Ground Applications of Vectobac® WDG with A1 Super-Duty Mist Sprayer® and Micronair® AU5000 Atomizer for Suppression of Aedes aegypti Populations in the Florida Keys

ABSTRACT Since 2011, the Florida Keys Mosquito Control District (FKMCD) has used the WALS® application strategy with VectoBac® WDG containing Bacillus thuringiensis israelensis via helicopter in Key West for the control of Aedes aegypti larval populations. In 2018, FKMCD conducted a study to determine the effectiveness of using a trailer-mounted A1 Super Duty Mist Sprayer® (A1 Mist Sprayers) with a Micronair® AU5000 (Micron Group) atomizer to apply VectoBac WDG by ground at the rate of 0.5 lb/acre (0.56 kg/ha). Bioassay cups were placed in a residential area encompassing open, moderate, and heavy cover scenarios between 0 and 300 ft (0–91.44 m) perpendicular to the spray line. An application rate of 0.5 lbs/acre (0.56 kg/ha) was used. Bioassay cups were collected after application and returned to the laboratory where 100 ml of distilled water and 10 F1 generation Ae. aegypti larvae were added. Laval mortality was monitored at 2, 4, and 24 h. Three separate runs were completed during the summer of 2018. Average larval mortality at 24 h was >90%. The field trial demonstrated sufficient efficacy to introduce this method of larviciding into operational use.

A Field Efficacy Evaluation of In2Care Mosquito Traps in Comparison with Routine Integrated Vector Management at Reducing Aedes aegypti

ABSTRACT Aedes aegypti is the predominant vector of dengue, chikungunya, and Zika viruses. This mosquito is difficult to control with conventional methods due to its container-inhabiting behavior and resistance to insecticides. Autodissemination of pyriproxyfen (PPF), a potent larvicide, has shown promise as an additional tool to control Aedes species in small-scale field trials. However, few large-scale field evaluations have been conducted. We undertook a 6-month-long large-scale field study to compare the effectiveness and operational feasibility of using In2Care Mosquito Traps (In2Care Traps, commercially available Aedes traps with PPF and Beauveria bassiana) compared to an integrated vector management (IVM) strategy consisting of source reduction, larviciding, and adulticiding for controlling Ae. aegypti eggs, larvae, and adults. We found that while the difference between treatments was only statistically significant for eggs and larvae (P < 0.05 for eggs and larvae and P > 0.05 for adults), the use of In2Care Traps alone resulted in 60%, 57%, and 57% fewer eggs, larvae, and adults, respectively, collected from that site compared to the IVM site. However, In2Care Trap deployment and maintenance were more time consuming and labor intensive than the IVM strategy. Thus, using In2Care Traps alone as a control method for large areas (e.g., >20 ha) may be less practical for control programs with the capacity to conduct ground and aerial larviciding and adulticiding. Based on our study results, we conclude that In2Care Traps are effective at suppressing Ae. aegypti and have the most potential for use in areas without sophisticated control programs and within IVM programs to target hotspots with high population levels and/or risk of Aedes-borne pathogen transmission.

A New Record of Uranotaenia sapphirina and Aedes japonicus in Lee and Ogle Counties, Illinois

ABSTRACT Mosquito surveillance was conducted in Nachusa Grasslands Preserve located in north central Illinois in May through October during 2018 and 2019. In the Lee and Ogle counties, Illinois, boundaries of the preserve, 3 Uranotaenia sapphirina and 3 Aedes japonicus were collected and documented over the 2 field seasons in wetland and stream habitats. While Ur. sapphirina has been reported in nearby states, this is the first record in Lee County and on the preserve. Aedes japonicus has previously been recorded in Lee County; however, this is the first observance of this species within Ogle County and on the preserve.

Bionomy of Mosquitoes in Bamboo Internodes in an Atlantic Forest Remnant of the State of Rio De Janeiro, Brazil

ABSTRACT Living bamboo stalks are one of the most specialized habitats for mosquito oviposition and immature development. Most of the mosquito species that breed in these habitats are sylvatic, and some are of importance for public health as possible vectors of pathogens. Perforated internodes are a very specialized environment due to the difficulty of access. Furthermore, due to their relatively simple fauna, they represent a valuable model for ecological studies that may be applicable to more complex environments. This study aims to assess the mosquito bionomics of species raised in bamboo internodes. Therefore, the diversity of mosquito species and the influence of abiotic variables (pH and temperature) on the distribution of mosquitoes that breed in this habitat were analyzed. The study area is a fragment of Atlantic Forest within the Association of da Armada (ATA) in Nova Iguaçu, state of Rio de Janeiro, Brazil. Immature mosquitoes were sampled with suction tubes (mouth aspirators) between August 2017 and July 2018. A total of 3,170 larvae were collected in 5 bamboo plants, each with 8 stalks perforated. Of these, 688 larvae reached the adult stage, representing 10 genera and 19 species. The most common species were Culex neglectus (43%), Trichoprosopon digitatum (22%), Culex iridescens (8%), Sabethes identicus (7%), and Orthopodomyia albicosta (7%). The richness of the immatures collected in the ATA was 19 species, with a diversity of 1.10 and Shannon evenness of 0.57. A diverse composition of Culicidae in bamboo stalks was found, although dominance was low.

DNA Barcoding of Mosquitoes from the Pantanos de Centla Biosphere Reserve, Southeastern Mexico

ABSTRACT Accurate identification of mosquito species is essential to support programs that involve the study of distribution and mosquito control. Numerous mosquito species are difficult to identify based only on morphological characteristics, due to the morphological similarities in different life stages and large numbers of some species that are members of morphologically similar species complexes. In the present study, the mosquitoes collected in the Pantanos de Centla Biosphere Reserve, southeastern Mexico, were evaluated using a combination of morphological and molecular approaches (mitochondrial cytochrome c oxidase subunit I [COI] DNA barcode). A total of 1,576 specimens of 10 genera and 35 species, mostly adult stages, were collected. A total of 225 COI DNA barcode sequences were analyzed; most species formed well-supported groups in the neighbor joining, maximum likelihood, and Bayesian inference trees. The intraspecific Kimura 2-parameter (K2P) genetic distance averaged 1.52%. An intraspecific K2P distance of 6.20% was observed in Anopheles crucians s.l., while a deep split was identified in Culex erraticus and Cx. conspirator. This study showed that COI DNA barcodes offer a reliable approach to support mosquito species identification in Mexico.

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.

Survey of Mississippi Mosquito Blood Meals for Vertebrate Host Identification

ABSTRACT Exploring particular mosquito and vertebrate relationships provide insight to potential transmission of several agents of disease. In the current study, the relationship between white-tailed deer (Odocoileus virginianus) and mosquitoes was explored by identifying blood meals within mosquitoes captured throughout Mississippi between June and September of 2013 and 2017. We captured 72 bloodfed mosquitoes between 2 collection years, with a majority of specimens identified as Culex erraticus or Psorophora mathesoni. Seventy-nine percent (26/33) of blood meals in Cx. erraticus originated from the white-tailed deer. These findings implicate mosquitoes may primarily be feeding on white-tailed deer in rural areas of Mississippi.

A Viability Assessment of Two Commercially Available Sticking Adjuvants Added to a Bifenthrin-Based Barrier Treatment on Aedes taeniorhycnhus

ABSTRACT In an effort to reduce Aedes taeniorhynchus numbers in the northernmost community of Key Largo, FL (known as Ocean Reef), during the peak summer months, Florida Keys Mosquito Control District (FKMCD) has utilized a bifenthrin-based barrier application (Wisdom TC Flowable®) for several years. The FKMCD conducted a study comparing whether 2 aftermarket wetting/sticking adjuvants could improve the efficacy of the barrier treatments used to control Ae. taeniorhynchus. Maximum label rate was used for 3 separate solutions: Wisdom TC Flowable (1 fl oz/gal [7.81 ml/liter] water) with no additives (Wisdom), Wisdom with Lesco Spreader-Sticker® (0.08 fl oz [2.37 ml]), and Wisdom with Xtended Performance® (2.56 fl oz [75.71 ml]). All solutions were applied to 100-ft (approximately 3 m) sections of tree-lined roadways in Key Largo, FL, using a SR 420® Mistblower backpack sprayer (Stihl Corp.). Leaves were collected from each application area for 8 consecutive weeks. Leaves were used to perform leaf bioassays against local populations of Ae. taeniorhynchus adults, and mortality was recorded at 1, 4, and 24 h postexposure. This process was replicated 3 times. Treatments had variable mortality rates at 1, 4, and 24 h postexposure across 7 wk following application. Mortality rates for all mixtures decreased for all exposure times throughout the study. Overall, the Lesco Spreader-Sticker solution was the only combination with a positive significant difference in adult mortality after 24 h.

Entomological Investigation Following a Zika Outbreak in Brownsville, Texas

ABSTRACT In November and December 2016, an outbreak of locally transmitted Zika occurred in Brownsville, TX. The Texas Department of State Health Services requested for a Centers for Disease Control and Prevention (CDC) Epi Aid, and as part of that Epi Aid a team of CDC entomologists was deployed in January 2017. The mission was to improve mosquito-based arbovirus surveillance and evaluate the possibility of continuing local Zika virus (ZIKV) transmission in the city. The mosquito-based arbovirus surveillance program was expanded from 4 to 40 BG-Sentinel traps evenly distributed throughout the city. Over a 2-wk period, 15 mosquito species were detected; the most abundant species were Culex quinquefasciatus, Aedes aegypti, and Ae. albopictus, which accounted for 66.7%, 16.2%, and 5.7% of the total mosquito collection, respectively. The relative abundance of Ae. aegypti (1.0 mosquitoes/trap/day) and Ae. albopictus (0.4 mosquitoes/trap/day) was very low and unlikely to initiate and/or sustain ZIKV transmission. Zika virus was not detected in the mosquitoes collected, suggesting no or extremely low ZIKV transmission at that time.