Males of Aedes aegypti mosquitoes formed swarms in the laboratory, triggered by the onset of the photophase or by the presence of odors from a rat (which is a potential host for females). The swarm attracted both males and females and increased mating activity. The number of copulas per mosquito was positively correlated with the number of mosquitoes in the swarm and with the duration of the swarm. Swarming and mating activity increased with the presence of a host for females. Young sexually immature males, less than 24 h old, flew but did not swarm nor copulate. Observations using an olfactometer showed that swarming males produced a volatile pheromone that stimulates the flying activity of females at a distance. Females also produce a volatile attractant. The results suggest that males, and possibly also females, produce an aggregation pheromone that attracts males and females towards the swarm. The characteristics of the pheromone-mediated swarm may be described as a 3-dimensional lek. Our results suggest that the development of pheromone-based control systems and/or pheromone traps for the monitoring of vector populations is feasible, adding a new tool to combat this vector of several human pathogens.

The impact of the attractants 1-octen-3-ol (octenol) and l-lactic acid (Lurex^TM) on collection of Aedes albopictus in suburban backyards was assessed in Mosquito Magnet^TM Pro traps. These carbon dioxide-producing traps were additionally baited with commercial formulated lures with octenol, lactic acid, octenol lactic acid, or no attractant (control) and evaluated in 4 residential sites. Three repetitions of the study resulted in the total collection of 1,321 Ae. albopictus. Significantly more Ae. albopictus were captured in traps baited with octenol lactic acid than in traps baited only with octenol. Lactic acid-baited and control trap captures were not significantly different from octenol lactic acid- or octenol-baited trap totals. Octenol- lactic acid-baited traps collected 36.2% and 52.0% more Ae. albopictus than lactic acid-baited and control traps, respectively. Male Ae. albopictus accounted for 26.7% of the total capture. Other mosquito species collected in sufficient numbers for analysis included Cx. nigripalpus, Ochlerotatus infirmatus, Psorophora ferox, and Cx. erraticus. Larger numbers of these species were collected in traps that were unbaited or baited with only octenol than in traps baited with lactic acid or octenol lactic acid.

The attraction of Anopheles pseudopunctipennis gravid females to oviposition substrates containing Spirogyra majuscula algae was investigated under laboratory conditions. Gravid females deposited significantly more eggs in cups containing natural algae in water from breeding sites than in cups containing artificial (nylon rope) life-like algae in water from the corresponding natural breeding site, or in cups containing natural algae in distilled water. Bioassays with Spirogyra majuscula organic extracts indicated that these extracts at concentrations of 0.1%, 0.01%, and 0.001% attracted more oviposition, but concentrations of 1%, 10%, and 100% were repellent. Gas chromatography and mass spectrometry analysis of algae organic extracts revealed a mixture of ethyl acetate and hydrocarbons compounds. These results suggest that the attraction of gravid An. pseudopunctipennis to natural breeding sites containing filamentous algae is probably mediated by organic compounds released by the algae.

Emulsifiable concentrate formulations of 2 insect growth regulator (IGR) benzoyl ureas (novaluron and diflubenzuron) and the pyrethroid cis-permethrin were individually bioassayed against late 3rd- or early 4th-stage larvae of susceptible Aedes aegypti. The emergence inhibition 50% were 0.038, 0.048, and 0.179 ppb for novaluron, diflubenzuron, and cis-permethrin, respectively. We also tested 1:1 (v:v) mixtures of cis-permethrin and benzoyl ureas. Emergence inhibition 50% for novaluron plus cis-permethrin and diflubenzuron plus cis-permethrin were 0.030 and 0.037, respectively, with combination indexes of 0.49 and 0.56, indicating a synergistic interaction between these insecticides. The percentage of larval mortality produced by 0.5 ppb of the mixtures of cis-permethrin and each IGR was compared to the addition of larval mortality produced in separated experiments by 0.25 ppb of each component, after 5, 9 and 13 days of continuous exposure. In all bioassays, the novaluron plus cis-permethrin mixture produced a significantly higher larvicidal effect (P < 0.05) compared with the individual contribution of each compound. The diflubenzuron plus cis-permethrin mixture showed significantly higher larval mortality (P < 0.05) compared with the contributive effect of each insecticide after 9 and 13 days of exposure, but there was no significant difference after 5 days of exposure.

West Nile virus (WNV) was detected for the first time in Louisiana in the fall of 2001. Surveillance data collected from East Baton Rouge Parish in 2002 were examined to establish baseline data on WNV activity, to support the current design of disease surveillance programs, and to target vector control efforts in the parish. The first indications of WNV activity were from a dead Northern Cardinal collected in February and from a live male cardinal sampled on 14 March. In mosquito pools, WNV was first detected on June 11. The onset of the first human case and the first detection of WNV in sentinel chickens occurred concurrently on June 24. The number of reported human cases and minimum infection rates in mosquitoes peaked in July. WNV prevalence in wild birds increased in late August and was highest in December. WNV-positive wild birds and mosquito pools were detected an average of 31 and 59 days in advance of the onset date of reported human cases, respectively, within 5 km of the residence of a human case. Antibodies to WNV were detected in sera from 7 (Northern Cardinal, House Sparrow, Northern Mockingbird, Blue Jay, Hermit Thrush, Yellow-rumped Warbler, and White-throated Sparrow) of the 42 wild bird species tested. Wild bird serology indicated WNV activity during the winter. Out of 18 mosquito species tested, the only species found positive for WNV was Culex quinquefasciatus, a result suggesting that this species was the primary epizootic/epidemic vector.

To better understand the ecology of West Nile virus transmission in Northern Colorado, field studies were conducted in Larimer and Weld counties from September 2003 through March 2005. During summer studies, 18,540 adult mosquitoes were collected using light traps and gravid traps. West Nile virus RNA was detected in 24 of the 2,140 mosquito pools tested throughout the study area in 2003 and 2004. Culex tarsalis had the highest minimum infection rate (MIR) in both 2003 (MIR  =  34.48) and in 2004 (MIR  =  8.74). During winter studies, 9,391 adult mosquitoes were collected by aspirator from various overwintering sites including bridges and storm drains. The most frequently collected species was Culex pipiens. West Nile virus was not detected in our overwintering collections. The relationship between spring adult emergence and temperature inside and outside overwintering sites is described. Species composition of collections as well as the spatial and temporal distribution of West Nile virus detections are presented.

Metofluthrin (SumiOne®) is a novel, vapor-active pyrethroid that is highly effective against mosquitoes. Laboratory and field trials were conducted in the United States to evaluate the mosquito repellent activity of metofluthrin-treated paper substrates (“emanators”). Initial studies were conducted to evaluate the field performance of 900-cm² paper fan emanators impregnated with 160 mg metofluthrin, where Aedes canadensis was the predominant species. Emanators reduced landing rates on human volunteers by between 85% and 100% compared to untreated controls. Subsequent tests with 4,000-cm² paper strip emanators impregnated with 200 mg metofluthrin were conducted in a wind tunnel as a precursor to conducting field trials using human bait and laboratory-reared Aedes aegypti. Paper strips, which were pre-aged in a fume hood to determine duration of protection, gave 89–91% reductions in landing rates compared with controls. Similar reductions in biting activity were also noted. Following these tests, field trials to assess effect on landing rates were conducted with emanators positioned 1.22 m on either side of volunteers protected from biting by Tyvek® suits, with pre- and posttreatment counts being made. In Florida (predominantly Ochlerotatus spp.) 91–95% reductions were noted 10–30 min after emanators were deployed, while in Washington State (mostly Aedes vexans) 95–97% reductions were observed. These results demonstrate that metofluthrin-treated emanators are highly effective at repelling mosquitoes.

Field tests of formulated permethrin (Permanone 30:30) and malathion applied by ground ultra-low volume equipment were conducted using caged, laboratory-reared, adult Ochlerotatus taeniorhynchus. Cages were placed in an open field and also in semi-dense scrub pine. Two doses, a high and a medium dose of each compound, were applied as suggested by the label. Regardless of application rate, neither chemical provided satisfactory control under the canopy. The average mortality count at the open site and vegetated site was 86.6% and 49.1%, respectively (F.pr. < 0.001, SED 3.87). Malathion for both open and canopied areas achieved significantly greater mortality compared to permethrin.

A novel method for evaluating the particle behavior of a spray-dried technical concentrate and a water-dispersible granule (WDG) formulation of B. thuringiensis subsp. israelensis in an aqueous column was established. The objective was to determine the distributional behavior (minus any extraneous environmental factors) of B. thuringiensis subsp. israelensis within a water column over time. Studies showed a fairly even distribution of particles over a 16-h period for the technical concentrate and WDG formulation. The particle behavior of the WDG formulation also showed homogeneous distribution of particles at 64 and 128 h. The results demonstrated that Brownian motion plays a significant role in the particle distributional behavior of this entomopathogen.

Wetland restorations benefit wildlife, but wetland vegetation may promote mosquitoes. We studied the effects of removing joint grass (Paspalum distichum L.) on the abundance and distribution of immature mosquitoes in seasonal freshwater wetlands in California. In 4 >4-ha plots and one 29.8-ha field, joint grass was removed via herbicide and disking. Four untreated plots and one 4.1-ha field were controls. Fields were sampled every 7–14 days in early autumn by taking 75 dips along levees, plus a 25-dip circular transect 6 m from field edges. Untreated plots had 7 times more larvae and 20 times more pupae than did vegetation-removal plots. Similar densities of mosquitoes were found along edges and within fields.

Genetic mutations controlling eye color, fat body color, structural abnormalities, and insecticide resistance are common in mosquitoes. We have identified a novel color variant of Culex pipiens quinquefasciatus characterized by a heavily pigmented integument in adult specimens circulating in field populations of this species in southern Zambia. Mosquitoes were collected monthly by pyrethrum spray catch between November and May 2004–05 and 2005–06, with between 25% and 80% of the total Cx. p. quinquefasciatus collections comprising this pigmented variety. The identity of pigmented specimens was morphologically confirmed as Cx. p. quinquefasciatus by examination of orientation of the dorsal and ventral arms of the male genitalia of F1 male progeny reared in the laboratory, and molecularly verified by diagnostic polymerase chain reaction and nicotinamide adenine dinucleotide phosphate dehydrogenase subunit 4 nucleotide sequence homology. Preliminary laboratory rearings indicated that the pigmentation was heritable and not influenced by larval habitat and environmental conditions. Further investigation into the mechanism of the mutation, inheritance patterns, and potential linkage to additional markers is pending.

Topomyia (Topomyia) hirtusa, Topomyia (Topomyia) bifurcata, and Topomyia (Suaymyia) cristata are recorded for the first time in India from the northeastern state of Arunachal Pradesh.

Larvae of Culex (Melanoconion) limacifer Komp and Culex (Melanoconion) dunni Dyar were collected during June 2004 in Guatemala. All specimens were individually reared to the adult stage. Specimens were identified based upon examination of the male genitalia and characters of the associated larval and pupal exuviae. These are the first records of these 2 species in Guatemala.

The male genitalia of flesh fly Parasarcophaga (Liosarcophaga) dux (Diptera: Sarcophagidae) was observed using scanning electron microscopy (SEM). The phallus is a short, broad structure that is formed by a tubular base connected to a trumpet-shaped, anteroventrally expanded ventralia. The juxta projects forward from a broad base, which is connected to an upright long structure, the harpes. The juxta is apically bifurcated. The lateral styli bear three small spines curved inward. The pregonite and postgonite are slightly curved upward apically. The cerci are pointed and curved apically. Sensillae were observed on the surfaces of postgonite, surstylus, epandrium, and cerci.

Three new devices for collecting and maintaining mosquitoes and other small insects are described. A suction tube, composed of two pieces of plastic transparent tube, the narrower fitted in the wider, with the mouth protected by the use of voile, is cheap and practical and can be transported around the neck. A 900-ml plastic transparent box is utilized for the restraint of sucked insects and, with the adaptation of two pieces of plastic tube, as a suction chamber.