191 research outputs found
field populations in Italy
No full textBackground: Incompatible insect technique (IIT) is a population suppression approach based on the release of males with manipulated Wolbachia infection inducing egg inviability in wild females. We here present results of multiple field releases of incompatible ARwP males carried out in 2019 in a 2.7-ha green area within urban Rome (Italy) to assess the effect on Aedes albopictus egg viability. Data are compared with results obtained in 2018, when the approach was tested for the first time in Europe. Results: An average of 4674 ARwP males were released weekly for 7 weeks, resulting in a mean ARwP:wild male ratio of 1.1:1 (versus 0.7:1 in 2018). Egg-viability dynamics in ovitraps significantly varied between treated and control sites, with an estimated overall reduction of 35% (versus 15% in 2018). The estimated proportion of females classified as mated with ARwP males was 41.8% and the viability rate of eggs laid by these females (9.5%) was on average significantly lower than that of females only mated with wild males (87.8%); however, high variability in fertility was observed. Values of ARwP male competitiveness were 0.36 and 0.73 based on the overall viability rate of eggs in ovitraps and on female fertility, respectively; thus, well above the conventional 0.2 threshold for an effective suppressive impact in the field. Conclusions: Results further support the potential of IIT as a tool to contribute to Ae. albopictus control in the urban context, stressing the need for larger field trials to evaluate the cost-efficacy of the approach in temperate regions. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry
DNA barcoding mosquitoes: advice for potential prospectors
No full textMosquitoes' importance as vectors of pathogens that drive disease underscores the importance of precise and comparable methods of taxa identification among their species. While several molecular targets have been used to study mosquitoes since the initiation of PCR in the 1980s, its application to mosquito identification took off in the early 1990s. This review follows the research's recent journey into the use of mitochondrial DNA (mtDNA) cytochrome oxidase 1 (COI or COX1) as a DNA barcode target for mosquito species identification - a target whose utility for discriminating mosquitoes is now escalating. The pros and cons of using a mitochondrial genome target are discussed with a broad sweep of the mosquito literature suggesting that nuclear introgressions of mtDNA sequences appear to be uncommon and that the COI works well for distantly related taxa and shows encouraging utility in discriminating more closely related species such as cryptic/sibling species groups. However, the utility of COI in discriminating some closely related groups can be problematic and investigators are advised to proceed with caution as problems with incomplete lineage sorting and introgression events can result in indistinguishable COI sequences appearing in reproductively independent populations. In these - if not all - cases, it is advisable to run a nuclear marker alongside the mtDNA and thus the utility of the ribosomal DNA - and in particular the internal transcribed spacer 2 - is also briefly discussed as a useful counterpoint to the COI
DNA barcoding mosquitoes: advice for potential prospectors
No full textSUMMARYMosquitoes’ importance as vectors of pathogens that drive disease underscores the importance of precise and comparable methods of taxa identification among their species. While several molecular targets have been used to study mosquitoes since the initiation of PCR in the 1980s, its application to mosquito identification took off in the early 1990s. This review follows the research's recent journey into the use of mitochondrial DNA (mtDNA) cytochrome oxidase 1 (COI or COX1) as a DNA barcode target for mosquito species identification – a target whose utility for discriminating mosquitoes is now escalating. The pros and cons of using a mitochondrial genome target are discussed with a broad sweep of the mosquito literature suggesting that nuclear introgressions of mtDNA sequences appear to be uncommon and that the COI works well for distantly related taxa and shows encouraging utility in discriminating more closely related species such as cryptic/sibling species groups. However, the utility of COI in discriminating some closely related groups can be problematic and investigators are advised to proceed with caution as problems with incomplete lineage sorting and introgression events can result in indistinguishable COI sequences appearing in reproductively independent populations. In these – if not all – cases, it is advisable to run a nuclear marker alongside the mtDNA and thus the utility of the ribosomal DNA – and in particular the internal transcribed spacer 2 – is also briefly discussed as a useful counterpoint to the COI.</jats:p
Roots of/routes to : practice and performance of identity in the Isle of Man
No full textThis thesis takes as its ethnographic focus the Isle of Man, a British Crown Dependency. In the 1960s, the Manx government faced an economic crisis. The response was to open the Island to international banking, becoming an 'offshore' financial centre. The new industry sector has encouraged substantial immigration, to the extent that the Island-born are now in the minority. The Island now has economic success on one hand, but a new 'identity' crisis of cultural confidence on the other, raising the question 'what is it (now), to be Manx?' The Manx have always accepted incomers and are not, or ever have been, a clearly defined ethnic group. Rather 'Manxness' is an idea, a set of values, a way of relating to place and to each other. Defined thus, 'Manx identity' could be, and has been, shared with incomers. The current situation is, however, perceived as substantially different in its speed and volume, resulting in concerns that Manx culture and identity is disappearing under the weight of an alien cultural import. Reaction is demonstrated in renewed interest in the Manx Gaelic language and other 'traditiona1' pursuits, with individuals selecting routes to identification with place that satisfy personal motivations. Included in this performance of culture are members of the 'incomer' group blamed for its demise, while many Island-born show little concern. Through subtle analysis of this complex context, I add to anthropological understanding of 'identity' and 'way of life' by juxtaposing personal and collective responses to this process of change, and investigating the importance of scales of difference. And, in a disciplinary context that has shifted attention from bounded to boundless 'homes', I ask how far anthropological constructions go in explicating how and why our informants still struggle to strike a meaningful balance between their roots of and routes to identit
Discrimination of All Members of the Anophelespunctulatus Complex by Polymerase Chain-Reaction Restriction-Fragment-Length-Polymorphism Analysis
No full textA method has been developed to identify the members of the Anopheles punctulatus complex using polymerase chain reaction-restriction fragment length polymorphism (PCR RFLP). Members of the An. punctulatus complex are the most important vectors of malaria in the southwest Pacific and consist of 10 cryptic species, An. farauti no. 1-7, An. punctulatus, An. sp. near punctulatus, and An. koliensis. For each species, PCR amplification of the ribosomal DNA internal transcribed spacer produced a 750-basepair product. Digestion with Msp I and electrophoresis on a 3.0% agarose gel results in banding patterns unique to each species. Isolates of the same species from different locations gave an identical pattern. The technique is sensitive enough so that a PCR-RFLP can be generated from as little as a single mosquito leg, allowing the rest of the mosquito to be used for other important epidemiologic analyses such as determining host feeding source, and for parasite detection
Resolving genetic diversity in Australasian Culex mosquitoes: Incongruence between the mitochondrial cytochrome c oxidase I and nuclear acetylcholine esterase 2
No full textInsects that vector pathogens are under constant surveillance in Australasia although the repertoire of genetic markers to distinguish what are often cryptic mosquito species remains limited. We present a comparative assessment of the second exon–intron region of the acetylcholine esterase 2 gene (ace-2) and the mitochondrial DNA cytochrome c oxidase I (COI) using two closely related Australasia mosquitoes Culex annulirostris and Culex palpalis. The COI revealed eight divergent lineages of which four were confirmed with the ace-2. We dissect out the nuclear chromosomal haplotypes of the ace-2 as well as the exon–intron regions by assessing the protein’s tertiary structure to reveal a hypervariable 5’-exon that forms part of an external protein loop and displays a higher polymorphic rate than the intron. We retrace the evolutionary history of these mosquitoes by phylogenetic inference and by testing different evolutionary hypotheses. We conclude that DNA barcoding using COI may overestimate the diversity of Culex mosquitoes in Australasia and should be applied cautiously with support from the nuclear DNA such as the ace-2. Together the COI and ace-2 provide robust evidence for distinct cryptic Culex lineages—one of which correlates exactly with the southern limit of Japanese encephalitis virus activity in Australasia
The dengue vector Aedes aegypti: What comes next
No full textAbstract Aedes aegypti is the urban vector of dengue viruses worldwide. While climate influences the geographical distribution of this mosquito species, other factors also determine the suitability of the physical environment. Importantly, the close association of A. aegypti with humans and the domestic environment allows this species to persist in regions that may otherwise be unsuitable based on climatic factors alone. We highlight the need to incorporate the impact of the urban environment in attempts to model the potential distribution of A. aegypti and we briefly discuss the potential for future technology to aid management and control of this widespread vector species
The dengue vector Aedes aegypti: What comes next
No full textAedes aegypti Is the urban vector of dengue viruses worldwide While climate influences the geographical distribution of this mosquito species, other factors also determine the suitability of the physical environment. Importantly, the close association of A aegypti with humans and the domestic environment allows this species to persist in regions that may otherwise be unsuitable based on climatic factors alone We highlight the need to incorporate the impact of the urban environment in attempts to model the potential distribution of A aegypti and we briefly discuss the potential for future technology to aid management and control of this widespread vector species (C) 2010 Elsevier Masson SAS All rights reserve
Comparative susceptibility of mosquito populations in North Queensland, Australia to oral infection with dengue virus.
No full textDengue is the most prevalent arthropod-borne virus, with at least 40% of the world's population at risk of infection each year. In Australia, dengue is not endemic, but viremic travelers trigger outbreaks involving hundreds of cases. We compared the susceptibility of Aedes aegypti mosquitoes from two geographically isolated populations to two strains of dengue virus serotype 2. We found, interestingly, that mosquitoes from a city with no history of dengue were more susceptible to virus than mosquitoes from an outbreak-prone region, particularly with respect to one dengue strain. These findings suggest recent evolution of population-based differences in vector competence or different historical origins. Future genomic comparisons of these populations could reveal the genetic basis of vector competence and the relative role of selection and stochastic processes in shaping their differences. Lastly, we show the novel finding of a correlation between midgut dengue titer and titer in tissues colonized after dissemination
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