom), Brumptomyia hamata (wBrham), and a putative new group associated with Culex nigripalpus (Cnig) from the Andean region, located in Supergroup A and Supergroup B, respectively. The sequences of Microsporidia were obtained of Pi. pia and Cx. nigripalpus, which are located on phylogeny in the IV clade (terrestrial origin). The Cardinium of Tr. triramula and Ps. shannoni were located in group C next to Culicoides sequences while Cardinium of Mi. cayennensis formed two putative new subgroups of Cardinium in group A. In total were obtained 550 bacterial amplicon sequence variants (ASVs) and 189 taxa to the genus level. The microbiota profiles of Sand flies and mosquitoes showed mainly at the phylum level to Proteobacteria (67.6%), Firmicutes (17.9%) and Actinobacteria (7.4%). High percentages of relative abundance for Wolbachia (30%-83%) in Lu. gomezi, Ev. dubitans, Mi. micropyga, Br. hamata, and Cx. nigripalpus were found. ASVs assigned as Microsporidia were found in greater abundance in Pi. pia (23%) and Cx. nigripalpus (11%). An important finding is the detection of Rickettsia in Pi. pia (58,8%) and Bartonella sp. in Cx. nigripalpus. Conclusions/Significance We found that Wolbachia infection significantly decreased the alpha diversity and negatively impacts the number of taxa on sand flies and Culex nigripalpus. The Principal Coordinate Analysis (PCoA) is consistent, which showed statistically significant differences (PERMANOVA, F = 2.4744; R2 = 0.18363; p-value = 0.007) between the microbiota of sand flies and mosquitoes depending on its origin, host and possibly for the abundance of some endosymbionts (Wolbachia, Rickettsia).

Species complex of mosquitos captured by mechanical traps and an equine host

Field studies were conducted to evaluate the efficacy of commercially available mosquito traps to capture suspected West Nile Virus (WNV) vectors and compare the relative abundance, and species composition of mosquitoes captured by traps. Traps included the Mosquito Magnet (MM) Pro, MM-Liberty, MM-X, the CDC-1012, and the Home and Garden (HGM) prototype trap. In the first study, conducted at the University of Florida Horse Teaching Unit (HTU), Gainesville, FL, from May 17 to September 30, 2002, the CDC-1012 caught significantly more mosquitoes than the other traps. The HGM trap did not catch any mosquitoes and was replaced with a horse on July 17. Percentages of WNV vector species captured in traps and vacuumed from the horse, respectively, were Culex nigripalpus Theobald 85-91% and 27%, and Mansonia titillans (Walker) 2-5% and 40%. In the second study, performed for 5 days in April 2003, the MM-Pro, MM-X, and CDC-1012 traps caught significantly more mosquitoes than did the MM-Liberty trap. All traps captured primarily Cx. salinarius Coquillett, Cx. erraticus (Dyar and Knab), and Anopheles crucians Wiedemann. The horse attracted a greater percentage of Ma. titillans and less Cx. erraticus than did the mechanical traps. The mechanical traps may offer horses some degree of protection from suspected WNV species, however, a large number of Ma. titillans were recovered from the horse but the traps captured very few.

Mosquito Communities Vary across Landscape and Vertical Strata in Indian River County, Florida

Mosquito and arbovirus surveillance is essential to the protection of public health. A majority of surveys are undertaken at ground level. However, mosquitoes shelter, breed, and quest for hosts across vertical strata, thus limiting our ability to fully describe mosquito and arboviral communities. To elucidate patterns of mosquito vertical stratification, canopy traps were constructed to sample mosquitoes at heights of 1.5, 5.0, and 8.7 m across three different landscape types in a Florida coastal conservation area. We assessed trapping efforts using individual-based rarefaction and extrapolation. The effects of height, landscape, site location, and sampling date on mosquito community composition were parsed out using permutational ANOVA on a Hellinger-transformed Bray–Curtis dissimilarity abundance matrix. Lastly, a generalized linear mixed effects model (GLMM) was used to explore species-specific vertical patterns. We observed differences in sampling effort and community composition structure across various heights and landscapes. Our GLMM revealed significant effects of trap height for Aedes taeniorhynchus, Anopheles crucians, Anopheles quadrimaculatus, and Culex coronator, but not for Culex nigripalpus, the ultra-dominant species present in this area. Together these data provide evidence that height and landscape significantly affect mosquito community structures and highlight a need to develop sampling regimes to target specific vector and nuisance species at their preferred height and across different landscape types.

Culex nigripalpus Distribution Expansion: First Record in Virginia, New County Records in North Carolina, and Revised United States Map

ABSTRACT Theobald first described Culex nigripalpus in 1901 from St. Lucia Island of the Lesser Antilles. It is a Neotropical mosquito species that is documented throughout Central and South America, the Caribbean, and the southeastern USA. Reports within the last 3 decades show the species has expanded its range farther into North America and is not only being discovered sporadically but appears to be establishing itself in several states, of which data are underreported and difficult to find. Five female specimens were collected—4 on October 13 and 1 on December 6, 2017—at 3 separate sites in the city of Suffolk, VA—2 in a BG-Sentinel 2® trap, 3 in Centers for Disease Control and Prevention light traps—during routine mosquito surveillance; subsequent collections were made in 2019 and 2020. These findings represent the 1st record of Cx. nigripalpus in the state of Virginia and the most northeastern records in the USA. An updated mosquito species checklist for the state of Virginia is provided. Additionally, this report serves to update the records of North Carolina to 28 total counties reporting Cx. nigripalpus. These new records, along with other reports and published studies, show this species now documented in 201 jurisdictions in 16 states of the USA. As recent literature on this species is scarce, we provide a review of the bionomics, defining morphological characters, and an updated US distribution map.

Ecological characterization of mosquitoes (Diptera: Culicidae) in areas of the Mato Grosso Pantanal, Mato Grosso State, Brazil

Bimonthly diurnal and nocturnal captures were conducted in four different sampling sites of the Mato Grosso Pantanal region over 24 consecutive months between March 2009 and January 2011. The goal of performing these collections was to elucidate aspects of the biology and ecology of mosquitoes in this region since little to nothing is known about these aspects for many species. A total of 17,532 specimens were captured, comprising two subfamilies, nine genera, and 44 species. The main species of culicids found in the Mato Grosso Pantanal had strong ecological compatibility with well-preserved environments and with some of the specific habitats found in at least one of the four selected collection sampling sites. Anopheles darlingi, An. albitarsis, and An. triannulatus are well-suited to environments with large water bodies and greater anthropic activity. Culex nigripalpus and Cx. quinquefasciatus prefer environments with bush fragments and pronounced human action and movement. Culex declarator and Psorophora albigenu, the most eclectic, prefer wild areas and with some anthropic activity. Mansonia titillans is associated with environments offering a wide variety of natural breeding areas that enable its development, in particular natural swamp areas covered with macrophytes, which is one of the natural components of the Pantanal biome. The effect of the flooding season on the population density of anophelines is especially advantageous, with an explosion in the number of individuals in periods of widespread flooding. The region’s environmental dynamics are regulated by flooding cycles with alternating periods of flooding and drought, which are the main factors governing the ecology of the local fauna and flora. Flooding periods contribute to raising culicid species’ richness and diversity, while the droughts result in a more even distribution of specimens within species. The flooding season of the Pantanal occurs between November and May and coincides with the greatest abundance of culicid species. During this period, the human population of the region has greater contact with mosquito vectors carrying pathogens, including arboviruses, which previous studies have confirmed via seropositivity in the region’s equines and birds.

EVALUATION OF MULTIPLE TRAP TYPES FOR THE CAPTURE OF VECTOR MOSQUITOES OF EASTERN EQUINE ENCEPHALITIS VIRUS IN SAINT JOHNS COUNTY, FLORIDA

Eastern equine encephalitis virus (EEEV) is a highly dangerous alphavirus vectored by multiple mosquito species in the United states. Vector surveillance and control is used to prevent the spread of EEEV, so highly efficient and attractive traps are needed to accurately assess mosquito abundance. Mosquitoes can be captured in various physiological states (host-seeking, gravid, resting, etc.), depending on what trap type is used. this study analyzed 6 trap types to determine which captured the most EEEV vectors in saint Johns county. the trap types analyzed were the biogents sentinel trap, centers for Disease control (cDc) Light trap, the sentinel Mosquito Arbovirus capture Kit, Mosquito Magnet X trap, cDc resting trap, and gravid traps. For the gravid traps, two different infusions were tested: hay infusion and cattail infusion. Aedes atlanticus Dyar and Knab was the most abundant EEEV vector captured in this study. Other EEEV vectors collected were Aedes vexans (Meigen), Culex erraticus (Dyar and Knab), and Culex nigripalpus theobald. bG traps caught the highest abundance of EEEV vectors (1520 ± 743) compared to all the other trap types analyzed. Despite capturing multiple EEEV vectors during the testing period at the chosen site, Culiseta melanura (coquillett) and Coquillettidia perturbans (Walker) were never captured.

Fighting the Bite during a Crisis: Capabilities of Florida Mosquito Control Districts during the COVID-19 Pandemic

Background: The national wide lockdown order imposed in early April 2020 due to the COVID-19 pandemic complicated mosquito control activities across the United States (US), and Florida is no exception. Mosquito control programs are the first line of defense against mosquitoes-borne pathogens in the state of Florida. The purpose of this study was to examine the capabilities of Florida mosquito programs to implement key mosquito measures during the COVID-19 pandemic.Methods: In a self-administered online survey, we examined capabilities of all Florida mosquito control programs during the COVID-19 pandemic (both state-approved mosquito districts (N=63) and open programs (N=27). Descriptive statistics were used to summarize information about the characteristics of responding programs, as well as the implemented mosquito control and surveillance activities. We used bivariate analysis to compare the characteristics of these responding programs and the self-reported mosquito measures.Results: Of the recruited mosquito control programs, 77 completed the survey (85.6% response rate; 77/90). Of these, 57.5% (n=42) were Board of County Commissioners (BOCC) mosquito control programs, 21.9% (n=16) were independent tax district programs, 13.7% (n=10) were municipal mosquito control programs, and only 6.8% (n=5) were either health or emergency department mosquito control programs. Except for arbovirus surveillance, most programs either fully or partially performed larval (61.8%) and adult (78.9%) surveillance; and for Aedes aegypti (85.2%, n=54), Aedes albopictus (87.3%, n=55), Culex quinquefasciatus (92.1%, n=58), and Culex nigripalpus (91.9%, n=57).Conclusions: Findings underscore the importance of ongoing mosquito control activities and suggests that Florida mosquito control programs are vigilant and have significant capability to handle potential mosquito-borne disease threats, but arbovirus surveillance systems; laboratory testing of mosquito pools and testing of human and nonhuman specimens for arboviruses are needed during pandemics as well.

ESPECIES DE MOSQUITOS (DÍPTERA: CULICIDAE) REGISTRADOS EN CAMAGÜEY (CUBA), 2007-2014.

El objetivo de la investigación fue informar las especies de culícidos registradas en la provincia de Camagüey (Cuba) entre el 2007 y el 2014, vinculándolas con aspectos bioecológicos, para lo cual se realizó un estudio descriptivo retrospectivo mediante revisión documental del libro de registro de muestras del Laboratorio Provincial de Entomología Médica de Camagüey, cuyos datos son el resultado de inspecciones intra y peridomiciliar en el 100% del universo urbano y rural lo que incluye viviendas, terrenos baldíos y criaderos naturales, En total se han colectado 12 géneros con 35 especies, destacándose Aedes aegypti (Linnaeus, 1762), Anopheles albimanus (Wiedemann, 1821), Culex nigripalpus (Theobald, 1901) y Culex quinquefasciatus (Say, 1823) con las mejores distribuciones, siendo los municipios con mayor diversidad de especies Jimaguayú, Minas, Camagüey, Nuevitas y Guáimaro. Se registró como nueva para la provincia a Ochlerotatus condolescens.

Taxonomy, ecology and distribution of the mosquitoes (Diptera: Culicidae) of the Dutch Leeward Islands, with a key to the adults and fourth instar larvae

Assessing mosquito biodiversity is important for disease surveillance and ecosystem health assessments. Such studies are particularly needed in regions like the Caribbean, which have experienced a series of recent mosquito borne disease outbreaks but received little attention regarding its invertebrate biodiversity. Here, we report on results from a mosquito survey on the Dutch Leeward Islands (Sint Eustatius, Sint Maarten and Saba), carried out in April and October 2018, which is the first integrative survey since those conducted by Van der Kuyp (1947) and Wagenaar Hummelinck (1949). Moreover, we present a novel key for adults and fourth instar larvae of the mosquitoes of the Dutch Leeward Islands. Overall, eleven species were recorded, eight on Sint Maarten, five on Saba and two on Sint Eustatius. Two new potential disease vectors, Culex nigripalpus and Aedes taeniorhynchus, were recorded on Sint Maarten. One previously recorded species, Cx. habilitator, was not retrieved from any of the islands, which is further discussed in the paper. Species indicative of natural forest which previously occurred on all three islands were absent from Sint Eustatius and Sint Maarten but still present on Saba. In contrast, species indicative of human inhabitation, Ae. aegypti and Cx. quinquefasciatus, were highly abundant on Sint Maarten and Sint Eustatius and present in low numbers on Saba. Overall, the results of this study emphasize the importance of biodiversity surveys and indicate that frequent mosquito inventories may contribute to a better understanding of mosquito community composition and distribution of potential vector species.