survival of starved aedes aegypti (diptera: culicidae) in puerto rico and thailand.survival of adult aedes aegypti (l.) was studied in thailand (1995) and puerto rico (1996) during periods of high and low dengue virus transmission. resting males and females were collected inside houses by aspiration. females were separated into different cages by their degree of engorgement and ovarian development. teneral adults were obtained from pupae collected from natural breeding sites. all mosquitoes were given access to water, held at ambient temperature in the shade, and their surviva ...199910337096
a male accessory gland protein that modulates female mosquito (diptera: culicidae) host-seeking behavior.the male accessory gland product that modulates the host-seeking behavior of female aedes aegypti (l.) mosquitoes was found to be a peptide of 7,600 mw. this peptide also prevented subsequent mating behavior and weakly stimulated oviposition. neither whole glands nor gland fractions from anopheles gambiae had any effect on ae. aegypti females, but those from aedes albopictus were active.199910342262
comparison of isozyme patterns of aedes aegypti populations collected from pre- and post-bacillus thuringiensis israelensis treatment sites in thailand.isozyme patterns of 13 field-collected populations of aedes aegypti from thailand were compared using starch gel electrophoresis. three populations were collected before the bacillus thuringiensis var. israelensis, (b.t.i.) application was initiated. the other 10 populations were collected after the b.t.i. treatment. results revealed that the number of polymorphic loci were lower in the b.t.i. treated populations as compared to controls. in addition, lower genetic variability was found in popula ...199910342268
[the incidence of culicidae in an urban area of ciudad de la habana during 1995].in the present paper it is made an analysis of the incidence of culicides in the municipality of marianao, havana city, during 1995, after following the requirements of the national program for the eradication of aedes aegypti. 6 species of mosquitoes were found in the municipality, with a predominance of the culex quinquefasciatus and aedes mediovittatus species. 4 focuses of aedes aegypti were detected during this period. it was found that the groups of deposits preferred by the culicides for ...199810349434
screening of medicinal plants from trinidad and tobago for antimicrobial and insecticidal properties.antibacterial activity in 51 extracts from 29 plant species currently used in traditional medicine in trinidad and the neighbouring caribbean islands was tested for by the agar dilution streak method using six bacteria: escherichia coli, pseudomonas aeruginosa. salmonella tophimurium, staphylococcus aureus, staphylococcus epidermidis and enterococcus faecalis. the extracts from eight of the plants tested showed significant activity against one or more micro-organisms and the most susceptible bac ...199910363843
activation of a delayed-early gene encoding mhr3 by the ecdysone receptor heterodimer ecr-b1-usp-1 but not by ecr-b1-usp-2.mhr3, a homolog of the retinoid orphan receptor (ror), is a transcription factor in the nuclear hormone receptor family that is induced by 20-hydroxyecdysone (20e) in the epidermis of the tobacco hornworm, manduca sexta. its 2.7-kb 5' flanking region was found to contain four putative ecdysone receptor response elements (ecres) and a monomeric (gggtca) nuclear receptor binding site. activation of this promoter fused to a chloramphenicol acetyltransferase (cat) reporter by 2 micrograms of 20e per ...199910373539
widespread intra-serotype recombination in natural populations of dengue virus.diversity analysis of 71 published dengue virus gene sequences revealed several strains that appeared to be mosaics comprising gene regions with conflicting evolutionary histories. subsequent maximum likelihood breakpoint estimation identified seven recombinants, including members of three of the four dengue virus serotypes, with breakpoints in the premembrane/membrane gene, the envelope gene, and at the junction of the envelope and first nonstructural genes. many of the individual recombinants ...199910377418
impact of bacillus thuringiensis var. israelensis on larvae of chironomus thummi thummi and psectrocladius psilopterus (diptera: chironomidae)chironomid larvae, especially species of the subfamily chironominae, are known to be sensitive to the mosquitocidal bacterium bacillus thuringiensis var. israelensis (b.t.i.). in this study, bioassays and electron microscopic investigations were carried out with third- and fourth-instar larvae of chironomus thummi thummi kieffer (subfamily chironominae) and psectrocladius psilopterus kieffer (subfamily orthocladiinae) in order to study the sensitivity of species belonging to different chironomid ...199910388545
production of cry11a and cry11ba toxins in bacillus sphaericus confers toxicity towards aedes aegypti and resistant culex populations.cry11a from bacillus thuringiensis subsp. israelensis and cry11ba from bacillus thuringiensis subsp. jegathesan were introduced, separately and in combination, into the chromosome of bacillus sphaericus 2297 by in vivo recombination. two loci on the b. sphaericus chromosome were chosen as target sites for recombination: the binary toxin locus and the gene encoding the 36-kda protease that may be responsible for the cleavage of the mtx protein. disruption of the protease gene did not increase the ...199910388698
reinvasion of calcutta city by aedes albopictus: the proven vector of dengue in suburban areas.dengue is a mosquito-borne viral disease transmitted by aedes aegypti in cities and a. albopictus in suburban and rural areas. dengue outbreaks occur almost regularly and sometimes reach epidemic proportions in cities and towns. dengue endemicity in calcutta was established for the first time in 1960, then re-established by another serosurvey in 1966. an outbreak of dengue was recently reported in the bankura district of the city, where it has not previously been reported. with the literatur ...199810389503
mutations of loop 2 and loop 3 residues in domain ii of bacillus thuringiensis cry1c delta-endotoxin affect insecticidal specificity and initial binding to spodoptera littoralis and aedes aegypti midgut mutagenesis was used to examine the role of predicted loops 2 (374qpwp377) and 3 (436qrsgtpf442) in domain ii of the bacillus thuringiensis cry1c delta endotoxin for insecticidal specificity and receptor binding. q374e, s438f, and g439a substitutions resulted in near or complete loss of toxicity toward both spodoptera littoralis and aedes aegypti. r437k, r437i, and g439v mutants exhibited significantly reduced toxicity to s. littoralis and a. aegypti, while mutations of t440, p441, ...199910398834
[chikungunya virus outbreak in senegal in 1996 and 1997].chikungunya disease is generally recognized in africa by serosurveys conducted in rural areas. epidemics are rarely documented. we report two outbreaks in senegal: one having occurred near kaffrine in 1996 during an epidemic of yellow fever (yf), the second in niakhar in 1997. both diagnoses were conducted by igm antibodies captures and confirmed by virus isolations. in kaffrine, a randomised study was carried out on 447 blood donors whose serum was systematically tested for the most frequently ...199910399593
detection of dengue virus rna in patients after primary or secondary dengue infection by using the taqman automated amplification consecutive serum samples from 25 tourists with acute dengue fever, virus-specific rna was detected by using fully automated taqman reverse transcriptase pcr. for this amplification technique new primers and special fluorochrome-labeled probes had to be synthesized. during amplification the increasing amount of viral dna could simultaneously be measured in the tightly sealed tubes. dengue virus rna was found in almost all patients (17 of 18), if the samples had been taken soon after the onset ...199910405398
identification of surface molecules on salivary glands of the mosquito, aedes aegypti, by a panel of monoclonal antibodies.malaria transmission by the mosquito vector requires sporozoite invasion into mosquito salivary glands. parasites probably enter the glands by specific receptor-ligand interactions with molecules on the surface of the glands. we have undertaken the characterization of salivary gland surface molecules of aedes aegypti to identify candidate receptors for plasmodium gallinaceum sporozoite invasion. monoclonal antibodies (mabs) were generated against antigen enriched for salivary gland membranes and ...199910406090
increased fecundity of aedes aegypti fed human blood before release in a mark-recapture study in puerto rico.laboratory experiments suggest that utilization of blood rather than natural sugar sources for energetic needs affords female aedes aegypti a reproductive advantage over conspecifics that use sugar. to test this hypothesis under field conditions, we carried out a mark-release-recapture study in florida, pr. adult females (f1) reared from field-collected eggs were provided with a diet of human blood alone or human blood plus a 20% honey solution before their release. backpack aspirators were used ...199910412105
buoyancy and diving behavior in mosquito pupae.mosquito pupal diving behavior has been studied mostly in aedes aegypti and in this species pupal buoyancy varies relative to several factors. the research reported herein addresses the 2 following questions. does diving behavior vary among different mosquito genera and species? how is diving behavior influenced by variation in buoyancy? depth and duration of dive, and dive pattern, were compared among ae. aegypti, culex pipiens, anopheles stephensi, aedes albopictus, and aedes triseriatus. in r ...199910412114
targeted identification of markers linked to malaria and filarioid nematode parasite resistance genes in the mosquito aedes aegypti.quantitative trait loci (qtl) have been identified for competence of the mosquito aedes aegypti to transmit the avian malaria parasite plasmodium gallinaceum and the human filarial parasite brugia malayi. efforts towards the map-based cloning of the associated genes are limited by the availability of genetic markers for fine-scale mapping of the qtl positions. two f2 mosquito populations were subjected to bulked segregant analysis to identify random amplified polymorphic dna (rapd)-pcr fragments ...199910425918
activation process of dipteran-specific insecticidal protein produced by bacillus thuringiensis subsp. israelensis.dipteran-specific insecticidal protein cry4a is produced as a protoxin of 130 kda in bacillus thuringiensis subsp. israelensis. here we performed the in vitro processing of cry4a and showed that the 130-kda protoxin of cry4a was processed into the two protease-resistant fragments of 20 and 45 kda through the intramolecular cleavage of a 60-kda intermediate. the processing into these two fragments was also observed in vivo. to investigate functional properties of the two fragments, gst (glutathio ...199910427035
population genetics of the yellow fever mosquito in trinidad: comparisons of amplified fragment length polymorphism (aflp) and restriction fragment length polymorphism (rflp) markers.recent development of dna markers provides powerful tools for population genetic analyses. amplified fragment length polymorphism (aflp) markers result from a polymerase chain reaction (pcr)-based dna fingerprinting technique that can detect multiple restriction fragments in a single polyacrylamide gel, and thus are potentially useful for population genetic studies. because aflp markers have to be analysed as dominant loci in order to estimate population genetic diversity and genetic structure p ...199910434416
[aedes albopictus in rural zone of brazil and its implication in the wild yellow fever transmission].larvae and adult forms of aedes albopictus were found during ecological study of anopheline mosquitos in the rural zone of the state of mato grosso do sul in brazil. this occurrence was registered, for the first time in brazil, in an enzoootic area if sylvatic yellow fever virus. this implies a potential risk of the transfer of this virus to an urban area infested with aedes aegypti.199910436626
development of dirofilaria immitis (leidy) in aedes aegypti (l.) and culex quinquefasciatus (say) from maceió, alagoas, brazil. 199910446022
[epidemiology of dengue and hemorrhagic dengue in santiago, cuba 1997].a dengue epidemic that cuba reported in 1997 registered more than 500,000 cases of dengue fever produced by viral serotype 1. in 1981, there was an epidemic of dengue hemorrhagic fever produced by serotype 2 of the virus. this time 344,203 clinical cases were reported, 10,312 of which were severe cases of hemorrhagic fever that led to 158 fatalities (101 of them among children). the reintroduction of dengue, and specifically of dengue viral serotype 2 (jamaica genotype), was quickly detected in ...199910446511
dengue reemergence in argentina.aedes aegypti, eradicated from argentina in 1963, has now reinfested the country as far south as buenos aires. in 1997, four persons with travel histories to brazil, ecuador, or venezuela had confirmed dengue, and surveillance for indigenous transmission allowed the detection of 19 dengue cases in salta province. these cases of dengue are the first in argentina since 1916 and represent a new southern extension of dengue virus.199910460181
bloodmeal microfilariae density and the uptake and establishment of wuchereria bancrofti infections in culex quinquefasciatus and aedes aegypti.the relationship between ingestion of microfilariae (mf), production of infective larvae (l3) and mf density in human blood has been suggested as an important determinant in the transmission dynamics of lymphatic filariasis. here we assess the role of these factors in determining the competence of a natural vector culex quinquefasciatus and a non vector aedes aegypti to transmit wuchereria bancrofti. mosquitoes were infected via a membrane feeding procedure. both mosquito species ingested more t ...199910464399
vector competence of aedes notoscriptus (diptera: culicidae) for barmah forest virus and of this species and aedes aegypti (diptera: culicidae) for dengue 1-4 viruses in queensland, australia.aedes notoscriptus (skuse) mosquitoes colonized from brisbane, queensland, australia, were fed on blood suspensions containing either barmah forest (bf) virus, dengue virus type 1 (den-1), dengue virus type 2 (den-2), dengue virus type 3 (den-3), or dengue virus type 4 (den-4). ae. notoscriptus was shown to be moderately susceptible to oral infection with bf virus, id50 = 10(3.3) ccid50 per mosquito, with titers in infected mosquitoes peaking 10 d after infection. bf virus transmission occurred ...199910467781
isolation and characterization of insect pc2-like prohormone convertase cdna.endoproteolytic processing of large precursor molecules at basic amino acid residues plays an important role in the maturation of many hormones, neuropeptides and other regulatory proteins. enzymes performing these reactions are designated as prohormone or proprotein convertases and belong to the subtilisin family of serine proteases. the screening of a larval cdna library of the sheep blowfly lucilia cuprina resulted in the isolation of two cdnas encoding a pc2-like prohormone convertase. the p ...199910469247
a magic sword or a big itch: an historical look at the united states biological weapons the late 1950s interest in entomological warfare increased, and literature describing the us biological warfare programmes on the use of the mosquito aedes aegypti, the vector for transmitting yellow fever, has now been released. yellow fever was considered as a suitable disease to use in southern regions of the former soviet union. the us destroyed its biological weapon stockpiles in the early 1970s. in addition to its offensive biological warfare programme, the us conducted extensive trials ...199910472190
selection and characterization of temephos resistance in a population of aedes aegypti from tortola, british virgin islands.a collection of aedes aegypti from tortola, british virgin islands, with a high level of temephos resistance (46.8-fold at the 95% lethal concentration [lc95]) was selected to higher resistance with temephos in the laboratory. after 13 generations of pressure, the temephos resistance ratio increased to 180.6 (lc95), whereas in the absence of selection pressure the resistance ratio declined to 8.5. relatively low levels of resistance or cross-resistance to other organophosphate and carbamate inse ...199910480122
residual activity of bacillus thuringiensis serovars medellin and jegathesan on culex pipiens and aedes aegypti larvae.bacillus thuringiensis serovar medellin strain 163-131 and bacillus thuringiensis serovar jegathesan (b.t.jeg.) strain 367 are very toxic to mosquito larvae. however, they are 10 times less toxic than bacillus thuringiensis var. israelensis (b.t.i.) to mosquito larvae under laboratory conditions. lyophilized powders were produced from these strains and their toxicities were compared to that of powder produced from the b.t.i. strain. larvicidal activity was titrated using aedes aegypti (bora-bora ...199910480130
heterochromatic banding pattern in two brazilian populations of aedes aegypti.we analysed samples of aedes aegypti from são josé do rio preto and franca (brazil) by c-banding and ag-banding staining techniques. c-banding pattern of ae. aegypti from são josé do rio preto examined in metaphase cells differed from franca. the chromosomes 2, 3 and x showed centromeric c-bands in both populations, but a slightly stained centromeric band in the y chromosome was observed only in são josé do rio preto. in addition, the x chromosome in both populations and the y chromosome of all ...199910483095
breeding habitats & seasonal variation in the larval density of aedes aegypti (l) & ae. albopictus (skuse) in an urban garden in calcutta city.a longitudinal study on the breeding habitats and variation in the relative larval density of ae. aegypti and ae. albopictus was conducted in an urban garden in calcutta city. the observations of the study, during october 1995 to september 1996 revealed that both the species showed preference for breeding in earthen, and cement pots, plant pots, chowbachhas and molluscan shells. ae. albopictus larvae were also found in accumulations of water in bamboo stumps and tree holes. the container positiv ...199910491914
effect of bacillus thuringiensis ssp. israelensis on the development of plasmodium gallinaceum in aedes aegypti (diptera: culicidae).adult, female aedes aegypti, some of which had survived a sublethal dose (lc50) of bacillus thuringiensis ssp. israelensis (bti) as larvae, were fed on chickens with gametocytaemia of plasmodium gallinaceum. parasite development was monitored by dissecting samples of the mosquitoes immediately after the feed and on days 1, 7 and 9 post-feed, to check for the presence of gametocytes, ookinetes, oocysts and sporozoites, respectively. as the proportions of batches of fed mosquitoes found positive f ...199910492676
[an evaluation of municipal actions in the control of dengue vectors in the region of são josé do rio prêto, são paulo, 1989 to 1995].the aim of this study was to determine the coverage of municipal activities in terms of the control of aedes aegypti and/or aedes albopictus by routine house-to-house visits and by emergency activity, carried out between 1989 and 1995 in the area of são josé do rio prêto, são paulo state, and to evaluate the cross-correlation between them and the breteau index (bi). for towns with up to 50,000 real estate properties, the joint coverage by routine and emergency activities was mostly appropriate a ...199910495663
[the factors associated with the occurrence of immature forms of aedes aegypti in ilha do governador, rio de janeiro, brazil].aedes aegypti is the vector of dengue, a disease that can result in epidemics. ecological studies are important because different geographical populations of the vector may differ in their bioecological characteristics, which can be helpful in guiding control actions. the objective of this study was to identify and to analyze some factors associated with the occurrence of immature forms of a. aegypti on ilha do governador, rio de janeiro, using data from the national health foundation (fns). the ...199910495666
hyperactive transposase mutants of the himar1 mariner transposon.mariner-family transposable elements are active in a wide variety of organisms and are becoming increasingly important genetic tools in species lacking sophisticated genetics. the himar1 element, isolated from the horn fly, haematobia irritans, is active in escherichia coli when expressed appropriately. we used this fact to devise a genetic screen for hyperactive mutants of himar1 transposase that enhance overall transposition from approximately 4- to 50-fold as measured in an e. coli assay. pur ...199910500193
[distribution of aedes aegypti and dengue in the state of maranhão, brazil].dengue and aedes aegypti are widespread in the state of maranhão. during 1995, 87 of the 136 of the state's counties, including 176 towns and 480,687 households, were studied, of which 30 counties (34. 4%), 118 towns (67.0%) and 10,357 households (2.1%) were positive for aedes aegypti. the positive counties are distributed as follow: 3 on são luís island, 7 in the amazonia of maranhão, 12 in the southern zone of the cerrados or savannas, and 5 in the mixed forest/savanna/palm grove zone. one pos ...199910502143
bacillus sphaericus interferes with the development of brugia malayi in aedes aegypti.aedes aegypti (black-eyed liverpool strain) were exposed to a sublethal dose (ld25) of bacillus sphaericus and were fed to mastomys coucha infected with brugia malayi. the development of the filarial parasite was found to be arrested mostly at the second larval stage. the infection (p < 0.05), infectivity rates (p < 0.001) and l3 load (p < 0.001) were found to be reduced significantly in the treated group.199910526424
insulin stimulates ecdysteroid production through a conserved signaling cascade in the mosquito aedes aegypti.selective activators and inhibitors of insulin signaling cascades in mammalian cells were tested for their effects on insulin stimulated steroidogenesis by ovaries of aedes aegypti. bovine insulin in the concentration range of 1.7 microm to 85 microm stimulated ecdysteroidogenesis in vitro. pervanadate, an inhibitor of tyrosine kinase phosphatase, stimulated ecdysteroid production at concentrations of 250 microm to 1 microm. okidaic acid, a serine/threonine phosphatase inhibitor, stimulated ster ...199910528406
production and characterization of monoclonal antibodies to two new mosquito aedes aegypti salivary proteins.mosquito salivary proteins, which are fundamental to the process of blood feeding, also facilitate disease transmission and cause allergic reactions. the identification and characterisation of these proteins have been hampered by the difficulty of obtaining them in purified form. in this report, we describe the production of mouse monoclonal antibodies (mabs) against mosquito salivary proteins. balb/c mice were immunised with aedes aegypti saliva proteins. hybridomas were produced by fusion of s ...199910528410
repellency of essential oils to mosquitoes (diptera: culicidae).the repellency of different concentrations (5, 10, 25, 50, 75, and 100%) and combinations of 5 essential oils (bourbon geranium, cedarwood, clove, peppermint, and thyme) to aedes aegypti (l.) and anopheles albimanus wiedemann when applied to human skin was determined in laboratory tests. cedarwood oil failed to repel mosquitoes and only high concentrations of peppermint oil repelled ae. aegypti. none of the oils tested prevented mosquito bite when used at the 5 or 10% concentration. thyme and cl ...199910534958
genotypic diversity among brevibacillus laterosporus comparison with other entomopathogenic bacillus species, the genome of brevibacillus laterosporus is poorly characterized. the aim of this study was to examine genetic variability in b. laterosporus by using a range of typing methodologies. strains of b. laterosporus were examined for variation in 13 chromosomal genes encoding enzymes by multilocus enzyme electrophoresis. optimal conditions of pulsed-field gel electrophoresis and randomly amplified polymorphic dna were established that allowe ...199910543843
a mosquito densovirus infecting aedes aegypti and aedes albopictus from thailand.a previously undescribed mosquito densovirus was detected in colonies of aedes aegypti and ae. albopictus from thailand, using a polymerase chain reaction (pcr)-based assay. phylogenetic analysis of this virus showed it to be most closely related to adnv isolated from russian ae. aegypti. both aedes species were susceptible to oral infection with the thai-strain virus. larval mortality for ae. albopictus was higher (82%) than for ae. aegypti (51%). aedes aegypti were able to transmit the virus v ...199910548296
dynamics of susceptibility and transmissibility of the live, attenuated, candidate vaccines dengue-1 pdk13, dengue-3 pgmk30f3, and dengue-4 pdk48 after oral infection in aedes aegypti.dengue-1 virus pdk13 and isolates from vaccinees (dengue-1 ib1 and dengue-1 ib 10), dengue-3 pgmk30f3, and dengue-4 pdk48 were studied for their abilities to infect, disseminate, and replicate in aedes aegypti mosquitoes by the oral route. in general, infection and dissemination rates were poorer for the vaccine compared with the parent viruses. the transmissibility was also lower for dengue-1 pdk13 than the parent virus, whereas it was not detected for isolates from vaccinees and dengue-3 pgmk3 ...199910548309
inhibition of luciferase expression in transgenic aedes aegypti mosquitoes by sindbis virus expression of antisense luciferase rna.a rapid and reproducible method of inhibiting the expression of specific genes in mosquitoes should further our understanding of gene function and may lead to the identification of mosquito genes that determine vector competence or are involved in pathogen transmission. we hypothesized that the virus expression system based on the mosquito-borne alphavirus, sindbis (togaviridae), may efficiently transcribe effector rnas that inhibit expression of a targeted mosquito gene. to test this hypothesis ...199910557332
membrane proteins of aedes aegypti larvae bind toxins cry4b and cry11a of bacillus thuringiensis ssp. israelensis.proteins of molecular weight 65 and 62 kd and having affinity for toxins cry4b and cry11a produced by bacillus thuringiensis ssp. israelensis have been isolated from brush border membranes of aedes aegypti larvae using affinity chromatography. using a ligand blotting technique, we show that the binding of these proteins to the biotinylated toxins is reversible and that the two toxins compete for binding to the two proteins. these proteins are likely to be cry4b and cry11a toxin receptors in gut ...199910561564
the chitinase pfcht1 from the human malaria parasite plasmodium falciparum lacks proenzyme and chitin-binding domains and displays unique substrate preferences.within hours after the ingestion of a blood meal, the mosquito midgut epithelium synthesizes a chitinous sac, the peritrophic matrix. plasmodium ookinetes traverse the peritrophic matrix while escaping the mosquito midgut. chitinases (ec are critical for parasite invasion of the midgut: the presence of the chitinase inhibitor, allosamidin, in an infectious blood meal prevents oocyst development. a chitinase gene, pgcht1, recently has been identified in the avian malaria parasite p. gal ...199910570198
[genetic control of vectorial competence in aedes mosquitoes].the transmission of pathogens by arthropods is dependent on the relationships that exist between the pathogen, the invertebrate host (the vector) and the vertebrate host, each of which is influenced by environmental variations. particular attention is given to the knowledge of intrinsic factors and the mechanisms controlling the ability of vectors to transmit pathogens (viruses or parasites). polymorphism in the expression of susceptibility to oral infection has been shown to occur among geograp ...199910572663
isolation and identification of a peptide and its cdna from the mosquito aedes aegypti related to manduca sexta allatotropin.immunocytochemistry revealed that an allatotropin-immunoreactive peptide is produced by several neuroendocrince cells in the abdominal ganglia of the mosquito aedes aegypti. the immunoreactive peptide was isolated and its structure determined to be ala-pro-phe-arg-asn-ser-glu-met-met-thr-ala-arg-gly-phe-amide. a cdna clone encoding this novel neuropeptide was shown to encode a single copy of this peptide. the cdna is unusual in that the first seven atgs are not used for translation initiation.199910573285
[changes in susceptibility of aedes aegypti to organophosphates in municipalities in the state of são paulo, brazil].baseline data on susceptibility of aedes aegypti to organophosphates detected alterations in cities of the state of s. paulo, brazil199910576756
interaction of plasmodium gallinaceum ookinetes and oocysts with extracellular matrix proteins.plasmodium ookinetes are elongate, motile and invasive while inside the mosquito gut but promptly metamorphose into spherical immobile oocysts upon coming in contact with the basement membrane surrounding the midgut. there they begin a prolonged growth period characterized by massive dna synthesis for the production of sporozoites. living plasmodium gallinaceum ookinetes attached avidly to the murine extracellular matrix proteins, laminin and collagen type iv. in elisa-type assays, the main ooki ...199910581609
ammonia as an attractive component of host odour for the yellow fever mosquito, aedes aegypti.behavioural responses of aedes aegypti mosquitoes to ammonia were investigated in a modified y-tube olfactometer. ammonia was attractive in concentrations from 17 ppb to 17 ppm in air when presented together with lactic acid. aqueous solutions of ammonia salts in concentrations comparable to those found in human sweat also increased the attractiveness of lactic acid. the role of lactic acid as an essential synergist for ammonia became further apparent by the fact that ammonia alone or in combina ...199910587497
brugia malayi microfilariae (nematoda: filaridae) enhance the infectivity of venezuelan equine encephalitis virus to aedes mosquitoes (diptera: culicidae).we examined the potentially conflicting effects that microfilarial (mf) enhancement of viral infectivity and mf-induced mortality in mosquitoes have on the vectorial capacity of aedes aegypti (l.), aedes triseriatus (say), and aedes taeniorhynchus (wiedemann) for venezuelan equine encephalitis virus (vee) when mosquitoes feed on gerbils co-infected with brugia malayi (buckley). groups of mosquitoes were fed on gerbils that were either dually infected (vee plus b. malayi mf) or singly infected (v ...199910593077
genomic structure and ecdysone regulation of the prophenoloxidase 1 gene in the malaria vector anopheles gambiae.prophenoloxidase, a melanin-synthesizing enzyme, is considered to be an important arthropod immune protein. in mosquitoes, prophenoloxidase has been shown to be involved in refractory mechanisms against malaria parasites. in our study we used anopheles gambiae, the most important human malaria vector, to characterize the first arthropod prophenoloxidase gene at the genomic level. the complete nucleotide sequence, including the immediate 5' flanking sequence (-855 bp) of the prophenoloxidase 1 ge ...199910611292
aedes albopictus from albania: a potential vector of dengue viruses.aedes albopictus collected in durazzo, the main port of albania, were tested for oral susceptibility to dengue type 2 virus and their infection rates were compared to those of an aedes aegypti strain (paea) and another strain of ae. albopictus (tananarive). infection rates for the albanian ae. albopictus were dose dependent, ranging from 38.9 +/- 13.6% to 85.1% with the titer of the meal increasing from 10 x 8.1 to 10 x 9.1 50% mosquito infectious doses (mid50)/ml. the percentage of infected fem ...199910612611
evaluation of costa rican copepods (crustacea: eudecapoda) for larval aedes aegypti control with special reference to mesocyclops thermocyclopoides.this study attempted to find organisms for the biological control of the mosquito aedes aegypti in costa rica. copepods of the genera arctodiaptomus, eucylops, mesocyclops, megacyclops, and thermocyclops were collected in several parts of the country and cultured for laboratory evaluations. mesocyclops thermocyclopoides was the most successful species in reducing the number of larval ae. aegypti (7.3 larvae in 24 h at a density of 200 aedes/liter). arctodiaptomus dorsalis, eucyclops cf. bondi, e ...199910612615
comparison of two rapid diagnostic assays for detection of immunoglobulin m antibodies to dengue virus.two easy-to-use commercial diagnostic assays, a dipstick enzyme-linked immunosorbent assay (elisa) (integrated diagnostics, baltimore, md.) and an immunochromatographic card assay (panbio, brisbane, australia) were evaluated for detection of immunoglobulin m (igm) antibody to dengue virus with an in-house igm antibody capture microplate elisa as a reference assay. the dipstick elisa was based on the indirect-elisa format using dengue 2 virus as the only antigen and enzyme-labeled goat anti-human ...200010618287
perspectives for the treatment of infections with flaviviridae.the family flaviviridae contains three genera: hepacivirus, flavivirus, and pestivirus. worldwide, more than 170 million people are chronically infected with hepatitis c virus and are at risk of developing cirrhosis and/or liver cancer. in addition, infections with arthropod-borne flaviviruses (such as dengue fever, japanese encephalitis, tick-borne encephalitis, st. louis encephalitis, murray valley encephalitis, west nile, and yellow fever viruses) are emerging throughout the world. the pestiv ...200010627492
differential toxicity of leaf litter to dipteran larvae of mosquito developmental sites.the relative toxicity of leaf litter to nematocerous dipteran larvae characteristic of mosquito developmental sites was investigated. culicidae, chironomidae, and simuliidae taxa originating from alpine hydrosystems were tested together with two laboratory nonindigenous culicid taxa. bioassays indicate that ingestion of 10-month-old decaying leaves from alnus glutinosa, populus nigra, and quercus robur by larvae is more deleterious for aedes aegypti, a. albopictus, culex pipiens, simulium varieg ...200010631052
ahr38, a homolog of ngfi-b, inhibits formation of the functional ecdysteroid receptor in the mosquito aedes anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. consequently, mosquitoes are vectors of numerous devastating human diseases. after ingestion of blood, 20-hydroxyecdysone activates yolk protein precursor (ypp) genes in the metabolic tissue, the fat body. an important adaptation for anautogenicity is the previtellogenic developmental arrest (the state-of-arrest) preventing the activation of ypp genes in previtellogenic females prior to blood feed ...200010637229
re-emergence of chikungunya and o'nyong-nyong viruses: evidence for distinct geographical lineages and distant evolutionary relationships.chikungunya (chik) virus is a member of the genus alphavirus in the family togaviridae: serologically, it is most closely related to o'nyong-nyong (onn) virus and is a member of the semliki forest antigenic complex. chik virus is believed to be enzootic throughout much of africa and historical evidence indicates that it spread to other parts of the world from this origin. strains from africa and asia are reported to differ biologically, indicating that distinct lineages may exist. to examine the ...200010644846
independent evolution of toll and related genes in insects and mammals.toll and toll-related proteins play an important role in antibacterial innate immunity in insect, plants, and mammals. we present the first comprehensive phylogenetic analyses of toll-related genes from both insects and mammals. drosophila melanogaster contains toll and a highly homologous gene, tehao. the protein, dm tehao, comprises 795 amino acid residues and its cytoplasmic domain shares a striking 61% identity with dm toll. two toll homologues were found in another dipteran of medical impor ...200010663571
recombinant juvenile hormone esterase, an effective tool for modifying juvenile hormone-dependent expression of the early trypsin gene in mosquitoes.the study of the changes in the steady-state levels of the early trypsin (et) messenger rna (mrna) was used as a sensitive assay for measuring the effects of recombinant juvenile hormone esterase (rjhe) on juvenile hormone (jh)-dependent gene expression in mosquitoes. et is a female-specific protease present in the midgut of the yellow fever mosquito aedes aegypti during the first few hours after ingestion of a blood meal. transcription of the early trypsin gene is part of the normal postemergen ...200010672068
characterization of a carboxypeptidase a gene from the mosquito, aedes aegypti.a gut-specific carboxypeptidase a gene (aecpa) from the mosquito, aedes aegypti, was cloned and characterized. the gene has an open reading frame that predicts a protein of 427 amino acids, 61% of which are identical to an anopheles gambiae carboxypeptidase a sequence. aecpa messenger rna (mrna) was not detected during larval and pupal development. in situ hybridization experiments indicated that aecpa mrna is expressed by posterior midgut epithelial cells. in sharp contrast to an. gambiae carbo ...200010672069
development of a sindbis virus expression system that efficiently expresses green fluorescent protein in midguts of aedes aegypti following per os infection.a double subgenomic sindbis (dssin) virus, mre/3'2 j/gfp, was constructed to efficiently express green fluorescent protein (gfp) in the midgut of aedes aegypti following per os infection. the mre/3'2 j/gfp rna genome contained the nonstructural genes and cis-acting sequences of the dssin virus, te/3'2 j/gfp, but had the structural genes of mre16 sin virus. mre/3'2 j/gfp virus, unlike te/3'2 j/gfp virus, efficiently infected mosquitoes orally. at 1-2 days postinfection, gfp was observed as multip ...200010672072
short report: microsatellite sequences as markers for population genetic studies of the mosquito aedes aegypti, the vector of dengue viruses.we report the isolation of microsatellites from an enriched library of genomic repeated sequences, using a biotin-labeled oligonucleotide bound to streptavidin-coated magnetic particles. four microsatellites were obtained from a partial library of 120 recombinant clones. this more efficient and rapid method to obtain these specific repeated sequences is preferred to the conventional isolation procedure based on the construction of a genomic library. microsatellite markers would be promising mole ...199910674685
structural organization of posterior midgut muscles in mosquitoes, aedes aegypti and anopheles order to adapt to diverse feeding behavior, animal intestines have evolved with distinct differences. such adaptation may include the structure of the longitudinal and circular muscles that maintain the integrity and the tensile strength of the gut tissue in higher metazoans. here we examined the structural organization of the posterior midgut muscles of two insects, aedes aegypti and anopheles gambiae. we found the estimated number of longitudinal muscles in a cross-section to be 168 in ae. ...200010675294
toward anopheles transformation: minos element activity in anopheline cells and embryos.the ability of the minos transposable element to function as a transformation vector in anopheline mosquitoes was assessed. two recently established anopheles gambiae cell lines were stably transformed by using marked minos transposons in the presence of a helper plasmid expressing transposase. the markers were either the green fluorescent protein or the hygromycin b phosphotransferase gene driven by the drosophila hsp70 promoter. cloning and sequencing of the integration sites demonstrated that ...200010681436
a case of dengue from pune, india.dengue is an acute infectious disease, caused by a single stranded ribonucleic acid (rna) virus of the family of flaviviridae, genus flavivirus, transmitted by aedes mosquitos, the most important vectors being aedes aegypti and aedes albopictus. there are four serotypes, den-1, den-2, den-3, den-4 that are nearly human specific. the geographical distribution of dengue is pantropical, except for madagascar and some african regions. it is endemo-epidemic in tropical and subtropical countries inclu ...200010689245
[oral receptivity of aedes aegypti formosus from franceville (gabon, central africa) for type 2 dengue virus].dengue is widely distributed in the tropics but epidemic activity was rarely reported in africa before the 1980's. in the past 15 years, increased epidemic dengue fever has been reported both in east and west africa, raising concern about the ability of local populations of aedes aegypti to transmit dengue viruses. ae. aegypti is present in two forms in africa: ae. aegypti aegypti and ae. aegypti formosus. this latter form, much darker, was not originally a local species but is now colonizing ar ...199910690473
[present status of an arbovirus infection: yellow fever, its natural history of hemorrhagic fever, rift valley fever].in the early 20th century, when it was discovered that the yellow fever virus was transmitted in its urban cycle by aedes aegypti, measures of control were introduced leading to its disappearance. progressive neglect of the disease, however, led to a new outbreak in 1927 during which the etiological agent was isolated; some years later a vaccine was discovered and yellow fever disappeared again. in the 1960s, rare cases of encephalitis were observed in young children after vaccination and the ad ...199910690474
controlling malaria transmission with genetically-engineered, plasmodium-resistant mosquitoes: milestones in a model system.we are developing transgenic mosquitoes resistant to malaria parasites to test the hypothesis that genetically-engineered mosquitoes can be used to block the transmission of the parasites. we are developing and testing many of the necessary methodologies with the avian malaria parasite, plasmodium gallinaceum, and its laboratory vector, aedes aegypti, in anticipation of engaging the technical challenges presented by the malaria parasite, p. falciparum, and its major african vector, anopheles gam ...199910697903
salivary gland-specific gene expression in the malaria vector anopheles gambiae.molecular studies on the tissue-specific gene expression in the salivary glands of anopheles gambiae may provide useful tools for the development of new strategies for the control of the most efficient malaria vector in the sub-saharan africa. we summarize here the results of a recent investigation focused on the isolation of secreted factors and putative receptors from the salivary glands of an. gambiae. using the signal sequence trap technique we have identified the first cdnas specifically ex ...199910697906
cyt1a from bacillus thuringiensis synergizes activity of bacillus sphaericus against aedes aegypti (diptera: culicidae).bacillus sphaericus is a mosquitocidal bacterium recently developed as a commercial larvicide that is used worldwide to control pestiferous and vector mosquitoes. whereas b. sphaericus is highly active against larvae of culex and anopheles mosquitoes, it is virtually nontoxic to aedes aegypti, an important vector species. in the present study, we evaluated the capacity of the cytolytic protein cyt1a from bacillus thuringiensis subsp. israelensis to enhance the toxicity of b. sphaericus toward a. ...200010698776
analysis of human skin emanations by gas chromatography/mass spectrometry. 2. identification of volatile compounds that are candidate attractants for the yellow fever mosquito (aedes aegypti).volatile compounds emanated from human skin were studied by gas chromatography/mass spectrometry (gc/ms). the purpose of this study was to identify compounds that may be human-produced kairomones which are used for host location by the mosquito, aedes aegypti (l.). the procedure used to collect volatiles was chosen because of prior knowledge that attractive substances can be transferred from skin to glass by handling. laboratory bioassays have shown that the residuum on the glass remains attract ...200010701259
genetics of mosquito vector competence.mosquito-borne diseases are responsible for significant human morbidity and mortality throughout the world. efforts to control mosquito-borne diseases have been impeded, in part, by the development of drug-resistant parasites, insecticide-resistant mosquitoes, and environmental concerns over the application of insecticides. therefore, there is a need to develop novel disease control strategies that can complement or replace existing control methods. one such strategy is to generate pathogen-resi ...200010704476
attenuation markers of a candidate dengue type 2 vaccine virus, strain 16681 (pdk-53), are defined by mutations in the 5' noncoding region and nonstructural proteins 1 and 3.the genome of a candidate dengue type 2 (den-2) vaccine virus, strain pdk-53, differs from its den-2 16681 parent by nine nucleotides. using infectious cdna clones, we constructed 18 recombinant 16681/pdk-53 viruses to analyze four 16681-to-pdk-53 mutations, including 5' noncoding region (5'nc)-57 c-to-t, premembrane (prm)-29 asp-to-val (the only mutation that occurs in the structural proteins), nonstructural protein 1 (ns1)-53 gly-to-asp, and ns3-250 glu-to-val. the viruses were studied for pla ...200010708415
chimeric dengue type 2 (vaccine strain pdk-53)/dengue type 1 virus as a potential candidate dengue type 1 virus vaccine.we constructed chimeric dengue type 2/type 1 (den-2/den-1) viruses containing the nonstructural genes of den-2 16681 virus or its vaccine derivative, strain pdk-53, and the structural genes (encoding capsid protein, premembrane protein, and envelope glycoprotein) of den-1 16007 virus or its vaccine derivative, strain pdk-13. we previously reported that attenuation markers of den-2 pdk-53 virus were encoded by genetic loci located outside the structural gene region of the pdk-53 virus genome. chi ...200010708416
evolutionary relationships of endemic/epidemic and sylvatic dengue viruses.endemic/epidemic dengue viruses (den) that are transmitted among humans by the mosquito vectors aedes aegypti and aedes albopictus are hypothesized to have evolved from sylvatic den strains that are transmitted among nonhuman primates in west africa and malaysia by other aedes mosquitoes. we tested this hypothesis with phylogenetic studies using envelope protein gene sequences of both endemic/epidemic and sylvatic strains. the basal position of sylvatic lineages of den-1, -2, and -4 suggested th ...200010708439
efficacy of aqueous suspension and granular formulations of bacillus thuringiensis (vectobac) against mosquito vectors.the efficacy of aqueous suspension (as) and granular (g) formulation of bacillus thuringiensis var. israelensis (vectobac) was tested against the immatures of mosquito vectors in the laboratory and under field conditions. laboratory tests showed that the aqueous suspension was relatively more effective against culex quinquefasciatus than aedes aegypti and anopheles stephensi, the respective lc(50) values being 0.046, 0.060 and 0.190 mg/l. in stream pools, with the application of vectobac as at 1 ...200010708664
expression of the early-late gene encoding the nuclear receptor hr3 suggests its involvement in regulating the vitellogenic response to ecdysone in the adult mosquito.the insect steroid hormone, 20-hydroxyecdysone (20e), is a key factor controlling critical developmental events of embryogenesis, larval molting, metamorphosis, and, in some insects, reproduction. we are interested in understanding the molecular basis of the steroid hormone ecdysone action in insect egg development. the yellow fever mosquito, aedes aegypti, in addition to being an important vector of human diseases, represents an outstanding model for studying molecular mechanisms underlying egg ...200010715536
aedes aegypti in ho chi minh city (viet nam): susceptibility to dengue 2 virus and genetic differentiation.aedes aegypti is the principal vector of dengue viruses, responsible for a viral infection that has become a major public health concern in asia. in viet nam, dengue haemorrhagic fever was first detected in the 1960s and is now a leading cause of death in childhood. we studied the variability in competence of ae. aegypti as a vector for dengue 2 virus and genetic differentiation in this mosquito species. twenty mosquito samples collected in 1998 in ho chi minh city were subjected to oral infecti ...199910717737
cytokine gene expression in innately susceptible balb/c mice and relatively resistant c57bl/6 mice during infection with virulent burkholderia pseudomallei.production of cytokines including gamma interferon (ifn-gamma) and tumor necrosis factor alpha (tnf-alpha) is an important early-stage host response following infection with intracellular pathogens. development of immunity to these pathogens is determined to a large extent by the timing and relative level of expression of the cytokines. numerous studies have shown that early cytokine responses involving interleukin-12 (il-12) and ifn-gamma are important for resistance to intracellular pathogens, ...200010722599
antifungal and larvicidal cordiaquinones from the roots of cordia addition to the known cordiaquinones a and b, two novel meroterpenoid naphthoquinones, named cordiaquinones j and k, have been isolated from the roots of cordia curassavica. their structures were elucidated by spectrometric methods including ei, d/ci mass spectrometry, 1h, 13c and 2d-nmr experiments. the four naphthoquinones demonstrated antifungal activities against cladosporium cucumerinum, candida albicans and toxic properties against larvae of the yellow fever-transmitting mosquito aedes ...200010724189
[spatial analysis of aedes aegypti larval distribution in the ilha do governador neighborhood of rio de janeiro, brazil].this study aims to help expand knowledge on aedes aegypti in rio de janeiro, based on spatial analysis of the mosquito's breeding sites in the neighborhood of ilha do governador, rio de janeiro, from june 1992 to july 1994. use of spatial analysis techniques is proposed for vector surveillance and control. information obtained from the number of dwellings per block that were used for the analysis. a smoothing method, a gaussian kernel, was used in the spatial distribution analysis. breaks in nat ...200010738148
a single deletion in the membrane-proximal region of the sindbis virus glycoprotein e2 endodomain blocks virus assembly.the envelopment of the sindbis virus nucleocapsid in the modified cell plasma membrane involves a highly specific interaction between the capsid (c) protein and the endodomain of the e2 glycoprotein. we have previously identified a domain of the sindbis virus c protein involved in binding to the e2 endodomain (h. lee and d. t. brown, virology 202:390-400, 1994). the c-e2 binding domain resides in a hydrophobic cleft with c y180 and w247 on opposing sides of the cleft. structural modeling studies ...200010756035
the use of chimeric venezuelan equine encephalitis viruses as an approach for the molecular identification of natural virulence determinants.venezuelan equine encephalitis (vee) virus antigenic subtypes and varieties are considered either epidemic/epizootic or enzootic. in addition to epidemiological differences between the epidemic and enzootic viruses, several in vitro and in vivo laboratory markers distinguishing the viruses have been identified, including differential plaque size, sensitivity to interferon (ifn), and virulence for guinea pigs. these observations have been shown to be useful predictors of natural, equine virulence ...200010756040
antifungal and larvicidal compounds from the root bark of cordia alliodora.two new natural products, a phenylpropanoid derivative characterized as 1-(3'-methoxypropanoyl)-2,4,5-trimethoxybenzene (1) and a prenylated hydroquinone, 2-(2z)-(3-hydroxy-3,7-dimethylocta-2, 6-dienyl)-1,4-benzenediol (2), have been isolated from the root bark of cordia alliodora. both compounds exhibited antifungal properties against the phytopathogenic mold cladosporium cucumerinum. the phenylpropanoid derivative (1), whose structure is closely related to beta-asarone, also demonstrated a mar ...200010757739
effects of temperature and larval diet on development rates and survival of the dengue vector aedes aegypti in north queensland, australia.immature development times, survival rates and adult size (wing-lengths) of the mosquito aedes aegypti (l.) (diptera: culicidae) were studied in the laboratory at temperatures of 10-40 degrees c. the duration of development from egg eclosion (hatching of the first instar) to adult was inversely related to temperature, ranging from 7.2 +/- 0.2 days at 35 degrees c to 39.7 +/- 2.3 days at 15 degrees c. the minimum temperature threshold for development (t) was determined as 8.3 +/- 3.6 degrees c an ...200010759309
the use of direct sequencing of dengue virus cdna from individual field-collected aedes aegypti for surveillance and epidemiological studies.the relative efficiencies of four methods to extract viral rna from individual dengue-2 virus (d-2v)-infected mosquitoes, aedes aegypti (l.) (diptera: culicidae), were compared. the most efficient of these methods was then used to extract viral rna for the preparation of cdna from the abdomens of six engorged d-2v-infected mosquitoes and sera from three dengue fever (df) patients collected in an isolated rural town in colombia. comparisons of viral envelope (e) gene sequences from each of these ...200010759317
national progress in dengue vector control in vietnam: survey for mesocyclops (copepoda), micronecta (corixidae), and fish as biological control agents.this paper describes the process of expanding a successful dengue control program in 3 provinces in northern vietnam into a national one and demonstrates the presence of a rich, low-cost resource that could have similar applicability to other countries in the region. the cornerstone of the preventive strategy is larval control of aedes aegypti (l.), the major vector, using predators such as copepods, mesocyclops spp., aided by the corixid bug micronecta quadristrigata bredd, and fish in large wa ...200010761718
transmission thresholds for dengue in terms of aedes aegypti pupae per person with discussion of their utility in source reduction efforts.the expense and ineffectiveness of drift-based insecticide aerosols to control dengue epidemics has led to suppression strategies based on eliminating larval breeding sites. with the notable but short-lived exceptions of cuba and singapore, these source reduction efforts have met with little documented success; failure has chiefly been attributed to inadequate participation of the communities involved. the present work attempts to estimate transmission thresholds for dengue based on an easily-de ...200010761719
vertical transmission of the yellow fever virus by aedes aegypti (diptera, culicidae): dynamics of infection in f1 adult progeny of orally infected females.vertical transmission of yellow fever virus from orally infected females to their progeny was experimentally demonstrated in 2 aedes aegypti colonies from the dakar and koungheul regions in senegal. a total of 10,530 f1 adult mosquito progeny were tested. the overall vertical transmission rate was 0.97%, with no significant difference between the dakar and koungheul colonies. the infection rates were significantly higher in females (1.15%) than in males (0.74%) in both colonies. the virus was no ...200010761742
a tubular network associated with the brush-border surface of the aedes aegypti midgut: implications for pathogen transmission by mosquitoes.the mosquito aedes aegypti is capable of transmitting a variety of pathogens to man and to other vertebrates. the midgut of this insect has been well-studied both as the tissue where the first contact occurs between ingested pathogens and the insect host, and as a model system for blood meal digestion in blood-sucking insects. to understand better the nature of the midgut surface encountered by parasites or viruses, we used scanning electron microscopy to identify the most prominent structures a ...200010769222
a new densovirus isolated from the mosquito culex pipiens (diptera: culicidae).we have isolated from a laboratory strain of culex pipiens in which abnormal larval mortality occurred a small icosahedral nonenveloped dna virus sharing the main biological and biophysical properties of densoviruses (dnvs). unlike dnvs isolated previously from aedes species, i.e. the aaednv and the aaldnv (afanasiev, b.n., galyov, e. e., buchatsky, l.p., kozlov, y.v., 1991. nucleotide sequence and genomic organization of aedes densonucleosis virus. virology 185, 323-336; boublik, y., jousset, f ...200010773314
larvicidal, adulticidal and repellent effects of kaempferia galanga.four fractions of kaempferia galanga (hexane fraction, dichloromethane fraction 1, dichloromethane fraction 2 and methanolic fraction) were tested for larvicidal activity toward fourth instar culex quinquefasciatus. the hexane fraction was found to exhibit the highest larvicidal effect with the lc50 of 42.33 ppm. testing for adulticidal activity, the hexane fraction did not show any promising adulticidal effect. however, it caused a knockdown effect which might be useful as a repellent. it was t ...199910774653
activation and germination of spores of bacillus thuringiensis var israelensis by alkaline ph and larval (aedes aegypti) gut fluid.alkaline activation of the spores of crystalliferous (cry+) and acrystalliferous (cry-) strains of bacillus thuringiensis var israelensis; wild type b. cereus and its transcipient crystalliferous derivatives and wild type b. subtilis was studied. also the effect of larval (aedes aegypti) gut fluid on the activation of spores of these strains was studied. only the spores of the crystal forming strains were found to be activated by 0.1 m k2co3 (ph 10) and by the larval gut fluid. the process of al ...199910774706
tomato yellow leaf curl geminivirus (tylcv-is) is transmitted among whiteflies (bemisia tabaci) in a sex-related manner.tomato yellow leaf curl virus (tylcv) is the name given to a complex of geminiviruses infecting tomato cultures worldwide. tylcv is transmitted by a single insect species, the whitefly bemisia tabaci. herein we show that a tylcv isolate from israel (tylcv-is) can be transmitted among whiteflies in a sex-dependent manner, in the absence of any other source of virus. tylcv was transmitted from viruliferous males to females and from viruliferous females to males but not among insects of the same se ...200010775612
effect of entomopathogenic fungus, beauveria bassiana on larvae of three species of mosquitoes.beauveria bassiana, an entomopathogenic fungus, was evaluated for its potential against second and third instar larvae of culex quinquefasciatus, anopheles stephensi and aedes aegypti. conidiospores of this fungus were effective in causing infection leading to mortality of different larval instars. larvae of cx. quinquefasciatus were more susceptible to infection than an. stephensi and the second instar larvae of these two species were more susceptible than third instar larvae. larvae of ae. aeg ...199910783749
a juvenile hormone-repressible transferrin-like protein from the bean bug, riptortus clavatus: cdna sequence analysis and protein identification during diapause and vitellogenesis.we found several juvenile hormone-responsive cdnas in the bean bug, riptortus clavatus, by using mrna differential display (hirai et al., 1998). one of them, a juvenile hormone-repressible cdna, jr-3, was cloned, sequenced, characterized and identified as a transferrin (rctf). rctf cdna encoded 652 amino acids with a calculated molecular weight of 71,453 da. the deduced amino acid sequence showed significant homology with the transferin genes of several insects, manduca sexta (43% identity), bla ...200010790182
[characterization of entomopathogenic bacillus samples isolated in senegal and study of their toxicity for malaria vectors].a screening program developed in senegal to isolate new strains of entomopathogenic bacillus has led to the isolation of 194 strains of bacillus thuringiensis and 9 strains of bacillus sphaericus from various sites and insect samples. the characterization of these strains regarding their h serotype, their crystal composition and their toxicity against mosquitoes (culex pipiens, aedes aegypti and anopheles stephensi) has led to the isolation of 27 mosquitocidal strains. as malaria is an important ...199810797955
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