Analysis of recent data on a fauna and ranges of malaria mosquitoes (Diptera: Culicidae: Anopheles) from the territory of Russia

The lists of malaria mosquitoes in Russia includes 12 species, rather than 13, as it was formerly considered (Gornostaeva, 2000; Gornostaeva, Danilov, 2002), because Anopheles subalpinus is a junior synonym of An. melanoon. Data accumulated up to present are still not sufficient to characterize ranges of many species in Russia, specifically An. beklemishevi, An. maculipennis, and An. messea. Careful investigations of biodiversity and ranges of the malaria mosquitoes in different territories of Russia have not been carried out since 40-60th. In the last 50 years, a cytodiagnostic method appeared to be the most perspective method for the study of biodiversity and ranges of the malaria mosquitoes in Russia. Critical analysis of data obtained by this methods shows that the studies of biodiversity and ranges of the malaria mosquitoes should be performed in a contact of entomologist and genetic experts to avoid errors in a collection of field data and laboratory tests. The study of biodiversity and ranges of the malaria mosquitoes is a quite important field of investigations, because of increase of local cases of the malaria disease and unfavorable prognosis for nearest years in relation to the malaria.     

Suitability of two carbon dioxide-baited traps for mosquito surveillance in the United Kingdom

Rapidly changing environments and an increase in human movement around the globe have contributed to a rise in new and emerging diseases, many of which are arthropod borne. The threat posed to the United Kingdom by such diseases is uncertain, and there is a real need to understand the distribution, seasonality and behaviour of potential vectors in the country. At present, there is no standard method for routine mosquito surveillance in the UK. Here we compared the catching efficiency of two carbon dioxide-baited traps, the CDC light trap and the MosquitoMagnet Pro trap, for collecting British mosquitoes. Two of each type of trap were operated at four sites in central and southern England from June to September, 2003. To determine whether trap height affected collections, three light traps were operated at 1, 2.5 and 5 m above the ground in one site in 2004. Both types of trap were efficient at catching mosquitoes, collecting 5414 mosquitoes of 16 species. MosquitoMagnet traps caught 2.7 times more mosquitoes than CDC light traps (P<0.001) and a wider range of species (16 species vs 11) than CDC light traps. Four to six times more female Culex pipiens s.l. were collected in light traps at 5 m (P<0.001) compared with traps at lower heights. MosquitoMagnet traps ran continuously for up to 8 weeks, whilst the battery of a CDC light trap had to be replaced every 24 hrs. Although MosquitoMagnets collected more specimens and a greater range of mosquito species, they were considerably more expensive, prone to breakdown and incurred higher running costs than the CDC light traps. MosquitoMagnets are useful tools for collecting mosquitoes during longitudinal surveys during the summer months, whilst CDC light traps are to be preferred for rapid assessments of the presence or absence of mosquitoes, particularly the important species Culex pipiens.     

Epidemiological studies on Japanese encephalitis in Kyoto City area, Japan. II. Annual patterns of virus dissemination on virus recoveries from unfed Culex tritaeniorhynchus summorosus.

Annual patterns of dissemination of Japanese encephalitis virus in vector mosquitoes have been investigated at the main collection station from 1965 through 1973 at some other stations from 1969 through 1971. The virus was recovered usually from Culex tritaeniorhynchus summorosus during a period of about a month from July to August every year till 1969, and from August to September after 1970, although at some of the stations the virus was recovered intermittently for longer or shorter terms. Higher infection rates were recorded with the mosquitoes caught at the stations near to pig sheds than at the stations far from pig sheds. The infection rates at the peak of virus recovery in high epidemic year (1965 to 1967) were higher, being over 2%, than those in lower or latent epidemic years (1968 to 1973). Human patients of Japanese encephalitis were found in 17 to 20 days after the appearance of the highest peak of the infection rate in mosquitoes.     

Mosquitoes (Diptera: Culicidae) of anthropogenic territories in the North of Tomsk Region (by an example of the Strezhevoy town)

An ecological-faunistic analysis of mosquitoes has been carried out in the Strezhevoy town (Tomsk Region). Thirty-one species of mosquitoes have been recorded in the territory examined. The population peak of mosquitoes is recorded in the 1-2 ten-days of July. Characteristics of the biotopic distribution and daily activity of the dominant mosquito species are revealed. Limiting factors of daily activity of mosquitoes in the investigated territory are characterized.     

Fauna and ecology of blood-sucking mosquitoes (Culicidae) in the northern taiga of the Sverdlovsk region

20 species of blood-sucking mosquitoes were recorded from the northern taiga of Ural (the northern part of the Sverdlovsk region): 15 species of the genus Aedes, 2 species of Culex, 2 species of Culiseta and 1 species of Anopheles. Larvae of Aedes occur in masse in small temporary water bodies. In summer after rains larvae of Culiseta and Culex as well as some species of Aedes appear. In May overhibernated Culiseta alaskaensis, C. bergrothi and An. maculipennis begin the flight of mosquitoes. The peak of the number and specific variety of attacking mosquitoes was recorded in July; in August their activity started to decrease. Aedes communis and A. punctor are mass species, A. excrucians, A. hexodontus and C. bergrothi are rather abundant, the other species are small in number or rare.     

Beta 1, 3-glucan recognition protein from the mosquito, Armigeres subalbatus, is involved in the recognition of distinct types of bacteria in innate immune responses

The activation of an immune response to invading microorganisms generally requires recognition by pattern recognition receptors. Beta 1, 3-glucan recognition proteins (GRPs) have specific affinity for beta 1, 3-glucan, a component on the surface of fungi and bacteria. In this study, we show that GRP from Armigeres subalbatus mosquitoes (AsGRP) is able to bind different bacterial species, and that this binding varies from species to species and is independent of Gram type. AsGRP knockdown with double-stranded RNA increases the mortality of mosquitoes to those bacteria that strongly bind AsGRP, but not to bacteria that do not detectably bind AsGRP. This increase in susceptibility is partially evidenced by decreased melanization in Salmonella typhimurium. Furthermore, AsGRP expression is differentially affected by the presence of different species of bacteria. These results demonstrate that AsGRP is selective in its affinity to different bacteria and; therefore, plays a role in the antibacterial immune response of mosquitoes.     

Population fluctuations of mosquitoes in the non-seasonal tropics

Abstract.

• 1 Seasonal and annual fluctuations in abundance of a number of species of mosquitoes were studied in a relatively non-seasonal climate near Almirante, Panama.
• 2 The fluctuations observed were large, but did not have a period of 1 year and should be classified as non-seasonal.
• 3 At each site the various species were not synchronous in their fluctuation pattern, but the fluctuations of each species were synchronous over an area of at least 4 km long, in spite of large differences in habitat.
• 4 Changes in abundance from year to year observed in these mosquitoes are large compared with those of insects, including mosquitoes, in other areas of Panama.
• 5 The importance of such large and unpredictable fluctuations in abundance for planning control measures is discussed.

     

THE MODE OF POLLINATION IN HABENARIA OBTUSATA (ORCHIDACEAE)

The role of mosquitoes and moths as pollinators of Habenaria obtusata was studied in northern Wisconsin during the summer of 1969. In each population studied, meter-square quadrants were marked and the number of plants, flowers per inflorescence, rate and time of pollinia removed, and capsule set recorded. Carbon dioxide and modified New Jersey Light Traps were set during the flowering period to capture pollinia-bearing insects. The study showed that female mosquitoes of the genus Aedes (particularly A. communis) and two species of Geometrid moths of the genus Xanthorhoe are important pollinators of H. obtusata. Pollination occurred during the last few days of flowering with an average of 18.0% of the pollinia removed and with 14.2% capsule set.     

Susceptibility and fitness cost of Aedes albopictus on their survivability after the exposure to the insecticide

The present study was undertaken to investigate the lethal and sub-lethal effects of insecticides on the life history of Aedes albopictus mosquitoes from urban and sub-urban areas in Penang, Malaysia. The female mosquitoes aged two to five days old were exposed to; (1) diagnostic dose (lethal dose) at 5% malathion and 0.75% permethrin; and (2) sub-lethal concentration of 1.5% malathion, and 0.2% permethrin, respectively and adult female survivors from sub-lethal concentrations were evaluated for fitness parameters. Fecundity, fertility, adult longevity, development time and survival of mosquitoes were the crucial point in their life history had studied. Aedes albopictus species from urban Sg. Dua strain has developed high resistance towards 0.75% permethrin and was confirmed on resistance after 24 h of reading. While sub-urban Batu Maung strain is still susceptible to both 5% malathion and 0.75% permethrin. At the sub-lethal dose, we discovered 0.2% permethrin insecticide have significantly more effects on the fitness cost of Ae. albopictus as compared to 1.5% malathion; with decreasing on fecundity, lesser time was needed to reach each development stages, and more male adult was emerged compared to female mosquitoes for both urban and sub-urban strains. Whereas, malathion insecticide only affected the number of eggs laid by the parent mosquitoes and the development time to reach adult stages. Even though, Ae. albopictus mosquitoes had developed resistance towards permethrin resulted in decreasing mortality, but subsequent effects on their fitness cost still continued on the first generation. Thus, it will benefit in reducing the transmission of mosquito-borne diseases.     

Formulation of the entomopathogenic fungus Beauveria bassiana JN5R1W1 for the control of mosquito adults and evaluation of its novel applicability

In this study, an effective control agent and control technology for adult mosquitoes using entomopathogenic fungi is proposed as a solution to the adverse effects of chemical insecticides used for mosquito control. A formulation study was conducted using Beauveria bassiana JN5R1W1 with high virulence against both Aedes albopictus and Culex pipiens adult mosquitoes. For the inverted emulsion formulation, three kinds of vegetable oils were used to evaluate the germination promotion, UV blocking effects, and adhesion rate of conidia. As a result, soybean oil was selected as the most effective vegetable oil, and the corresponding formulation was made. Direct contact treatment of the inverted emulsion by spraying resulted in a mortality rate of approximately 100 % for both species of adult mosquitoes. However, in reality, since it is difficult to directly apply fungal agent treatment against adult mosquitoes, we evaluated a control method by indirect contact with mosquitoes after applying the inverted emulsion on a net. As an indirect treatment method, the prepared inverted emulsion showed a mortality rate of approximately 93 % or 89 % against Ae. albopictus and Cx. pipiens adult mosquitoes, respectively. Therefore, these results suggested that the inverted emulsion using B. bassiana JN5R1W1 is an effective control agent for controlling adult mosquitoes.     

Experimental logging alters the abundance and community composition of ovipositing mosquitoes in the southern Appalachians

1. The loss of intact forest via logging can influence vector‐borne disease dynamics in part by altering the abundance or diversity of mosquito species. Using an experimental field approach, we characterised how two types of logging (clearcut and repeat‐entry shelterwood) affected temperate forest mosquito abundance and diversity in southwestern Virginia. 2.From May to September in 2008–2010, infusion‐baited gravid traps were used to collect ovipositing female mosquitoes across experimental forest plots that varied in logging treatment. Of the 29 680 collected adult female mosquitoes, the three dominant taxa captured were Aedes triseriatus (55%), Aedes japonicus (21%), and Culex pipiens/restuans (20%). 3. Logging treatment had a significant effect on the overall number of female mosquitoes caught per trap night, with lower average abundance of females on both logged treatments relative to two types of unlogged, control plots. When the three most abundant mosquito species were examined separately, logging treatment significantly influenced the abundance of both Aedes species, but did not significantly affect C. pipiens/restuans abundance. 4. Logging treatment did not influence the richness or diversity of mosquito species captured in gravid traps. However, logging treatment significantly altered the multivariate community composition of captured mosquitoes, an effect probably mediated by differential species‐specific impacts of logging on abundance. 5. Overall, the results of the present study suggest that the risk of arboviruses transmitted by container‐breeding Aedes species may be lower following a logging event in Appalachian forests because of reduced A. japonicus and A. triseriatus abundance with logging.     

Nectar feeding by mosquitoes in Sweden, with special reference to Culex pipiens and Cx torrentium

1. Nectar feeding by mosquitoes collected from tansy (Tanacetum vulgare) flowers was studied in July and August 1983-85 at two sites in central and south-western Sweden. Prior to fructose analysis, gonotrophic state and parity was determined. 2. A total of 1010 mosquitoes (70% males) of eighteen species was collected. Fructose was detected in 75% of the males and 78% of the females. Most (86%) mosquitoes collected belonged to Culex pipiens and Cx torrentium. 3. Among 219 Cx pipiens females, for most of which the abdomen appeared gravid (52%) or empty (42%), 81% were fructose-positive. Females of other species were also proved to have fed on plant sugars in both early and later stages of the gonotrophic cycle. 4. In Cx pipiens and males of Cx torrentium peak nectar feeding occurred between 22.00 and 04.00 hours. Data for males of both species suggested a V-shaped pattern of nectar feeding activity during the night. 5. At about 16 degrees C nearly all mosquitoes became fructose-negative in the anthrone test within 20 h after collection from tansy flowers. 6. At least 44% of Cx pipiens females that were attracted to a dove-baited trap had fed on plant sugars shortly before.     

Taxonomic Review and Revised Keys of the Korean Mosquitoes (Diptera: Culicidae)

ABSTRACT A bibliographic review on the Korean mosquitoes (Diptera: Culicidae) resulted in the recognition of 51 species and two forms of adult mosquitoes belonging to 10 genera, three subfamilies. Revised keys to genera and species of female adults of Korean mosquitoes are provided using available macro-characters. Pictorial keys are also provided for easy usage.     

Defense reactions of mosquitoes to filarial worms: effect of host age on the immune response to Dirofilaria immitis microfilariae

The melanization response of Aedes aegypti black-eyed Liverpool strain (LVP) and Aedes trivittatus against intrathoracically inoculated Dirofilaria immitis microfilariae (mff) was assessed in mosquitoes less than 1, 14, 21, and 28 days after adult ecdysis. There was a significant decrease in the melanization response of A. aegypti 14 days of age and older at 1, 3, and 5 days postinoculation (PI) compared to less than 1-day-old mosquitoes. The response also was reduced significantly in 14- to 28-day-old A. trivittatus on days 1 and 3 PI. Although essentially 100% of recovered mff were melanized by day 5 PI in A. trivittatus, the amount of melanin deposited was much less than that seen in 0-day-old mosquitoes. Potential mechanisms responsible for a reduced immune competence in older mosquitoes and the possible relationship to vector potential are discussed.     

Evaluation of the enantiomers of 1-octen-3-ol and 1-octyn-3-ol as attractants for mosquitoes associated with a freshwater swamp in Florida, U.S.A

Field studies were conducted at wooded wetlands in Gainesville, FL, U.S.A., to assess responses of natural populations of adult mosquitoes (Diptera: Culicidae) to American Biophysics MM-X and Coleman MD-2500 traps baited with enantiomers of 1-octen-3-ol, a naturally occurring compound, and 1-octyn-3-ol, a closely related synthetic compound. Overall, the same species of mosquitoes were attracted by all enantiomers, although the (R)-(+) isomer of octenol generally attracted more species, and it is the isomer produced in greatest proportion in nature. Traps baited with the R-enantiomer caught greater numbers of mosquitoes than those baited with the S-enantiomer of each compound, whereas traps baited with S-enantiomers were equally or slightly less attractive than those baited with carbon dioxide only.     

Malaria Vector Surveillance in Ganghwa-do, a Malaria-Endemic Area in the Republic of Korea

We investigated the seasonality of Anopheles mosquitoes, including its species composition, density, parity, and population densities of mosquitoes infected with the parasite in Ganghwa-do (Island), a vivax malaria endemic area in the Republic of Korea. Mosquitoes were collected periodically with a dry-ice-tent trap and a blacklight trap during the mosquito season (April-October) in 2008. Anopheles sinensis (94.9%) was the most abundant species collected, followed by Anopheles belenrae (3.8%), Anopheles pullus (1.2%), and Anopheles lesteri (0.1%). Hibernating Anopheles mosquitoes were also collected from December 2007 to March 2008. An. pullus (72.1%) was the most frequently collected, followed by An. sinensis (18.4%) and An. belenrae (9.5%). The composition of Anopheles species differed between the mosquito season and hibernation seasons. The parous rate fluctuated from 0% to 92.9%, and the highest rate was recorded on 10 September 2008. Sporozoite infections were detected by PCR in the head and thorax of female Anopheles mosquitoes. The annual sporozoite rate of mosquitoes was 0.11% (2 of 1,845 mosquitoes). The 2 mosquitoes that tested positive for sporozoites were An. sinensis. Malarial infections in anopheline mosquitoes from a population pool were also tried irrespective of the mosquito species. Nine of 2,331 pools of Anopheles mosquitoes were positive. From our study, it can be concluded that An. sinensis, which was the predominant vector species and confirmed as sporozoite-infected, plays an important role in malaria transmission in Ganghwa-do.     

Landscape Effects on the Presence,Abundance and Diversity of Mosquitoes in Mediterranean Wetlands

Environment determines the distribution of mosquito-borne diseases in that it influences the vector-host-pathogen transmission cycle, including vector distribution, abundance and diversity. In this study, we analyse the relationship between environmental variables estimated by remote sensing and the spatial distribution (presence, abundance and diversity) of seven mosquito species vectors of West Nile and other pathogens (Usutu, avian malaria and dirofilariasis) in the Doñana Natural Park, Spain. Traps were distributed over an area of 54,984 ha divided into six ecological units: marshland, sand dunes, scrubland, ricefields, crops and fishponds. We collected mosquitoes once a month from up to 112 locations using BG-Sentinel traps baited with BG-lure and CO₂ during March-November 2010. Hydroperiod, NDVI and Inundation surface were estimated at several resolution scales (100, 250, 500, 1000 and 2000 metres) from corrected and normalized Landsat Images. We sampled 972,346 female mosquitoes, the most abundant species being Culex theileri, Ochlerotatus caspius, Culex modestus, Culex perexiguus, Culex pipiens, Anopheles atroparvus and Ochlerotatus detritus. Our results suggest that: (1) hydroperiod, inundation surface and NDVI are strongly related to the spatial distribution of mosquitoes; (2) the spatial scales used to measure these variables affected quantification of these relationships, the larger scale being more informative; (3) these relationships are species-specific; (4) hydroperiod is negatively related to mosquito presence and richness; (5) Culex abundance is positively related to hydroperiod; (6) NDVI is positively related to mosquito diversity, presence and abundance, except in the case of the two salt marsh species (Oc. caspius and Oc. detritus); and (7) inundation surfaces positively condition the abundance and richness of most species except the salt marsh mosquitoes. Remote sensing data provided reliable information for monitoring mosquito populations. Landscape significantly affected mosquito distribution and abundance, and as a result may alter disease risk. These results suggest that while environmental conditions affect the distribution and abundance of mosquitoes, other factors such as human modification of landscapes may give rise to significant changes in mosquito populations and consequently disease risk.     

Comparing iDNA from mosquitoes and flies to survey mammals in a semi-controlled Neotropical area

Ingested-derived DNA (iDNA) from insects represents a powerful tool for assessing vertebrate diversity because insects are easy to sample, have a diverse diet and are widely distributed. Because of these advantages, the use of iDNA for detecting mammals has gained increasing attention. Here we aimed to compare the effectiveness of mosquitoes and flies to detect mammals with a small sampling effort in a semi-controlled area, a zoo that houses native and non-native species. We compared mosquitoes and flies regarding the number of mammal species detected, the amount of mammal sequence reads recovered, and the flight distance range for detecting mammals. We also verified if the combination of two mini-barcodes (12SrRNA and 16SrRNA) would perform better than either mini-barcode alone to inform local mammal biodiversity from iDNA. To capture mosquitoes and flies, we distributed insect traps in eight sampling points during 5 days. We identified 43 Operational Taxonomic Units from 10 orders, from the iDNA of 17 mosquitoes and 46 flies. There was no difference in the number of species recovered per individual insect between mosquitoes and flies, but the number of flies captured was higher, resulting in more mammal species recovered by flies. Eight species were recorded exclusively by mosquitoes and 20 by flies, suggesting that using both samplers would allow a more comprehensive screening of the biodiversity. The maximum distance recorded was 337 m for flies and 289 m for mosquitoes, but the average range distance did not differ between insect groups. Our assay proved to be efficient for mammal detection, considering the high number of species detected with a reduced sampling effort.     

Hemocyte population changes during the immune response of Aedes aegypti to inoculated microfilariae of Dirofilaria immitis

Ultrastructural and lectin-binding studies have established that the melanotic encapsulation reaction of Aedes aegypti Liverpool strain against inoculated Dirofilaria immitis microfilariae (mff) is a hemocyte-mediated reaction. Total hemocyte counts from mff-inoculated (= immune-activated), saline-inoculated, and uninoculated female A. aegypti were determined using a hemocoel perfusion technique. Total hemocyte populations in uninoculated mosquitoes were significantly larger in younger mosquitoes, but no significant change was noted as mosquitoes aged beyond 14 days. Hemocyte populations in immune-activated mosquitoes increased from 1 to 3 days postinoculation (PI) and decreased on days 4 and 5 PI. Hemocyte populations at 1 to 4 days PI were significantly elevated in mff-inoculated A. aegypti as compared with saline-inoculated controls. Saline-inoculated mosquitoes displayed little change in total hemocyte numbers from 1 to 5 days PI, and their hemocyte populations were similar to those seen in uninoculated insects of the same age. Experiments involving the inoculation of [3H]thymidine along with mff or saline alone and studies involving the administration of colchicine suggest that increased hemocyte populations in immune-activated A. aegypti are a result of mitotic division of circulating blood cells.     

Seasonal prevalence of mosquitoes collected from light traps in the Republic of Korea in 2003

Surveillance of adult mosquitoes was conducted at 29 US military installations and training sites in six provinces in the Republic of Korea during 2003. Adult mosquitoes were collected in New Jersey light traps and dry ice‐baited New Jersey light traps from 1 May to 15 October. Mosquito surveillance was conducted to determine threshold levels to initiate pesticide applications and identify malaria infection rates at selected army installations and training sites. A total of 42 024 adult mosquitoes (32 594 females [77.6%] and 9430 males [22. 4%]) comprising 14 species and Anopheles sinensis s.l. (a complex of five species), representing seven genera, were collected. The most common species were members of the Anopheles sinensis Wiedemann complex (54.9%), followed by Aedes vexans nipponii (Theobald) (19.0%), Culex pipiens Coquillett (14.3%) and Culex tritaeniorhynchus Giles (10.6%). Trap indices varied widely for species over their range, due in part to geographical distribution and degree of association with urban communities.