Black Salt-marsh Mosquito Research Articles

BASELINE SUSCEPTABILITY AND FIRST OBSERVATION OF KNOCKDOWN RESISTANCE IN AEDES TAENIORHYNCHUS POPULATION OF ST. JOHNS COUNTY, FLORIDA.

The black saltmarsh mosquito, Aedes taeniorhynchus, is a prominent nuisance mosquito within St. Johns County, Florida. Due to their characteristically large outbreaks, and the elevated amount of insecticide application correlated with the outbreaks, local populations of Ae. taeniorhynchus are at an increased risk of developing insecticide resistance. This study was established to form a baseline susceptibility of Ae. taeniorhynchus against two technical grade materials, permethrin, and chlorpyrifos. Centers for Disease Control and Prevention bottle bioassays were conducted with technical-grade materials during two outbreaks in the fall of 2023. Results indicated a baseline susceptibility against the materials tested, but most notably, the phenotypic expression of knockdown resistance (kdr) was observed. Results highlight the need for continued monitoring and investigation into the resistance status and resistance level of this common Florida species.

BASELINE SUSCEPTIBILITY AND EFFECTIVENESS OF ADULTICIDES TO LOCAL AEDES TAENIORHYNCHUS FROM COLLIER COUNTY, FLORIDA.

The black salt marsh mosquito, Aedes taeniorhynchus, is the primary nuisance mosquito in the coastal regions of Florida. This study aimed to establish the baseline susceptibility of Ae. taeniorhynchus to adulticide products used for mosquito control by the Collier Mosquito Control District (CMCD). The Centers for Disease Control and Prevention bottle bioassay was used to test technical-grade and formulated products, and Merus 3.0® was evaluated in semifield cage trials through aerial applications. The results revealed the baseline susceptibility of Ae. taeniorhynchus to the tested materials and the effectiveness of Merus 3.0 to effectively control the Ae. taeniorhynchus. The study provides important information for the development of an integrated mosquito management strategy for controlling Ae. taeniorhynchus mosquito populations in southwest Florida.

The Impact of Hurricane Irma on Population Density of the Black Salt-Marsh Mosquito,Aedes taeniorhynchus, in Collier County, Florida

In 2017, the southeastern USA and Caribbean endured an extremely active year for tropical storm and hurricane activity. On September 10, 2017, Hurricane Irma made a 2nd landfall in Florida, striking Collier County-including Naples and Marco Island, FL. Areas affected by Hurricane Irma are abundant in salt-marsh and mangrove swamps, prime habitats for the black salt-marsh mosquito, Aedes taeniorhynchus. Using both human landing rate and Biogents BG-Counter trap data, here we report the year-to-year fluctuations in population density of Ae. taeniorhynchus. In 2017, Collier County experienced a population explosion of Ae. taeniorhynchus, with daily landing rates reaching as high as 150 adult females/2-min period. The following year a dramatic population crash of Ae. taeniorhynchus was observed, representing some of the lowest Ae. taeniorhynchus numbers ever recorded in Collier County. Analysis of human landing rate and trap data following major hurricane strikes, including Hurricane Irma (2017) and Hurricane Wilma (2005), have revealed severe reductions in Ae. taeniorhynchus populations. Because Ae. taeniorhynchus accounts for a large majority of adulticiding missions in the state of Florida, an enhanced understanding of the factors contributing to Ae. taeniorhynchus population dynamics may allow for improved operational planning and decision-making.

Black salt marsh mosquito Aedes taeniorhynchus (Wiedemann) (Insecta: Diptera: Culicidae)

The black salt marsh mosquito is very common in the eastern coastal areas of the Americas, and is responsible for a large part of mosquito insecticide applications in Florida. Although it is not a primary vector of major concern, it can transmit pathogens to humans and other animals. Its characteristic emergence in large numbers after rains and flooding events as well as its aggressive biting contribute to its notoriety as a pest insect. The black salt marsh mosquito is considered a nuisance in Florida. It is sheltered from large-scale mosquito control as part of the Everglades National Park conservation program to preserve their delicate ecosystem. This 7-page fact sheet was written by Natasha Marie Agramonte and C. Roxanne Connelly, and published by the UF Department of Entomology and Nematology, April 2014.
 EENY591/IN1035: Black Salt Marsh Mosquito Aedes taeniorhynchus (Wiedemann) (Insecta: Diptera: Culicidae) (ufl.edu)

Host selection and parasite infection in Aedes taeniorhynchus, endemic disease vector in the Galápagos Islands

Host selection in blood-sucking arthropods has important evolutionary and ecological implications for the transmission dynamics, distribution and host-specificity of the parasites they transmit. The black salt-marsh mosquito (Aedes taeniorhynchus Wiedemann) is distributed throughout tropical to temperate coastal zones in the Americas, and continental populations are primarily mammalphilic. It is the only indigenous mosquito in the Galápagos Islands, having colonised the archipelago around 200,000years ago, potentially adapting its host selection, and in the process, altering the dynamics of vector mediated pathogen interactions in the archipelago. Here, we use blood–meal analysis and PCR-based parasite screening approach to determine the blood-feeding patterns of A. taeniorhynchus in the Galápagos Islands and identify potential parasite transmission with which this mosquito could be involved. Our results show that A. taeniorhynchus feeds equally on mammals and reptiles, and only one avian sample was observed in 190 successful PCR amplifications from blood meals. However, we detected endemic filarial worms and Haemoproteus parasites known to infect various Galápagos bird species in mosquito thoraces, suggesting that feeding on birds must occur at low frequency, and that A. taeniorhynchus may play a role in maintaining some avian vector-borne pathogens, although more work is needed to explore this possibility. We also isolated three different DNA sequences corresponding to hemogregarine parasites of the genus Hepatozoon from mosquito and iguana blood samples, suggesting that more than one species of Hepatozoon parasites are present in Galápagos. Phylogenetic analysis of Hepatozoon 18sRNA sequences indicates that A. taeniorhynchus may have facilitated a recent breakdown in host–species association of formerly isolated Hepatozoon spp. infecting the reptile populations in the Galápagos Islands.

Adaptation, isolation by distance and human-mediated transport determine patterns of gene flow among populations of the disease vector Aedes taeniorhynchus in the Galapagos Islands

The black salt-marsh mosquito (Aedes taeniorhynchus) is the only native mosquito in the Galapagos Islands and potentially a major disease vector for Galapagos wildlife. Little is known about its population structure, or how its dynamics may be influenced by human presence in the archipelago. We used microsatellite data to assess the structure and patterns of A. taeniorhynchus gene flow among and within islands, to identify potential barriers to mosquito dispersal, and to investigate human-aided transport of mosquitoes across the archipelago. Our results show that inter-island migration of A. taeniorhynchus occurs frequently on an isolation by distance basis. High levels of inter-island migration were detected amongst the major ports of the archipelago, strongly suggesting the occurrence of human-aided transport of mosquitoes among islands, underlining the need for strict control measures to avoid the transport of disease vectors between islands. The prevalence of filarial nematode infection in Galapagos flightless cormorants is correlated with the population structure and migration patterns of A. taeniorhynchus, suggesting that A. taeniorhynchus is an important vector of this arthropod-borne parasite in the Galapagos Islands. Therefore mosquito population structure in Galapagos may have the potential to influence mosquito-borne parasite population dynamics, and the subsequent impacts of such pathogens on their host species in the islands.

The association between meteorological variables and the abundance of Aedes taeniorhynchus in the Florida Keys

The black salt marsh mosquito, Aedes taeniorhynchus, is a serious nuisance pest and a potential vector of a number of arboviruses. This study examined the effect of wind direction, wind speed, temperature, and time of year on the abundance of Ae. taeniorhynchus collected in CO₂ -baited light traps at 12 sites in the Florida Keys during 2004. The dependent variable analyzed was the natural log of weekly mosquito abundance. The previous week's wind speed and wind direction, and the current week's temperature were used as independent variables. Simple and multiple linear regression models were used to assess the significance and nature of association between the meteorological variables and the natural log of mosquito abundance, and to determine whether the meteorological variables had significant associations with mosquito abundance after also controlling for time of year. Week of year was treated as a circular independent variable in the regression models, using the sine and cosine of week in radians to model the periodic seasonal fluctuation in mosquito abundance. Mosquito abundance was significantly associated with all meteorological variables and with week of year. Individually, previous week's wind speed and wind direction, and current week's temperature were able to explain respectively 24.5%, 24.5%, and 52.1% of the variation in mosquito abundance observed over the year. Week of year had the strongest individual association with mosquito abundance, explaining 65.7% of the variation in mosquito abundance. The meteorological variables were still significantly associated with mosquito abundance, after controlling for week of year. Week and the meteorological variables together explained 79.2% of the variation in mosquito abundance. The regression models fit to the data from this study suggest a strong periodic seasonal variation in mosquito abundance, with meteorological conditions explaining a significant portion of the variation beyond the seasonal trend.

Mosquito Fauna of Wilderness Islands Within the National Key Deer Refuge and the Great White Heron National Wildlife Refuge, Monroe County, Florida

Dry ice-baited light traps, counts of mosquitoes biting and landing on technicians, and larval surveillance were used to determine mosquito species abundance on Annette Key, Little Knockem-down Key, Little Pine Key, Raccoon Key, and the Water Keys, all of which are located offshore, within the National Key Deer Refuge and Great White Heron National Wildlife Refuge in Monroe County, FL. Due to the close proximity of these wilderness islands to the inhabited islands of the Florida Keys, it is important to understand the abundance and composition of the mosquitoes and the effects they may have on populations on inhabited islands. Thirty different species were collected during 2004-2008. Aedes taeniorhynchus, the black salt-marsh mosquito, was the most abundant mosquito species collected at all locations. Other mosquitoes collected in large numbers at all locations were Anopheles atropos, Culex bahamensis, Cx. nigripalpus, and Deinocerites cancer. Because these wilderness islands are difficult to traverse due to vegetative growth, the placement of mosquito traps close to the perimeter of the islands may influence assessment of the abundance and diversity of mosquito species collected on each island.

Seasonal and diel patterns of biting midges (Ceratopogonidae) and mosquitoes (Culicidae) on the Parris Island Marine Corps Recruit Depot

The Marine Corps Recruit Depot on Parris Island, SC, is surrounded by tidal salt marshes, which are breeding habitats for many pestiferous biting flies. Knowledge of biting fly behavior patterns is needed to develop effective pest management strategies in urban areas adjacent to salt marshes. We measured biting midge (Ceratopogonidae) and mosquito (Culicidae) seasonal abundance and diel activity patterns on Parris Island using CO(2)-baited suction traps from November 2001 - November 2004. Of the three biting midge species collected, Culicoides furens was most abundant (86.2% of total) and was present in high numbers from late March to November. Culicoides hollensis (12.0% of total) was present during spring and fall but absent in summer and winter; and Culicoides melleus (1.7% of total) was present in spring through fall but absent in winter. Abundance of C. furens had a positive linear correlation with air temperature and rainfall. There were nonlinear correlations between air temperature and C. hollensis and C. melleus numbers, which were most abundant at moderate temperatures. Of 18 mosquito species collected, the most abundant were Aedes taeniorhynchus (42.7% of total), Aedes sollicitans (26.3% of total), Culex salinarius (15.6% of total), Culex quinquefasciatus (7.3% of total), and Aedes vexans (5.7% of total); other species comprised <5% of collections. Aedes taeniorhynchus numbers were positively correlated with temperature and rainfall, and Cx. salinarius was correlated with soil moisture. Activity of most biting midges and mosquitoes were highest the first two hours following sunset. Species of biting flies were present in all months, suggesting that year-round control measures are necessary to reduce exposure to potential disease vectors and nuisance biting.

Natural colonization and adaptation of a mosquito species in Galapagos and its implications for disease threats to endemic wildlife.

Emerging infectious diseases of wildlife have been recognized as a major threat to global biodiversity. Endemic species on isolated oceanic islands, such as the Galápagos, are particularly at risk in the face of introduced pathogens and disease vectors. The black salt-marsh mosquito (Aedes taeniorhynchus) is the only mosquito widely distributed across the Galápagos Archipelago. Here we show that this mosquito naturally colonized the Galápagos before the arrival of man, and since then it has evolved to represent a distinct evolutionary unit and has adapted to habitats unusual for its coastal progenitor. We also present evidence that A. taeniorhynchus feeds on reptiles in Galápagos in addition to previously reported mammal and bird hosts, highlighting the important role this mosquito might play as a bridge-vector in the transmission and spread of extant and newly introduced diseases in the Galápagos Islands. These findings are particularly pertinent for West Nile virus, which can cause significant morbidity and mortality in mammals (including humans), birds, and reptiles, and which recently has spread from an introductory focus in New York to much of the North and South American mainland and could soon reach the Galápagos Islands. Unlike Hawaii, there are likely to be no highland refugia free from invading mosquito-borne diseases in Galápagos, suggesting bleak outcomes to possible future pathogen introduction events.

Microsatellite markers characterized in the mosquito Aedes taeniorhynchus (Diptera, Culicidae), a disease vector and major pest on the American coast and the Galápagos Islands

The black salt-marsh mosquito, Aedes taeniorhynchus, plays an important role in the transmission of arboviruses such as West Nile virus and other pathogens of concern for human and animal health in North and Latin America. This mosquito is notably the only widely distributed mosquito species found in the Galápagos Islands, where its impact as disease vector has not yet been studied. The use of microsatellite markers can significantly improve our understanding of the population structure and dynamics of A. taeniorhynchus and its role in the transmission of diseases. Here we report the isolation of 12 unique microsatellite loci using an enrichment protocol. We also identified other multi-locus microsatellites linked to transposable elements. The presence of such elements may explain why the isolation of useful scorable microsatellite markers in the Aedes genus is often difficult. Four of the markers isolated amplified polymorphic products in Aedes aegypti, Aedes albopictus and/or Aedes japonicus.

SEMIOCHEMICALS, TRAPS/TARGETS AND MASS TRAPPING TECHNOLOGY FOR MOSQUITO MANAGEMENT

Technologies which utilize semiochemicals, traps/targets and mass trapping are relatively new for management of adult mosquito populations. To date most of the emphasis has been on developing barriers of attractant-baited and insecticide-impregnated targets. The most successful continuous use of this type of technology has been at Stevens' Landing, Collier County, FL. Recently, commercially available traps have been evaluated for their ability to reduce nuisance populations of mosquitoes. Use of Mosquito Magnet Pro traps along a nature trail on an isolated island (Atsena Otie) in the Gulf of Mexico resulted in a significant reduction in annoyance caused by the black salt marsh mosquito Ochlerotatus taeniorhynchus (Wiedemann). This chapter presents a brief discussion of semiochemicals (behavior modifying) and mosquito traps, strategies for using them for insect control, and an overview of the recent advancements in research activities conducted to evaluate using combinations of semiochemicals and mass trapping techniques for adult mosquito management.

Traps and Trapping Techniques for Adult Mosquito Control

An overview is presented of the recent advancements in research activities conducted to evaluate mosquito traps, insecticide-impregnated targets baited with combinations of attractants, and strategies for using mass trapping techniques for adult mosquito population management. Technologies that use semiochemicals (attractants), traps and targets, and mass trapping are relatively new for management of adult mosquito populations. To date, emphasis has been placed primarily on developing barriers of attractant-baited and insecticide-impregnated targets. The most successful continuous use of this type of technology has been at Stevens' Landing, Collier County, Florida. Recently, commercially available traps have been evaluated for their ability to reduce nuisance populations of mosquitoes. Whereas use of Mosquito Magnet Pro (MM-Pro) traps along a nature trail on an isolated island (Atsena Otie) in the Gulf of Mexico resulted in a significant reduction in annoyance caused by the black salt-marsh mosquito, Ochlerotatus taeniorhynchus (Wied.), a perimeter of the same traps did not result in the same level of mosquito reduction in a residential area in Gainesville, FL.

Factors affecting immatures of Ochlerotatus taeniorhynchus (Diptera: Culicidae) in San Diego County, California.

The effects of tide, temperature, rainfall, and salinity on the occurrence and abundance of immatures (instars and pupae) of the black salt marsh mosquito, Ochlerotatus taeniorhynchus (Wiedemann), were examined at a tidal pond in the Tijuana Estuary during 1996-1998. Immatures were found between May and early September. Tide had the greatest influence on immatures of this mosquito. Eggs eclosed when tides averaged 1.96 +/- 0.10 (SD) m (1.83-2.19) 1-3 d before a flood tide. Eclosion averaged once every 14.4 d during 1996 (nine broods) and 1997 (eight broods) and once every 20.2 d during 1998 (six broods). Immatures were most abundant during late May-early August when tides were usually > or = 2.0 m, and mean (+/-SD) pond temperature was 27.6 +/- 2.6 degrees C (23.8-33.9) and salinity was 44.6 +/- 13.9 g/kg (33-95). Temperature primarily influenced egg diapause and influenced rate of development of immatures. Increased amounts of seasonal rainfall during 1997-1998 (42.9 cm: caused by El Niño), compared with 1995-1996 (11.4 cm) and 1996-1997 (17.3 cm), may have increased the mortality of overwintering eggs and/or diluted salinity of the substrate making it less conducive for oviposition.

Simulated populations of the black salt march mosquito ( Aedes taeniorhynchus) in a Florida mangrove forest

A simulation model of the population dynamics of the black salt marsh mosquito ( Aedes taeniorhynchus) in a mangrove basin forest in southwestern Florida is described. This mosquito is a major pest in coastal Florida, with large populations migrating many kilometres from the breeding site. The basic model realistically simulated annual population trends and the occurrence of larval broods. Model output (adult females and sum of eggs, larvae and adult females) was most sensitive to adult survival, larval predator populations and immigration of adult females. Detailed analysis of dispersal indicated that persistence of mosquitoes was dependent upon immigration and the absence of tidal flooding and attendant larval predators. Model versions incorporating fish-mediated oviposition repellency and increased survival in young autogenous adult females led to a respective 21% decrease and 267% increase in mean adult female population. These results suggest that a model offering alternative, predator-free oviposition sites for migrating females would more realistically simulate natural populations.

Pathology of a mosquito iridescent virus (MIV) infecting Aedes taeniorhynchus

An investigation was initiated to study the pathology and biology of the regular mosquito iridescent virus (RMIV) in the black salt marsh mosquito, Aedes taeniorhynchus. RMIV was capable of infecting a variety of tissues within its host. Cells of the fat body, tracheal epithelium, imaginal discs, and epidermis were the primary sites of viral replication. Extensive destruction of the fat body by this virus resulted in the death of most infected mosquitoes before they reached the adult stage. Other tissues which were involved to a lesser extent were hemocytes, esophagus, nerve, muscle, and both larval and adult ovaries. The transovarial transmission of RMIV was confirmed, and when transovarial transmission occurred, either all or none of the progeny of a given female were infected. The presence of virus in the ovaries was taken as evidence that RMIV is transmitted within the egg.

The pupation rhythm in Aedes taeniorhynchus (Diptera: Culicidae). V. Physiology of growth and endogenous diurnal rhythm of pupation.

A study of mitosis in the brain cells, size of nuclei of the median neurosecretory cells of the brain, dry weight, and accumulation of glycogen and trehalose during the 4th larval stage of the black salt-marsh mosquito, A. taeniorhynchus (Wiedemann), under the conditions where pupal ecdysis is manifested as a diurnal rhythm with more than 3 peaks, showed diurnal rhythmic patterns in mitosis in brain cells, size of nuclei in the median neurosecretory cells, and amounts of available trehalose in the body. Dry weight and glycogen did not show any diurnal rhythmicity even with different quantities of food provided to 4th-stage larvae. Higher quantities of food than basic ration synchronized larval development as well as pupal ecdysis, thus only 1 major peak of mitosis in brain cells was exhibited, and trehalose diurnal rhythmicity was suppressed. A light regime did not show phase-shift of the diurnal rhythm of trehalose. Maximum amounts of trehalose with indications of diurnal rhythmicity were expressed under 12 hours light: 12 hours dark as compared with con tinuous light or continuous dark, at 32°C. It is suggested that diurnal rhythmic patterns investigated here in the larvae endure to the pupal stage with the occurrence of pupal ecdysis as a diurnal rhythm.

The pupation rhythm in Aedes taeniorhynchus. IV. Further studies of the endogenous diurnal (circadian) rhythm of pupation.

The basic characteristics of the endogenous diurnal rhythm of pupation in the black salt-marsh mosquito, A. taeniorhynchus (Wiedemann), have been investigated in detail. A distinct sinusoidal pattern of pupation, which is evident only under continuous darkness, was the result of simultaneous hatching of the eggs. A nonrepeated light pulse synchronized each peak of pupation and established a new phase for the rhythm. If the nonrepeated light pulse was at least 4 hours in duration, it was effective in phase-establishment as early as immediately after simultaneous hatching of the eggs and as late as 72 hours after hatch. The amount of phase-shift was proportional to the duration of the light stimulus, the greater phase-shift resulting from the longest signals. A light pulse, given at different phases of the subjective light-dark (LD) cycle, showed that sensitivity to light stimuli was greater during the first 12 hours than during the second 12 hours of the subjective LD cycle, and the phase-response curve obtained for the pupation rhythm under standardized conditions was very similar to those reported for different single animals and populations. The persistence of the pupation rhythm under constant conditions of light and temperature following alternate conditions, the distinct displaying of phase-shift, transients, and phase resetting substantiate that this pupation rhythm is an endogenous diurnal rhythm. LD cycles of less than 24 hrs, varying from 12 to 22 hours, imposed during earlier stages of development did entrain the pupation rhythm, although these LD cycles were not learned. Phase-shifts, transients, and phase-resetting by temperature perturbations differ from those generated by light perturbations. The temperature stimuli produce spectacular transients with relatively little phase-shift in the ultimate steady-state, whereas light pulses have spectacular effects on the steady state phase-shift. It is concluded that though the diurnal rhythm of pupation in A. taeniorhynchus is endogenous in its characteristics, it is suitable to study neither time measurement nor the general properties of circadian clocks. However, this endogenous rhythm is valuable in studying the physio-ecological processes in this insect.

The Pupation Rhythm in Aedes taeniorhynchus. III.1 Factors in Developmental Synchrony2

Food, light, and temperature together establish the degree of developmental synchrony in a simultaneously hatched larval population of the black salt-marsh mosquito, Aedes taeniorhynchus (Wiedemann). Periodic starvation does not enhance synchrony, nor does larval crowding per se, nor light regimes divergent from 12 hours light: 12 hours dark, with daylight intensity (>10,000 lux) white light alternating with total darkness. Maximum synchrony is achieved with the highest food ration which will not contaminate the culture and cause extra mortality, at temperatures between 29 and 32°C, with hatching at sunrise of a 12-hour light regime. Approximately 90% of simultaneously hatched larvae can be made to pupate within a span of 12 hours. Such synchronization, never approached in nature with this species, can be very useful in research.

Field Tests with Repellent-Treated Netting Against Black Salt-Marsh Mosquitoes13

In 1965 and 1966, 25 single compounds and 6 mixtures were tested as repellents on 4-mesh-per-inch cotton netting against the black salt-marsh mosquito, Aedes taeniorhynchus Wiedemann. Twenty single compounds gave 90% protection for periods ranging from 16 to 92 days. Four of the 6 mixtures gave protection for 19 days. The 3 most effective chemicals were dipentyl tartrate, 92 days; hexyl p-isopropylmandelate, 78 days; and N, N -dibutyl-o-ethoxy-benzamide, 56 days.