Rift Valley fever virus (RVFV), a mosquito-borne virus, has been responsible for large outbreaks in Africa that have resulted in hundreds of thousands of human infections and major economic disruption due to loss of livestock and to trade restrictions. Culex pipiens was implicated as the principal vector of the Egyptian outbreak in 1977 that affected about 200,000 people. In the northern USA, Cx. pipiens occurs both as a mix of forms pipiens and molestus (i.e., US Culex pipiens) as well as pure Cx. pipiens form molestus, the latter mostly in underground locations such as sewers and basements. In order to understand the potential risk of spread of RVFV in the USA, we compared their relative abilities to transmit RVFV in the laboratory. After feeding on hamsters with high viremias, >10⁹ plaque-forming units (PFU)/ml, both US Cx. pipiens and Cx. pipiens form molestus were highly susceptible to infection (∼80%) and about 20% of each form developed a disseminated infection. In contrast, when fed on a hamster with a moderate viremia, 10^7.5 PFU/ml, US Cx. pipiens were significantly (P < 0.001) more susceptible (84%) than were the pure form molestus (47%). Similarly, dissemination rates were significantly (P  =  0.0261) higher in US Cx. pipiens (34%) than they were in pure Cx. pipiens form molestus (10%). These results underscore differences in vector competence between genetic forms in the Cx. pipiens complex but also indicate that if RVFV were to arrive in the USA, competent vectors abound in the highly urbanized Northeast.

Okinawa is the largest, most urbanized, and densely populated island in the Ryukyus Archipelago, where mosquito species diversity has been thoroughly studied. However, the south-central Okinawa mosquito fauna has been relatively poorly studied. Here, we present results from a mosquito faunal survey in urban environments of Nishihara city, south-central Okinawa. Mosquitoes were sampled biweekly, from April 2007 to March 2008, at 3 different environments: a forest preserve, an animal farm, and a water reservoir. We employed 4 mosquito collection methods: 1) oviposition traps; 2) light traps; 3) sweep nets; and 4) larval surveys of tree holes, leaf axils, and artificial water containers. We collected a total of 568 adults and 10,270 larvae belonging to 6 genera and 13 species, including 6 species of medical importance: Aedes albopictus, Armigeres subalbatus, Anopheles Hyrcanus group, Culex bitaeniorhynchus, Cx. quinquefasciatus, and Cx. tritaeniorhynchus. Mosquito species composition was similar to data from previous studies in Okinawa Island. The flattening of the species accumulation curve suggests that our diversity sampling was exhaustive with light and oviposition traps, as well as the coincidence between the species richness we found in the field and estimates from the Chao2 index, a theoretical estimator of species richness based on species abundance. This study highlights the importance of combining several sampling techniques to properly characterize regional mosquito fauna and to monitor changes in the presence of mosquito species.

We conducted an inventory of the mosquito fauna of the internodes of bamboo plants grown in municipal parks in the city of São Paulo, Brazil. During October 2010 to July 2013, a total of 8,541 immature stages belonging to 21 mosquito species were collected from bamboos over 61 municipal parks. Of these, Aedes albopictus was the most abundant species followed by Ae. aegypti found in broken bamboos in most parks. The former species was 7.2 times more abundant than the latter when both species shared the same habitat. Other species collected from bamboos included Culex quinquefasciatus and Haemagogus leucocelaenus. In bamboos with perforated internodes, species of the genus Wyeomyia were the most prevalent. Differences were also observed in species composition and abundance of mosquitoes collected in transversely broken bamboos and those collected from perforated bamboo internodes. Constant surveillance of these breeding sites is crucial due to the epidemiological importance of the species found. Furthermore, these breeding sites may help maintain some native wild mosquito populations along with a variety of other invertebrates found in these urban green areas.

Carbon dioxide (CO₂) sources improve the efficacy of mosquito traps. However, traditional CO₂ sources (dry ice or compressed gas) may be difficult to acquire for vector surveillance during military contingency operations. For this reason, a new and convenient source of CO₂ is required. Two novel CO₂ generators were evaluated in order to address this capability gap: 1) an electrolyzer that converts solid oxalic acid into CO₂ gas, and 2) CO₂ produced by yeast as it metabolizes sugar. The flow rate and CO₂ concentration produced by each generator were measured, and each generator's ability to attract mosquitoes to BG-Sentinel™ traps during day surveillance and to Centers for Disease Control and Prevention light traps with incandescent bulbs during night surveillance was compared to dry ice and compressed gas in Jacksonville, FL. The electrolyzed oxalic acid only slightly increased the number of mosquitoes captured compared to unbaited traps. Based on the modest increase in mosquito collection for traps paired with the oxalic acid, it is not a suitable stand-in for either of the 2 traditional CO₂ sources. Conversely, the yeast-generated CO₂ resulted in collections with mosquito abundance and species richness more closely resembling those of the traditional CO₂ sources, despite achieving a lower CO₂ flow rate. Therefore, if dry ice or compressed gas cannot be acquired for vector surveillance, yeast-generated CO₂ can significantly improve trap capability.

Laboratory and field evaluations were conducted to assess the activity and efficacy of Mosquiron® 0.12CRD, a new formulation containing 0.12% novaluron, against immature Culex mosquitoes. In laboratory bioassays, this formulation was highly active against Culex quinquefasciatus as indicated by low inhibition of emergence (IE) values (IE₅₀ and IE₉₀). When Mosquiron 0.12CRD was applied at 1 briquet per underground stormwater vault, counts of late instars showed a significant reduction on day 28 posttreatment. When the late instars and pupae collected from Mosquiron-treated water were brought back to the laboratory for posttreatment observation, emergence inhibition was >90% on day 7. When the late instars from a laboratory colony of Cx. quinquefasciatus were exposed to the Mosquiron-treated water, 99% and 95% emergence inhibition was noted on day 7 and day 14, respectively. When Mosquiron 0.12CRD was applied at 11 briquets per vault, significant reductions of larval populations were encountered on days 7 and 35 posttreatment for early instars, and on days 14, 21, and 35 posttreatment for late instars. Laboratory observation of late instars and pupae sampled from the treated vault water showed nearly complete emergence inhibition from day 7 to day 28 posttreatment. A similar trend was observed in laboratory-reared late instars of Cx. quinquefasciatus when exposed to the treated water. Preliminary evaluations indicated that Mosquiron 0.12CRD is a useful new tool to control Culex mosquitoes breeding in persistent sources.

This study was conducted to determine the efficacy of truck-mounted ultra-low volume applications of pyriproxyfen against Aedes aegypti larvae in artificial water containers and wild adult Ae. albopictus populations in an urban setting. The study was conducted over a 3.5-month period (June–October 2012), during which 3 pyriproxyfen applications were conducted. Beginning 6 wk prior to the 1st pyriproxyfen spray, 10 Biogents-Sentinel® traps were used each week to survey the adult Ae. albopictus population at each experimental plot through the end of the study. The treatment and control plots contained specimen cups, each containing 10 laboratory-reared Ae. aegypti larvae, placed at 8, 15, and 23 m from the spray line. Emergence inhibition (EI) of 82% or greater was observed among Ae. aegypti larvae exposed to the 3 pyriproxyfen sprays. The EI of these same Ae. aegypti larvae at the 3 distances from the spray ranged from 84% to 92% and were not significantly different. Laboratory analysis of water samples taken from the larval cups independently confirmed the presence of pyriproxyfen. Similar levels of EI were achieved in Ae. aegypti and Ae. albopictus larvae when the measured field concentrations of pyriproxyfen were recreated in laboratory assays. Trap captures of wild adult Ae. albopictus were not markedly reduced following the 1st pyriproxyfen spray, perhaps due to heavy rainfall at the time and the lower rate of pyriproxyfen applied. Within 2 wk following Spray 2, however, Ae. albopictus collections from the treatment plot averaged approximately 50% of those from the control plot, and the reduction trend continued following Spray 3.

Studies were conducted to compare levels of insecticide resistance and to determine the metabolic resistance mechanisms in larval and adult stages of Aedes aegypti from Cuba. Three insecticide-resistant reference strains of Ae. aegypti from Cuba were examined. These strains were derived from a Santiago de Cuba strain isolated in 1997; it was previously subjected to a strong selection for resistance to temephos (SAN-F6), deltamethrin (SAN-F12), and propoxur (SAN-F13) and routinely maintained in the laboratory under selection pressure up to the present time, when the study was carried out. In addition, an insecticide-susceptible strain was used for comparison. The insecticide resistance in larvae and adults was determined using standard World Health Organization methodologies. Insecticide resistance mechanisms were determined by biochemical assays. The esterases (α EST and β EST) and mixed function oxidase (MFO) activities were significantly higher in adults than in the larvae of the three resistant strains studied. The association of resistance level with the biochemical mechanism for each insecticide was established for each stage. The observed differences between larval and adult stages of Ae. aegypti in their levels of insecticide resistance and the biochemical mechanisms involved should be included as part of monitoring and surveillance activities in Ae. aegypti vector control programs.

The first confirmed collection of Aedes stimulans in Louisiana was made in St. Tammany Parish, LA. A single adult female was collected by a large-bore aspirator in March 2011, and identified by microscopic and molecular methods. Notes are provided on the morphology, location, habitat, and potential mosquito associates that may be found with Ae. stimulans.

Malaria is endemic in Wangxia Village of Hainan Island. In this area little is known about the host seeking behavior and feeding habit of mosquitoes. Three sites representing the most common habitat types in the village were selected to study the host seeking behavior and feeding habit of mosquitoes. Of the total 9 species belonging to 4 genera (Armigeres, Culex, Aedes, and Anopheles) collected in Wangxia Village, Culex tritaeniorhynchus and Cx. pipiens quinquefasciatus were the most commonly collected species. Armigeres subalbatus and Anopheles sinensis were moderately common species. Blood meal analysis confirmed that Cx. tritaeniorhynchus and Cx. p. quinquefasciatus fed on multiple hosts, mainly poultry but occasionally other animals. Anopheles sinensis, a vector of malaria, fed predominately on cattle hosts, followed by humans. Anopheles maculatus and An. barbirostris fed on both humans and domestic animals. Our results indicate that most mosquitoes in this area preferred domestic animals over humans and showed a tendency to feed on multiple hosts within the same gonotrophic cycle. Therefore, the potential role of domestic animals in arbovirus transmission should be evaluated as part of a strategy for controlling mosquito-borne diseases in this region.

A study to evaluate the protection provided by permethrin-treated military fabric following cold-water washing against host-seeking mosquitoes is reported. The landing/probing of native mosquitoes on Australian Defence Force Disruptive Pattern Combat Uniform shirts treated by dipping in 0.6% permethrin emulsion (Perigen Defence®, containing 500 g/l permethrin), and commercial factory treatments in the USA (Factory A) and Europe (Factory B) were recorded after 0, 1, 3, 5, and 10 washes. The study showed that significantly shorter landing/probing times compared with untreated controls were recorded for shirts treated with Factory A treatment after 0 and 1 wash, and for the Factory B treatment after 0 washes, and there were no differences between permethrin treatment and control landing. The study concludes that better methods to assess protection from landing/probing mosquitoes in the field are needed.