摘要:

ABSTRACT.When monitored by the agar gel immunodiffusion test for antibody to bluetongue viruses, a sentinel flock of twenty‐five lambs remained seropositive through the year, whereas in a sentinel herd of twenty calves only two individuals seroconverted and these became negative again within 2 months. A light trap operated with the calf herd yielded high numbers ofCulicoides insignisLutz (over 18,000 per trap night) along withC.filariferusHoffman,C.pusillusLutz,C.leopoldiOrtiz,C.foxiOrtiz,C.limaiBarretto,C.diabolicusHoffman andC.guyanensisFloch and Abonnenc.Culicoideswere trapped at the sheep station which had housed the lambs 3 years following the sentinel study. No virus was isolated from pools ofC.insignis, C.filariferusandC.pusillus.Six other species were collected in insufficient numbers to warrant attempted virus isolation

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00482.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00483.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Culex annulirostrisSkuse, colonized from Brisbane. Queensland, and Mildura, Victoria, Australia, were effective vectors of Murray Valley encephalitis virus at 20, 27 and 32–35oC with full extrinsic‐incubation periods of 15, 10 and 4 days respectively. At 20oC, 7–11 days post‐infection, transmission by the Mildura colony (0–20%) was less efficient than the Brisbane colony (30–70%) but both were capable of 75–100% transmission after longer extrinsic incubation periods. Discriminant analysis of body and salivary gland titres showed that these were not satisfactory indicators of transmission. Wild‐caughtAedes sagax(Skuse) andCx annulirostrisfrom the Murray Valley showed equal competence, butAedes alboannulatus(Macquart) was a poor vector. The results provide data on rural amplification of Murray Valley encephalitis virus during spring and suggest that further work on the potential ofA e. sagaxas a natural vect

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00484.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Vector competence for La Crosse virus (LACV) was compared for four species in theAedes (Protomacleaya) triseriatusgroup:Ae.triseriatus(Say),Ae.hendersoniCockerel],Ae.zoosophusDyar and Knab andAe.brelandiZavortink (Diptera: Culicidae). Rates of replication and dissemination of virus in the mosquito hosts were compared and rates of oral transmission of virus to suckling mice were determined. Barriers to virus dissemination which limited the ability of each species to transmit virus were identified.Ae.zoosophusdisplayed the highest vector competence for LACV. Both infection and transmission rates were high: 99% and 85% respectively; no significant barriers to LACV were found. Disseminated infection ofAe. triseriatuswith LACV was controlled primarily be a midgut escape barrier. When virus was introduced directly into the haemocoel, transmission rates were significantly increased (37% v. 79%).Ae.hendersonishowed high susceptibility to LACV infection but a very low rate of oral transmission (7%).Ae.brelandiwas also highly susceptible to infection by LACV and transmitted virus at an intermediate rate (27%). Modulation of vector competence in bothAe.hendersoniandAe. brelandiresulted from a salivary gland escape barrier.As these four species of mosquitoes comprise a closely related monophyletic series, their differences of vector competence for LACV provide an excellent model for studying the genetic basis of the barriers involved.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00485.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Four species of sandflies:Phlebotomus (Larroussius) perniciosusNewstead,Sergentomyia minuta(Rondani),Phlebotomus (Paraphlebotomus) sergentiParrot andPhlebotomus (Larroussius) ariasiTonnoir, were collected, by aspiration and light traps, from three dog kennels and an area of high prevalence of human and canine visceral leishmaniasis in the Algarve, Portugal. Midgut infections with leishmanial promastigotes were observed only inP.perniciosuswith a minimum infection rate of 5%. The engorgement, gravidity, population dynamics and sex ratios of the sandflies, and the temperature, source and altitude of collection sites were examined. Host preferences were noted forP.perniciosus.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00486.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.. Larval instars 2, 3 and 4 ofPhlebotomus tobbiAdler, Theodor&Lourie from the Greek islands of Corfu and Zakynthos were found to have two caudal setae instead of the four usually present on these instars ofPhlebotomuslarvae. In a scanning electron microscope comparison with larvae ofP.papatasi(Scopoli), a sensillum was seen in place of each outer seta ofP. tobbilarvae, suggesting secondary loss of the setae. As the larvae of less than a tenth of the species and subspecies of the genusPhlebotomushave been seen and described, it cannot be assumed that those ofP. tobbiare unique in having only two caudal setae. However, four caudal setae in late instars can no longer be considered as a constant character of the genusPhlebotomus.Observations on the larvae ofP. tobbialso raise the question of the unknown function of the caudal setae.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00487.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.The efficacy of 10% (w/w) permethrin impregnated eartags for the control of the haematophagous fly pestsStomoxys calcitransL.,Haematopota dissimilisMeigen andHippobosca maculataLeach on equines in India was determined. The tags were found to be effective for 1–2 months againstS.calcitransandH. dissimilisbut completely ineffective againstH. maculata.No tags were lost during the study. Tags can be used as part of an integrated control programme. This is the first reported use of eartags for control of haematophagous flies on horse

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00488.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.The process of maturation ofTrypanosoma congolenseBroden in tsetse has been shown to be initiated by lectin secreted in the fly midgut. In the present study the duration of lectin signal required to induce maturation was determined by the sequential addition or removal of a specific lectin inhibitor (D+glucosamine) to the diet of infected maleGlossina morsitansWestwood. An established midgut infection ofT.congolensewas found to require, at most, 72 h exposure to midgut lectin to begin the process of maturation. Longer exposure to midgut lectin increased the frequency of maturation, suggesting clonal variation in response to lectin stimulation occurs within trypanosome stocks. It is suggested that this variation corresponds to differences in lectin binding sites on the trypanosome surface. Midgut trypanosomes retained their ability to mature throughout their life in the fly; when lectin activity in the midgut was inhibited, the trypanosomes remained as procyclic forms but when this inhibition was removed maturation was able to proceed. This indicates that the process of maturation is dependent upon a signal from the fly and is not predetermined by the trypanosomes undergoing a fixed number of division cycles. The possible role of lectins in the maturation of trypanosomesin vitrois discussed.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00489.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00491.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.The roles of visual and/or olfactory stimuli in eliciting mating responses from maleGlossina morsitans morsitansWestwood were examined, using a system for automatically recording the number and duration of mating strikes made towards decoys, under controlled conditions. The results confirm that there is no olfactory component of the female sex recognition pheromone sensed by the male antennae, and the attraction of males to females appears to be visual. The absence of male‐male mating strikes was the result of the absence of female sex‐pheromone, rather than the presence of a repellent mating deterrent in the male cuticle. Experiments with coloured, artificial, sex‐pheromone‐dosed, cotton decoys showed that colour had only weak effects on attractiveness and number of encounters with decoys, and that no colour caused significant enhancement of mating responses over those shown to decoy

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00492.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY