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1.
Remarkable progress has been made towards a deeper understanding of mosquito biology since the completion of the Anopheles gambiae Giles genome project. Combined with the development of efficient transgenic technologies for genetic modification of major vector species and the availability of powerful molecular, genetic and bioinformatics tools, this is allowing the identification of genes involved in mosquito biological functions crucial to malaria transmission, ranging from host-seeking behaviour and innate immunity to insecticide resistance. Moreover, population genetic studies are beginning to elucidate the complex structure of vector populations. Finally, novel methods for malaria control are emerging that are based on the use of genetically modified mosquitoes either to interrupt the journey of the Plasmodium parasite within its insect host or to suppress those mosquito species that function as vectors for parasite transmission.  相似文献   

2.
A formulation was developed from the metabolite(s) of a novel Pseudomonas fluorescens Migula strain (VCRC B426) and tested against 4th-instar larvae and pupae of three species of vector mosquitoes, Anopheles stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti (L). The larvae and pupae of An. stephensi were the most susceptible to the formulation, followed by those of C. quinquefasciatus and Ae. aegypti, in that order, and the dosage requirement for pupal mortality was less than that required for larval mortality. The LC50 dosage requirements for larvae of these mosquito species were, respectively, 70.4, 511.5 and 757.3 microg protein ml(-1), whereas for pupae they were, respectively, 2.0, 9.4 and 19.2 microg protein ml(-1). The lethal fraction was purified from the culture broth and its molecular mass, as determined by high performance liquid chromatography, was 44kDa. This is the first report of a microbial formulation acting upon mosquito pupae, a non-feeding stage. Its mode of action and efficacy to control mosquitoes under field conditions need to be studied further.  相似文献   

3.
Agricultural insecticides can affect mosquito production in rice fields by controlling mosquitoes, disrupting biological control or contributing to selection of insecticide resistance. The duration of insecticidal activity of the pyrethroid lambda-cyhalothrin was quantified on predatory insects in rice fields and on three kinds of mosquito larva: a pyrethroid-susceptible strain of Culex tarsalis Coquillet, a pyrethroid-resistant strain of Cx pipiens L. (sensu lato) and non-resistant Cx pipiens s.l. Lambda-cyhalothrin killed most caged, susceptible mosquitoes for up to 21 days. It killed fewer resistant Cx pipiens s.l., but suppressed their survival for over a week. Lambda-cyhalothrin suppressed field populations of predatory insects through day 29. Agricultural use of lambda-cyhalothrin can provide incidental mosquito control. However, the pyrethroid persisted in sediment and gradually decreased in activity, which could contribute to selection of pyrethroid-resistant mosquitoes. Because caged mosquitoes showed good survival before predators recovered, disruption of biological control is possible. It is therefore advisable for growers and mosquito control agencies to communicate about pesticide use.  相似文献   

4.
Interspecific comparisons of bioassay and biochemical data suggest two major patterns of target site resistance to carbamates and organophosphates. Pattern I resistance, which is generally more effective for carbamates, has been shown in two sub-species of mosquitoes to be due to a particular Gly-Ser mutation in the oxyanion hole within the active site of one of their two acetylcholinesterase enzymes. Intriguingly, different substitutions at the equivalent site confer organophosphate hydrolytic ability on other esterases responsible for metabolic resistance in some other species. In the case of the aphid, Myzus persicae, Pattern I resistance is due to a Ser-Phe mutation in the vicinity of the acyl pocket of acetylcholinesterase. Pattern II resistance is at least as effective for organophosphates as it is for carbamates and may even be specific to organophosphates in some cases. Molecular studies on this pattern of resistance in three higher Diptera show that it is due to changes that constrict the acetylcholinesterase active site gorge and limit binding of the insecticide to the catalytic residues at the base of the gorge. One case of Pattern II resistance in the mosquito, Culex tritaeniorhynchus, involves the same site near the acyl pocket of acetylcholinesterase, albeit a different substitution, as that involved in Pattern I resistance in M. persicae.  相似文献   

5.
1984年在河南信阳地区发现两种蚊体寄生索线虫,在同一孳生地内生长繁殖,分别寄生于中华按蚊和致倦库蚊及三带喙库蚊等幼虫体内,自然寄生率为5.48%、4.32%、5.82%。通过人工感染试验,感染率均较高,可达61.5%~95.7%。试验证明两者对按蚊和库蚊具有显然不同的生理特性。这两种罗索线虫在稻田、田沟等多种水体内均有孳生,宿主范围广泛,有应用价值。  相似文献   

6.
用球形芽孢杆菌Ts—1冻干菌粉,对国内10种蚊幼虫生物测定的结果表明,不同蚊种之间敏感性有很大差异。库蚊属蚊虫(特别是淡色库蚊和致倦库蚊)对Ts—1敏感性很高,按蚊其次,而伊蚊属除东乡伊蚊外对Ts—1均不敏感。此外,同一蚊种不同地理株之间,对Ts一1的敏感性也有显著差异。  相似文献   

7.
In the years 1973 and 1975 mosquitoes and some other Diptera (Tabanidae, Simuliidae, Hippoboscidae) were tested for virus. 13,924 mosquitoes, 75 horseflies and 60 blackflies were processed in 1973. Five strains of Tahyna virus were isolated from mosquito species Aedes vexans. 3,378 mosquitoes and 12 sheep keds were tested for virus in 1975. Twelve strains of Calovo virus were isolated from Anopheles maculipennis and one strain of Tahyna virus was obtained from Aedes vexans mosquitoes.  相似文献   

8.
豫南罗索线虫感染库蚊、伊蚊和阿蚊的实验研究   总被引:2,自引:0,他引:2  
试验的伊蚊、库蚊和阿蚊,对豫南罗索线虫均表现敏感,当蚊幼与线幼虫数之比为1:5时,4种伊蚊的感染率均在95%以上;致倦库蚊和三带喙库蚊的感染率分别为98.6%和97.1%,骚扰阿蚊为66.4%。线虫在蚊体内发育良好,感染度亦较高,表明此线虫具有应用前景。  相似文献   

9.
The efficacy of tolypin against mosquito and blackfly larvae was studied under laboratory conditions. It was tested against Culex molestus, Aedes aegypti, Anopheles maculipennis, Simulium noelleri and Odagmia ornata. A concentration 0.1 mg/ml caused 100% mortality in all species tested and a concentration 0.001 mg/ml caused 100% mortality only in the two species of blackflies used within 24 hours.  相似文献   

10.
Insecticide resistance in disease vectors of public health importance   总被引:3,自引:0,他引:3  
Vector-borne diseases are a global problem--a trend that may only increase if global temperature rises and demographic trends continue--and their economic and social impact are enormous. Insecticides play a vital role in the fight against these diseases by controlling the vectors themselves in order to improve public health; however, resistance to commonly used insecticides is on the rise. This perspective outlines the major classes of disease vector control agents and the mechanisms of resistance that have evolved, arguing that effective resistance management strategies must carefully monitor resistance in field populations and use combinations of the limited modes of action available to best effect. Moreover, the development of novel insecticide classes for control of adult mosquitoes and other vectors becomes increasingly important.  相似文献   

11.
Dengue fever is an important mosquito-borne viral disease in Taiwan. Insecticide resistance has been shown to significantly reduce the efficacy of vector control interventions. The detection of insecticide resistance is an important component in mosquito abatement programs. In this study, we used the insecticide-impregnated papers bioassay method to reveal high levels of resistance to permethrin in the LYPR and field strains of Aedes aegypti. We used the standard glass cylinder method to observe the knockdown effect of paralysis within 2 to 4 minutes after exposing mosquitoes to pyrethroid vapors. Biochemical assays showed elevated detoxification enzyme activities. Glutathione S-transferases, monooxygenases and β-esterases were the enzymes predominantly responsible for the permethrin resistance of Ae. aegypti in Taiwan. Molecular screening for common insecticide target-site mutations revealed the presence of V1023G and D1794Y mutations. Pearson’s correlation analysis was used to investigate the correlations between the allelic frequency of kdr mutation associated increase with the LC50 values of permethrin and the KT50 values of pyrethroid vaporizers. These findings will be used to assess resistance levels, estimate resistance potential, and formulate monitoring and resistance management strategies.  相似文献   

12.
Botanical pyrethrins and synthetic pyrethroids are highly potent and environmentally safe insecticides that are used to control a wide range of disease vector and pest arthropods. Unfortunately, resistance to these insecticides has been demonstrated in numerous medically important mosquito species. In this study, adult Culex pipiens sensu lato were captured in agricultural and urban locations in Fresno County, California, and subsequently exposed to a commercial formulation of pyrethrin insecticide by ultra-low-volume spraying. Following insecticide exposure, two pyrethroid-like, fluorescent substrates (4-methyl-2-oxo-2H-chromen-6-yl, cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (cis-DCVC) and 4-methyl-2-oxo-2H-chromen-6-yl, cis-3-((Z)-2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate (cis-TFMCVC)) and 1-chloro-2,4-dinitrobenzene (CDNB) were used to measure esterase and glutathione S-transferase (GST) activities in surviving mosquitoes. Elevated esterase activity (2.5-fold) was found in surviving urban mosquitoes at 12-h post-pyrethrin exposure (in comparison to non-insecticide-exposed control mosquitoes) when cis-TFMCVC was used as a substrate. Additionally, when CDNB was used as a substrate, 2.8-fold higher GST activity was found. A simple assay was established using our pyrethroid-like, fluorescent substrates that was able to detect low-level esterase activities in homogenates made from individual mosquitoes. The cis-TFMCVC-based assay suggested that esterase activity plays a role in pyrethrin resistance in urban mosquitoes in California.  相似文献   

13.
The relation between the number of mosquito specimens of the most abundant species Aedes aegypti (L.) and Culex quinquefasciatus Say and the construction of houses which they inhabited was studied. The effect of the building materials and of the height at which the floor was situated above the ground were assessed in five and four localities, respectively. It was found that in the localities having the character of a town the mosquitoes were most abundant in houses constructed from corrugated plate and in those the floor of which was situated 2-3.5 m above the ground. In the locality of a village character, the mosquitoes were most numerous in brick houses with the floors at the ground level.  相似文献   

14.
According to the standard WHO method criteria, the mosquitoes Anopheles campestris and Culex vishnui were found to be susceptible to DDT in the territory of Phnom Penh. An. vagus and An. sinensis were approximately at the limit of susceptibility and the remaining five species (Aedes vexans, Cx. tritaeniorhynchus, Cx. fuscocephala, Cx. gelidus, Cx. bitaeniorhynchus) were found to be more or less resistant. Except for An. vagus, the males of all species were more susceptible than the females.  相似文献   

15.
In Africa, adult mosquito populations are primarily controlled with insecticide‐impregnated bed nets and residual insecticide sprays. This coupled with widespread applications of pesticides in agriculture has led to increasing insecticide resistance in mosquito populations. We have developed multiple alternative strategies for exploiting transgenic Metarhizium spp. directed at: (i) shortening the lifespan of adult mosquitoes; (ii) reducing transmission potential of Plasmodium spp.; (iii) reducing vector competence via pre‐lethal effects. The present challenge is to convert this promising strategy into a validated public health intervention by resolving outstanding issues related to the release of genetically modified organisms. © 2019 Society of Chemical Industry  相似文献   

16.
17.
Indoor resting mosquitoes were collected in 7 localities (250 houses) of Phnom Penh at various periods. The mosquitoes were collected for 8 min in every house by means of an aspirator and net. A total of 16 species of mosquitoes resting in houses were found, one of them for the first time in Kampuchea. Culex quinquefasciatus was the predominant species in 6 of the localities observed; its predominance in houses was more or less evident; Aedes aegypti prevailed in one locality. The percentage of A. aegypti predominance in houses corresponds with the risk of occurrence of dengue haemorrhagic fever. Anopheles vagus was found resting in higher abundance in houses of one locality. This fact is of little epidemiological significance because of the zoophilic character of An. vagus in Kampuchea. On the other hand even uncommon occurrence of Anopheles subpictus found in houses may signalize a possibility of an endemic occurrence of malaria in Phnom Penh.  相似文献   

18.
The susceptibility to 4% DDT was tested in adult Aedes aegypti and Culex quinquefasciatus mosquitoes collected in houses in Phnom Penh (Kampuchea). It was found that in spite of the fact that insecticide treatment had not been performed for many years, the populations of both species as a whole remained resistant. However, there were some differences in the susceptibility between males and females and between engorged and hungry females. Possible causes of these differences are discussed in the present paper.  相似文献   

19.
The repellency of fennel (Foeniculum vulgare Miller)-containing products (5% aerosol and 8% cream) against mosquitoes was compared with those of citronella oil, geranium oil and deet, as well as three commercial repellents, Baby Keeper cream containing IR3535, MeiMei cream containing citronella and geranium oils, and Repellan S aerosol containing 19% N,N-diethyl-m-toluamide (deet) under laboratory and field conditions. In a laboratory study with female Aedes aegypti (L), fennel oil exhibited good repellency in a release-in-cage test and repellency in skin and patch tests of the oil was comparable with those of citronella and geranium oils. In paddy field tests with five human volunteers, 5% and 8% fennel oil-containing aerosol and cream produced 84% and 70% repellency, respectively, at 90 min after exposure, whereas Baby Keeper cream and MeiMei cream gave 71% and 57% repellency at 90 min after exposure, respectively, and Repellan S aerosol gave 89% repellency at 210 min. The species and ratio of mosquitoes collected were the genera Culex (44.1%), Anopheles (42.2%), Aedes (7.8%) and Armigeres (5.9%). Fennel oil-containing products could be useful for protection from humans and domestic animals from vector-borne diseases and nuisance caused by mosquitoes.  相似文献   

20.
进行了苏云金杆菌H—14对我国8种重要病媒蚊种,即3株埃及伊蚊、6株白纹伊蚊、黄斑伊蚊、淡色库蚊、致倦库蚊、三带喙库蚊、中华按蚊及嗜人按蚊的幼虫的毒力测定,从24小时结果可看出,淡色库蚊最敏感,其次是白纹伊蚊的宜兴株和广东海南株,LC_(50)分别为52.5,57.0和64.5国际毒力单位/立升水,最不敏感的是嗜人按蚊和中华按蚊。对嗜人按蚊24小时LC_(50)约为48小时的5倍,别的蚊种则的为2倍。  相似文献   

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