摘要:

ABSTRACT.Growth rates of tsetse populations were estimated by calculating the dominant eigenvalues of appropriate Leslie matrices. The individual effects of four variables (pre‐adult and adult survival probability, interlarval period and pupal duration), have been investigated by varying each one over a wide range of values, while the other three are held constant.R, the log of the growth rate, was found to vary approximately linearly with adult and pre‐adult death rate; a 1% change in the adult death rate causes approximately a 10‐fold change inR. Rvaries linearly with the log of fecundity and of the pupal duration. An increase in the pupal duration results in a decrease in the growth rate for populations which have a positive growth rate, but an increase for populations which have a negative growth rate. For a population at equilibrium, a change in the pupal duration has no effect. Small changes in fecundity have less effect on the growth rate than small changes in the death rate; this fact is advanced as an important contributor to the generally very cautious nature of female tsetse, and their aversion to man, particularly as a potential host.A simple linear model is described which relatesRto all four variables and their first order interactions. The model is used to produce a set of graphs which encapsulate the relationship between the growth rate and the vital parameters over a wide range of values. It is also used to draw the loci on one side of which tsetse populations grow, and on the other of which they decline.Population resilience is discussed in relation to the problem of tsetse eradication; it is concluded that if one can impose and sustain an added mortality of 4% per day on any female tsetse population then it must go extinct, regardless of the strength of the density dependent processes; and it seems likely that in most field conditions only an added 2–3% is required. It is pointed out that ground and aerial spraying techniques produce much higher daily mortalities than this, but they may often not be sustained for sufficiently long to achieve eradication. When odour‐baited targets are used the increased death rate is much smaller, but it can be sustained as required; recent work in Zimbabwe shows that there is a good correspondence between the calculated imposed death rate and the observed rate of decline of tsetse po

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00184.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00185.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.Differential responses ofAnopheles culicifaciesGiles sibling species A and B to DDT were evident from higher survival rate of species B in laboratory bioassays and greater proportions of species B in DDT‐sprayed villages of northern India, compared with those under HCH pressure. Both species A and B have become almost completely resistant to HCH in this area due to regular house‐spraying with HCH for about the last 10 years. Because species A predominates in northern India, where it has been incriminated as an important vector of malaria, and species A is more susceptible than species B to DDT, it is suggested that DDT would control malaria transmission more effectively than HCH in this situation. Monitoring of insecticide resistance in species A is therefore recommended as the basis for future choice of insecticides to be used by the National Malaria Eradication Progra

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00186.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00187.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.In traditional medical practice, the larvae of some Diptera: Calliphoridae, notablyLucilia illustris(Meigen),L. sericata(Meigen) andPhormia regina(Meigen), have been employed for maggot therapy, i.e. to help clean lesions antiseptically, especially for treatment of chronic osteomyelitis. This mode of treatment remains appropriate for cases where antibiotics are ineffective and surgery impracticable.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00188.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.Floodwater aedine mosquito eggs were recovered from soil samples taken from grassland depressions, called pans, in the Orange Free State Province of South Africa. A sedge,Mariscus congestus(Vahl) C. B. C1., was a useful indicator ofAedes(Ochlerotatus)juppiMcintosh oviposition areas. No transovarial transmission of virus was demonstrated byAe. juppifemales reared from the eggs and allowed to feed shortly after eclosion on hamsters. No virus was recovered from 557 pools of 5425 adultAe. juppithat were collected as eggs and reared to the adult stage in the laboratory. Rift Valley fever virus replicated to high titres in experimentally infectedAe. juppifemales, but horizontal transmission experiments proved inconclusive.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00189.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.. A survey of the sandflies (Diptera: Psychodidae) of Jordan increased the number of species known from the country from three to thirteen. Composition of the phlebotomine fauna and the relative abundance of sandfly species differ among the six climatic zones, with a general distinction between the dry desert zones and the more humid Mediterranean zones. Species ofPhlebotomuspredominate in the former andSergentomyiain the latter. Within the desert zone some species are restricted to the eastern desert and others to the Jordan Valley in the west.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00190.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.In Yishan County, Guangxi Province, China, where malaria and Brugian filariasis are transmitted by vectors belonging to theAnopheles hyrcanusPallas group, a study was conducted from June to November 1986 to evaluate the effectiveness of permethrin‐impregnated mosquito bednets to reduce man/vector contact. In three experimental villages a total of 246 mosquito nets were treated with permethrin EC at a dosage of 0.5 g/m2.Control bioassays (1 h exposure) of treated nets gave up to 100% mortality ofArmigeres subalbatus(Coquillett),Anopheles sinensisWiedemann andCulex tritaeniorhynchusGiles for up to 19 weeks. During 5 months evaluation in the villages, permethrin‐impregnated mosquito‐nets reduced the number of mosquitoes found inside nets by 99.3% forCulex quinquefasciatusSay, by 94.4% forAnopheles sinensisWiedemann and by 75% forAnopheles lesteri anthropophagusXu&Feng. This measure could thus be considered an appropriate means of controlling vectors in vil

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00191.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.TeneralGlossina morsitans centralisMachado,G. austeniNewstead,G. palpalis palpalisRobineau‐Desvoidy,G. p. gambiensisVanderplank,G. fuscipes fuscipesNewstead,G. tachinoidesWestwood andG. brevipalpisNewstead, from laboratory‐bred colonies, were fed at the same time on the flanks of ten goats infected withTrypanosoma congolenseBroden isolated in Tanzania or in Nigeria. The seven tsetse species were infected over the range 0.3–49.2%. Survival of bothT. congolenseisolates was best inG. m. centralis, poorest inG. austeniand the fourpalpalisgroup tsetse, withG. brevipalpisintermediate. It is suggested that there are differences in the gut of different laboratory‐bred cultures ofGlossinaWestwood species and subspecies such thatT. congolenseparasites can survive better in the gut of some than in others and undergo cyclical development to metacyclics in the hypo

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00192.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.Malaria sporozoite infection rates in a mixed species group of 244Anopheles gambiaeGilessensu latoand 115An. funestusGiles wild female mosquitoes were compared using three methods to determine cutoff absorbance values for positivity of aPlasmodium falciparumWelch enzyme‐linked immunosorbent assay (ELISA). Positive controls were based onP. falciparumcircumsporozoite protein. As negative controls, four wild maleAnopheleswere included on each microtitre plate; tests were repeated on four consecutive days for each plate.Infection rates were estimated at 13.1–22.8% using the mean absorbance value of negative controls plus three standard deviations, 11.7–12.8% using double the mean and 12.5–13.6% using the fixed cut‐off value of 0.20 (allowing for 20% variation in negative control absorbance values).Observed agreement for positivity or negativity among samples tested four times was 98.6% for the 2× mean method, 97.2% for the fixed cut‐off 0.20 value, but only 82.7% for the mean +3 SD method. It was concluded that the 2× mean cut‐off method is most reliable for field studies.P. falciparumsporozoite rates of 12.2% inAn. funestusand 11.9% inAn. gambiae s. l. were thus determined on the basis of the 2× mean cut‐off method.This comparative evaluation demonstrates that vector infectivity rates can be seriously over‐estimated from sporozoite ELISA tests, by as much as 87% in one case considered here, depending on the absorbance cut‐off method applied

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1988.tb00193.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY