摘要:

Abstract.Malacophagous larvae of the flySepedon scapularisAdams were shown experimentally to be effective predators of three species of aquatic pulmonate snails tested as prey:Bulinus africanus(Krauss) an important intermediate host ofSchistosoma haematobium(Bilharz),Bulinus tropicus(Krauss) and the invasive speciesPhysa acutaDraparnaud. Survival ofS.scapularislarvae from instar to instar was negatively affected by the size of prey snails, since larvae tended to be asphyxiated by the mucous secretions of the snails, or by the larval hydrofuge hairs becoming entangled in snail faeces.In experiments to test the choice ofS.scapularislarvae for different species and sizes of snails,B. africanuswas significantly disfavoured compared with the other two snail species. Small snails (7mm), whereas second and third instars preyed effectively on all sizes of snails. Third instars killed significantly more snails than younger instars. For larvae offered only one species of snail as prey, the mean total number of snails killed per larva during its entire development was 49B.africanus,45B.tropicusor 34P.acuta.It is concluded thatS.scapularisis potentially useful as a biological control agent for use against indigenousBulinusand exoticPhysasnails.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00604.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.1In tropical rain forest, phlebotomine sandflies (Diptera: Psychodidae), such asLutzomyia vespertilionisandL.ylephiletor,have an aggregated distribution on their tree buttress diurnal resting sites, as studied during 1987‐88 at Finca la Selva in the Caribbean lowlands of Costa Rica.2Experimental transfer of flies to trees not used as resting sites indicated that many apparently suitable sites remain unoccupied.3Observations of sandflies on the buttresses revealed that males and females are juxtaposed more frequently than expected by chance alone. Courtship behaviour by three of the four species of sandfly studied was observed on the buttresses.4It is suggested that the use of buttresses as swarming sites for mating behaviour is more likely to account for the observed distribution patterns of sandflies than their use of buttresses simply as diurnal resting site

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00605.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Experiments were undertaken to determine the relative attractiveness of humans, dogs and chickens toLutzomyia longipalpis,the principal vector ofLeishmania chagasicausing American visceral leishmaniasis Field experiments in two villages on Marajo Island, Para State, Brazil, showed that one boy attracted significantly more flies than one dog or chicken, and slightly fewer flies than a group of six chickens. Experiments with laboratory‐bred female flies showed that a significantly greater number of flies engorged on a single human than on either a single dog or chicken, and man‐biting catches demonstrated the willingness of flies to bite in the field. It appears thatLu. longipalpishas catholic feeding habits, the attractiveness of different hosts being largely a function of their relative sizes. These results are discussed with reference to the epidemiology of visceral leishmaniasis in Bra

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00606.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The eggshell structure of four sandfly species:Phlebotomus perniciosusNewstead,P.perfiliewiParrot,P.papatasiScopoli andP.duboscqiNeveu‐Lemaire, was examined by scanning and transmission electron microscopy (SEM and TEM). At the TEM level, the eggshell appears to have a homogeneous vitelline envelope and a thick chorion. At SEM level, the eggshell of all species is characterized by the outer chorion forming a series of fifteen to twenty longitudinal sinuous ridges, cross‐linked in places to form a pattern of polygons, each line of the chorion consisting of columns arranged in a palisade. The aeropyle region of the egg is decribed for the first time in phlebotomine sandflies. Specific characters of the eggshell topography are described for distinguishing between these and other species ofPhleboto

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00607.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.An analysis of cytoplasmic crossing type variation in Australian populations ofCulex quinquefasciatus,a member of theCulex pipienscomplex of mosquitoes, revealed high levels of variability causing partial incompatibility between natural populations. Segregating crossing types were commonly found together within sampled sites. No correlation was evident between similarity of crossing type and environmental parameters of the sites, nor distance between sites. The nature of the observed variation did not support the hypothesis of paternally expressed nuclear ‘restorer’ genes. Such high levels of crossing type variation would be likely to impede attempts to control populations of theCulex pipienscomplex using cytoplasmic incompatibil

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00608.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Lectins that agglutinate red blood cells (RBC) were demonstrated inAnopheles gambiaemosquito haemolymph and gut extracts. No apparent differences in haemagglutinin titres were detected between male and female mosquitoes and overall agglutinin levels were not increased following a bloodmeal.Titres were highest in the haemolymph and midgut extracts versus human AB, horse, chicken and goat RBCs and in hindgut against human AB, chicken and sheep; foregut extract gave relatively low titres.Adsorption of haemolymph and gut extracts with selected RBCs coupled with carbohydrate inhibition and the use of enzyme‐treated RBCs revealed the presence of multiple (hetero‐) agglutinins.An.gambiaelectins were specific for (1‐1)‐, (1–4)‐ or (l‐6)‐linked glucose based disaccharides, glucose and its (1–2) or (1–3) linkages with fructose and, to a lesser extent, aminated or N‐acetylated glucose, or galactose and its deoxy derivatives.This study presents the first report of the occurrence of heterogenous anti‐RBC agglutinins in haemolymph and gut extracts of the mosquitoAn.gambiae, together with the sugar‐binding speci

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00609.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.TeneralGlossina morsitans centralisMachado were fed on the flanks of the African buffalo(Syncerus cofferSparrman), N'Dama(Bos taurusL.) or Boran(Bos indicusL.) cattle infected withTrypanosoma congolenseBroden. The infected tsetse were maintained on rabbits and on day 30 after the infected feed, the surviving tsetse were dissected to determine the infection rates. The mean infection rates (%±SE) in the midgut of tsetse fed on buffalo, N'Damas and Borans were 23.5 ± 3.3, 31.6 ± 2.7 and 33.7 ± 4.6, respectively. The differences were not significant. However, the mean mature infection rate in tsetse fed on the buffalo (13.2 ±2.1%) was significantly lower compared to the rates in tsetse fed on the N'Dama (20.4 ± 1.4) or the Boran cattle (21.4 ± 1.1). When groups of teneralG.m.centralis, G.pallidipesAusten,G.p.gambiensisVanderplank,G.f.fuscipesNewstead,G.brevipalpisNewstead andG.longipennisCorti were fed simultaneously on either an infected buffalo, an N'Dama or a Boran steer, the mature infection rates ranged from 0 to 16.1%. Irrespective of the host species used, theT.congolenseinfection rate was highest inG.m.centralis, lowest in thepalpalisandfuscagroup tsetse, withG.pallidipesbeing intermediate. Nevertheless, the trypanoresistant African buffalo and N'Dama may serve as reservoirs ofT.congolenseas can trypanosusceptible Boran

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00610.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Free‐living haematophagous insects risk death through host grooming responses or through increased susceptibility to predation whenever they take a bloodmeal. In this paper we investigate the effects of these risks on the feeding strategy of tsetse. A model is presented that allows for death of tsetse by starvation if they do not succeed in feeding within a fixed time (set at 6 days in the first instance) and for mortality specifically associated with feeding. In addition there is background mortality that applies to all flies at all times.The model is used to compute the individual life‐time fertility (number of female puparia per female) as a function of the probability of obtaining a meal (indicated by field data to be very high, usually>0.85 per day) and the day on which flies start to search for a meal. We suggest that the feeding strategy that would be selected for is that which allows the maximum reproductive output. The model shows that this strategy involves making no attempts to feed for 3–4 days after the previous meal and then attempting to feed with the greatest possible probability until a meal is obtained. The predicted feeding interval, obtained independently of any trapping data, agrees closely with all previous estimates from field studies using a variety of methods. Preliminary results from a laboratory experiment reveal an increased risk of predation of recently fed as compared with hungry tsetse. The lower the actual feeding mortality the more frequently will flies be able to feed should conditions so demand. It is adaptive, however, for tsetse to delay attempting to feed for as long as they can, which is made possible by the near certainty of locating and feeding on a host within 1 day, using their sophisticated sensory sy

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00611.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Of fifteen compounds tested as synergists for chlorpyrifos against susceptible and resistant strains ofBlattella germanica, the German cockroach, eleven were active against the resistant strain but only seven were synergistic against the susceptible strain. Overall, the most effective synergist was S,S,S‐tributyl phosphorotrithioate (DEF) followed by phenyl saligenin cyclic phos‐phonate (PSCP) and two substituted N,7V‐dimethylcarbamates: SK‐102 and SK‐37. The most effective synergist for overcoming chlorpyrifos resistance was SK‐37 which reduced the resistance ratio by 3.2‐fold. Four other synergists which reduced chlorpyrifos resistance, in order of their effectiveness, were: SK‐102>PSCP>DEF>tridiphane. The potential usefulness of these synergists for German cockroach contr

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00612.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Nymphs of the Oriental cockroachBlatta orientaliswere exposed during the penultimate and final instars to vinyl tiles treated with the juvenile hormone analogue hydroprene. Adults moulting from these nymphs exhibited deformities such as twisted wings in both sexes and modified genitalia in females. Females with deformities were unable to produce viable oothecae.B. orientalisconfined on tiles treated with hydroprene at rates of 25‐100mg/m2did not reproduce. The treatment rate of 10mg/m2reduced fecundity and caused 47–57% of resultant adults to have deformities, but some adults reproduced successfully and population growth was not suppres

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00613.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY