摘要:

Abstract.In order to develop and evaluate control strategies for blowfly strike, a greater understanding of the epidemiology is essential. A postal survey of sheep farmers yielded information about ten farm and management factors and their relationship to blowfly strike prevalence. The risk of a farm reporting at least one case of blowfly strike increased as flock size and stocking density increased (adjusted odds ratio of 1.13 for an increase in flock size of 100 sheep and 1.38 for an increase in stocking density of ten sheep per hectare). As farm altitude increased, the risk of blowfly strike decreased (adjusted odds ratio 0.67 for an increase in farm altitude of 100 m). The risk of high strike prevalence (more than 2% of sheep struck) decreased as both farm altitude and flock size increased. High strike prevalence was also associated with on‐farm sheep carcase disposal (odds ratio 1.35). Farmers in the south‐west of England were more likely to report at least one case of blowfly strike and high strike prevalence compared to all other regi

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00385.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The daily flight activity patterns of one of the main vectors of animal trypanosomiasis in West Africa,Glossina morsitans submorsitans, were assessed using four different methods. Results from all the methods showed that there was some flight activity nearly every hour in all seasons but they differed in the level of contact between grazing cattle herds andG.m.submorsitans.In the late dry season, trap data indicated that there was negligible activity from midday to late afternoon, whereas observations of tsetse contact with cattle herds or hand‐net collections on herd followings showed no fall in attack rates on the cattle byG.m.submorsitans.Differences between trap and animal‐baited collection data may be attributable to the type ofG.m.submorsitanssampled by each method. MaleG.m.submorsitanscaptured by traps were more fat depleted than those caught on ox‐baited flyrounds or by hand‐net collections on herd followings. All methods showed that maleG.m.submorsitanswere most fat depleted in the late dry season and least in the early dry season. It was concluded that the traps were mainly sampling the spontaneous flights ofG.m.submorsitans.Hunger and endogenous rhythms increase the likelihood of spontaneous flights towards dusk, particularly in conditions such as those at midday in the very hot, late dry season. However, the presence of cattle herds in infested habitats probably activated nearbyG.m.submorsitansand the continual movement through the grazing areas ensured contact with tsetse throughout grazing.The data indicated that strategic management of herd grazing times cannot eliminate the risk of trypanosomiasis transmission occurring, irrespective of the harshness of the dry season climate. An assessment of the level of this risk could only be measured suitably by collecting tsetse using animal‐baited methods, not from

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00386.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Field studies were conducted with EVS (encephalitis vector surveillance) traps in south‐eastern Queensland, Australia, to determine the relative response rates of mosquitoes to three levels (0.1, 4.5 and 30mg/h) of 1‐octen‐3‐ol (octenol) in combination with a standard bait of 2200 g carbon dioxide (CO2), compared with CO2alone or CO2with light from a 6V incandescent bulb. Compared to CO2alone,Aedes vigilaxcollections increased significantly when CO2was supplemented by all three octenol emission levels, but not by the addition of light. Furthermore, the 4.5 and 30 mg/h release rate of octenol gave a significant increase in numbers ofAe.vigilaxrelative to that from CO2+ light. In contrast, collections ofCulex annulirostrisandCulex sitienswere not enhanced significantly by either the addition of light or octenol at all three levels. FewerCx sitienswere collected with octenol released at 4.5 mg/h in comparison to CO2alone. These differential sampling rates should be taken into account when using EV

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00387.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.The insect repellent N,N‐diethylphenylacetamide (DEPA) was compared with two commercial repellents, N,N‐diethyl‐m‐toluamide (DEET) and dimethyl phthalate (DMP), for protection against 3‐day‐old unfed females of the sandflyPhlebotomus papatasi(Scopoli) under laboratory conditions, using host rabbits. Both DEPA and DEET were found to be more effective than DMP, but there was no significant difference between the efficacy of DE

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00388.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Susceptibility of the malaria vectorAnopheles gambiaeto permethrin decreased following the installation of mosquito nets impregnated with 0.5 g permethrin per square metre in four villages near Kisumu, Kenya. During the first year that permethrin‐impregnated bednets and curtains were in place, the exposure time to 50% mortality (LT50) increased 2.5‐fold from 13 to 33min, while the LT5()forAn.gambiaewas unchanged in two other villages where no intervention measures were used. Two years after permethrin‐impregnated mosquito nets were distributed the LT50s forAn.gambiaewere 28, 28 and 16min, respectively, in the villages with bednets, curtains and with no such intervention.Using a colony ofAn.gambiaederived from females collected in the villages using permethrin‐impregnated moquito nets, we lengthened the LT5nfrom 28 to 41 min in two generations by exposing all females to permethrin‐treated papers for 60 min and rearing offspring of the survivors.Permethrin‐impregnated bednets and curtains are intended to reduce vectorial capacity. Reduced susceptibility to permethrin could counter this benefi

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00389.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.. The phenomenon of aggregated oviposition in blackflies (Diptera: Simuliidae) was investigated under controlled laboratory conditions, using wild‐caught females of theSimulium damnosumcomplex in Sierra Leone. A method was developed for inducingSimuliumfemales to lay eggs, and used as a bioassay to measure the responses of gravidS. damnosum s.l.to freshly laid eggs of the same species complex. In a series of two‐choice tests, significantly more ovipositing flies chose substrates already containing eggs over control substrates (P= 0.004). The time from introduction of flies into the oviposition system to the onset of egg‐laying was significantly less when eggs were already present (P= 0.049). Flies responded more quickly when more eggs were present and the relationship between egg‐batch number and the time of this response was curvilinear (P= 0.012). Ecological advantages and disadvantages of such aggregation behaviour and the possible role of semiochemicals in its mediation are di

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00390.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.. Midgut infection rates ofTrypanosoma congolenseinGlossina palpalis palpalisand ofTrypanosoma brucei rhodesienseinGlossina pallidipesare potentiated by the addition of D+ glucosamine to the infective feed, but not to the levels of super‐infection reported forG. m. morsitans. G. p. palpalisandG.pallidipesare shown to possess two trypanocidal molecules: a glucosyl lectin which can be inhibited by D+ glucosamine and a galactosyl molecule inhibited by D+ galactose. Addition of both D+ glucosamine and D+ galactose to the teneral infective feed promotes super‐infection of the midguts ofG.p.palpalis.The glucosyl lectin is specific for rabbit erythrocytes and is present in guts of fedG.m.morsitansandG.p.palpalis, titres of lectin activity do not increase substantially after the second bloodmeal. The galactosyl specific molecule does not show any erythrocyte specificity, although haemolytic activity is observed only inG.p.palpalisand not inG.m.morsitans.The presence of two trypanocidal molecules in some species of tsetse may account for the innate refractoriness of these flies to trypanosome infection.As D+ glucosamine also inhibits the killing of procyclic trypanosomes taken as an infective feed, it is suggested that the midgut lectin is normally responsible for the agglutination of trypanosomes in the fly midgut by binding to the pro‐cyclic surface coat, prior to establishment in the ecto‐peritrophi

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00391.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract.Anopheles subpictusGrassi is shown to comprise four reproductively distinct species, designated A, B, C and D, occurring sympatrically in villages of Pondicherry, southeast India.Adult females were reared individually from wild larvae and examined for their morphological and chromosomal characters. Paracentric fixed inversions on the X‐chromosome serve to distinguish the species cytogenetically, with no inversion heterozygotes (i.e. no interspecific hybrids) among totals of 717 species A (X+a,+b), 1863 species B (Xa, b), 869 species C (Xa,+b) and 1365 species D (X +a,b) identified.Morphologically, diagnostic characters for each of the four species are seen in the egg float ridge number, larval mesothoracic seta 4, pupal seta 7‐1 and the palpi of female adults. Species A. C and D immatures inhabit freshwater, whereas the malaria vector species B breeds in saltwater and was found only in coastal villa

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00392.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00393.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1994.tb00394.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY