摘要:

Abstract.To obtain information on adult populations of Afrotropical malaria vector mosquitoes, mark‐release‐recapture experiments were performed withAnophelesfemales collected from indoor resting‐sites in a savanna area near Ouagadougou, Burkina Faso, during September 1991 and 1992. Results were used to estimate the absolute population densities, daily survival rates, and dispersal parameters of malaria vectors in that area.In 1991 a total of 7260 femaleAnopheleswere marked and released, of which 106 were recaptured in the release village and 6 in the neighbouring villages, a total recapture rate of 1.5%. The following year 13, 854 femaleAnopheleswere released and 116 recaptured in Goundri and 8 in the neighbouring villages, a total recapture rate of 0.9%. Recaptures were found in three of eight villages near Goundri. Nearly all of the recaptured mosquitoes wereAn.gambiae s.l.Of these, molecular determination revealed thatAn.gambiae s.s.andAn.arabiensiswere present in a ratio of ‐2:3.Two simple random models of dispersal were simulated and the parameters of the models determined by searching for the least‐squared fit between simulated and observed distributions. The mean distance moved by individual mosquitoes, estimated in this way, ranged 350–650 m day‐1, depending on die model and the year considered. Population densities were estimated using the Lincoln Index, Fisher‐Ford and Jolly's methods. The estimates of population size had high standard errors and were not particularly consistent. A ‘consensus’ value of 150,000–350,000 mosquitoes is believed to apply forht An.gambiae s.l.female population. Survival was estimated

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00733.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.Mosquito responses to carbon dioxide were investigated in Noungou village, 30 km northeast of Ouagadougou in the Sudan savanna belt of Burkina Faso, West Africa. Species of primary interest were the main malaria vectors Anopheles gambiae S.S. and An.arabiensis, sibling species belonging to the An.gambiae complex. Data forAn.finestus, An.pharoensis, Culex quinquefasciatus and Mansonia uniformis were also analysed.Carbon dioxide was used at concentrations of 0.04‐0.6% (cf. 0.03% ambient concentration) for attracting mosquitoes to odour‐baited entry traps (OBETs). The ‘attractiveness’ of whole human odour was also compared with CO2, emitted at a rate equivalent to that released by the human bait. In a direct choice test with two OBETs placed side‐by‐side, the number of An.gambiae s. I. entering the trap with human odour was double the number trapped with CO2, alone (at the human equivalent rate), but there was no significant difference between OBETs for the other species of mosquitoes. When OBETs were positioned 20 m apart, again CO2, alone attracted half as many An.gambiae s.l. and only 40% Anlfunestus, 65% Ma.uniformis but twice as many An.pharoensis compared to the number trapped with human odour.The dose‐response for all mosquito species was essentially similar: a linear increase in catch with increasing dose on a log‐log scale. The slopes of the dose‐response curves were not significantly different between species, although there were significant differences in the relative numbers caught. If the dose‐response data are considered in relation to a standard human bait collection (HBC), however, the behaviour of each species was quite different. At one extreme, even the highest dose of CO2, did not catch more An.gambiae s.1. than one HBC. At the other extreme, the three highest doses of CO2, caught significantly more Ma.unifonnis than did one HBC. An.pharoensis and Cx quinquefasciatus showed a threshold response to CO2, responding only at doses above that normally released by one man. An.funestus did not respond to CO2, alone at any dose in sufficient numbers to assess the dose response. Within the An.gambiae complex, An.arabiensis 'chose' the CO2,‐baited trap with a higher probability than An.gambiae S.S. Also An.arabiensis, the less anthropophilic of the two species, was more abundant in CO2,‐baited OBETs than in

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00734.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.A subregion of the mitochondrial large subunit (16s) rRNA gene was amplified by polymerase chain reaction (PCR) from nine species of blackflies (Diptera: Simuliidae) which serve as natural or experimental vectors of human or bovineOnchocercaparasites. PCR products from each species of blackfly were tested by directed heteroduplex analysis (DHDA), and their genotypes established according to diagnostic banding patterns of the heteroduplex products. Three alleles of mitochondrial 16s rRNA were found to exist in members of theSimulium (Ewardsellum) damnosum sensu latocomplex from West Africa, and two alleles were found in the NeotropicalSimulium (Psilopelmia) ochraceumWalker complex and theSimulium (Simulium) metallicumBellardi complex. Different single alleles were detected inAustrosimulium bancrofti, in EnglishS.(S.)noelleriand in two North American laboratory vectors:Simulium (Psilozia) vittatumZetterstedt andS.(S.)decorumWalker. Phylogenetic analysis of 16s sequences indicated that blackflies from West Africa and the Americas formed distinct clades. Neotropical onchocerciasis vectors were found to be more closely related to Nearctic and Palaearctic non‐vectorSimuliumspecies than to the African vectors of onchocerciasi

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00735.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.In laboratory trials designed to examine the alighting response of the blowflyLucilia sericataMeigen to colour, yellow sticky cloth targets caught the largest number of both males and females, followed by pale blue, black, green, dark blue and red. The number caught by any colour showed a strong positive relationship with the percentage of its spectral reflectivity in the 450–580 nm wavelength band. In field trials, targets baited with the synthetic attractant ‘swormlure’ caught significantly fewerL.sericatathan targets baited with liver and sodium sulphide, suggesting that the former bait is a relatively poor attractant for this species, at the release rates used in the present study. However, there was no effect of target colour on catch, neither was there any interaction between colour and odour bait type. The results, from both the laboratory and field trials, suggest that the strength of responses byLsericatato visual cues are weak relative to responses to odour. Responses to hue are readily overridden by a range of factors such as brightness and contrast with the background and are therefore likely to be difficult to detect or manipulate reliably in trapping systems in the

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00736.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.A total of 924 questingDermacentor reticulatus(Fabricius), 504Ixodes ricinus(L.), sixtyHaemaphysalis concinnaKoch and 718 mosquitoes(Aedesspp.) were examined in a floodplain forest ecosystem during the 1994‐95 outbreak of tularaemia in South Moravia, Czech Republic.Francisella tularensiswas not isolated fromH.concinnaticks orAedesspp. mosquitoes, whereas twenty‐one isolates were recovered from the other haematophagous arthropods.Dermacentor reticulatusrevealed a significantly higher infection rate (2.6%) thanI.ricinus(0.2%). This tick species acts as principal vector for tularaemia in the enzootic focus. Monitoring ofD.reticulatusforF.tularensisthus seems to be a very efficient approach in the surveillance of tularaemia in the flood‐plain forest ecosystems of E

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00737.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.Haemagglutination activity (HA) was studied in gut extracts of both sexes of adults of six sandfly species. HA was sex dependent, with the activity in males more than 50 times lower man that of unfed females. In females, high HA was demonstrable in both the thoracic and abdominal midgut but not in the hindgut. In unfed flies the activity was similar in the midgut wall and the gut contents whereas, in fed females, a high increase was seen in the midgut contents. After blood‐feeding, HA was elevated, reaching peak titres 2 days later and then falling to the base level or less immediately after defaecation. The magnitude of the HA response differed according to species, ranging from 2‐fold inLutzomyia carmelinoiup to 16‐fold inPhlebotomus duboscqi.Quantitative differences between sandflies in their HA response may influence their ability to support the development ofLeishman

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00738.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.The effects of introducing permethrin‐impregnated bednets on local populations of the malaria vector mosquitoesAnopheles funestusand theAn.gambiaecomplex was monitored during a randomized controlled trial at Kilifi on the Kenyan coast. Pyrethrum spray collections inside 762 households were conducted between May 1994 and April 1995 after the introduction of bednets in half of the study area. All‐night human bait collections were performed in two zones (one control and one intervention) for two nights each month during the same period. PCR identifications ofAn.gambiae sensu latoshowed that proportions of sibling species wereAn.gambiae sensu stricto>An.merus>An.arabiensis.Indoor‐resting densities ofAn.gambiae s.l.and the proportion of engorged females decreased significantly in intervention zones as compared to control zones. However, the human blood index andPlasmodium falciparumsporozoite rate remained unaffected. Also vector parous rates were unaltered by the intervention, implying that survival rates of malaria vectors were not affected. The human‐biting density ofAn.gambiae s.l., the predominant vector, was consistently higher in the intervention zone compared to the control zone, but showed 8% reduction compared to pre‐intervention biting rates ‐ versus 94% increase in the control zone.Bioassay, susceptibility and high‐performance liquid chromatography results all indicated that the permethrin content applied to the nets was sufficient to maintain high mortality of susceptible vectors throughout the trial. Increased rates of early outdoor‐biting, as opposed to indoor‐biting later during the night, were behavioural or vector composition changes associated with this intervention, which would require further monitoring during control programmes employing insecticid

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00739.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.A formulated protein meal developed by Kogan (1990) for adult femaleAedes aegyptimosquitoes was evaluated and modified to increase egg and pupal yield. A vigorous laboratory colony was maintained with the females fed exclusively on this dietary formula for about twenty‐five generations over more than 2 years. Extra modifications were made to produce a diet suitable forAnopheles arabiensisandAnopheles stephensifemales to produce eggs. Both formulations contain bovine albumin, haemoglobin and globulin in a ringer based solution, plus ATP as a phagostimulant forAe.aegypti.Compared to Kogan's original, ourAedesformula doubled the production of pupae per female after a single meal, although the yield was still significantly lower than from mosquitoes fed on animal hosts or defibrinated pig blood. In varying the proportions of different constituents during attempts to optimize the formula, no relationship was found between total protein content (within the range 80–220 mg/ml) and fecundity, percentage hatch or pupal yield ofAe.aegypti.Equivocal results were found when an isoleucine supplement was added to the form

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00740.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.The tropical house mosquitoCulex quinquefasciatuswas cultured by feeding the females on an artificial diet, not on live animals or whole blood. This anautogenous strain has been maintained for more than fifty generations. The blood replacement diet for female mosquitoes, designed to simulate the tonicity and density of host blood, was based on ovalbumin, soya infant formula, globulins and adenosine triphosphate.Female adults ofCx quinquefasciatuswere fed the artificial blood formula from ‘Parafilm’ wax membrane‐covered beakers. The diet was heated by radiant heat from a chamber containing an exothermic chemical reaction. This maintained the diet at a temperature of 33–37d̀C for a period of up to 6 h, sufficient time to enable all the female mosquitoes to imbibe to satiation. After six generations on the artificial diet, female fecundity stabilized to a satisfactory level: the number of eggs per gonotrophic cycle averagedc.85% of the ‘control’ strain fed on whole blood from live anaesthetized guinea‐pigs, i.e. 156 eggs per female from nine feeds on the artificial diet compared with 183 from six feeds of whole blood. Adult weight ofCx quinquefasciatusfemales was not significantly different, from generation 6 onwards, for strains fed on artificial diet or whole blood. Sex ratio and the rate of egg viability were also equivalent for t

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00741.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.Human sweat samples were chemically fractionated into acid and non‐acid components. The most abundant volatile compounds present in the fractions were identified by linked gas chromatography mass spectrometry. The acid fractions were found to be composed of a range of twenty aliphatic and three aromatic carboxylic acids ranging, on average, from 0.02 to 20igper ml of sweat sampled. Non‐acid fractions were found to contain: 6‐methyl‐5‐hepten‐2‐one, l‐octen‐3‐ol, decanal, benzyl alcohol, dimethylsulphone, phenylethanol, phenol and 4‐mefhylphenol, collectively amounting to 0.1 and 3 |ig per ml of sweat. The major component of sweat was found to be L‐lactic acid which constituted from 1 to 5 mg/ml.Using the intact antennae of the anthropophilic malaria vector mosquitoAnopheles gambiaeGiles, the peripheral olfactory activities of compounds identified in the sweat fractions were investigated by electroantennography (EAG). Short‐chain saturated carboxylic acids, methanoic, ethanoic, propanoic, butanoic, pentanoic and hexanoic acids were found to elicit significantly larger EAG responses than longer chain saturated carboxylic acids from femaleAn.gambiae.For a given dose the largest amplitude EAG response was elicited by methanoic acid. Pentanoic acid elicited larger EAG responses than either butanoic or hexanoic acids. Two non‐acidic compounds, l‐octen‐3‐ol and 4‐methylphenol, were found to elicit significant dose‐dependent EAG responses from femaleAn.gambiae.1 ‐Octen‐3‐ol elicited larger EAG responses than 4‐methylphenol for a given dose, but both compounds elicited smaller EAG responses than the same dose of C]‐C6straight‐chain aliphatic carboxylic acids. The possible behavioural significance of the EAG‐active compo

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1996.tb00742.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY