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The objective of this study was to update mosquito species distribution in Argentine Patagonia based on new field collections and to examine the material deposited in the La Plata Museum. Culex coronator, Cx. brethesi, and Cx. castroi represented new records for the region, increasing mosquito fauna of Patagonia to 15 species. The expansion of the geographic distribution of Cx. apicinus, Cx. articularis, and Cx. eduardoi at the province level was also provided. Current knowledge about mosquito fauna of Patagonia is restricted mainly to geographic distribution records. Further studies on the bionomic of mosquito species in Patagonian conditions are needed.
The previously unknown pupae of Ochlerotatus flavescens and Oc. melanimon are described and illustrated. They will both be included in a forthcoming key to known pupae of genera Aedes and Ochlerotatus in the Nearctic Region. Characters to recognize each are explained.
The pupae of Ochlerotatus dorsalis and Oc. squamiger are completely described and illustrated for the first time. Considering the entire pupal morphology, characters to separate the 2 pupae are discussed.
To investigate whether the unique assemblage of habitats in zoos could affect mosquito oviposition behavior and to provide zoos with suggestions for mosquito control, larvae were sampled and associated habitat variables were measured in 2 zoos in South Carolina, USA. Fifty-nine sites were sampled from March 2008 to January 2009. A total of 1,630 larvae representing 16 species was collected and identified. The dominant species was Aedes albopictus (46.0%), followed by Ae. triseriatus (23.6%), Culex restuans (12.4%), and Cx. pipiens complex (9.7%). Principal components and multiple logistic regression analyses showed that across both zoos the distribution of Ae. albopictus larvae was predicted by ambient and site temperature, precipitation, dissolved oxygen, and container habitats. The distribution of Ae. triseriatus larvae was predicted by natural containers and shade height ≤2 m. Overall larval mosquito presence (regardless of species) was predicted by ambient and site temperature, precipitation, dissolved oxygen, presence of natural habitats, and absence of aquatic vegetation. Additionally, C8 values of pairwise species associations indicated significant habitat-based relationships between Ae. albopictus and Ae. triseriatus, and Cx. pipiens complex and Cx. restuans. In general, species–habitat associations conformed to previously published studies. Recommendations to zoo personnel include elimination of artificial container habitats, reduction of shade sources ≤2 m over aquatic habitats, use of approved mosquito larvicides, and training in recognizing and mitigating larval mosquito habitats.
Early identification of increasing mosquito activity is critical to effective mosquito control, particularly when increasing host-seeking behavior may be associated with increased risk of mosquito-borne disease. In this paper, we analyzed the temporal abundance pattern of the West Nile Virus vector, Culex tarsalis, in Fort Collins, CO, using an autoregressive integrated moving average model. We determined that an autoregressive model order 5 with lagged minimum temperatures was best at describing the seasonal abundance of Cx. tarsalis. We then tested the effect of using both temporal and spatial subsets of the data to determine the effect of reduced sampling effort on abundance predictions. We found that, if reduced trapping is necessary due to limited resources, removal of the least productive 1/3 or 1/4 of the traps produced the least erroneous predictions of seasonality represented in the observed data. We show that this productivity-based subset scheme performs better than other sampling effort reductions in generating the best estimate of Cx. tarsalis abundance per trap-night.
Efficacy of fenitrothion as thermal fogging (TF) or ultra-low volume (ULV) applications against 6 successive generations of caged adult Culex pipiens and subsequent development of resistance in both adults and larvae were investigated in this study. In addition, larval acetylcholinesterase (AChE) activity was measured in each generation. Results indicated that the ULV application method was significantly more effective (P < 0.05) than TF against the adults in all treated generations. Selection pressure of TF and ULV applications on the adults after 5 generations resulted in larval resistance by ratios of 30.92- and 28.18-fold, respectively. A gradual decrease in the larval AChE activity was observed with increasing resistance as generations progressed. The AChE activity of susceptible larvae was higher than that of the F5 resistant generation in TF and ULV treatments by 6- and 8-fold, respectively. The results indicated that both the biological efficacy of fenitrothion and the rapidity of resistance development were affected by the application methods.
Aedesaegypti has reappeared in urban communities in the southwestern USA in the 1990s after a 40-year absence. In 2003 and 2004, a systematic survey was conducted throughout metropolitan Tucson, AZ, to identify human and environmental factors associated with Ae. aegypti distribution within an arid urban area. Aedes aegypti presence and abundance were measured monthly using the Centers for Disease Control and Prevention enhanced oviposition traps at sampling sites established in a grid at 3- to 4-km intervals across the city. Sampling occurred in the summer rainy season (July through September), the peak of mosquito activity in the region. Multiple regression analyses were conducted to determine relationships between mosquito density and factors that could influence mosquito distribution. House age was the only factor that showed a consistent significant association with Ae. aegypti abundance in both years: older houses had more mosquito eggs. This is the 1st study of Ae. aegypti distribution at a local level to identify house age as an explanatory factor independent of other human demographic factors. Further research into the reasons why mosquitoes were more abundant around older homes may help inform and refine future vector surveillance and control efforts in the event of a dengue outbreak in the region.
Stormwater catch basins in urban areas provide important larval habitat for Culex mosquitoes. In this study we quantified adult Culex emergence using a newly designed emergence trap deployed in catch basins in suburban Chicago, IL. Traps were deployed from late June to mid-October, 2009–10, in 19 catch basins for a total of 461 trap-days. Based on laboratory trials, the percentage of adults emerging under the trap and reaching the collection cup ranged from 37.7 ± 6.5% for closed-cup and 50.5 ± 3.8% for open-cup configurations. In 2009, catch basins containing immature mosquitoes produced an estimated 58.9 ± 30.8 female and 86.2 ± 36.4 male Culex spp. per day. Most (84.4%) were Culex pipiens and the remainder were Cx. restuans. The trap was also effective in documenting reductions in adult emergence following intense precipitation events that caused “flushing” of larvae and pupae. In general, the new emergence trap was effective for studying Culex production in catch basins and should be broadly useful in studies of container-breeding mosquitoes.
During an 11-year study period (1999–2010) on the islands of the Ryukyu Archipelago, Japan, 20 mosquito species were identified. The results revealed new records of species hitherto not reported on these islands. This contribution updates the mosquito fauna of the various islands of the Ryukyu Archipelago.
Collecting resting mosquitoes is important for studies of the bloodfeeding patterns of medically important mosquitoes. We developed a novel resting shelter, called a wire-frame resting shelter, for collecting resting mosquitoes and evaluated its efficacy at sites in Alabama and the Florida Panhandle. The shelter is made of a 1 × 2-m section of galvanized metal-wire field fencing rolled into a cylinder and placed inside a heavy-duty black plastic bag. In the field evaluation, the wire-frame shelters were comparable to other artificial resting shelters (trash cans) in the number of Culex (Melanoconion) females collected. While a number of other resting shelter designs are available, the wire-frame shelter has a number of beneficial attributes, including being easily assembled in the field, lightweight, inexpensive, and easily modified.
Márcia M. M. Marques, Selene M. Morais, Ícaro G. P. Vieira, Mariano G. S. Vieira, Ana Raquel. A. Silva, Raimundo Rafael De Almeida, Maria Izabel F. Guedes
The aim of this study was to evaluate the activity of essential oil from Tagetes erecta against 3rd instars of Aedes aegypti and to determine the amounts of larvicidal thiophenes in all plant tissues. The oil obtained by steam distillation and analyzed by gas chromatography/mass spectrometry showed 14 compounds. The main compounds were piperitone (45.72%), d-limonene (9.67%), and piperitenone (5.89%). The essential oil was active against larvae of Ae. aegypti, with LC50 of 79.78 µg/ml and LC90 of 100.84 µg/ml. The larvicidal thiophene contents were higher in the roots and flowers as demonstrated by high-performance liquid chromatography analysis. Thus, T. erecta constitutes a good source of varied compounds showing larvicidal activity against Ae. aegypti.
Different ecosystems were probed in the vicinity of the city of Bhubaneswar in the Indian state of Orissa for the presence of bacterial spore-formers with activity against mosquito larvae. The most productive sites were places that were flooded during the monsoon season, including roadside ditches and shorelines of ponds. Among 630 isolates screened, 44 (7%) showed larvicidal activity against larvae of Aedes aegypti. The specific activity of the bacterial spore-formers varied greatly. Isolates were found with specific activities superior to the Bacillus thuringiensis israelensis reference strain of the Pasteur Institute. All mosquitocidal strains produced crystal proteins, and based on the biochemical analyses could be classified into the species B. thuringiensis. Such strains possess the potential for the development of new microbial products for mosquito control in India.
Indoor ultra-low volume (ULV) applications of Aqua Reslin® Super (Permethrin s-bioallethrin) were carried out using portable Solo® Port 423 sprayers in an urban area of Reforma, Chiapas, Mexico. Sprayers were calibrated to discharge a flow rate of 110 ml/min with a dose range of approximately 0.55 to 0.792 mg AI/m3 space. Entomological evaluation, based on 3 cages per house, each containing 15 sugar-fed, 2–4-day-old Aedes aegypti females and placed in hidden locations in 4 randomly selected houses for 15 min, showed 98.8% to 100% mortality. After the spraying, ovitrap data showed no mosquito adults present 4 days after the applications, and only 1 ovitrap out of 60 positive 8 days after the intervention. This evaluation suggests that indoor ULV application can be useful during emergencies after disasters, during dengue outbreaks, or to prevent mosquito population outbreaks before rainy seasons and, therefore, the onset of dengue transmission in Mexican dengue transmission risk areas.
The release of infected mosquitoes or other arthropods by bioterrorists, i.e., arboterrorism, to cause disease and terror is a threat to the USA. A workshop to assess mosquito control response capabilities to mount rapid and effective responses to eliminate an arboterrorism attack provided recommendations to improve capabilities in the USA. It is essential that mosquito control professionals receive training in possible responses, and it is recommended that a Council for Emergency Mosquito Control be established in each state to coordinate training, state resources, and actions for use throughout the state.
The efficacy of a new smoke-generating formulation (fumigant), containing the active ingredient permethrin (69 g/kg) and deltamethrin (3.9 g/kg) per cartridge, was evaluated against adult female Anopheles albimanus, Aedes aegypti, and Culex quinquefasciatus in a large vehicle storage building (22 × 13 × 4.5 m3), Florida, USA, and against Cx. pipiens complex and Ae. albopictus in a furnished apartment (12 × 7 × 3.5 m3) in Israel. In the storage building, the use of 2 fumigant cartridges resulted in 100% mortality for all 3 species in 15 min. Using 1 cartridge resulted in 100% mortality in An. albimanus, 98% in Ae. aegypti, and 97% in Cx. quinquefasciatus in 15 min; and 100% mortality for both Ae. aegypti and Cx. quinquefasciatus at 30 min. In the apartment in Israel, both Ae. albopictus and Cx. pipiens showed 100% mortality when exposed to the fumigant cartridge for 15 min. Based on these preliminary data, the test formulation (fumigant) could be a valuable tool for controlling mosquitoes.
The downstream movement, or drift, of larval black flies as well as many other aquatic insects has been well documented. This phenomenon has most often been associated with the dusk-to-overnight time frame. Operationally, larvicide applications targeting black flies are typically initiated early in the day and can extend until near sunset. To determine if larvicide applications conducted late in the day would be affected by the drift behavior of larval black flies, 6 larvicide applications were conducted. Three applications were conducted at midmorning and 3 during the evening. Larvicidal applications of Bacillus thuringiensis subsp. israelensis insecticidal proteins targeting Simulium appalachiense demonstrated no difference in larval mortality between morning and evening applications. These findings indicate that the larvae responded in a similar manner to the larvicide during the late morning to early afternoon and evening to night. The drift behavior of larval black flies does not appear to be an impediment to black fly suppression activities.
We evaluated Bactimos PT (Bacillus thuringiensis subsp. israelensis [Bti]) against larval populations of Glyptotendipes paripes at 30 kg/ha in man-made lakes on Hilton Head Island, SC. Three treatments were “whole-pond” treatments, while the 4th consisted of treating a “band” along the edge of a pond where significant larval populations had been observed. Larval populations were reduced by an average of 95% at day 7, 70% at day 14, and 50% at day 21 posttreatment in the whole-pond treatments. Initial larval suppression with the band treatment was similar to the whole-pond treatments, indicating that suppression activities can be targeted to specific areas of a larval habitat.
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