The larva of Culex salinarius is completely described and illustrated, except for the mouth parts, and compared with the morphologically similar larva of Cx. nigripalpus. At least 8 characters have been found to separate larvae of the two species of which 7 give 90% or higher divergence while the remaining character gives 87% separation.

The Anopheles minimus Complex Theobald (Diptera: Culicidae) is composed of the 3 sibling species A, C, and E. The malaria vectors An. minimus A and C are distributed over the Southeast Asian region, whereas species E is restricted to the Ryukyu Japanese islands. Because species A and C can be sympatric and present specific behaviors and have a role in malaria transmission, it is important to differentiate them. The literature mentioned the presence of a presector pale spot on the wing costa of An. minimus A, whereas species C may exhibit both presector and humeral pale spots. However, the reliability of their diagnostic power has not been established over large temporal and geographic surveys. From the analyses of 9 populations throughout Southeast Asia, including published data and field populations from 2 sites in Thailand, we showed that the wing patterns present spatial and temporal variations that make these two morphological characters unreliable for the precise identification of An. minimus A and C. Therefore, molecular identification remains the most efficient method to obtain an unambiguous differentiation of these 2 species. Correct species identification is essential and mandatory for any relevant study on the Minimus Complex and for the application of successful control strategies.

Anopheles (Cellia) maculatus Theobald is a major malaria vector in southern Thailand and peninsular Malaysia, and previous population genetic studies suggested that mountain ranges act as barriers to gene flow. In this study we examine the genetic variance among 12 collections of natural populations in southern Thailand by analyzing 7 microsatellite loci. Based on analysis of molecular variance (AMOVA), three geographic populations of An. maculatus are suggested. The northern population exists in western Thailand north of 12° north latitude. Mosquitoes to the south fall into two genetic populations: 1) the middle southern collections located on the west side of the Phuket mountain range between 8° and 10° north latitude, and 2) the southern collections located on the east of the Phuket mountain range located between approximately 6.5° and 11.5° north latitude. AMOVA revealed significant genetic differentiation between northern and middle southern and southern populations. The middle southern population was moderately differentiated from the southern population. Furthermore, gene flow was restricted between proximal collections located on different sides of the Phuket mountain range. Collections separated by 50 km exhibited restriction of gene flow when separated by geographic barriers, whereas greater gene flow was evident among collections 650 km apart but without geographic barriers.

Several techniques were used to sample adult and immature mosquitoes in 4 constructed treatment wetlands in Florida. Adults of 19 species (7 genera) of mosquitoes were collected, and immatures of the most abundant species and of 60% of all species also were collected. Few significant differences between sites and stations in the numbers of mosquitoes collected were discovered. Culex nigripalpus Theobald was the most abundant mosquito found in adult (carbon dioxide-baited suction traps) and ovitrap collections, whereas Mansonia spp. and Uranotaenia spp. were most common in pump-dip-grab samples. The roles of rooted and floating vegetation and of water quality in determining mosquito production from these areas are discussed.

Ovitrap collections were done to determine the seasonal distribution and ovipositional activity of Culex restuans and Culex pipiens in southwestern Virginia during summers 2002 and 2003. In both years, Cx. restuans was the first species collected and was the dominant species throughout the collecting period. More than 90% of the collections were comprised of Cx. restuans. Two oviposition peaks occurred in both years for Cx. restuans, the first in June and second in the middle of July. Culex pipiens made up less than 7% of the total catch and started to occur in the traps in the middle of the trapping season with a peak occurring in August. Although ovipositional activity began to decline for Cx. restuans, at the end of the trapping period, there was a slight increase in ovipositional activity for Cx. pipiens, but not enough to result in a crossover. A third species, Culex salinarius, was collected in the traps, but the total number of egg rafts accounted for less than 1% of the total collections.

Surveys for anopheline mosquitoes were conducted throughout the mainland of Papua New Guinea from 1992 to 1998 with the aim of mapping the distribution of the anopheline fauna. Larval collections, adult trap, and human landing collections indicated the presence of seven species (other than those belonging to the Anopheles punctulatus group); these were An. bancroftii, An. annulipes, An. karwari, An. longirostris, An. meraukensis, An. novaguinensis, and An. subpictus. The distribution and ecology of these species is discussed.

A larval survey of dengue vectors was conducted from July to November 1996 and from May to November 1997 in Chiangmai Province, Thailand. Three villages in urban, transition, and rural areas were selected for the survey to clarify the spatial distribution of Ae. aegypti and Ae. albopictus along an urban–rural ecological gradient. The average number of Ae. aegypti larvae in larvitraps was higher in the urban area than in the rural area, as we expected, whereas the opposite was found for Ae. albopictus, rural area > urban area. A house survey of larvae-inhabiting containers showed significant differences in the number and composition of these containers among the study areas. Significant differences also were found in the average distance between houses, average tree height, and average percentage of vegetation cover for each house. The seasonal pattern of rainfall recorded in each study area did not show great differences among the study areas. The response of Ae. aegypti and Ae. albopictus to the urban–rural gradient is discussed in relation to the possibility of applying geographic information system techniques to plan the control strategy and surveillance of dengue vectors.

A novel mosquito trapping system, the BG-Sentinel® trap, was evaluated as a monitoring tool for adult Aedes aegypti in field tests in the city of Belo Horizonte, Brazil. Human landing/biting collections, a gas-powered CO₂ trap, and a Fay-Prince trap with only visual cues serving as references to evaluate the efficacy of the new trap. The BG-Sentinel is a simple suction trap that uses upward-directed air currents as well as visual cues to attract mosquitoes. The trap was tested with a new dispenser system (BG-Lure®) that releases artificial human skin odors and needs no CO₂. In comparison with the two other traps, the BG-Sentinel caught significantly more Ae. aegypti. Although human landing rates were the highest, there was no significant difference between human landing rates and the capture rates of the BG-Sentinel trap. This finding indicates that the trap can be considered as an acceptable alternative to human landing/biting collections in the surveillance of adult host- seeking dengue vectors. The addition of the BG-Lure to the gas-powered CO₂ trap greatly increased its efficacy. This combination, however, was not significantly more effective than the BG-Sentinel without CO₂. In a 6-month comparison between the BG-Sentinel and a sticky ovitrap for gravid females, the BG-Sentinel proved to be a far more efficient and sensitive tool to measure the density of Ae. aegypti populations.

The vertical distribution of mosquitoes (Diptera, Culicidae) was evaluated in Paju County in northern South Korea by using Centers for Disease Control and Prevention (CDC) miniature light traps with ultraviolet light and dry ice (CO₂) as attractants. CDC traps were placed at 1, 3, and 5 m above the ground near rice paddies in a relatively open agricultural area. Traps were hung on two scaffold towers (6 m height) spaced approximately 300 m apart. Each trap operated 9 nights from August 3 to 16, 2002, and collected 9,971 mosquitoes: Aedes vexans nipponii, 145.2; Culex tritaeniorhynchus, 34.9; Anopheles sinensis, 21.3; and Culex pipiens, 17.3 female mosquitoes/trap/night. Average flight height was calculated from the total number of catches in both stations. Overall, Cx. pipiens (2.52 ± 0.35 m) was found to be the highest flying species followed by An. sinensis (2.04 ± 0.79 m), Ae. vexans nipponii (1.96 ± 0.44 m), and Cx. tritaeniorhynchus (1.76 ± 0.68 m), respectively. Although no significant difference in flying height among species was encountered, every species showed their own flight preference range, matching with their host preference.

As part of the West Nile virus surveillance program for the state of New Mexico, 13 sites along the Rio Grande River were sampled for mosquitoes during spring and summer 2003. We evaluated 3 different trapping procedures for their effectiveness at capturing selected species of mosquitoes. The 3 methods used were a dry ice-baited Centers for Disease Control and Prevention (CDC) light trap set 1.5 m above the ground (standard method), a CDC light trap suspended within the forest canopy, and a gravid trap set on the ground. Thirteen sites were sampled for 10 1-night periods biweekly from May through September. The relative numbers of captured Culex tarsalis, Cx. salinarius, Cx. quinquefasciatus, and Aedes vexans as well as the numbers of total recorded captures of all species were compared for each trapping method. Significant differences were observed for each species by location and by trapping method. Culex tarsalis was most commonly caught in canopy or standard CDC traps, especially in cottonwood bosque. Culex salinarius was found most frequently in association with marshy water, and was most often caught in gravid or standard light traps. Culex quinque-fasciatus was captured almost exclusively in gravid traps within urban areas. Aedes vexans was primarily sampled in standard CDC light traps and found most frequently in wooded areas near floodplains. With the exception of Cx. quinquefasciatus, no species was collected significantly more frequently in gravid or canopy traps than in the standard CDC light trap. Our findings do not support altering the methods currently used in New Mexico, namely, the use of 1.5-m CDC light traps and gravid traps. An increased use of gravid traps seems to be warranted in monitoring urban vector populations (specifically Cx. quinquefasciatus and Cx. salinarius) that may be involved in human transmission.

This descriptive prevalence study describes the relationships between mosquito density and the presence of arboviruses (in mosquitoes and humans) with various socioeconomic and environmental factors present near the time of the arbovirus outbreak in Harris County, Texas, in 2002. This study suggests that mosquito density increased if the trap was located in an area with a large number of containers that may inadvertently retain rainwater (P = 0.056). When considering only virus-positive mosquitoes, significant relationships were observed if the trap was located near waste materials (P < 0.001) or near containers that may inadvertently retain rainwater (P = 0.037). Furthermore, the presence of arbovirus activity (in mosquitoes or humans) in a geographic area tended to be associated with the socioeconomic status of the local community. Although the results of the socioeconomic comparisons were not significant, they were suggestive, demonstrating an interesting trend. Compared with communities where virus activity was not observed, the socioeconomic status of the arbovirus-positive community was consistently lower. Specifically, results showed that the populations residing in virus-positive census tracts attained less education, earned less income per household, and were more likely to be below the poverty level. In addition, this study found that virus-positive mosquitoes were randomly distributed throughout the study area, whereas severe human infection cases were clustered. Based on the results of this study, we conclude that the health outcome of a local community as it relates to West Nile virus and St. Louis encephalitis is dependent on many factors, including the socioeconomic and environmental characteristics of the community.

A West Nile virus (WNV) surveillance system was created and implemented in New York State (NYS) in 2000 and described previously (White et al. 2001). We examine and evaluate the results of mosquito and virus surveillance for 2000 through 2004 exclusive of New York City. Forty-nine counties submitted 1,095,426 mosquitoes in 35,280 pools for WNV assay. Specimens of 47 species were tested, with Culex species accounting for 47.6% of all pools tested. WNV was detected in 814 pools from 10 species, with combined Culex pipiens/Culex restuans pools accounting for 90.8% of all detections. Pools submitted from gravid traps were 5.7 times more likely to be positive than submissions from carbon dioxide-baited light traps. Most human WNV cases resided in counties that conducted mosquito surveillance. Local health departments' use of mosquito surveillance information often led to an enhanced disease prevention response. In NYS, Cx. pipiens/Cx. restuans group are the most likely vectors of WNV. Future efforts to improve system efficacy are discussed.

The vector competence of Culex tarsalis Coquillett for the BFS1703 strain of western equine encephalomyelitis virus (WEEV) changed significantly as a function of time after infection, mosquito genotype, and infectious virus dose. After ingesting a high virus dose (5 log₁₀ plaque-forming units [PFU]/0.1 ml), females of the susceptible high virus producer (HVP) strain rapidly amplified virus, developed a disseminated infection, and efficiently transmitted WEEV by 4 days postinfection (dpi). The quantity of virus expectorated peaked at 4 dpi (mean 3.4 log₁₀ PFU), and the percentage of females transmitting per os peaked at 7 dpi (80%); both measures of transmission subsequently decreased to low levels throughout the remainder of infected life. HVP females imbibing a low virus dose (3 log₁₀ PFU/0.1 ml) were infected less frequently and took longer to amplify virus to levels recorded for the high virus dose group and did not transmit virus efficiently, thereby indicating midgut infection and escape barriers were dose and time dependent. These data emphasized the importance of elevated avian viremias in Cx. tarsalis vector competence. Females from the WEEV-resistant (WR) strain and two wild-type strains from Kern and Riverside counties were significantly less susceptible to infection at both high and low doses than was the HVP strain. Overall, females with a high virus titer more frequently had a disseminated infection, but there did not seem to be a distinct threshold demarcating this relationship. In marked contrast, all infected females transmitting virus had body titers >4.3 log₁₀ PFU, and most had titers >4.8 log₁₀ PFU. These data indicated that not all females with a disseminated infection transmitted virus because of the presence of one or more salivary gland barriers.

We performed longitudinal surveys of mosquito larval abundance (mean mosquito larvae per dip) in 87 stormwater ponds and constructed wetlands in Delaware from June to September 2004. We analyzed selected water quality factors, water depth, types of vegetation, degree of shade, and level of insect predation in relation to mosquito abundance. The 2004 season was atypical, with most ponds remaining wet for the entire summer. In terms of West Nile virus (WNV) vectors, wetlands predominantly produced Aedes vexans, Culex pipiens pipiens, and Culex restuans. Retention ponds generally produced the same species as wetlands, except that Cx. p. pipiens was more abundant than Cx. restuans in retention ponds. Aedes vexans and Culex salinarius were the most abundant species in Conservation Restoration Enhancement Program ponds. Sand filters uniquely produced high numbers of Cx. restuans, Cx. p. pipiens, and Aedes japonicus japonicus, a newly invasive vector species. Sites that alternately dried and flooded, mostly detention ponds, forebays of retention ponds, and some wetlands often produced Ae. vexans, an occasional WNV bridge vector species. Overall, seasonal distribution of vectors was bimodal, with peaks occurring during early and late summer. Ponds with shallow sides and heavy shade generally produced an abundance of mosquitoes, unless insect predators were abundant. Bright, sunny ponds with steep sides and little vegetation generally produced the fewest mosquitoes. The associations among mosquito species and selected vegetation types are discussed.

Larvicidal activity of essential oils derived from 11 aromatic medicinal plants against early 4th-stage larvae of Aedes aegypti and Culex pipiens pallens was tested in the laboratory. At 100 ppm, the essential oils of all plants caused 100% mortality against Ae. aegypti and Cx. pipiens pallens. At 25 ppm, the essential oils of Citrus bergamia, Cuminum myrrha, and Pimenta racemosa caused 100% mortality against larvae of Ae. aegypti and Cx. pipiens pallens. The oil of C. bergamia caused 32.5% and 24.5% mortality against Ae. aegypti and Cx. pipiens pallens at 12.5 ppm, but 24.2% and 0% mortality against Ae. aegypti and Cx. pipiens pallens at 6.25 ppm, respectively. The oil of P. racemosa caused 52.3% and 38.5% mortality against Ae. aegypti and Cx. pipiens pallens at 12.5 ppm, but 32.2% and 0% mortality against Ae. aegypti and Cx. pipiens pallens at 6.25 ppm, respectively. The larvicidal activity of oils of C. bergamia, C. myrrha, and P. racemosa was significantly reduced when used at 6.25 ppm. These plants warrant further studies as possible agents for mosquito control.

In this study, we compared the efficacy of the newly available BG-Sentinel with an established “gold standard,” the CDC Backpack Aspirator, and a CO₂-baited EVS trap for the collection of Aedes aegypti (L.) in Cairns, Australia. BG-Sentinels collected significantly more (P = 0.017) female Ae. aegypti (mean per collection, 1.92 ± 0.39) than both the CDC Backpack Aspirator (1.00 ± 0.35) and the EVS trap (0.71 ± 0.27). Male-only and combined male-female Ae. aegypti collections for the BG-Sentinel and the CDC Backpack Aspirator were also greater than EVS trap collections. The CDC Backpack Aspirator and the BG-Sentinel captured proportionally fewer females compared with the EVS trap. The BG-Sentinel was the most Ae. aegypti-specific collection method. The CDC Backpack Aspirator collected proportionally more bloodfed Ae. aegypti than the other methods, which collected a greater proportion of nullipars. The data presented here will aid researchers in deciding what Ae. aegypti sampling device best suits their needs. BG-Sentinels and CDC Backpack Aspirators should be considered as alternatives to human-bait collections for Ae. aegypti sampling.

We studied the efficacy of space ultra-low volume treatments of 3 insecticides for the control of the dengue virus vector Aedes aegypti in southern Mexico. Insecticides tested were permethrin (Aqua-Reslin® Super), d-phenothrin (Anvil®), and cyfluthrin (Solfac®), applied at rates of 10.87, 7.68, and 2 g/ha, respectively, by using London Fog®, HP910-PHXL®, or Micro-Gen® pumps mounted on vehicles. Studies included 1) open field penetration tests and 2) house penetration tests. Open field tests indicated that Anvil and Solfac were more effective than Aqua-Reslin Super. In house tests, Anvil yielded the highest mosquito mortalities (≥ 88%) of the three insecticides in the front porch, living room, bedroom, and backyard. Therefore, Anvil proved to be better than other insecticides evaluated to control Ae. aegypti in Chiapas, México.

Diethyl methyl benzamide or deet, a commercial plant-based repellent (Repel Care®), and essential oils from 3 species of plants (finger root rhizomes, guava leaves, and turmeric rhizomes), steam distillated and formulated as insect repellents, were evaluated in the field on human volunteers against hematophagous mosquitoes, black flies, and land leeches in Thailand. Field trials were conducted against wild mosquitoes in Bang Bua Thong District, Nonthaburi Province, and in the Thap Lan National Park Headquarters, Nadee District, Prachinburi Province; anthropophilic black flies (Diptera: Simuliidae) at the Forestry Fire Control Station in Doi Inthanon National Park, Chomthong District, Chiang Mai Province; and land leeches (Arhynchobdellida: Haemadipsidae) in the Khao Yai National Park, Pak Chong District, Nakhon Ratchasima Province. The 3 experimental plant-based essential oil formulations as well as Repel Care and deet provided complete protection from mosquito landing and biting for up to 9 h (duration of the experiment). Similar results were obtained with the 5 products against black flies, providing 100% protection for 9 h but 96–82% protection after 10 and 11 h posttreatment. The 5 repellent products also provided 100% protection against land leeches for at least 8 h. This is the 1st report of repellency of plant-based repellents against black flies and land leeches in Thailand. The identification and availability of inexpensive sources of plant-based oils, i.e., finger root rhizomes, guava leaves, and turmeric rhizomes providing long-lasting repellency against blood-sucking organisms are promising leads into commercial production of relatively safe and effective repellents.

One hundred ninety hexanic and ethanolic extracts from 27 plant species from the Cerrado biome of Brazil were tested for larvicidal activity against 3rd-stage Aedes aegypti larvae at 500 μg/ml. Fourteen extracts from 7 species showed activity (>65% mortality) against the larvae. Of these, Duguetia furfuracea, Piptocarpha rotundifolia, Casearia sylvestris var. lingua, Serjania lethalis, and Xylopia aromatica were active at 56.6, 162.31, 232.4, 285.76, and 384.37 μg/ml, respectively. Annona crassiflora and Cybistax antisyphilitica showed activity at 23.06 and 27.61 μg/ml. The larvicidal properties of these species are described for the first time, and may prove to be promising in active chemical compound isolation.

This is the first description of 3rd and 4th instars of Anopheles (Cellia) carnevalei. Adults were caught in the mainland region (Rio Muni) of Equatorial Guinea. Larvae present characteristic palmate setae different from Anopheles nili.

The Hyrcanus group of Anopheles consists of many related species, of which An. sinensis, An. lesteri, and An. anthropophagus are known as malaria vector species. It is not possible to identify these species morphologically in the adult and larval stages. Nucleotide sequence alignment of 2nd internal transcribed spacer (ITS2) regions from 4 specimens of An. lesteri collected in Japan, 2 specimens of An. anthropophagus collected in China, and 1 specimen of An. sinensis collected in Korea were sequenced and compared. Sequences of ITS2 regions varied only at 4 sites between An. lesteri and An. anthropophagus, and individual variations among each An. lesteri and An. anthropophagus were found at 5 and 7 sites, respectively, whereas sequences varied at 161 sites between An. lesteri and An. sinensis. This molecular evidence strongly supports that An. lesteri from Japan and An. anthropophagus from China are the same species.

A revised checklist of the mosquito fauna known to occur in Maine is reported. In addition we are detailing the finding of eight new state records in five genera, that is, Anopheles barberi, Culiseta minnesotae, Ochlerotatus dorsalis, Oc. japonicus, Oc. riparius, Oc. taeniorhynchus, Psorophora ferox, and Uranotaenia sapphirina. Locality records are given.

We report the first finding of Culex coronator Dyar and Knab in Florida, based on multiple adult collections from several locations in the western panhandle of Florida. GPS coordinates and habitat descriptions are given and disease implications are discussed. These records extend the known distribution of Cx. coronator from six other states (Arizona, Louisiana, Mississippi, New Mexico, Oklahoma, and Texas), and from Mexico to Argentina.

This study evaluated the efficacy of methoprene, a widely used juvenile hormone mimic, formulated as 30-day slow release Altosid^® pellets, at controlling mosquitoes in underground storm water drainage catch basins. Data from applications to ¼-sized cement catch basins in the laboratory, field observations from treated and untreated basins, and an experiment that confined mosquito larvae in floating emergence jars in catch basins showed that methoprene effectively controlled mosquitoes for a month under field conditions and substantially longer under laboratory conditions when applied at a dose of 3.5-g pellets per average-sized catch basin.

The mosquito larvicide methoprene is a juvenile growth hormone mimic that is widely used to control mosquitoes. This chemical disrupts normal mosquito development, drastically inhibiting emergence from the pupal to the adult stage. If the presence of methoprene attracts or deters mosquitoes from ovipositing it could have implications for mosquito control. This study evaluates whether methoprene attracts or deters mosquitoes likely to oviposit in catch basins. In a field experiment, methoprene formulated as liquid larvicide did not affect oviposition of either Culex spp. or Aedes japonicus in 19-l plastic buckets.

The mosquito Culex pipiens L. is an important pest in urban and suburban areas in many parts of the world. Septic tanks are the most important habitats supporting the production of this species in the city of Antalya, southwestern Turkey. Diflubenzuron, in a 25% wettable powder (Du-dim® 25 WP), and a 4% granular formulation (Du-dim® 4 G) was evaluated against late 2nd to early 3rd instars of Cx. pipiens in single-family septic tanks. Both formulations were tested at 0.01, 0.02, and 0.03 mg (AI)/liter. The results indicated that both formulations applied at the rate of 0.02 and 0.03 mg (AI)/liter achieved 100% adult inhibition, at intervals of 7, 14, 21, and 28 days after treatment. Septic tanks treated with 0.01 mg (AI)/liter WP formulation resulted in complete (100%) adult inhibition through 14 days, whereas the G formulation gave the same effect through 21 days posttreatment at this rate.

We describe the ovicidal action of a 3.75% (w/v) sodium hypochlorite solution on the eggs of Aedes albopictus (Skuse). The effectiveness of this ovicide has also been confirmed by a field trial. On the basis of the data collected in the city of Bologna, Italy, we hypothesize a relationship between the numerical increase of the Ae. albopictus eggs laid and the reduced daily variation of the relative humidity, facilitating the possibility of planning ovicidal treatments.