Wyeomyia Mitchellii Research Articles

New State Record for Culex rejector and Cx. restrictor in Yucatan, Mexico.

Several known mosquito species occur in the Mexican state of Yucatan, including competent and suspected vectors responsible for transmitting zoonotic arboviruses. Between February and July 2022, mosquito collections were carried out in several forested areas in Yucatan. As part of the ongoing monitoring, we present the first reports of Culex (Microculex) rejector and Cx. (Anoedioporpa) restrictor. Another 14 species were identified during the monitoring: Aedes albopictus, Ae. bimaculatus, Ae. tormentor, Ae. cozumelensis, Anopheles albimanus, Cx. coronator s.l., Cx. erraticus, Cx. lactator, Cx. salinarius, Coquillettidia venezuelensis, Limatus durhamii, Psorophora ciliata, Toxorhynchites theobaldi, and Wyeomyia mitchellii. Currently, the mosquito fauna in Yucatan consists of 65 species. The subgenera Microculex and Anoedioporpa had not been documented in Yucatan State prior to the current investigation.

Collection and DNA Detection of Dirofilaria immitis (Rhabditida Onchocercidae), Using a Novel Primer Set, in Wild-Caught Mosquitoes From Gainesville, FL

Dirofilaria immitis, the causative agent of dog heartworm disease, is an important cause of canine morbidity and mortality, expensive to treat, and severe infections are often fatal. Much is known about the pathogen in the canine host, yet little is known on the basic ecology of the nematode in the mosquito vector. Thus, to evaluate the effectiveness of collection techniques on ability to capture dog heartworm-infected mosquitoes (Diptera Culicidae), we conducted a field study spanning 111 wk. Four methods were used: two aspirators types, sweep netting, and a CDC trap. All sites had canines present in either residential yards (n = 4) or dog kennel facilities (n = 3). Collected mosquitoes were sorted by site, trap, species, and date, then pooled into groups of up to 25 individuals. Mosquito head and thorax pools were extracted for DNA, that was screened using currently available protocols. These protocols were found unreliable; thus, we developed a novel qPCR primer and probe set. Using this method, the original samples were re-assayed and provided 494 positive pools. Approximately 10% of positive samples were confirmed by Sanger sequencing. Twenty-two mosquito species tested positive for dog heartworm DNA, including a new association with Wyeomyia mitchellii (Theobald). Although Aedes atlanticus (Dyar and Knab), Anopheles crucians Wiedemann, and Culiseta melanura (Coquillett) composed nearly 36% of the total collection, these species represented 42% of the qPCR positive pools. Infection rates within commonly collected mosquitoes ranged up to 2.5%, with more rarely collected species ranging up to 14%. The CDC trap was the most effective collection method at trapping infected mosquitoes.

Highlights of Medical Entomology 2018: The Importance of Sustainable Surveillance of Vectors and Vector-Borne Pathogens.

The theme of the 2018 Entomological Society of America, Entomological Society of Canada, and Entomological Society of British Columbia Joint Annual Meeting was Crossing Borders: Entomology in a Changing World. Following the theme of the meeting, papers selected for the 2018 'Highlights of Medical Entomology' included reports of expanded ranges for Aedes albopictus (Skuse) (Diptera: Culicidae), Aedes japonicus japonicus (Theobald) (Diptera: Culicidae), Culex coronator Dyar and Knab (Diptera: Culicidae), Mansonia titillans (Walker) (Diptera: Culicidae), and Wyeomyia mitchellii (Theobald) (Diptera: Culicidae); a first report of mosquito feeding on earthworms and leeches; Cache Valley virus detection in Ae. j. japonicus; surveillance in high-risk areas of Canada for Lyme Disease; and increasing lone-star tick detections in Connecticut. The selection of papers served as a reminder of the increasingly difficult challenge of sustaining vector surveillance programs. Fluctuating funding and a decline in vector taxonomists and identification expertise contribute to the erosion of vector surveillance.

Ornamental bromeliads of Miami-Dade County, Florida are important breeding sites for Aedes aegypti (Diptera: Culicidae)

BackgroundA major public health concern is the emergence and geographical spread of vector-borne diseases such as Zika and yellow fever. Ornamental bromeliads retaining water in their leaf axils represent potential breeding sites for mosquitoes. As the role of ornamental bromeliads in breeding Aedes aegypti in Miami-Dade County, Florida is unknown, we hypothesize that ornamental bromeliads are important breeding sites for Ae. aegypti. Our objective was to survey bromeliads in areas with high densities of adult Ae. aegypti, including those with 2016 local transmission of Zika virus.MethodsOrnamental bromeliads were surveyed for the presence of immature mosquitoes at 51 locations of Miami-Dade County, Florida. Bromeliads were sampled for the presence of immature stages of mosquitoes, their reservoirs were drained and screened for the presence of immature mosquitoes. Immature mosquitoes were stored in plastic containers and preserved in 70% ethanol until morphological identification. Biodiversity of species assemblages was assessed by Shannon’s and Simpson’s indices, and individual rarefaction curves and plots of cumulative abundance, Shannon’s index and evenness profiles.ResultsOrnamental bromeliads were present in all surveyed areas, yielding a total of 765 immature mosquitoes, comprising five taxonomic units: Ae. aegypti, Wyeomyia mitchellii, Wyeomyia vanduzeei, Culex quinquefasciatus and Culex biscaynensis. The biodiversity indices point to a low diversity scenario with a highly dominant species, Ae. aegypti.DiscussionOur findings suggest that ornamental bromeliads are contributing for the proliferation of Ae. aegypti in the County of Miami-Dade, which may indicate a shift in the paradigm of usage of bromeliads as breeding sites, highlighting that ornamental phytotelmata bromeliads are to be considered in future vector-control strategies to control Zika and other arboviruses.

COMPARATIVE SUSCEPTIBILITY OF INTRODUCED FOREST-DWELLING MOSQUITOES IN HAWAI'I TO AVIAN MALARIA, PLASMODIUM RELICTUM

To identify potential vectors of avian malaria in Hawaiian native forests, the innate susceptibility of Aedes albopictus, Wyeomyia mitchellii, and Culex quinquefasciatus from 3 geographical sites along an altitudinal gradient was evaluated using local isolates of Plasmodium relictum. Mosquitoes were dissected 5-8 and 9-13 days postinfective blood meal and microscopically examined for oocysts and salivary-gland sporozoites. Sporogony was completed in all 3 species, but prevalence between species varied significantly. Oocysts were detected in 1-2% and sporozoites in 1-7% of Aedes albopictus that fed on infected ducklings. Wyeomyia mitchellii was slightly more susceptible, with 7-19% and 7% infected with oocysts and sporozoites, respectively. In both species, the median oocyst number was 5 or below. This is only the second Wyeomyia species reported to support development of a malarial parasite. Conversely, Culex quinquefasciatus from all 3 sites proved very susceptible. Prevalence of oocysts and sporozoites consistently exceeded 70%, regardless of gametocytemia or origin of the P. relictum isolate. In trials for which a maximum 200 oocysts were recorded, the median number of oocysts ranged from 144 to 200. It was concluded that Culex quinquefasciatus is the primary vector of avian malaria in Hawai'i.

Field studies on the potential of butanone, carbon dioxide, honey extract, l‐octen‐3‐ol, L‐lactic acid and phenols as attractants for mosquitoes*

Various combinations of six candidate attractants--butanone, carbon dioxide (CO2), honey, octenol, lactic acid and mixed phenols--were tested against natural populations of mosquitoes in Everglades National Park, Florida, U.S.A., using unlighted CDC-baited traps. With few exceptions, the attractancy of these candidate compounds to mosquitoes, when used alone, was less than that of CO2 alone. The exceptions were that octenol and honey extract alone attracted larger numbers of Coquillettidia perturbans (Walker). Addition of lactic acid and/or octenol to CO2 increased trap collections of Aedes taeniorhynchus (Wiedemann), Anopheles atropos D. & K., and An. crucians Wiedemann by 1.4-13.8 times. Culex nigripalpus Theobald collections were increased 2.7 times by the addition of lactic acid, while the addition of octenol produced mixed results. Whereas the addition of lactic acid reduced collections of Cx (Melanoconion) spp., the addition of octenol generally increased collections. The opposite happened for Wyeomyia mitchellii (Theobald). For the biting midge, Culicoides furens (poey), octenol (1.6-23.4 x ) and phenol (2.7 x ) alone attracted larger numbers, and lactic acid alone attracted approximately the same numbers as CO2 alone. The combinations octenol + phenol and octenol + 200 ml/min CO2 increased C. furens collections c. 100 times over CO2 alone. The combination of octenol + CO2 increased (1.6 x ) collections of the tabanid Diachlorus ferrugatus (Fabricius). Butanone appeared to decrease the trap collections of all species when combined with CO2 or octenol + CO2.

Efficacy of Bacillus sphaericus Neide against Larval Mosquitoes (Diptera: Culicidae) and Midges (Diptera: Chironomidae) in the Laboratory

The primary powders of strains 1593 (IF-119) and 2362 (IF-118 and ABG-6184) of Bacillus sphaericus Neide were tested as larvicides of laboratory-reared mosquitoes and field-collected midges, and were compared with the activity of strain 1593-4 (RB-80), the international standard of B. sphaericus. Two mosquito species, Aedes aegypti (Linn.) and Ae. taeniorhynchus (Wiedemann), and two midge species, Chironomus crassocaidatis Malloch and Glyptotendipes paripes Edwards were insensitive to B. sphaericus (LC@^50 > 50 ppm)$. Among the five susceptible mosquito species, Culex quinquefasciatus Say, Cx. nigripalpus Theobald, Anopheles albimanus Wiedemann, and An. quadrimaculatus Say, were most susceptible to ABG-6184 (strain 2362) with LC@^90 values of 0.0044, 0.0067, 0.54, and 7.35 ppm, respectively. Wyeomyia mitchellii (Theobald) was almost equally susceptible to ABG-6184 LC@^90 = 0.276 ppm) and strain 1593 (IF-119) (LC@^90 = 0.261 ppm).

Circadian Rhythm of Emergence in the Mosquito Wyeomyia mitchellii and the Effects of Light Cycles on the Pupation Rhythm of Culex nigripalpus1

The rhythmic control of emergence was studied in 2 Florida mosquitoes, Wyeomyia mitchellii (Theobald) and Culex nigripalpus Theobald. In W. mitchellii , there were no indications of a pupation rhythm in the various light cycles tested but there was a pronounced emergence rhythm. This rhythm proved to be an endogenous circadian rhythm of the kind reported in Drosophila pseudoobscura . It showed distinct phase shifts and resetting under altered light regimes, was synchronized by a non-repeated light signal of 12 h, and, once initiated during the pupal stage, continued in DD for at least 4 days. This is the 1st report of an endogenous circadian rhythm of emergence, as opposed to a pupation rhythm, in mosquitoes. In C. nigripalpus , where a pupation rhythm occurred in LD 12:12, other light cycles during the pupal stage shifted the onset and the mean time of the emergence peak 1–3 h. This slight shift was not due to entrainment, however, but the result of the light cycles affecting the developmental period, and hence, the timing of the pupation and emergence peaks.

Observations on the Mosquito, Toxorhynchites rutilus rutilus (Coquillett), in Alachua County, Florida

Toxorhynchites rutilus rutilus (Coquillett) is a brilliantly ornamented, diurnal mosquito occurring in the southeastern part of the United States. It was recorded from Florida and Georgia by Howard et. al. (1912-17) and later from South Carolina by Carpenter and Jenkins (1945). In Florida, larvae of T. rutilus have been taken in association with Wyeomyia mitchellii (Theobald) and W. vanduzeei Dyar and Knab from one of the bromeliads, Tillandsia utriculata Linn., by Seabrook and Duffey (1946). Basham et. al. (1947) collected larvae and pupae of this mosquito from rot cavities in water oak, live oak, orange, pecan, and pine trees, and in assorted containers under, or near trees. Larvae of T. rutilus were reported to be cannibalistic and predatorial on larvae of Aedes triseriatusa (Say) and Orthopodomyia signifera (Coq.) by Jenkins and Carpenter (1946). Basham et. al. (1947) reared three specimens, feeding them larvae of A. triseriatus, 0. signifera, and Culex quinquefascicatus Say. From 1954 to 1956 the writer routinely observed 19 rot cavities in trees at Gainesville, Florida. T. rutilus was commonly found in three large sweetgum cavities, and occasionally in a small cavity in water oak. An aerial oviposition of a female mosquito, believed to be T. rutilus, was observed at 5:30 p.m., on August 10, 1954. While depositing, the female flew up and down about four to five inches above the orifice of a large, basal, sweetgum cavity, located on the western edge of a densely wooded area. In general, the flight was directed counterclockwise. Frequently the course of the flight veered, allowing eggs to drop on dry areas of the trunk, and on the ground. The female flew into the wooded area, following the deposition. After the oviposition flight 136 eggs were counted; however, some may have been deposited by other females, and the observed female may have deposited in other cavities. The number, therefore, should not be regarded as an indication of the egg potential. Some of the deposited eggs were collected from the ground and the periphery of the orifice, and placed in an aquarium containing water from ,the cavity. Many A. triseriatus and 0. s'gnifera larvae were in the water. The eggs hatched, and eventually three females and two males emerged. The males were identified as T. rutilus. The random arrangement of deposited eggs of T. rutilus was observed about the same cavity twice during the summer of 1955. Between 11:00 a.m. and 2:00 p.m. on March 16, 1956, eight eggs of the species were neatly stacked in a cluster on the surface of water in a small cavity, eight feet above the ground, in water oak. The cavity contained about 500 ml. of water, which had a copper tint. Thirty-two A. triseriatus and thirteen 0. signifera larvae, all in the first instar, were present. It was evident that the eggs had been deposited while the female was in a stationary position.