First report of an Onchocercidae worm infecting Psychodopygus carrerai carrerai sandfly, a putative vector of Leishmania braziliensis in the Amazon

Sandflies are insects of public health interest due to their role as vectors of parasites of the genus Leishmania, as well as other pathogens. Psychodopygus carrerai carrerai is considered an important sylvatic vector of Leishmania (Viannia) braziliensis in Amazonia. In this study, sandflies were collected in a forested area in the Xapuri municipality, in the State of Acre (Northern Brazil). Two Ps. carrerai carrerai females were found parasitized with a larval form of a filarial worm, one in the labium of the proboscis, the other after the head was squashed, suggesting they were infective larvae. Sandflies were identified through morphological characters as well as amplification and sequencing of the cytochrome oxidase gene (COI). This was the first sequence obtained for Ps. carrerai carrerai for this marker. The obtained nematodes were also characterized through direct sequencing of a fragment of COI and 12S genes, both mitochondrial, and ITS1, a nuclear marker. Phylogenetic analyses revealed that the filarial nematodes belong to a species without sequences for these markers in the database, part of family Onchocercidade and closely related to genus Onchocerca (12S tree). Although sandfly infection with nematodes including members of the Onchocercidae has been reported in the Old World, this is the first report of sandfly infection by a member of the Onchocercidae family in the New World, to the best of our knowledge. Considering that the phylogenetic relationships and location in the insect, it can be expected that this is a parasite of mammals and the transmission cycle should be clarified.publishersversionpublishe

Insecticide susceptibility of Aedes albopictus and Ae. aegypti from Brazil and the Swiss-Italian border region

Aedes aegypti and Ae. albopictus are two highly invasive mosquito species, both vectors of several viruses, including dengue, chikungunya and Zika. While Ae. aegypti is the primary vector in the tropics and sub-tropics, Ae. albopictus is increasingly under the public health watch as it has been implicated in arbovirus-transmission in more temperate regions, including continental Europe. Vector control using insecticides is the pillar of most control programmes; hence development of insecticide resistance is of great concern. As part of a Brazilian-Swiss Joint Research Programme we set out to assess whether there are any signs of existing or incipient insecticide resistance primarily against the larvicide Bacillus thuringiensis svar. israelensis (Bti), but also against currently applied and potentially alternative insecticides in our areas, Recife (Brazil) and the Swiss-Italian border region.; Following World Health Organization guidelines, dose-response curves for a range of insecticides were established for both colonized and field caught Ae. aegypti and Ae. albopictus. The larvicides included Bti, two of its toxins, Cry11Aa and Cry4Ba, Lysinibacillus sphaericus, Vectomax CG®, a formulated combination of Bti and L. sphaericus, and diflubenzuron. In addition to the larvicides, the Swiss-Italian Ae. albopictus populations were also tested against five adulticides (bendiocarb, dichlorodiphenyltrichloroethane, malathion, permethrin and λ-cyhalothrin).; Showing a similar dose-response, all mosquito populations were fully susceptible to the larvicides tested and, in particular, to Bti which is currently used both in Brazil and Switzerland. In addition, there were no signs of incipient resistance against Bti as larvae were equally susceptible to the individual toxins, Cry11Aa and Cry4Ba. The field-caught Swiss-Italian populations were susceptible to the adulticides tested but DDT mortality rates showed signs of reduced susceptibility.; The insecticides currently used for mosquito control in Switzerland and Brazil are still effective against the target populations. The present study provides an important reference as relatively few insecticide susceptibility surveys have been carried out with Ae. albopictus

Insecticide resistance in Aedes aegypti populations from Ceará, Brazil

<p>Abstract</p> <p>Background</p> <p>Organophosphates and pyrethroids are used widely in Brazil to control <it>Aedes aegypti</it>, the main vector of dengue viruses, under the auspices of the National Programme for Dengue Control. Resistance to these insecticides is widespread throughout Brazil. In Ceará the vector is present in 98% of districts and resistance to temephos has been reported previously. Here we measure resistance to temephos and the pyrethroid cypermethrin in three populations from Ceará and use biochemical and molecular assays to characterise resistance mechanisms.</p> <p>Results</p> <p>Resistance to temephos varied widely across the three studied populations, with resistance ratios (RR₉₅) of 7.2, 30 and 192.7 in Juazeiro do Norte, Barbalha and Crato respectively. The high levels of resistance detected in Barbalha and Crato (RR₉₅≥ 30) imply a reduction of temephos efficacy, and indeed in simulated field tests reduced effectiveness was observed for the Barbalha population. Two populations (Crato and Barbalha) were also resistant to cypermethrin, whilst Juazeiro do Norte showed only an altered susceptibility. The <it>Ile1011Met kdr </it>mutation was detected in all three populations and <it>Val1016Ile </it>in Crato and Juazeiro do Norte. <it>1011Met </it>was significantly associated with resistance to cypermethrin in the Crato population. Biochemical tests showed that only the activity of esterases and GSTs, among the tested detoxification enzymes, was altered in these populations when compared with the Rockefeller strain.</p> <p>Conclusions</p> <p>Our results demonstrate that two <it>A. aegypti </it>populations from Ceará are under strong selection pressure by temephos, compromising the field effectiveness of this organophosphate. Our results also provide evidence that the process of reducing resistance to this larvicide in the field is difficult and slow and may require more than seven years for reversal. In addition, we show resistance to cypermethrin in two of the three populations studied, and for the first time the presence of the allele <it>1016Ile </it>in mosquito populations from northeastern Brazil. A significant association between <it>1011M</it>et and resistance was observed in one of the populations. Target-site mechanisms seem not to be implicated in temephos resistance, reinforcing the idea that for the studied populations, detoxification enzymes most likely play a major role in the resistance to this insecticide.</p

Sensitivity of RT-PCR method in samples shown to be positive for Zika virus by RT-qPCR in vector competence studies

Abstract Tissue samples from mosquitoes artificially infected with Zika virus and shown to be positive by RT-qPCR were reexamined by RT-PCR. Using these samples we compared the two methods employed in virus RNA detection for vector competence studies. Results demonstrated that, albeit useful, RT-PCR gave false negatives with low viral loads (< 106 RNA copies/ml)

High prevalence and lack of diversity of Wolbachia pipientis in Aedes albopictus populations from Northeast Brazil

The use of Wolbachia as a tool to control insect vectors has recently been suggested. In this context, studies on the prevalence and diversity of this bacterium in wild populations are relevant. Here, we evaluated the diversity of two Wolbachiagenes (ftsZ and wsp) and the prevalence of this endosymbiont in wild Aedes albopictus. Using semi-nested polymerase chain reaction, our results showed that 99.3% of the individuals were superinfected with Wolbachia. In regards to genetic diversity, the two genes showed no variation within or among mosquito populations. An analysis of other Wolbachia markers may help to clarify the relationship between insect and endosymbiont

Sensitivity of RT-PCR method in samples shown to be positive for Zika virus by RT-qPCR in vector competence studies

Submitted by Adagilson Silva ([email protected]) on 2017-06-19T19:35:02Z No. of bitstreams: 1 28534930 2017 pai-sen.oa.pdf: 584338 bytes, checksum: 8d6cf9195aca582f536010d665b450e4 (MD5)Approved for entry into archive by Adagilson Silva ([email protected]) on 2017-06-19T19:36:01Z (GMT) No. of bitstreams: 1 28534930 2017 pai-sen.oa.pdf: 584338 bytes, checksum: 8d6cf9195aca582f536010d665b450e4 (MD5)Made available in DSpace on 2017-06-19T19:36:01Z (GMT). No. of bitstreams: 1 28534930 2017 pai-sen.oa.pdf: 584338 bytes, checksum: 8d6cf9195aca582f536010d665b450e4 (MD5) Previous issue date: 2017-05-22Universidade Federal de Pernambuco. Centro Acadêmico do Agreste. Caruaru, PE, Brazil / Fundação Oswaldo Cruz. Instituto Aggeu Magalhães. Departamento de Entomologia. Recife, PE, Brasil.Universidade Federal de Pernambuco. Centro Acadêmico do Agreste. Caruaru, PE, Brazil.University of California-Davis. Department of Molecular and Cellular Biology. Davis, CA, USA.Universidade Federal de Pernambuco. Centro Acadêmico do Agreste. Caruaru, PE, Brazil.Tissue samples from mosquitoes artificially infected with Zika virus and shown to be positive by RT-qPCR were reexamined by RT-PCR. Using these samples we compared the two methods employed in virus RNA detection for vector competence studies. Results demonstrated that, albeit useful, RT-PCR gave false negatives with low viral loads (< 106 RNA copies/ml)

Sensitivity of RT-PCR method in samples shown to be positive for Zika virus by RT-qPCR in vector competence studies.

Tissue samples from mosquitoes artificially infected with Zika virus and shown to be positive by RT-qPCR were reexamined by RT-PCR. Using these samples we compared the two methods employed in virus RNA detection for vector competence studies. Results demonstrated that, albeit useful, RT-PCR gave false negatives with low viral loads (&lt; 106 RNA copies/ml)

Sensitivity of RT-PCR method in samples shown to be positive for Zika virus by RT-qPCR in vector competence studies.

Tissue samples from mosquitoes artificially infected with Zika virus and shown to be positive by RT-qPCR were reexamined by RT-PCR. Using these samples we compared the two methods employed in virus RNA detection for vector competence studies. Results demonstrated that, albeit useful, RT-PCR gave false negatives with low viral loads (&lt; 106 RNA copies/ml)

Detection of alleles associated with resistance to chemical insecticide in the malaria vector Anopheles arabiensis in Santiago, Cabo Verde

Abstract Background Mosquitoes of the Anopheles gambiae complex are the main malaria vectors worldwide. Due to the lack of a vaccine to prevent malaria, the principal way to reduce the impact of this disease relies on the use of chemical insecticides to control its vectors. However, the intensive use of such compounds has led to the emergence of insecticide resistance in several Anopheles populations in Africa. This study aimed to investigate the presence of resistance alleles in an Anopheles arabiensis population from the City of Praia, capital of the Archipelago Cabo Verde, one of the countries on the World Health Organization list of countries that are on a path to eliminate local transmission of malaria. Methods Larvae from the Anopheles genus were collected using a one-pint dipper in three areas of City of Praia. Larvae were fed and maintained until the emergence of adult mosquitoes, and these were morphologically identified. In addition, molecular identification was performed using IGS markers and all An. arabiensis samples were subjected to PCR to screen for mutations associated to resistance in the Ace-1, Na v and GSTE2 genes. Results From a total of 440 mosquitoes collected, 52.3% were morphologically identified as An. gambiae sensu lato (s.l.) and 46.7% as Anopheles pretoriensis. The molecular identification showed that 100% of the An. gambiae s.l. were An. arabiensis. The mutations G119S in the Ace-1 gene and L119F in the GSTE2 gene were screened but not found in any sample. However, sequencing analysis for GSTE2 revealed the presence of 37 haplotypes, 16 polymorphic sites and a high genetic diversity (π = 2.67). The L1014S mutation in the Na v (voltage-gated sodium channel gene) was detected at a frequency of 7.3%. Conclusion This is the first study to investigate the circulation of insecticide resistance alleles in An. arabiensis from Cabo Verde. The circulation of the L1014S allele in the population of An. arabiensis in the city of Praia suggests that pyrethroid resistance may arise, be quickly selected, and may affect the process of malaria elimination in Cabo Verde. Molecular monitoring of resistance should continue in order to guide the development of strategies to be used in vector control in the study region

Diapause and quiescence: dormancy mechanisms that contribute to the geographical expansion of mosquitoes and their evolutionary success

Abstract Mosquitoes are insects belonging to the order Diptera and family Culicidae. They are distributed worldwide and include approximately 3500 species, of which about 300 have medical and veterinary importance. The evolutionary success of mosquitoes, in both tropical and temperate regions, is due to the various survival strategies these insects have developed throughout their life histories. Of the many adaptive mechanisms, diapause and quiescence, two different types of dormancy, likely contribute to the establishment, maintenance and spread of natural mosquito populations. This review seeks to objectively and coherently describe the terms diapause and quiescence, which can be confused in the literature because the phenotypic effects of these mechanisms are often similar