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PubMed1991

Selection of cyanobacteria isolated from mosquito breeding sites as a potential food source for mosquito larvae.

One way to increase the persistence of larvicidal toxins in mosquito breeding sites is to clone the corresponding genes in microorganisms, such as cyanobacteria, which could serve as a source of food for the larvae. We isolated and cultured 10 strains of cyanobacteria from three mosquito breeding sites along the French Mediterranean coast. Most of the strains were tolerant to a relatively wide range of salt concentrations, and all of them were totally or partially resistant to at least four of the five biological or chemical larvicides used in the local mosquito control program. Six unicellular strains from these habitats and Synechococcus strain PCC 7942, a strain maintained for more than 10 years under laboratory conditions, were assessed for ingestion and digestion by larvae Culex pipiens and Anopheles gambiae mosquitoes. The numbers of cells ingested and digested were dependent on the cyanobacterial strain and varied with the mosquito species. Three of the new isolates, Synechococcus strain PCC 8905 and Synechocystis strains PCC 8906 and PCC 8912, were ingested and digested rapidly by larvae of both mosquito species. Since these strains are also tolerant to larvicides and relatively resistant to elevated salt concentrations, they meet the basic requirements for potential recipients of bacterial genes that encode endotoxins.

Animals↗
PubMed1989

Significant associations between mosquito control service requests and mosquito populations.

Correlation and multiple regression analyses were used to examine the relationships between mosquito population densities and the numbers of telephone requests for mosquito control services made by people in Polk County, Florida. In 32 of 42 census tracts, there were significant (P less than 0.05) correlations between mosquitoes and requests and that, for 16 tracts, a significant linear relationship could be demonstrated between service requests and only one mosquito taxon. The significant associations were dependent on the types of mosquitoes rather than the relative abundance among mosquito groups. Service requests were most often related to Aedes, followed in importance by Culex salinarius and Anopheles; least often to Cx. nigripalpus. Evidence to support a cause and effect relationship is also presented.

Aedes↗
PubMed2002

Plasmodium-mosquito interactions, phage display libraries and transgenic mosquitoes impaired for malaria transmission.

Malaria continues to kill millions of people every year and new strategies to combat this disease are urgently needed. Recent advances in the study of the mosquito vector and its interactions with the malaria parasite suggest that it may be possible to genetically manipulate the mosquito in order to reduce its vectorial capacity. Here we review the advances made to date in four areas: (1) the introduction of foreign genes into the mosquito germ line; (2) the characterization of tissue-specific promoters; (3) the identification of gene products that block development of the parasite in the mosquito; and (4) the generation of transgenic mosquitoes impaired for malaria transmission. While initial results show great promise, the problem of how to spread the blocking genes through wild mosquito populations remains to be solved.

Animals↗
PubMed2006

Bird-baited traps for surveillance of West Nile mosquito vectors: effect of bird species, trap height, and mosquito escape rates.

Host-seeking mosquitoes were sampled in bird-baited traps at four sites in New York state in 2003-2004. Trap placement and efficacy of chickens, Gallus gallus domesticus L., as bait compared with house sparrows, Passer domesticus L., an important reservoir of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), was evaluated. Each site had a chicken-baited trap near ground level (approximately 1.5 m) and in the tree canopy (approximately 9 m), and a house sparrow-baited trap at ground level and canopy level. Each trap allowed mosquito access to birds on one end, and an inner mesh screen blocked bird access on the other end. The two most abundant mosquitoes, Culex restuans Theobald and Culex pipiens pipiens L., were differentiated using molecular characters. In 2003, Cx. restuans and Cx. p. pipiens made up 88% of total mosquito catch. In 2004, Cx. restuans comprised 43% of total catch and Cx. p. pipiens comprised 33%. The remaining species representing at least 1% of total catch were Ochlerotatus trivittatus (Coquillett), Coquilletidia perturbans (Walker), and Culiseta morsitans (Theobald). Capture rates were similar for chicken and house sparrow-baited traps; however, significantly more mosquitoes were captured in the canopy for both bird species. Cx. restuans preferred canopy traps, whereas equal numbers of Cx. p. pipiens were captured at ground and canopy levels. Mosquitoes were more likely to escape (74%) when excluded from birds than when allowed free access to birds (54%). Sentinel bird surveillance for WNV can be improved by trapping in the tree canopy in addition to ground level to capture the most important avian vectors.

Animals↗
PubMed1994

Inhibition of malaria parasite development in mosquitoes by anti-mosquito-midgut antibodies.

The mosquito midgut plays a central role in the development and subsequent transmission of malaria parasites. Using a rodent malaria parasite, Plasmodium berghei, and the mosquito vector Anopheles stephensi, we investigated the effect of anti-mosquito-midgut antibodies on the development of malaria parasites in the mosquito. In agreement with previous studies, we found that mosquitoes that ingested antimidgut antibodies along with infectious parasites had significantly fewer oocysts than mosquitoes in the control group. We also found that the antimidgut antibodies inhibit the development and/or translocation of the sporozoites. Together, these observations open an avenue for research toward the development of a vector-based malaria parasite transmission-blocking vaccine.

Animals↗
PubMedDate not supplied

Mosquito allergy: recombinant mosquito salivary antigens for new diagnostic tests.

In patients with mosquito allergy, lack of a readily available, sensitive, specific, safe test is the major obstacle to accurate diagnosis. Three recombinant mosquito salivary antigens, rAed a 1 (68 kD), rAed a 2 (37 kD) and rAed a 3 (30 kD), from Aedes aegypti have been cloned, expressed, purified and characterized. All three recombinant antigens are shared by Aedes vexans and other mosquito species, and all have been found to have biologic activity in humans. In recent studies, 43% of 28 mosquito bite test-positive subjects had a positive skin test to rAed a 1, 11% to rAed a 2 and 32% to rAed a 3. The sizes of the skin test reactions to the recombinant antigens correlated with the sizes of the A. aegypti bite test reactions. None of 15 A. aegypti bite test-negative subjects had a positive skin test to any of the recombinant antigens. Recombinant mosquito salivary antigens will facilitate the diagnosis of mosquito allergy.

Aedes↗
PubMed2005

PCR cloning of a histone H1 gene from Anopheles stephensi mosquito cells: comparison of the protein sequence with histone H1-like, C-terminal extensions on mosquito ribosomal protein S6.

BACKGROUND: In Aedes and Anopheles mosquitoes, ribosomal protein RPS6 has an unusual C-terminal extension that resembles histone H1 proteins. To explore homology between a mosquito H1 histone and the RPS6 tail, we took advantage of the Anopheles gambiae genome database to clone a histone H1 gene from an Anopheles stephensi mosquito cell line. RESULTS: We designed specific primers based on RPS6 and histone H1 alignments to recover an Anopheles stephensi histone H1 corresponding to a conceptual An. gambiae protein, with 92% identity. Southern blots suggested that Anopheles stephensi histone H1 gene has multiple variants, as is also the case for histone H1 proteins in Chironomid flies. CONCLUSIONS: Histone H1 proteins from Anopheles stephensi and Anopheles gambiae mosquitoes share 92% identity to each other, but only 50% identity to a Drosophila homolog. In a phylogenetic analysis, Anopheles, Chironomus and Drosophila histone H1 proteins cluster separately from the histone H1-like, C-terminal tails on RPS6 in Aedes and Anopheles mosquitoes. These observations suggest that the resemblance between histone H1 and the C-terminal extensions on mosquito RPS6 has been maintained by convergent evolution.

Amino Acid Sequence↗
PubMed2005

Identification and characterization of larval and adult anopheline mosquito habitats in the Republic of Korea: potential use of remotely sensed data to estimate mosquito distributions.

BACKGROUND: Plasmodium vivax malaria reemerged in the Republic of Korea in 1993, with more than 2,000 cases reported in the northwestern part of the country over the last 10 years. To better assess the risk of malaria transmission we conducted a surveillance study to identify and characterize the habitats that produce potential Anopheles vector mosquitoes. Immature and adult mosquito collection data were incorporated into a Geographic Information System (GIS) along with remotely sensed satellite imagery, and imagery classified to land use to determine if remote sensing data could be used to estimate mosquito habitats. RESULTS: More than 2,100 anopheline larvae were collected and mapped from 186 immature habitats, which were categorized into 9 types. Anopheles sinensis was the most commonly collected species, representing more than 97% of the specimens, followed by Anopheles pullus 1.0%, Anopheles lesteri 1.0%, and Anopheles sineroides 0.8%. Anopheles sinensis, pullus, and lesteri were found most frequently in rice paddies followed by: ditches, flooded areas, ground pools, wheel tracks, swamps, irrigation canals, and stream margins. Anopheles sineroides was found most commonly in flooded areas. Supervised classification was conducted on a LANDSAT 7 ETM+ image to identify 5-6 land-use classes that were considered to be of interest. The spatial distribution of the larval mosquito collections was overlaid on the land-use image derived from the LANDSAT image, and the number of mosquitoes habitats in each class calculated. On Ganghwa Island 67% of the immature habitats containing Anopheles sinensis were in the Paddy land-use class, although the class only represented 17% of the land area. In Paju District 53% of the immature habitats containing Anopheles sinensis were in the Paddy land-use class which represented only 9 % of the area of the district. There was significant (p < 0.05) correlation between habitats containing all four species and land use on Ganghwa Island; however, only Anopheles sinensis was significantly correlated with land-use in Paju District. In Ganghwa Island almost 50% of the Anopheles sinensis adults were collected in the paddy land-use class, and there was a positive correlation between larval and adult distributions. However, in Paju District adult Anopheles sinensis adults were most commonly collected in the Bare land-use class and only 17% collected in the Paddy class. There was a negative correlation between larval and adult distributions. CONCLUSION: Immature habitats most commonly associated with Anopheles sinensis, Anopheles pullus, Anopheles sineroides and Anopheles lesteri were flooded rice paddies. Adult Anopheles sinensis, the most commonly collected anopheline, were found closely associated with rice habitats on Ganghwa Island but not in Paju District. Both QuickBird and LANDSAT satellite data were used to display spatial data in the form of geographic coverage and descriptive information in the form of relational databases associated with the mapped features. Supervised classification of LANDSAT imagery permitted good separation between Paddy, Forest, and Water land-use classes. The immature collections of Anopheles sinensis were significantly correlated with land-use as determined in the land-use classification in both Ganghwa Island and Paju District. These data suggest that classified remotely sensed data could potentially be used to estimate the distribution of immature and adult mosquito populations in the Republic of Korea.

Journal Article↗
PubMed2001

Isolation of bacterial strains colonizable in mosquito larval guts as novel host cells for mosquito control.

We screened for microorganisms that can be utilized as new host cells for mosquito larvicides. As long persistence in the environment is required of host cells, we examined the bacterial populations in the guts of mosquito larvae collected from natural breeding habitats. Larvae of Aedes aegypti and Culex quinquefasciatus were examined, and Bacillus species, particularly Bacillus cereus, were found to be the dominant bacterial species in their guts. To investigate the relationship between these Bacillus strains and the mosquito larvae, we re-introduced the bacteria into larvae of Aedes aegypti, C. quinquefasciatus and another common mosquito strain, Anopheles dirus. The cell numbers of Bacillus cereus strains Ae10 and Cx5 in the guts were consistent throughout a 7-d period without food supplementation, suggesting that these strains were able to colonize in the guts of the larvae. To confirm this, we introduced a plasmid containing a kanamycin resistance marker into Ae10 and Cx5 and fed these recombinant strains to C. quinquefasciatus larvae. Even when food was supplemented for 7 d, the recombinant strains, particularly Ae10, were still found in the guts. Under similar conditions, B. thuringiensis serovar israelensis c4Q2-72 was hardly detectable after 2 d, while Escherichia coli could not be detected at all. Their stable retention in mosquito larvae guts and the feasibility of genetic manipulation indicates these strains possess high potential as novel host cells for application in mosquito control.

Journal Article↗
PubMed2006

Field evaluation of New Mountain Sandalwood Mosquito Sticks and New Mountain Sandalwood Botanical Repellent against mosquitoes in North Queensland, Australia.

The mosquito repellent efficacy of New Mountain Sandalwood Mosquito Sticks (containing 0.5% w/w essential oils) and New Mountain Sandalwood Botanical Repellent (containing soybean and geranium oils) was assessed. Tests were conducted in the field with 4 volunteers in a wooded area near Cairns, North Queensland, Australia. Predominant biting species were Verrallina funerea and Ve. lineata. A pair of burning Mosquito Sticks immediately upwind of the subject (acting as an area repellent) provided a 73.1% mean reduction in mosquito landing and probing over the 3-h test period. The Botanical Repellent and a DEET-based control were both 100% effective in preventing mosquito probing for 3 h. These data are consistent with other studies of area repellents in that such products provide significant protection from mosquito bites, albeit inferior to the protection provided by topically applied repellents.

Animals↗
PubMed2001

A live attenuated recombinant dengue-4 virus vaccine candidate with restricted capacity for dissemination in mosquitoes and lack of transmission from vaccinees to mosquitoes.

2Adelta30 is a live dengue-4 virus vaccine candidate with a 30-nucleotide deletion in its 3'-untranslated region. To assess the transmissibility of 2Adelta30 by mosquitoes, we compared its in vivo replication in mosquitoes with that of its wild type DEN-4 parent. Both the vaccine candidate and wild type virus were equally able to infect the mosquito Toxorhynchites splendens after intrathoracic inoculation. Relative to its wild type parent, 2Adelta30 was slightly restricted in its ability to infect the midgut of Aedes aegypti mosquitoes fed on an artificial blood meal and was even more restricted in its ability to disseminate from the midgut to the salivary glands. Thus, the 30-nucleotide deletion rendered the vaccine candidate more sensitive than its wild type parent to the mosquito midgut escape barrier. Most significantly, 2Adelta30 was not transmitted to 352 Ae. albopictus mosquitoes fed on 10 vaccinees, all of whom were infected with the vaccine candidate.

Adult↗
PubMed2005

Evaluation of methods to assess transmission potential of Venezuelan equine encephalitis virus by mosquitoes and estimation of mosquito saliva titers.

Determining the dose of an arbovirus transmitted by a mosquito is important to design transmission and pathogenesis studies simulating natural infection. Several different artificial infection and transmission methods used to assess vector competence and to estimate the dose injected during mosquito feeding have not been fully evaluated to determine whether they accurately reflect natural transmission. Additionally, it is not known whether different mosquito vectors transmit similar amounts of a given virus. Therefore, we compared three traditional artificial transmission methods using Venezuelan equine encephalitis virus (VEEV) and Aedes albopictus and Ochlerotatus taeniorhynchus mosquitoes. Both the mosquito species and the infection route used affected the amount of virus detected in the saliva after a 10-day extrinsic incubation period. Median titers of virus detected in saliva of Ae. albopictus and Oc. taeniorhynchus mosquitoes ranged from 0.2 to 1.1 log(10) (mean 0.7-1.4 log(10)) and 0.2 to 3.2 log(10) (mean 1.0-3.6 log(10)) plaque-forming units, respectively. The results of this study will aid in the design of transmission and pathogenesis studies involving arboviruses.

Aedes↗
PubMed2004

Infection and pathogenicity of the mosquito densoviruses AeDNV, HeDNV, and APeDNV in Aedes aegypti mosquitoes (Diptera: Culicidae).

These studies compared three genetically distinct mosquito densoviruses Aedes aegypti (AeDNV), Hemagogus equinus (HeDNV), and Aedes Peruvian (APeDNV) densoviruses in a laboratory investigation to begin to evaluate their potential as mosquito control agents. A real-time polymerase chain reaction (PCR) assay for quantification of viral genomes and a standardized mosquito infection protocol were developed. Mortality associated with exposure to AeDNV increased in a dose-dependent manner, with the maximum mortality of 75.1% occurring in those organisms exposed to the highest dose of virus. The majority of death occurred as larvae. Similar results were observed with AeDNV produced from ground larvae and AeDNV produced from cell culture. Exposure of mosquitoes to HeDNV and APeDNV resulted in lower mortality, with values peaking at 33.5% for HeDNV and 27.8% for APeDNV. AeDNV-exposed larvae develop at a slower rate than nonexposed and HeDNV- and APeDNV-exposed larvae. Decreased virulence does not reflect a decrease in virus replication. PCR analysis of infectivity rates and titers in adults revealed reproduction of all three viruses, with an average viral titer of approximately 10 logs/mosquito after exposure to the highest dose of each virus. Accumulation of virus in the larval-rearing water was also observed with values approaching 10-11 logs/ml for each virus. These data indicate that there are dramatic differences in the pathogenicity among mosquito densoviruses.

Aedes↗
PubMed2002

Late season commercial mosquito trap and host seeking activity evaluation against mosquitoes in a malarious area of the Republic of Korea.

Field trials evaluating selected commercially available mosquito traps variously baited with light, carbon dioxide, and/or octenol were conducted from 18-27 September 2000 in a malarious area near Paekyeon-ri (Tongil-Chon) and Camp Greaves in Paju County, Kyonggi Province, Republic of Korea. The host-seeking activity for common mosquito species, including the primary vector of Japanese encephalitis, Culex tritaeniorhynchus Giles, was determined using hourly aspirator collections from a human and propane lantern-baited Shannon trap during hours when temperatures exceeded 15 degrees C. The total number of mosquitoes and number of each species captured during the test was compared using a block design. Significant differences were observed for the total number of mosquitoes collected, such that, the Mosquito MagnetTM with octenol > Shannon trap > ABC light trap with light and dry ice > Miniature Black Light trap (manufactured by John W. Hock) > or = New Jersey Trap > ABC light trap with light only. Significant differences in numbers collected among traps were noted for several species including: Aedes vexans (Meigen), Anopheles lesteri Baisas and Hu. An. sinensis Weidemann. An. sineroides Yamada, An. yatsushiroensis Miyazaki, Culex pipiens pallens Coquillett L., Cx. orientalis Edwards and Cx. tritaeniorhynchus. Host-seeking activity for most common species showed a similar bimodal pattern. Results from these field trap evaluations can significantly enhance current vector and disease surveillance efforts especially for the primary vector of Japanese encephalitis, Cx. tritaeniorhynchus.

Animals↗
PubMed2006

Impact of education on knowledge, agricultural practices, and community actions for mosquito control and mosquito-borne disease prevention in rice ecosystems in Sri Lanka.

Mosquito-borne diseases are a major public health threat in Sri Lanka. A 20-week pilot education program to improve community knowledge and mosquito control with participatory and non-chemical approaches was developed, implemented, and evaluated using pre-educational and post-educational surveys in two intervention and two comparison villages. Correlates of baseline knowledge were sex, number of family members, ratio of family members with malaria history, school education level, and availability of electricity at the residence. Participation in the educational program led to improved knowledge of mosquito ecology and disease epidemiology, changes in agricultural practices, and an increase in environmentally sound measures for mosquito control and disease prevention. The variety of actions at the post-educational stage were determined by improved knowledge, but not by sociodemographic characteristics. Such community-based educational interventions are effective in increasing understanding and active involvement in mosquito control and disease prevention in rice ecosystems regardless of sociodemographic characteristics.

Adult↗
PubMed1994

Public perception of mosquito annoyance measured by a survey and simultaneous mosquito sampling.

For randomly chosen residents of the Minneapolis-St. Paul, Minnesota, metropolitan area, survey responses, reported bites, and observed defensive behaviors (e.g., brushing, swatting) for a 5-min period in their yard were compared with simultaneous mosquito counts from a human-baited drop-net trap 6 m from the resident. When mosquitoes trapped, reported bites, or observed behaviors per 5 min were 3 or more, the majority of respondents described the mosquito levels as greater than "moderate" and anticipated reduced outdoor time and/or possible repellent use. At 25 or more mosquitoes trapped, 11 or more reported bites, or 16 or more observed behaviors per 5 min, response was "bad", with most people anticipating a major reduction in outdoor time (without repellent), "probably" or "definitely" planning to use repellent, and anticipating some outdoor time loss even if using repellent. Levels of less than 3 mosquitoes trapped per 5 min were related to moderate annoyance in 20-45% of the population. Individual response was highly variable, and the personal and environmental covariates measured did not account for more than half the variability.

Adult↗
PubMed1998

Efficacy of mosquito coils containing 0.3% and 0.4% pyrethrins against An.gambiae sensu lato mosquitoes.

OBJECTIVE: To investigate the efficacy of a formulation containing 0.4% pyrethrins against registered mosquito coil containing 0.3% pyrethrins. DESIGN: Non intervention analytical study. SETTING: Four villages in Mashonaland East province, Mumurwi, Chitengu, Katiyo and Nyagande. SUBJECTS: Biological efficacy of Doom and IT mosquito coils. MAIN OUTCOME MEASURES: To measure insecticidal, knock down and inhibition of biting activities of the coils in the presence of mosquitoes. RESULTS: A two hour exposure of mosquitoes to both coils results in a 99% and 98.5% mortality rate for a 0.4% and a 0.3% formulation respectively. The KT50 and KT90 of a formulation containing 0.4% pyrethrins were half those of a 0.3% formulation, suggesting that a 0.4% formulation has a rapid knock down effect. A formulation containing 0.4% pyrethrins inhibited 92.5% from biting as compared to a 0.3% formulation (80%). CONCLUSION: A formulation containing 0.4% pyrethrins is more effective in repelling mosquitoes than a 0.3% formulation.

Animals↗
PubMed1995

The expression of chloramphenicol acetyltransferase in mosquitoes and mosquito cells using a packaged Sindbis replicon system.

Sindbis (SIN) replicon virus was used to express chloramphenicol acetyltransferase (CAT) in Aedes albopictus (C6/36) cells and Aedes triseriatus mosquitoes. RNA transcribed in vitro from a SIN replicon plasmid (pSINrep5/CAT) and from SIN virus helper constructs (pDH-EB or pDH(26S)5'SIN) was coelectroporated into BHK-21 cells to generate replicon viruses, designated rep5/CAT/EB and rep5/CAT/26S. C6/36 cells infected with rep5/CAT/EB or rep5/CAT/26S virus at a multiplicity of infection of 3, expressed 3.8 x 10(6) and 6.0 x 10(6) CAT trimers per cell, respectively, at 2 days postinfection (pi). Both viruses attained peak titers by Day 2 pi. Adult female A. triseriatus mosquitoes were intrathoracically inoculated with 7 x 10(4) IFU rep5/CAT/EB or 1 x 10(5) IFU rep5/CAT/26S virus. Virus titers remained at approximately 10(5) IFU/ml through Day 2 pi and decreased roughly 1 log by Day 10 pi. CAT enzyme activity was detected 2 days pi (rep5/CAT/EB, 1.49 x 10(-4) units CAT/10 micrograms protein; rep5/CAT/26S, 2.03 x 10(-5) units CAT/10 micrograms protein) and remained near these levels through Day 10 pi. CAT was detected in the head, salivary glands, midgut, and ovaries of inoculated mosquitoes by indirect immunofluorescence or CAT activity assays. These results suggest that packaged replicon viruses can be useful for expression of heterologous genes in mosquito cells and whole mosquitoes.

Aedes↗