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PubMed1996

Molecularly engineered resistance to California serogroup virus replication in mosquito cells and mosquitoes.

Introduction of genetic elements derived from a viral pathogen's genome may be used to reduce the vectorial capacity of mosquitoes for that virus. A double subgenomic Sindbis virus expression system was utilized to transcribe sequences of LaCrosse (LAC) virus small (S) or medium (M) segment RNA in sense or antisense orientation; wild-type Sindbis and LaCrosse viruses have single-stranded RNA genomes, the former being positive sense and the latter being negative sense. Recombinant viruses were generated and used to infect Aedes albopictus (C6/36) mosquito cells, which were challenged with wild-type LAC virus and then assayed for LAC virus replication. Several recombinant viruses containing portions of the LAC S segment were capable of inducing varying degrees of interference to the challenge virus. Cells infected with TE/3'2J/ANTI-S virus, expressing full-length negative-sense S RNA of LAC virus, yielded 3-6 log10TCID50 (tissue culture 50% infective dose) less LAC virus per ml than did cells infected with a double subgenomic sindbis virus containing no LAC insert. When C6/36 cells infected with TE/3'2J/ANTI-S were challenged with closely related heterologous bunyaviruses, a similar inhibitory effect was seen. Adult Ae. triseriatus mosquitoes infected with TE/3'2J/ANTI-S were also resistant to challenge by LAC virus. Organs that were productively infected by the double subgenomic Sindbis virus expressing the LAC anti-S sequences demonstrated little LAC virus or antigen. These studies indicate that expression of carefully selected antiviral sequences derived from the pathogen's genome may result in efficacious molecular viral interference in mosquito cells and, more importantly, in mosquitoes.

Aedes↗
PubMed1995

Mosquito carboxylesterase Est alpha 2(1) (A2). Cloning and sequence of the full-length cDNA for a major insecticide resistance gene worldwide in the mosquito Culex quinquefasciatus.

Organophosphorus insecticide resistance in Culex mosquitoes is commonly caused by increased activity of one or more esterases. The commonest phenotype involves elevation of the esterases Est alpha 2 (A2) and Est beta 2 (B2). A cDNA encoding the Est alpha 2 esterase has now been isolated from a Sri Lankan insecticide-resistant mosquito (Culex quinquefasciatus, Say) expression library. In line with a recently suggested nomenclature system (Karunaratne, S. H. P. P. (1994) Characterization of Multiple Variants of Carboxylesterases Which Are Involved in Insecticide Resistance in the Mosquito Culex quinquefasciatus. Ph.D. thesis, University of London), as the first sequenced variant of this esterase, it is now referred to as Est alpha 2(1). The full-length cDNA of est alpha 2(1) codes for a 540-amino acid protein, which has high homology with other esterases and lipases and belongs to the serine or B-esterase enzyme family. The predicted secondary structure of Est alpha 2(1) is similar to the consensus secondary structure of proteins within the esterase/lipase family where the secondary and tertiary structures have been resolved. The level of identity (approximately 47% at the amino acid level) between the est alpha 2(1) and the various Culex est beta (B1 and B2) cDNA alleles that have been cloned and sequenced suggests that the two esterase loci are closely related and arose originally from duplication of a common ancestral gene. The lack of a distinct hydrophobic signal sequence for Est alpha 2(1) and two possible N-linked glycosylation sites, both situated close to the active site serine, suggest that it is a nonglycosylated protein that is not exported from the cell. Southern and dot blot analysis of genomic DNA from various insecticide-resistant and susceptible mosquito strains show that the est alpha 2(1) gene, like est beta 2(1), is amplified in resistant strains. The restriction fragment length polymorphism patterns, after probing Southern blots of EcoRI-digested genomic DNA with esta alpha 2(1) cDNA, show that the amplified and nonamplified est alpha alleles differ in the resistant and susceptible Sri Lankan mosquitoes.

Amino Acid Sequence↗
PubMed1994

A quantitative study of specific immunoglobulins to mosquito salivary gland antigen in hypersensitive and common types of mosquito bite reaction.

This study was designed with two purposes: first, to elucidate immunologic mechanisms in different cutaneous reactions, particularly in hypersensitivity to mosquito bites, and, second, to develop a more reliable and safer method of identifying the causative species of mosquito in severe cases. The amounts of IgG, IgG4 and IgE specific to the mosquito salivary gland extract of Aedes albopictus were determined in the sera of 116 volunteers with normal reactions, either immediate or delayed, and 4 patients with severe systemic symptoms caused by mosquito bites. Titers of IgG and IgE in the severe cases were considerably higher than in volunteers with normal reactions, but there were no differences in IgG4 titers between the two groups. These results indicate that high titers of IgG and IgE may be involved in development of systemic symptoms in severe cases and verify the possibility of in vitro tests to identify causative species of the mosquito.

Adolescent↗
PubMed1988

Evaluation of permethrin-impregnated mosquito-nets against mosquitoes in China.

In Yishan County, Guangxi Province, China, where malaria and Brugian filariasis are transmitted by vectors belonging to the Anopheles hyrcanus Pallas group, a study was conducted from June to November 1986 to evaluate the effectiveness of permethrin-impregnated mosquito bednets to reduce man/vector contact. In three experimental villages a total of 246 mosquito nets were treated with permethrin EC at a dosage of 0.5 g/m2. Control bioassays (1 h exposure) of treated nets gave up to 100% mortality of Armigeres subalbatus (Coquillett), Anopheles sinensis Wiedemann and Culex tritaeniorhynchus Giles for up to 19 weeks. During 5 months evaluation in the villages, permethrin-impregnated mosquito-nets reduced the number of mosquitoes found inside nets by 99.3% for Culex quinquefasciatus Say, by 94.4% for Anopheles sinensis Wiedemann and by 75% for Anopheles lesteri anthropophagus Xu & Feng. This measure could thus be considered an appropriate means of controlling vectors in villages.

Animals↗
PubMed2006

An assessment of the effectiveness of the Mosquito Magnet Pro Model for suppression of nuisance mosquitoes.

We tested the effectiveness of the American Biophysics Corporation Mosquito Magnet Pro Model (ABC-PRO) to reduce mosquito abundance in an urban (Wolseley) and in a rural (Fort Whyte) setting in Winnipeg, Manitoba in 2001 and 2002. Assessment was based on comparisons with control sites by using Centers for Disease Control (CDC) light traps and landing counts on human observers. Over a period of 94 trap nights, the ABC-PRO collected more than an estimated 2,000,000 mosquitoes of 6 species. Aedes vexans dominated trap catches in both years. Ochlerotatus sticticus was the 2nd most abundant species at the rural site in 2001, and Coquillettidia perturbans was the 2nd most abundant species in the urban site in 2002. When consideration was made for the confounding effects of wind speed and temperature, there were no significant differences in landing counts at Fort Whyte in either year, although CDC trap catches were significantly greater in the ABC-PRO location in 2001. In Wolseley, there were no significant differences in CDC trap catches in either year, although landing counts at the ABC-PRO site were significantly higher in 2002. We could not demonstrate that continuous operation of the ABC-PRO in these 2 locations in Winnipeg significantly reduced mosquito activity.

Aedes↗
PubMed1970

Evaluation of compounds for insecticidal activity on adult mosquitos. 1. Responses of adult mosquitos to some new insecticides.

Responses shown by female mosquitos to topical applications of solutions, to deposits from water-dispersible-powder formulations, or to exposure to the vapour from such deposits, are described for a number of compounds that have shown promise as residual contact insecticides.The behaviour of Anopheles stephensi females in laboratory tests indicates that departures of mosquitos from treated buildings, and their survival rates, are likely to be increased as a result of irritation and consequent activity after only a brief period of contact with phthalthrin (OMS-1011) and other synthetic pyrethroids but not with dieldrin (OMS-18) and lindane (OMS-17) or the carbamates and organophosphorus compounds tested. Mosquitos were not disturbed by exposure to the vapour from deposits of any of the compounds.The rates of action of the different compounds following their application in solution directly to the insect cuticle or contact of the mosquitos with deposits on plywood and plaster emphasize the importance of the lipid-solubility and partitioning properties of an insecticide in determining its passage from a surface deposit into, and through, the cuticle to the site of action.

Animals↗
PubMed1994

Do mosquito coils and killer sticks work against Anopheles gambiae sensu lato mosquitoes in Zimbabwe?

Tests against Anopheles gambiae s. 1. mosquitoes (malaria transmitting mosquitoes) were carried out in Chegutu, Chiredzi and Kamhororo (Gokwe). These tests were done in relatively closed rural huts and experimental huts. The tests demonstrated that a one hour exposure to smoke from the burning of insecticidal coils contain 0.3 pc pyrethrin, achieve 100 pc knockdown of mosquitoes. Mosquito killer sticks gave 85 pc knockdowns with 30 pc recoveries and less than 10 pc recoveries for the coils. With caged insects in Gokwe the KD50 for both the coils and sticks was been 15 to 20 minutes and the KD90 ranged from 40 to 50 minutes. The coils were observed to more lethal than the sticks. Mortalities were 100 pc for the coils and 85 pc for the killer sticks after a 24 hour holding period.

Animals↗
PubMed1995

Community perception of mosquitos and mosquito control in some areas of urban Delhi and rural Alwar, Rajasthan.

There is little information regarding community perception of mosquitos and and their control in India. A qualitative study based on In depth discussions with the people in Urban Delhi, and rural Alwar was carried out in August-September, 1995. In the Ghazipur and Munirka areas of Delhi, 63 respondent groups with 171 head counts, and 59 respondent groups and 305 persons in Alwar were met. Community responses to uniform set of questions on mosquito types, seasonality, biting, breeding places, ongoing control activities, and methods of personal protection were recorded. Most people in the areas surveyed viewed mosquitos primarily as a biting nuisance, and secondarily as agents of disease and debilitators of health. In general the knowledge regarding mosquitos was deficient. An overwhelming tendency to attribute mosquitogenic conditions to the unsavoury features of one's physical environment was observed in both areas. The methods of personal protection and attitudes to organised control are discussed.

Animals↗
PubMed1998

BVA 2 mosquito larvicide--a new surface oil larvicide for mosquito control.

BVA 2 mosquito larvicide was evaluated in laboratory pan tests against 3rd-instar Aedes taeniorhynchus (Wied.), Culex quinquefasciatus Say, and Culex nigripalpus Theobald larvae. BVA 2 was as effective as the standard, GB-1111, at 14 liters/ha (> 99.1% vs. 99.8%). In small field plot tests BVA 2 mosquito larvicide applied at 28 liters/ha was as effective as GB-1111 (99.0% vs. 99.8%) 24 h posttreatment. Operationally, applied by helicopter at 46.8 liters/ha, BVA 2 mosquito larvicide was more effective (> 90%) in the slightly less vegetated site than in the heavily vegetated site. As a pupicide applied at 14 liters/ha in laboratory pan tests, no significant differences were noted between BVA 2 mosquito larvicide and GB-1111 against Ae. taeniorhynchus, Cx. quinquefasciatus, and Cx. nigripalpus pupae.

Aedes↗
PubMed1996

Stable expression of insect GABA receptors in insect cell lines. Promoters for efficient expression of Drosophila and mosquito Rdl GABA receptors in stably transformed mosquito cell lines.

We are interested in establishing stably transformed insect cell lines efficiently expressing the insect gamma-aminobutyric acid (GABA) receptor subunit gene Resistance to dieldrin or Rdl. In order to facilitate this we utilized a system based on stable transformation of Aedes albopictus mosquito cell lines using the dihydrofolate reductase (dhfr) gene as a selected marker. Here we report the production of stable mosquito cell lines carrying high copy numbers of Rdl genes from both Drosophila and Aedes aegypti mosquitoes and the subsequent high efficiency expression of functional GABA gated chlorine ion channels. We also used this system to compare the activity of a range of immediate early baculovirus promoters in mosquito cell culture and demonstrate that IE1 promoter constructs work efficiently across insect species. Results are discussed in relation to the potential use of these constructs in the generic transformation of non-Drosophilid insects.

Aedes↗
PubMed2005

Vascular lesion in a patient of chronic active Epstein-Barr virus infection with hypersensitivity to mosquito bites: vasculitis induced by mosquito bite with the infiltration of nonneoplastic Epstein-Barr virus-positive cells and subsequent development of natural killer/T-cell lymphoma with angiodestruction.

This report describes a vasculitis and subsequently developing angiodestructive lymphoma in an 11-year-old Japanese-Filipino girl exhibiting mosquito allergy with the background of chronic active Epstein-Barr virus (EBV) infection. She developed necrotic skin ulcer at the site of mosquito bite, and histopathological examination revealed EBV-positive mononuclear cell infiltration throughout the wall of small-sized muscular artery. These EBV-positive lymphoid cells were oligoclonal in Southern blot analysis for EBV terminal repeats. Effectiveness of steroid therapy also supports the nonneoplastic nature. Approximately 1 year later, she developed progressive large skin ulcer without mosquito bites. Microscopically, the angiocentric or angiodestructive pattern of EBV-positive atypical cells supported the diagnosis of extranodal natural killer/T-cell lymphoma. Southern blot analysis revealed the monoclonal neoplastic nature of EBV-positive cells. In contrast to the primary mosquito bite lesion, natural killer/T-cell lymphoma cells exhibited the higher expression of EBV latent membrane protein 1 mRNA and the apparent protein expression detected by immunohistochemistry.

Animals↗
PubMedDate not supplied

The late biting habit of parous Anopheles mosquitoes and pre-bedtime exposure of humans to infective female mosquitoes.

Using the all-night landing catch method (18:00-06:00) we showed, for Anopheles gambiae in Sierra Leone and A. punctulatus in Papua New Guinea, that parous females have a tendency to bite later than nulliparous ones. The biting habit of sporozoite-infected A. punctulatus was also investigated. The sporozoite rates for Plasmodium falciparum and P. vivax were 1.8 and 1.4% respectively, but only one (1.3%) of 76 females infected with P. falciparum was caught between 18:00 and 21:00. A significantly higher proportion (11.6%) of mosquitoes infected with P. vivax was caught in the same period. The late biting habit of mosquitoes infected with P. falciparum is discussed in relation to the differential biting habits of parous and nulliparous females. We conclude with a hypothesis that, in areas where Anopheles mosquitoes have a late-biting cycle and low parous rate, exposure to mosquitoes infected with P. falciparum during the pre-bedtime period (18:00-22:00) is very low. This hypothesis could explain why insecticide-treated bed nets protect children better in areas of seasonal transmission, where nulliparous females tend to predominate, than in areas of perennial transmission, where parous females are usually more numerous. The same hypothesis is compatible with the finding in Papua New Guinea that insecticide-impregnated bed nets are more protective against P. falciparum than against P. vivax malaria.

Animals↗
PubMed2001

Molecular cloning of a second prophenoloxidase cDNA from the mosquito Armigeres subalbatus: prophenoloxidase expression in blood-fed and microfilariae-inoculated mosquitoes.

Melanization constitutes an important component in various aspects of insect life, including cuticular sclerotization, egg-shell tanning, melanization of parasites and wound healing. Recently, a cDNA encoding prophenoloxidase (pro-PO), a key enzyme in the biosynthesis of melanotic material in insects, was cloned from microfilariae (mf)-inoculated mosquitoes, Armigeres subalbatus. However, results of Northern blot analyses indicated that two pro-POs might be present in Ar. subalbatus and these pro-POs might be responsible for two distinct physiological functions, egg-shell tanning and melanization of parasites. Subsequently, the second pro-PO cDNA (As-pro-PO II) was cloned from blood-fed Ar. subalbatus by rapid amplification of cDNA ends polymerase chain reaction. The 2210 bp As-pro-PO II cDNA contains a 41 bp 5'-non-coding region, a 2064 bp open reading frame and a 105 bp 3'-non-coding region. A hydrophobic signal peptide for endoplasmic reticulum targeting is not found in the N-terminal region. The deduced amino acid sequence of As-pro-PO II shares a high degree of identity (81.5%) with that of the As-pro-PO I obtained from mf-inoculated Ar. subalbatus. Both Northern blot and reverse transcription polymerase chain reaction analysis demonstrated that these two mosquito pro-POs are persistently expressed in mosquito haemocytes and not in fat body, midgut, or ovaries. The expression of As-pro-PO I and As-pro-PO II in mosquitoes is associated with melanization of mf and blood feeding, respectively.

Amino Acid Sequence↗
PubMed1988

An orbivirus of mosquitoes which induces CO2 sensitivity in mosquitoes and is lethal for rabbits.

An orbivirus, JKT-7400, isolated from Culex mosquitoes in Indonesia, replicated to a high titer and induced cytopathic effects in Aedes albopictus cell cultures. The virus produced lethal sensitivity to carbon dioxide in Culex and Aedes mosquitoes as well as in Drosophila melanogaster fruit flies but was not the agent of the hereditary sensitivity to carbon dioxide previously described for Culex quinquefasciatus. When injected intravenously in high doses, JKT-7400 virus was lethal for rabbits, apparently without replicating to a significant extent. It was not pathogenic for adult mice inoculated intravenously or for adult or suckling mice inoculated intracerebrally and intraperitoneally. Unlike an orbivirus isolated from Culex mosquitoes in China, JKT-7400 did not interfere with the replication of Japanese encephalitis virus in mosquitoes.

Aedes↗
PubMed1998

Mosquitoes and mosquito repellents: a clinician's guide.

This paper is intended to provide the clinician with the detailed and scientific information needed to advise patients who seek safe and effective ways of preventing mosquito bites. For this review, clinical and analytical data were selected from peer-reviewed research studies and review articles, case reports, entomology texts and journals, and government and industry publications. Relevant information was identified through a search of the MEDLINE database, the World Wide Web, the Mosquito-L electronic mailing list, and the Extension Toxicology Network database; selected U.S. Army, U.S. Environmental Protection Agency, and U.S. Department of Agriculture publications were also reviewed. N,N-diethyl-3-methylbenzamide (DEET) is the most effective, and best studied, insect repellent currently on the market. This substance has a remarkable safety profile after 40 years of worldwide use, but toxic reactions can occur (usually when the product is misused). When DEET-based repellents are applied in combination with permethrin-treated clothing, protection against bites of nearly 100% can be achieved. Plant-based repellents are generally less effective than DEET-based products. Ultrasonic devices, outdoor bug "zappers," and bat houses are not effective against mosquitoes. Highly sensitive persons may want to take oral antihistamines to minimize cutaneous reactions to mosquito bites.

Animals↗
PubMed1992

Isolation of mosquito-toxic bacteria from mosquito-breeding sites in Kenya.

A large number of source materials were collected for isolating entomopathogenic bacteria from larval mosquito habitats in Kirinyaga District, Kenya. Mosquito-toxic bacteria were included among the numerous types of microorganisms isolated from the habitats. The pathogenic isolates shared common structural characteristics; they were gram-positive, spore-forming bacilli that produced parasporal inclusions conferring broad-spectrum larvicidal activity against Anopheles, Culex and Aedes mosquitoes. Based on structural and growth characteristics, coupled with larvicidal activity, the pathogenic isolates were tentatively identified as variants of Bacillus thuringiensis. Although the collection consisted of a variety of items including soil, silt and mud, the most productive materials were larval bodies. Using healthy mosquito larvae held in a fully permeable plastic bottle, a baiting technique was developed as a means of recovering bacteria from the environment.

Aedes↗
PubMed1989

Ecologic studies of mosquitoes and birds as hosts of Ockelbo virus in Sweden and isolation of Inkoo and Batai viruses from mosquitoes.

Field studies were conducted in central Sweden from 1983 through 1985 to obtain information on the etiologic agent of Ockelbo disease, described in Sweden in the 1960s and probably identical to Pogosta disease in Finland and to Karelian fever in the western USSR. Mosquitoes (63,644) collected during this 3 year period yielded 21 virus strains. Ockelbo virus isolations were from Culiseta morsitans (5 strains), Culex pipiens and/or Cx. torrentium (6 strains), and Aedes cinereus (3 strains). Inkoo (6 strains) and Batai (1 strain) viruses were recovered from Ae. communis. Blood samples collected March-May from migrating birds on the southeast and est coast of Sweden and in July and August from resident birds in east-central Sweden were tested for neutralizing antibody to Ockelbo virus. Antibody was not detected in 328 birds sampled during spring migrations. Two of 58 (3.4%) birds bled in July and 8 of 78 birds (10%) bled in August had antibody to Ockelbo virus. Ockelbo virus circulates in a mosquito-bird-mosquito cycle, with Cs. morsitans and Cx. pipiens and/or Cx. torrentium as enzootic vectors. Antibody was detected in passerine birds. Other classes of birds or other vertebrates were not sampled. Aedes cinereus may serve primarily to transmit virus to people. The role of other mosquito species as vectors for people is unknown.

Aedes↗
PubMed2002

Xenomonitoring of Culex quinquefasciatus mosquitoes as a guide for detecting the presence or absence of lymphatic filariasis: a preliminary protocol for mosquito sampling.

A protocol for the collection of resting, blood-engorged Culex quinquefasciatus Say and their examination for microfilariae has been developed as a way of detecting whether lymphatic filariasis (LF) occurs in a particular locality. The protocol was first implemented in a pilot study in Trinidad, West Indies. For gathering prevalence data, such xenomonitoring is a suitable alternative to the use of human bait, which is ethically questionable. The resting mosquitoes were collected, either indoors or outdoors, using electrical and mouth aspirators. A 'cocoeya broom', made from a bunch of the midribs of coconut-palm leaves, was found to be useful in flushing out the mosquitoes resting in hard-to-reach areas within bedrooms. The rationale behind the strategy and the five-step methodology, of householder notification, mapping, preparation of equipment, mosquito collecting and laboratory processing, are described. Data from the pilot study indicate that this xenomonitoring protocol may be applicable worldwide, albeit with modifications to take account of variations in the vector species involved and their ecology and resting behaviour.

Animals↗