摘要:

ABSTRACT.We report the successful introduction of heterologous DNA sequences into embryos of the mosquitoAedes aegypti(L.) by microinjection. The injected DNA carrried P transposable element sequences, derived from and known to facilitate transformation inDrosophila melanogaster.Two plasmids, one of which carried a dominant selectable marker, were introduced into the posterior of embryos prior to pole cell formation and subsequently taken up into the germ line of transformed individuals. Stable transfer of the selectable marker (G418 resistance) was demonstrated over two generations. The precise nature of these putative P mediated integration events is currently being investigated. However, the results presented here establish the technique of DNA transformation for the genetic manipulation ofAedes aegypti.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00467.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.A rapid method of distinguishing insecticide insensitive acetylcholinesterase (AChE) genotypes was applied to three species of mosquitoes. This relies on comparing rates of an AChE mediated reaction in the presence and absence of insecticides which are inhibitors, using a kinetic microtitre plate reader. Clearer and more rapid resolution between genotypes was achieved than with previous assays which measure the amount of product formed at a fixed end‐point. Results are presented for the Fls from crossing resistant and susceptibleAnopheles albimanusWiedemann andCulex pipiensL., for a strain ofAn.albimanuswith a translocation linking the AChE gene to the Y chromosome and for field collectedAn.nigerrimusGiles. Propoxur and malaoxon were used as inhibitors. In all three species the enzyme was more insensitive to propoxur than malaoxon. Susceptible enzymes in all species also showed higher uninhibited AChE activity than their resistant counterparts. Presentation of both inhibited and uninhibited activities side by side may be useful to identify insects likely to be misclassified due to abnormally low AChE activities. Estimated frequencies of the three resistance genotypes in field populations ofAn.nigerrimusconformed to Hardy‐Weinberg ratios. The implications of this technique for laboratory and field studies on insects are discus

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00468.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Field and commensal rodents were live‐trapped at three villages in an active focus of plague(Yersinia pseudotuberculosis pestis)in Lushoto District, Western Usambara Mountains, Tanga Region, Tanzania, from December 1983 to November 1984. Their flea ectoparasites were collected, identified and counted. The rodent carcasses were serologically examined for specific plague antibodies and antigens, and bacteriologically examined for bipolar staining bacilli.A total of 1758 traps were set during the 12‐month period and 924 animals were caught. From these, 1037 fleas were collected.Rattus rattus(L.),Praomys natalensis(Smith) andLophuromys flavopunctatusThomas comprised the largest proportions of the rodent population, whileDino‐psyllus lypususJordan&Rothschild,Ctenophthalmus calceatusWaterston andXenopsylla brasiliensis(Baker) were the dominant flea species.Rodents were most abundantly trapped during December and January. Flea indices were highest from December to May. Human plague was most active from November to March. Rodents contained plague antibodies every month except May and July, with a peak in September. Plague antigens and bipolar bacilli were detected in rodent organs during January‐April. From the product of abundance and infection rate, the most prevalent rodent hosts of plague appeared to beR. rattus, Otomys ango‐niensisWroughton,P.natalensisandPelomys fallax(Peters).Continuous integrated control of rodents and fleas was recommended, reinforced by quarantine and maintenance of a surveillance service for clinical detection, diagnosis and treatment of patients in the plague end

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00469.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Ctenophthalmus harputussp.n. is described from the mole ratSpalax ehrenbergiNehring collected near Elaziǧ city in eastern Turkey. This new flea species is classified in theCtenophthalmus (Palaeo‐ctenophthalmus) fissurusWagner group. A key is given to the six species ofSpalaxfleas (Siphonaptera: Hystrichopsyllidae,Ctenophthalmusspp.) recorded from Turke

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00470.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Female houseflies (Musca domesticaL.) from a susceptible and a multi‐insecticide‐resistant strain were used to evaluate the relative toxicity of an insecticide bait formulation of the carbamate insecticide methomyl. Individual flies were allowed to feed on bait granules for an unrestricted period or for 5 s. Resistant flies took longer than susceptible flies to initiate a feeding response. When allowed to feed continuously, those from the resistant strain spent longer feeding than susceptible ones. The time taken to knock‐down (KD), including feeding times, was significantly greater for resistant than susceptible flies (P<0.001), but once the proboscis was withdrawn from the granule there was no difference in KD times between the strains. All flies from both strains were knocked down, and only a very small number of resistant and susceptible flies recovered. The toxic effects of methomyl on flies which were restricted to a 5 s feed ranged from no observed effect to KD in<1 min. After feeding for 5 s, 81 % of resistant and 98% of susceptible flies developed signs of methomyl poisoning. More resistant than susceptible flies recovered from KD, giving final mortalities of 46% and 88% respectively. With both feeding regimes, some flies of both strains which had apparently recovered from KD had lost their ability to fly. Observations have also shown that 8% of resistant flies may have been repelled by methomyl granules. The implication of these results on the survival ofM. domesticain intensive animal units following exposure to methomyl bait is also disc

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00471.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Acquired immunity in guinea‐pigs and rabbits to immature stages of the two‐host tickRhipicephalus evertsi evertsiNeumann was demonstrated. Repeated infestations of both hosts with larvae resulted in a significant reduction in the weight of later engorged nymphs. A sharp decline in the numbers of nymphs which successfully fed on both hosts was also observed. This study provides evidence for a gradual decrease in the mean weight of engorged nymphs towards the end of the detachment period suggesting that, in two‐host ticks, the onset of nymphal feeding acts as an immune booster in a host already primed by the larval feed and that this results in a reduced feeding perfor

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00472.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Variation in susceptibility of the vectorAnopheles stephensiListon to the human malaria parasitePlasmodium falciparum(Welch) was demonstrated using twelve strains of mosquitoes and one strain of parasites culturedin vitro.The Beech strain ofAn. stephensiexhibited greatest natural refractoriness, but with high intrapopulation variability. By selection for the required characteristic, two refractory lines of the Punjab strain and one highly susceptible line of the Sind strain were obtained. The median number of oocysts in the two refractory lines was less than4%of that in the unselected line, whilst the highly susceptible line yielded about twice as many oocysts as the unselected line.Selection progressed more by keeping the descendants of individual females separate and selecting between them (individual selection) rather than pooling the progeny of all selected mosquitoes (mass selection). Using the former procedure many lines were lost due to inbreeding depression, but the outcome was more successful.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00473.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.Host‐seeking behaviour in newly emergedAedes aegypti(L.) females is not expressed immediately after adult eclosion but develops gradually over a period of approximately 3–4 days. This development is accompanied by an apparent maturation of the antennal chemosensory afferent neurons involved in the detection of the airborne host attractant lactic acid. Since these events coincide in time with juvenile hormone‐dependent previtellogenic ovarian growth and since the expression of other reproduction‐associated behaviour has previously been shown to be dependent on juvenile hormone, the effects of juvenile hormone removal and replacement on the development of host‐seeking behaviour and the response characteristics of the lactic acid‐sensitive receptors were investigated. No effect of juvenile hormone removal by allatectomy or juvenile hormone replacement or augmentation by topical application of the juvenile hormone mimic methoprene was found. It was concluded that this hormone is not involved in the appearance of host‐seeking behaviour or the apparent maturation of the lactic acid receptors that occurs during early

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00474.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.A collapsible animal‐type silhouette trap was designed to catch zoophilic female blackflies (Diptera: Simuliidae) which feed on the head or ventral surface of cattle. The trap was assessed for its ability to sample attacking blackflies by comparison with simultaneous manual catches from a bait cow, in an enzootic bovine onchocerciasis area in North Wales. In thirteen 1‐hour collections, the trap provided a representative sample of the blackfly population in terms of the relative abundance of species. There was a strong correlation between the catch sizes from both methods (r=+0.73), and the body site feeding preferences for all species were similar with both trap and cow. There was no significant difference between theOnchocercaspp. infection rates of flies caught by either met

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00475.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACT.A method for the storage of non‐diapausing eggs ofSimulium ornatumMeigen has been developed. High survival rates for 5–6 months depend on the age of eggs when placed at reduced temperature. A period of precooling or conditioning is required for 28 days before storage of the eggs at 1oC with lowering of oxygen partial pressure. Induced quiescence does not appear to affect development from egg to ad

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1989.tb00476.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY