Since the initial discovery of Aedes japonicus japonicus in 1998 from sites in the northeastern United States (New York, Connecticut, and New Jersey), this invasive mosquito species now permeates local faunas throughout eastern North America and continues to expand its distribution westward. In July and August of 2006, the 1st reported specimens of Ae. japonicus were detected in east central Illinois at 2 woodlots in southern Urbana. Sampling efforts were concentrated around the site of the original detection. Dry ice–baited light traps and gravid traps caught 26,421 mosquitoes, with 5 and 6 Ae. japonicus recovered from each trap type, respectively. Although numerous larvae were found in 1 woodlot, they were restricted to a single container, a child's plastic swimming pool. Routine weekly mosquito sampling for West Nile virus (WNV) surveillance in Urbana and the adjacent city of Champaign (gravid and dry ice–baited traps placed in agricultural, industrial, residential, and urban parks) failed to detect Ae. japonicus outside of the 2 woodlots. Despite previous reports of Ae. japonicus from the adjacent states of Indiana and Missouri in 2004 and 2005, the extremely localized spatial distribution and low abundance of this species strongly suggests a recent introduction. If Ae. japonicus follows previous trends in the United States and Canada, within 1–3 years after it becomes established, its abundance, frequency of detection, and spatial distribution will significantly expand. Aedes japonicus has some characteristics of a bridge vector for West Nile virus because of its vector competency, ability to feed on mammals and birds, and potential abundance near sites of known WNV transmission in Illinois.

Sampling was conducted for 1 year in a marsh near Buenos Aires from axils of Scirpus giganteus, a larval habitat of the poorly known sabethine mosquito, Isostomyia paranensis. Immatures of this species were recovered on every sampling date, averaging 3–4/plant in April and decreasing to 0–1/plant in October–December. The spatial distribution of Is. paranensis immatures was clumped, and larval age skewed toward 1st instars. The percentage of mosquito-positive S. giganteus was negatively correlated with accumulated rainfall 1 wk before collection. Microcrustacea were the only other invertebrates common in this phytotelmata, and no parasites or pathogens were detected in Is. paranensis. Fourth instars of this species attacked and killed one another in the laboratory, but only algae were recovered from dissected digestive tracts of field-collected larvae. Adult females of this species emerged from independent collections of pupae refused blood, but females captured at human bait readily consumed human blood. Mean (±SD) number of eggs developed by females collected at human bait and fed with blood (77.4 ± 22.8) was not significantly different from the mean number of eggs developed by females collected as pupae and fed on sugar (72.0 ± 23.0).

Movement of Ochlerotatus japonicus japonicus into virus-endemic areas in the USA has raised concern about its vector potential and prompted monitoring of its spread. The abundance and seasonal distribution of Oc. japonicus in southwestern Virginia was measured in 2003 and 2004 using gravid traps. In 2003, collections were made over 192 trap-nights from June to August yielding 5,879 mosquitoes of which only 24 were Oc. japonicus. In 2004, 12,151 mosquitoes were trapped from June to September over 160 trap-nights. Ochlerotatus japonicus was the second most abundant mosquito species and the dominant Ochlerotatus species collected in gravid traps. Ochlerotatus japonicus was collected in low numbers in June, but the abundance increased significantly in July and remained consistent throughout the rest of the season. Of the other major mosquito species collected in this study, only Aedes albopictus exhibited a similar seasonal pattern as Oc. japonicus. Other biological similarities of Oc. japonicus and Ae. albopictus are discussed.

Associations between Culex quinquefasciatus, Aedes albopictus and West Nile virus (WNV) activity, temperature, and rainfall in Harris County, Texas 2003–06 are discussed. Human cases were highly correlated to Cx. quinquefasciatus (r = 0.87) and Ae. albopictus (r = 0.78) pools, blue jays (r = 0.83), and Ae. albopictus collected (r = 0.71), but not Cx. quinquefasciatus collected (r = 0.45). Human cases were associated with temperature (r = 0.71), not rainfall (r = 0.29), whereas temperature correlated with Ae. albopictus and Cx. quinquefasciatus collections (r = 0.88 and 0.70, respectively) and Cx. quinquefasciatus pools (r = 0.75), but not Ae. albopictus pools (r = 0.55). Both species (collections and pools) and blue jays were weakly correlated (r ≤ 0.41) with rainfall, but blue jays were better correlated with Cx. quinquefasciatus pools (r = 0.87), compared with Ae. albopictus pools (r = 0.67), Ae. albopictus collections (r = 0.69), and Cx. quinquefasciatus collections (r = 0.46). Peak minimum infection rate for Cx. quinquefasciatus (4.55), and Ae. albopictus (4.41) was in August with highest human cases (17.87), blue jays (55.58), and temperature (29.01°C). Between both species, blood meal analysis indicated 68.18% of Cx. quinquefasciatus mammalian hosts were dog, while 22.72% were human, whereas Ae. albopictus had higher human (44.44%) but fewer dog hosts (22.22%). Ten bird species were identified as hosts for Cx. quinquefasciatus, with northern cardinal and blue jay representing 26.66% and 20.00%, respectively. No bird feeding activity was observed in Ae. albopictus. The earliest and latest human blood meal occurred in May (Ae. albopictus) and November (Cx. quinquefasciatus); 66.66% of human host identifications between both species occurred in October–November, after the seasonal human case peak. Based upon our data, WNV activity in both mosquito species warrants further investigation of their individual roles in WNV ecology within this region.

The recapture rates of wild-caught, unengorged Anopheles vestitipennis and Anopheles albimanus females were determined at 0, 400, and 800 m from a fixed release point in Belize, Central America. Three sampling trials, each consisting of two 12-hour collections, were performed at each distance during September–October 2003. A total of 1,621 An. vestitipennis and 1,326 An. albimanus were marked and released during the course of the study. The recapture rate of An. vestitipennis was greatest at 0 m (7.9%; 44/556) and declined from 3.0% (16/531) at 400 m to 0.2% (1/534) at 800 m. Anopheles albimanus females were recaptured only at the 0-m distance and in extremely low numbers (1.1%; 5/446). Biting patterns for the unmarked natural populations were similar to those previously described for Belize, and recaptures for both species occurred during these normal biting times. The overall recapture rates for An. vestitipennis (3.76%; 61/1,621) and An. albimanus (0.38%; 5/1,326) indicate that An. vestitipennis has a higher probability of being attracted to a human habitation.

Two proprietary controlled-release (CR) formulations (CR55 and CR56) of 20% AI3-37220 (1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine) in an aqueous dispersion, and the same repellent formulated in water (W220), were compared with a repellent-free control for oviposition deterrent and larvicidal activity against natural populations of Stegomyia albopicta. A single application of each formulation (final concentration: 0.1%) prevented oviposition by St. albopicta for 4 wk, with highest deterrence (46%) observed for CR55 at 8 wk posttreatment. At the same application rate, each repellent formulation reduced larval activity in experimental containers by 100% through week 4 posttreatment and, for CR55, by 92–100% through week 8. In a municipal cemetery (Gainesville, Florida, USA), 1 application of CR55 or CR56 (final concentration: 0.1%) in concrete flower vases eliminated St. albopicta larvae for 10 wk. With formulation improvements to enhance efficacy at low repellent concentrations, AI3-37220 may have potential for use in the control of container-inhabiting mosquitoes.

Chemical lures can enhance the ability of traps to collect mosquitoes, selectively target species for capture, and provide a realistic assessment of the species and host-equivalent numbers of mosquitoes present in the local area. One approach to the development of chemical lures is to manufacture blends that comprise odors released in human emanations. These blends need to be safe for use in the environment, desirable from an economic standpoint, and transportable to the field for use in traps. In this report, we compared the attraction of mosquitoes to various chemicals, blends, and odors from humans. Noncompetitive (single-treatment) bioassays established that some blends are equivalent or more attractive to Aedes aegypti than human odors. Competitive bioassays were conducted; these involved simultaneous comparison of 2 treatments: single compounds to binary blends; binary blends to a trinary blend of L-lactic acid, acetone, and dimethyl disulfide; and the trinary blend to human odors from 3 volunteers. The overall trend was that the trinary blend was more attractive than binary blends, and binary blends were more attractive than single compounds. However, human odors were still significantly more attractive than the trinary blend. Therefore, further modifications and refinements to blends will be needed to better compete against human odors.

Comparison of an artificial, whole-blood membrane feeding procedure was performed by feeding Aedes aegypti (Liverpool strain) on the blood of patients infected with Wuchereria bancrofti microfilariae with the use of 3 types of membranes produced from chicken and mouse skin and swine intestine. Direct feeding of Ae. aegypti on the skin of infected human patients served as control. For all 3 types of membranes, mosquito survival, infection, and number of infective-stage larvae per mosquito did not differ significantly from the control. However, the blood feeding response between swine intestine layer (32%) compared to chicken skin (75.3%), mouse skin (70%), and direct feeding (84%) differed significantly. The response in direct feeding method was significantly higher than those in all membranes tested (F = 18.89; df = 3; P < 0.05) Chicken skin preparation was shown to be the preferred membrane for blood feeding Ae. aegypti and experimental infection with W. bancrofti.

In the search for new alternatives for the control of Aedes aegypti the larvicidal activity of Eucalyptus grandis essential oil and pine resin essential oil (turpentine) and their major components (α- and β-pinene and 1,8-cineole) was determined. Gas chromatography–mass spectroscopy analysis of E. grandis essential oil revealed that its major components are α-pinene and 1,8-cineole. Similar analysis of turpentine obtained by distillation of the resin pitch of conifers showed that α- and β-pinene are the only major components. Third and early 4th instars of the CIPEIN-susceptible strain of Ae. aegypti were exposed to acetonic solutions of E. grandis essential oil, turpentine, and their major components for 24 h. Turpentine, with an LC₅₀ of 14.7 ppm, was more active than the essential oil of E. grandis (LC₅₀: 32.4 ppm). Larvicidal activity of the essential oil components showed that α- and β-pinene present low LC₅₀ values (15.4 and 12.1 ppm, respectively), whereas pure 1,8-cineole showed an LC₅₀ of 57.2 ppm. These results suggest that α-pinene in E. grandis and α- and β-pinene in turpentine serve as the principal larvicidal components of both oils. Results obtained on larvicidal effects of essential oil of Eucalyptus grandis and turpentine could be considered a contribution to the search for new biodegradable larvicides of natural origin.

The activity of QN50, a sequiterpene alcohol derived from Australian sandalwood (Santalum spicatum), was tested for its effectiveness against larvae of 2 mosquito species (Culex molestus and Aedes camptorhynchus [Diptera: Culicidae]), nymphs of 2 species of water boatmen (Micronecta robusta and Agraptocorixa [Hemiptera: Corixidae]), immature Daphnia sp. (Crustacea), and mosquito eggs (Cx. molestus). In a series of laboratory bioassays, field-collected mosquito larvae, eggs, and immature corixids and daphnids were placed in beakers with either QN50, methoprene or source water only (control). The mosquito larvae exposed to QN50 had reduced survivorship and average longevity relative to the control and to methoprene at most concentrations used in this study. The hatching rate of mosquito eggs was unaffected by methoprene or QN50. Corixid nymphs and daphnids experienced high mortality in both methoprene and QN50 relative to the control, but there was no difference in the effect between the compounds. The results of this preliminary study suggest that further research into the mode of action and efficacy of QN50 as a potential alternative to methoprene for mosquito abatement is warranted.

Neat (undiluted) and diluted ground-applied ultra-low volume (ULV) cold aerosol formulations of sumithrin (Anvil®) were evaluated against Anopheles quadrimaculatus adults. Both formulations were applied at 1.938 g/AI/ha (0.00173 lb/AI/acre). Caged sentinel mosquitoes were placed on 1.5-m stakes 30.4, 60.9, and 91.0 m downwind and perpendicular to the line of spray. Mortality was observed at 1, 12, and 24 h posttreatment. Except for 1-h readings at 30.4 and 91.0 m the neat formulation was significantly more effective than the dilute. Droplet size and density averaged 13.6 µm and 422/cm² for dilute formulation and 14.3 µm and 251/cm² for the neat. There was no apparent relationship between droplet size and density when compared with mosquito mortality.

The atomization characteristics of 4 handheld sprayers (Leco P-1, Colt ULV Aerosol Generator, ULVAFAN MK2, Turbair ElectraFan 12) and a Stihl SR400 backpack sprayer were evaluated with the use of water- and oil-based solutions. The effects on droplet-size spectrum (i.e., droplet size) for 3 insecticides (Tempo SC Ultra®, Anvil 10 10®, and Aqua-Reslin®) were also evaluated. Generic solutions were used to simulate the physical properties of the active-ingredient solutions in some tests. Significant differences were observed in the droplet spectrum generated by the different sprayers. The volume median diameter of the equipment tested ranged from 14.9 to 90.5 µm for the water-based solutions and from 11.7 to 92.4 µm for the oil-based solutions. The Colt ULV sprayer was the only one tested that complied with label requirements for aerosols, yielding acceptable D_V0.5 values of 14.9–16.0 µm with water-based Aqua-Reslin and 14.1 µm with Anvil 10 10. The information presented will allow equipment operators to make an informed decision when selecting equipment and operational parameters.

The control of medically important arthropod vectors of human and animal disease is a high priority for both public health and military officials. Because droplet size of pesticide spray material is a critical factor affecting vector control applications, the droplet-size spectra produced by 11 sprayers and 3 spray formulations were evaluated. Droplet-size spectra were measured by a laser diffraction instrument, a hot-wire system, and rotating slides. There were considerable differences in the droplet-size spectra produced by the different sprayers tested. The volume median diameter (D_V0.5) for the water-based sprays ranged from 4.7 to 211 µm, depending on the sprayer, and the percent of spray volume contained in droplets less than 20 µm (%vol <20 µm) ranged between 0.5% and 98.9%. The D_V0.5 measurements for the oil-based sprays ranged from 9.4 to 125.3 µm and the %vol <20 µm ranged between 2.4% and 97.9%. The correlations between the D_V0.5 measured by the laser system (D_V0.5-laser) and the mass median diameter, Sauter diameter, and D_V0.5 measured by the AIMS probe were all significant. Generally, the slide D_V0.5s were numerically similar to the D_V0.5 from the laser system and the Sauter diameter from the Army Insecticide Measuring System probe. There was less consistent agreement between the % <32 µm values obtained from the slides and those from the other 2 samplers. The information presented can be used by applicators to select the sprayer that produces the droplet-size spectra needed for their particular application situation.

A field population of Culex pipiens pallens was collected from Nanjing, China on July in 2000 and reared in an insectarium. Larvae were subjected to single, mixed, and alternating exposure to deltamethrin and/or fenthion, and the surviving early 4th instars were reared for establishment of adult colonies. Larvae from the colonies were then subjected to the same selection pressures over the subsequent 15 generations. Resistance rates and ratios were measured as LC₅₀ values derived from larval bioassays. In populations exposed to deltamethrin or fenthion alone (single exposure), resistance levels rose rapidly. The LC₅₀ values for deltamethrin and fenthion alone were 29.3 and 1.565 mg/liter, respectively, and the ratios of resistance were 697.6- and 24.8-fold, respectively. Exposure to a mixture of deltamethrin and fenthion (1:1; mixed selection) reduced the development of resistance. The LC₅₀ value and ratio of resistance for the mixture of deltamethrin and fenthion were 0.607 mg/liter and 14.8-fold, respectively, at generation 15. Exposure to alternating treatments of deltamethrin and fenthion (alternating selection) showed an even lower development of resistance. For the alternating treatments, the LC₅₀ value and ratio of resistance to deltamethrin were 0.795 mg/liter and 17.7-fold, respectively (generation 14), and those to fenthion were 0.219 mg/liter and 3.6-fold, respectively (generation 15). Together, these results indicate that the single continuous insecticide selection generated a much more severe resistance than a mixture and/or alternating treatments.

In August 2006, a pyrethrin insecticide synergized with piperonyl butoxide (EverGreen® Crop Protection EC 60-6, McLaughlin Gormley King Company, Golden Valley, MN) was sprayed in ultra-low volumes over the city of Davis, CA, by the Sacramento–Yolo Mosquito and Vector Control District to control mosquitoes transmitting West Nile virus. Concurrently, we evaluated the impact of the insecticide on nontarget arthropods by 1) comparing mortality of treatment and control groups of sentinel arthropods, and 2) measuring the diversity and abundance of dead arthropods found on treatment and control tarps placed on the ground. We found no effect of spraying on nontarget sentinel species including dragonflies (Sympetrum corruptum), spiders (Argiope aurantia), butterflies (Colias eurytheme), and honeybees (Apis mellifera). In contrast, significantly higher diversity and numbers of nontarget arthropods were found on ground tarps placed in sprayed versus unsprayed areas. All of the dead nontarget species were small-bodied arthropods as opposed to the large-bodied sentinels that were not affected. The mortality of sentinel mosquitoes placed at the same sites as the nontarget sentinels and ground tarps ranged from 0% to 100%. Dead mosquitoes were not found on the ground tarps. We conclude that aerial spraying with pyrethrins had no impact on the large-bodied arthropods placed in the spray zone, but did have a measurable impact on a wide range of small-bodied organisms.

A gynandromorph of Culiseta morsitans was found in a collection made from resting shelters located near the village of Central Square, Oswego County, New York in June of 2004. This is the 1st report of a gynandromorph of this species. The polar (anterior–posterior) gynandromorph possessed a head and legs with male characteristics, and an abdomen with female characteristics. The specimen is further described and compared to a normal male and female of this species.

The pupa of Ochlerotatus gilcolladoi is described and illustrated for the first time. Specimens were caught near Madrid. A table lists the range and mode of the branches of each pupal seta.

Mosquito faunal studies were carried out 2004–2005 in Maryland's Eastern Shore wetlands managed by the US Department of Agriculture. The wetlands included flooded fields, inundated woodlands, and tidal salt marshes. Sampling methods included larval collections, adult landing counts, and CDC light and oviposition traps. A total of 1,186 larvae and 1,363 adults identified represented 14 species. Temporary pools were found to have the highest potential for rapid mosquito colonization with Psorophora columbiae the predominant species. Aedes vexans, Culex territans/pipiens, Ps. ciliata/howardii, and Anopheles crucians were collected primarily from pond and flooded woodlands. Ochlerotatus sollicitans larvae were sampled from tidal pools. The predominant daytime landing count species was Oc. sollicitans with Ps. ciliata, Ae. vexans, and Cx. territans also identified. Light traps collected An. crucians, the principal crepuscular species from flooded wooded areas. Aedes atlanticus, An. quadrimaculatus, Coquillettidia perturbans, Cx. restuans, Oc. sollicitans, Ps. ciliata, Ps. columbiae, and Uranotaenia sapphirina were also identified. Oviposition traps collected small numbers of An. crucians at the tidal marsh, 1 Ae. albopictus, and 1 each of Cx. territans/pipiens from the flooded woodlands. As a result of this study, it was recommended that abatement strategies be implemented during and after wetland construction to minimize the creation of temporary pool breeding sites.

The repellency of Nepeta cataria (catmint or catnip) was tested against Aedes aegypti, Ae. vigilax, Culex annulirostris, and Cx. quinquefasciatus, and compared with a blend of natural plant extracts and N,N-diethyl-3-methylbenzamide (deet) on human skin. The catmint and natural plant extract blend did not provide the same level of protection from biting mosquitoes as deet. There were significant differences in the level of protection provided by catmint to the 4 species of mosquito, with mean protection times ranging from 0 min for Ae. aegypti up to 240 ± 60 min for Cx. quinquefasciatus. Significant differences in the mean landing rates of the 4 mosquito species on untreated forearms highlighted the difficulties in comparing laboratory tests of repellents between species.

Gut pH and pH optimum of amylase were measured in 4th-stage larvae of 2 pestiferous chironomid species, Chironomus crassicaudatus and Glyptotendipes paripes. The gut pH in both species was close to neutral, varying from 6.7 to 7.4 and 6.9 to 7.6 pH units for C. crassicaudatus and G. paripes, respectively. In both species, slightly alkaline pH values were measured in the anterior part of the mesenteron, whereas slightly acidic pH values were recorded in gastric caecae and the posterior part of mesenteron. Amylase pH optimum in both chironomid species remained between pH values of 5.5 and 7, being closer to pH value 7 than 5.5. This profile was consistent with the measured values of the gut pH. The recorded larval gut pH profile in the 2 species of chironomids in the present study is much lower than gut pH reported for mosquitoes or Lepidoptera larvae. This could be the reason for the relatively much lower susceptibility of chironomid larvae to Bacillus thuringiensis serovar israelensis toxin proteins than some other nematoceran Diptera, specifically mosquitoes.

The Harris County Gravid Trap (HCGT) used for West Nile virus (WNV) surveillance from 2003–06 is described. The HCGT collected 1,918,483 Culex quinquefasciatus females (over 36,627 periods), with 466,296.37 (8,452.74) yearly. Only 48,094 Aedes albopictus females (over 15,139 periods) were collected, with 10,277.79 (3,260.33) yearly. The highest mosquito production occurred in July for Cx. quinquefasciatus (63,851.25 ± 0.13), and for Ae. albopictus (2,981.80 ± 0.09). Integrating gravid traps within our program has increased our ability to detect WNV efficiently in both species.

Three field trials were conducted at Guana River State Park, Florida to evaluate the effectiveness of the granule formulation of methoprene, Altosid® XR-G, against salt-marsh mosquitoes. Three applications of Altosid XR-G (1.5% s-methoprene) were made at application rates of 9.0, 4.5, and 2.3 kg/ha. Pupae were collected from control and treated sites after inundation. Under field conditions, Altosid XR-G gave 44.6% control at 67 days posttreatment at Site 1 (9.0 kg/ha), 43.7% control at 67 days posttreatment at Site 2 (4.5 kg/ha), and 38% control at 53 days posttreatment at Site 3 (2.3 kg/ha). All treatments taken together achieved an adjusted 10-wk cumulative mosquito emergence inhibition of 69%. Collections were composed of Ochlerotatus sollicitans 68%, Oc. taeniorhynchus 27%, and Psorophora columbiae 5%.