摘要:

AbstractFemaleAedes albopictusmosquitoes, aged 1 week, were infected withDEN‐2dengue virus. The kinetics of infection in mosquito brain and mesenteron were monitored using DNA probes with polymerase chain reaction (PCR) amplification of target DNA sequences coding forDEN‐2virus envelope protein, compared with the standard immunofluorescence assay technique (IFA).Rates of virus detection in the mesenteron of orally infected mosquitoes rose to 38% by day 4 post‐inoculation, then declined until day 8, followed by irregular peaks around days 11–14 and subsequently. In mosquito head squashes, virus was detected from day 4 onwards, reaching 38% positive by day 18. Salivary glands of all the same females were found to be positive for virus by day 8 onwards. Parenterally infectedAe.albopictusfemales were all positive forDEN‐2in the brain and salivary glands 8 days post‐inoculation. In every case, results obtained with the PCR matched those from the IFA. Our DNA probe with PCR procedure can therefore be utilized as a sensitive and reliable method for studies ofD

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00626.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractApplications of neem,Azadirachta indica(Meliaceae), to rice‐fields were evaluated with the dual objective of controlling the culicine mosquito vectors of Japanese encephalitis virus (JEV) and enhancing the grain yield. Since crude neem products deteriorate under improper storage conditions, a laboratory bioassay was developed to screen neem cake powder against mosquito larvae,Cule.x quinquefasciatus.Only samples of neem giving over 90% bioassay mortality were used in field trials.When good quality neem cake powder was applied at the dose of 500 kg/ha, either alone or coated over urea, there was a striking reduction in the abundance of late instar culicine larvae and pupae. Only fourteen pupae were obtained over a period of 13 weeks in neem cake powder treated plots, and four in those treated with neem coated urea, compared with 101 in control plots. Both treatments were significantly less than the control, but on par with one another.In another field trial, neem cake coated urea was tested at 500 and 250kg neem/ha in combination with water management practices. No reduction in efficacy was noted at the lower dose. Larval abundance in plots under water management alone did not differ significantly from the controls, but was significantly reduced when water management was combined with neem products. Two stable formulations, ‘Neemrich‐I’ (lipid rich) and ‘Neemrich‐H’ (azadirachtin rich), also gave good suppression of immature culicines.All the treatments with neem also gave higher grain yield than the control. Therefore, it is feasible to develop an acceptable package for community use, particularly as the Agricultural Department already recommends the use of both water management and neem cake coated ur

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00627.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA study was conducted in three villages in western Venezuela between February 1988 and October 1989 to determine the biting and resting activity of anophelines in relation to human habits, rainfall and fenitrothion spraying of houses. Mosquitoes were collected landing on humans inside and outside experimental huts throughout the night. Only three mosquitoes were found resting in the huts in the morning, but 2470 were collected resting on vegetation in the early morning. The collections yielded eleven species of anopheline, the most abundant beingAnopheles nuneztovari, comprising over 75% of the total anophelines collected, followed byAn.triannulatus, An.albitarsis s.l.andAn.oswaldoi.The four most abundant species showed different diel patterns of biting. ForAn.nuneztovarithe peak of activity was close to midnight indoors and outdoors, forAn.triannulatusbetween 19.00 and 20.00 hours outdoors, forAn.albitarsismainly before midnight indoors and outdoors and forAn.oswaldoioutdoors at 19.00 hours, with an additional smaller peak indoors at midnight. Most of the human population use bednets, go to bed before 22.00 hours and are therefore most exposed to mosquitoes that bite outdoors early in the night.Fenitrothion house‐spraying failed to prevent large mosquito populations developing in the wet season, presumably because of their exophilic resting habits. The possible advantages of impregnation of existing bednets with pyrethroids, and provision of nets for people who do not have them, are discusse

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00628.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAmong theAnopheles (Cellia) maculatusgroup of Oriental mosquitoes, positive assortative mating occurs within sympatric and synchronous populations ofAn.willmoriandAn.pseudowillmoriin the presence of populations ofAn.maculatusandAn.sawadwongporni, judged from the occurrence of inversion homozygotes and the absence of any heterozygotes in their distinctive, polytene chromosomes. Genotypic frequencies for enzyme electromorphs give additional evidence for the species status ofAn.pseudowillmoriand a practical means of identification in field studies of malaria vectors.Autosomal rearrangements are referred to those ofAn.stephensiwhich is unique for 4y.An. willmoridiffers by a single inversion, 4x;An.pseudowillmoriby three Arm 2 inversions; andAn.disparby one Arm 2 inversion and 4x.Fixed autosomal rearrangements in the Maculatus group are summarized and their phylogenetic distribution suggests some unknown, intrinsic mechanism by which genome structure is disrupted in association with speciation events. This could be relevant to the potential genetic manipulation of malaria vectors.

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00629.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIn Turkey, the mosquitoAnopheles sacharovihas been under field selection pressure sequentially with DDT, dieldrin, malathion and pirimiphos‐methyl over a period of 30 years for the purpose of malaria control. In 1984, the field population ofAn.sacharoviin the malarious Çukurova plain of Adana Province contained an altered acetylcholinesterase‐based resistance gene giving broad spectrum resistance against organophosphorus and carbamate insecticides. The cross‐resistance spectrum from this mechanism conferred resistance to malathion but not to the organophosphorus insecticide pirimiphos‐methyl. Over the 6 years that pirimiphos‐methyl has been applied for malaria vector control in this area, the frequency of the altered acetylcholinesterase resistance gene has declined, although in 1989 and 1990 it was still present at measurable frequencies inAn.sacharovifrom Çukurova.In addition to the acetylcholinesterase resistance mechanism there is evidence of an increased level of glutathione S‐transferase in some of theAn.sacharovipopulations tested. This is known to be correlated with DDT resistance in other anophelines. In TurkishAn.sacharovi, DDT resistance and elevated glutathione S‐transferase occur in the same populations at similar frequencies. The continued prevalence of resistance to DDT and dieldrin, long after the 1971 cessation of DDT spraying for malaria control in Turkey, suggests that the DDT resistance gene has insufficient reduced fitness associated with it to have been lost from the field population during the past two decades. The implications of the slow decline in resistance gene frequencies in this field population are discussed in relation to mathematical models for mana

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00630.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractRecordings were made of the activation of hungryGlossina morsitans morsitansWestwood,G.pallidipesAusten, andG.austeniNewstead in response to odours from ox breath and ox urine, and a moving visual stimulus, in a wind tunnel. The spontaneous activity ofG.m.morsitanswas very low (less than 4% of males and 2% of females active per min during control periods). That ofG.austeniandG.pallidipeswas in the region of 20% except forG.pallidipesfemales when in excess of 40% were active during control periods. Addition of ox urine odours to the airstream had no effect on activity in any of the species investigated but addition of ox breath odours to the airstream significantly increased activity ofG.pallidipesand ofG.m.morsitans, although for the latter only approximately 12% of flies were active. ForG.austenithe addition of ox breath odours resulted in a significant increase in activity of females but not of males. The moving visual stimulus resulted in a significant increase in the activity of both sexes ofG.austeniandG.m.morsitansbut no change in the activity ofG.pallidipes.The low level of spontaneous activity and the low response to ox breath odours in a strain ofG.m.morsitansmaintained in the laboratory since 1969 was compared with a new colony of this species which originated from puparia collected in Zimbabwe in 1991. No differences in either spontaneous activity or the response to ox breath odour was recorded, but females from the new colony were significantly more responsive to a moving visual stimulus. In a further series of experiments the activity ofG.m. morsitansandG.pallidipeswas recorded at varying wind speeds. For both species, activity decreased as the wind speed increased. The results are discussed in terms of the likely host‐location strategies used by these specie

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00631.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractWild‐caught, tethered females of the reindeer warble fly,Hypoderma tarandi(L.) (=Oedemagena tarandi(L.)), (Diptera, Oestridae) were stimulated to oviposit on hairs of a reindeer hide. Newly laid eggs incubated at constant temperatures and relative humidities hatched within 3 days to 2 weeks, depending on the experimental conditions. Over a range of 7–40oC, hatching only occurred between 20 and 37oC. Eggs held at 100% relative humidity had lower hatchability and longer time to hatch relative to eggs held at 77% relative humidity. The average number of degree‐days for hatching was 50.35. Between 20 and 33oC there was a temperature‐dependent linear trend in developmental rate, and the proportion of eggs hatching was highest, and least variable, at the mid‐temperature ranges. The temperature range found in the natural host micro‐habitat whereH. tarandicommonly affix their eggs (close to the skin at the base of a host hair) was consistent with the experimental temperature treatments that produced the highest hatching rate. Newly emerged larvae displayed positive thermotaxis, while showing no phototaxic or geotaxic behaviour. Results indicate that constraints of the host environment, coupled with temperature‐dependent hatching success, may impose a selective pressure on oviposit

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00632.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00633.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractUnfed nymphalIxodes ricinus, Haemaphysalis concinna, and adultDermacentor reticulatuswere collected in two locations of Saxony in July and September 1991 by flagging. In July, the abundance of nymphalI. ricinuswas about 2–3 times higher than that of nymphalH.concinna, a time of the year when nymphs of both species are reported to have a seasonal peak of activity. NoD.reticulatuswere flagged concurrently. In September, host‐seeking activity of nymphalI.ricinuswas again quite high as was that of adultD.reticulatusbut only low numbers of nymphalH.concinnawere collected. The flagged ticks were individually examined forBorreliaby an indirect immunofluorescence assay{I.ricinus:n = 414;H.concinna: n = 96; D.reticulatus: n= 116). The prevalence ofBorrelia(probablyB.burgdorferi)inI.ricinusvaried from 12.1% to 21.0%. No borreliae were found inH. concinna.Of the examinedD. reticulatusfrom one site (n= 97) 11.3% contained eitherB. burgdorferior a relatedBorrelia.This may be the first finding ofBorreliain an EurasianDermacentorspec

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00634.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractWater in leaf axils of the screwpinePandanuswas sampled for mosquito immature stages at seventy villages in Upolu, fifty‐five in Savai'i and three in Manono, the main islands of Samoa. Ten plants in every patch ofPandanusplantation were sampled at each village. Among 23,049 mosquito larvae collected from Upolu, 77% were the filariasis vectorAedes (Finlaya) samoanus, 17.7% wereAe.(Fin.)oceanicusand 5.3% wereAe.(Fin.)tutuilae.Out of 6981 larvae taken in Savai'i, 23.2% wereAe.samoanus, 67.6%Ae.oceanicusand 9.2%Ae.tutuilae.When larval counts per plant were analysed for each district,Ae.samoanuswas found to predominate inPandanusin Upolu andAe.oceanicusin Savai'i. However, the adult density ofAe.samoanuswas higher in Savai'i and this was attributed to the large areas of forests withFreycinetiaforAe.samoanusbreeding. InPandanusin Savai'i the number ofAe.samoanuswas negligible. In Upolu, with more urbanization and larger plantations, there was greater breeding ofAe.samoanusinPandanus.Two control trials were conducted againstAe.samoanuslarvae inPandanus, one using a sand culture of the parasitic nematodeRomanomermis culicivoraxand the other with temephos, an organophosphate insecticide. WhileR.culicivoraxdid not adapt to the leaf axil habitat, all plants were without larvae for 5 weeks after treatment with temepho

ISSN:0269-283X    

DOI:10.1111/j.1365-2915.1992.tb00635.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY