1
|
Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance. Toxins (Basel) 2021; 13:toxins13080523. [PMID: 34437394 PMCID: PMC8402332 DOI: 10.3390/toxins13080523] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 12/25/2022] Open
Abstract
Larvicides based on the bacteria Bacillus thuringiensis svar. israelensis (Bti) and Lysinibacillus sphaericus are effective and environmentally safe compounds for the control of dipteran insects of medical importance. They produce crystals that display specific and potent insecticidal activity against larvae. Bti crystals are composed of multiple protoxins: three from the three-domain Cry type family, which bind to different cell receptors in the midgut, and one cytolytic (Cyt1Aa) protoxin that can insert itself into the cell membrane and act as surrogate receptor of the Cry toxins. Together, those toxins display a complex mode of action that shows a low risk of resistance selection. L. sphaericus crystals contain one major binary toxin that display an outstanding persistence in field conditions, which is superior to Bti. However, the action of the Bin toxin based on its interaction with a single receptor is vulnerable for resistance selection in insects. In this review we present the most recent data on the mode of action and synergism of these toxins, resistance issues, and examples of their use worldwide. Data reported in recent years improved our understanding of the mechanism of action of these toxins, showed that their combined use can enhance their activity and counteract resistance, and reinforced their relevance for mosquito control programs in the future years.
Collapse
|
2
|
Paiva MHS, Guedes DRD, Krokovsky L, Machado LC, Rezende TMT, Sobral MCDM, Ayres CFJ, Wallau GL. Sequencing of ZIKV genomes directly from Ae. aegypti and Cx. quinquefasciatus mosquitoes collected during the 2015-16 epidemics in Recife. INFECTION GENETICS AND EVOLUTION 2020; 80:104180. [PMID: 31918041 DOI: 10.1016/j.meegid.2020.104180] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 01/02/2020] [Accepted: 01/05/2020] [Indexed: 01/03/2023]
Abstract
Zika virus (ZIKV) is a negative sense RNA virus from the Flaviviridae family, which was relatively unknown until the first human epidemic in Micronesia, in 2007. Since then, it spread to French Polynesia and the Americas. Recife, the capital of Pernambuco state and epicenter of the Zika epidemic in Brazil, experienced a large number of microcephaly cases and other congenital abnormalities associated to the ZIKV infection from, 2015 to 16. Evidences suggest that both Aedes aegypti and Culex quinquefasciatus mosquitoes from Recife are capable of replicating and transmitting the virus. Here, we conducted high throughput sequencing of ZIKV genomes directly from Ae. aegypti and Cx. quinquefasciatus mosquitoes collected during the ZIKV epidemics in Recife, in order to investigate the variability and evolution of the virus. We obtained 11 draft ZIKV genomes derived from 5 pools from each Ae. aegypti and Cx. quinquefasciatus species. Genome coverage breadth ranged from 16 to 100% and average depth from 45 to 46,584×. Two of these genomes were obtained from pools of Cx. quinquefasciatus females with no sign of blood in the abdomen. Amino acid substitutions found here were not species-specific. In addition, molecular clock dating estimated that ZIKV draft genomes obtained here were co-circulating in other regions of the country during the epidemics. Overall results highlight that viral mutations and even minor variants can be detected in genomes directly sequenced from mosquito samples and insights about natural viral genomic variability and viral evolution can be useful when designing tools for mosquito control programs.
Collapse
Affiliation(s)
- Marcelo Henrique Santos Paiva
- Universidade Federal de Pernambuco, Caruaru, Brazil; Entomology Department of the Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| | | | - Larissa Krokovsky
- Entomology Department of the Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| | - Lais Ceschini Machado
- Entomology Department of the Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil
| | | | | | | | - Gabriel Luz Wallau
- Entomology Department of the Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil.
| |
Collapse
|
3
|
Paiva MHS, Barbosa RMR, Santos SA, Silva NM, Paula MB, Ayres CFJ, Leal WS. An unsettling explanation for the failure of skatole-baited ovitraps to capture Culex mosquitoes. INSECT SCIENCE 2019; 26:873-880. [PMID: 29442435 PMCID: PMC6488435 DOI: 10.1111/1744-7917.12578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/28/2017] [Accepted: 01/31/2018] [Indexed: 05/13/2023]
Abstract
Culex mosquitoes are primarily found in temperate and tropical regions worldwide where they play a crucial role as main vectors of filarial worms and arboviruses. In Recife, a northeast city in Brazil, high densities of Culex quinquefasciatus are often found in association with human populated areas. In marked contrast to another part of the city, field tests conducted in the neighborhood of Sítio dos Pintos showed that trapping of mosquitoes in skatole-baited ovitraps did not differ significantly from captures in control (water) traps. Thus, classical and molecular taxonomic approaches were used to analyze the Culex species circulating in Sítio dos Pintos. Results obtained from both approaches agreed on the cocirculation of Culex quinquefasciatus and Culex nigripalpus in three different areas of this neighborhood. What was initially considered as an unexpected failure of this lure turned out to be a more unsettling problem, that is, the first report in Recife of Culex nigripalpus, a vector of Venezuelan equine encephalitis virus and West Nile virus. Unplanned urbanization processes close to remnants of the Atlantic forest, such as observed in Sítio dos Pintos, may have contributed to the introduction of Cx. nigripalpus in urban areas.
Collapse
Affiliation(s)
- Marcelo H. S. Paiva
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fundação Oswaldo Cruz, Av. Professor Moraes Rego, s/n - Campus da Universidade Federal de Pernambuco, Recife, PE, 50.740-465 Brazil
- Universidade Federal de Pernambuco, Centro Acadêmico do Agreste, Rodovia BR-104, km 59/Nova Caruaru, Caruaru, PE, 55.002-970 Brazil
| | - Rosângela M. R. Barbosa
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fundação Oswaldo Cruz, Av. Professor Moraes Rego, s/n - Campus da Universidade Federal de Pernambuco, Recife, PE, 50.740-465 Brazil
| | - Suzane A. Santos
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fundação Oswaldo Cruz, Av. Professor Moraes Rego, s/n - Campus da Universidade Federal de Pernambuco, Recife, PE, 50.740-465 Brazil
| | - Norma M. Silva
- Departamento de Biologia Celular, Universidade Federal de Santa Catarina, Embriologia e Genética, Centro de Ciências Biológicas, Florianópolis, SC, 88.040-900 Brazil
| | - Marcia B. Paula
- Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, Av. Dr. Arnaldo, 715, São Paulo, SP, 01246-904 Brazil
| | - Constância F. J. Ayres
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fundação Oswaldo Cruz, Av. Professor Moraes Rego, s/n - Campus da Universidade Federal de Pernambuco, Recife, PE, 50.740-465 Brazil
| | - Walter S. Leal
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616 USA
| |
Collapse
|
4
|
Development of an urban molecular xenomonitoring system for lymphatic filariasis in the Recife Metropolitan Region, Brazil. PLoS Negl Trop Dis 2018; 12:e0006816. [PMID: 30325933 PMCID: PMC6203399 DOI: 10.1371/journal.pntd.0006816] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 10/26/2018] [Accepted: 09/05/2018] [Indexed: 12/02/2022] Open
Abstract
Introduction Molecular xenomonitoring (MX)—pathogen detection in the mosquito rather than human—is a promising tool for lymphatic filariasis (LF) surveillance. In the Recife Metropolitan Region (RMR), the last LF focus in Brazil, Culex quinquefasciatus mosquitoes have been implicated in transmitting Wuchereria bancrofti parasites. This paper presents findings on the ideal mosquito collection method, mosquito dispersion, W. bancrofti infection in mosquitoes and W. bancrofti antigen in humans to aid MX development. Methods Experiments occurred within two densely populated urban areas of Olinda, RMR, in July and August 2015. U.S. Centers for Disease Control and Prevention (CDC) light traps were compared to battery-powered aspirators as collection methods, and mosquito dispersion was measured by mosquito mark release recapture (MMRR). Female Cx. quinquefasciatus were tested by PCR for W. bancrofti infection, and study area residents were screened by rapid tests for W. bancrofti antigen. Results Aspirators caught 2.6 times more total Cx. quinquefasciatus, including 38 times more blood-fed and 5 times more gravid stages, than CDC light traps. They also collected 123 times more Aedes aegypti. Of the 9,644 marked mosquitoes released, only ten (0.01%) were recaptured, nine of which were < 50m (34.8m median, 85.4m maximum) from the release point. Of 9,169 unmarked mosquitoes captured in the MMR, 38.3% were unfed, 48.8% blood-fed, 5.5% semi-gravid, and 7.3% gravid. PCR on 182 pools (1,556 mosquitoes) found no evidence of W. bancrofti infection in Cx. quinquefasciatus. Rapid tests on 110 of 111 eligible residents were all negative for W. bancrofti antigen. Conclusions Aspirators were more effective than CDC light traps at capturing Ae. aegypti and all but unfed stages of Cx. quinquefasciatus. Female Cx. quinquefasciatus traveled short (< 86m) distances in this urban area. Lack of evidence for W. bancrofti infection in mosquitoes and antigen in humans in these fine-scale studies does not indicate that LF transmission has ceased in the RMR. A MX surveillance system should consider vector-specific collection methods, mosquito dispersion, and spatial scale but also local context, environmental factors such as sanitation, and host factors such as infection prevalence and treatment history. Lymphatic filariasis (LF) is a parasitic disease transmitted by mosquitoes, and can cause elephantiasis. It is the world’s leading cause of disability due to infectious diseases, affects over 120 million people globally, and is scheduled for global elimination via mass drug administration (MDA) and mosquito control. Molecular xenomonitoring (MX) is a process of screening mosquitoes—not humans—for parasites to estimate whether they are circulating in human populations. MX is especially useful during and following MDA, when new case detection becomes difficult, but is challenging to design and conduct in cities. Using two study sites in the Recife Metropolitan Region, Brazil, we investigated two crucial questions for urban MX development—“What is the best operationally feasible tool to catch adult mosquitoes?” and “How far do mosquitoes disperse in cities?”—in order to determine placement of future surveillance sites. We also screened a proportion of mosquitoes and all eligible residents from the study sites for LF infection. We determined that handheld battery powered aspirators were the best mosquito collection tool; that mosquitoes flew no more than about 85m; and—in this small sample of mosquitoes and very small sample of humans—there was no evidence of LF infection in mosquitoes or study area residents.
Collapse
|
5
|
Cabral S, Bonfim C, Oliveira R, Oliveira P, Guimarães T, Brandão E, Aguiar-Santos AM, Medeiros Z. Knowledge, attitudes and perceptions regarding lymphatic filariasis: study on systematic noncompliance with mass drug administration. Rev Inst Med Trop Sao Paulo 2017; 59:e23. [PMID: 28443941 PMCID: PMC5436738 DOI: 10.1590/s1678-9946201759023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 03/31/2017] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to investigate the epidemiological characteristics, antigenic profile, perceptions, attitudes and practices of individuals who have been systematically non-compliant in mass drug administration (MDA) campaigns targeting lymphatic filariasis, in the municipality of Olinda, State of Pernambuco, Northeastern Brazil. A pretested questionnaire was used to obtain information on socioenvironmental demographics, perceptions of lymphatic filariasis and MDA, and reasons for systematic noncompliance with treatment. A rapid immunochromatographic test (ICT) was performed during the survey to screen for filariasis. It was found that the survey subjects knew about filariasis and MDA. Filariasis was identified as a disease (86.2%) and 74.4% associated it with the presence of swelling in the legs. About 80% knew about MDA, and the main source of information was healthcare workers (68.3%). For men the main reasons for systematic noncompliance with MDA were that “the individual had not received the medication” (p=0.03) and for women “the individual either feared experiencing adverse reactions”. According to the ICT, the prevalence of lymphatic filariasis was 2%. The most important causes of systematic noncompliance were not receiving the drug and fear of side-effects. For successful implementation of MDA programs, good planning, educational campaigns promoting the benefits of MDA, adoption of measures to minimize the impact of adverse effects and improvement of drug distribution logistics are needed.
Collapse
Affiliation(s)
- Silvia Cabral
- Fundação Oswaldo Cruz, Centro de Pesquisa Aggeu Magalhães, Programa de Doutorado em Saúde Pública, Pernambuco, Brazil
| | - Cristine Bonfim
- Fundação Joaquim Nabuco, Departamento de Pesquisa Social, Pernambuco, Brazil.,Universidade Federal de Pernambuco, Programa de Pós-Graduação Integrada em Saúde Coletiva, Pernambuco, Brazil
| | - Rosalira Oliveira
- Fundação Joaquim Nabuco, Departamento de Pesquisa Social, Pernambuco, Brazil
| | - Paula Oliveira
- Secretaria da Saúde de Olinda, Pernambuco, Brazil.,Fundação Oswaldo Cruz, Centro de Pesquisa Aggeu Magalhães, Departamento de Parasitologia, Pernambuco, Brazil
| | | | - Eduardo Brandão
- Fundação Oswaldo Cruz, Centro de Pesquisa Aggeu Magalhães, Departamento de Parasitologia, Pernambuco, Brazil
| | - Ana Maria Aguiar-Santos
- Fundação Oswaldo Cruz, Centro de Pesquisa Aggeu Magalhães, Departamento de Parasitologia, Pernambuco, Brazil
| | - Zulma Medeiros
- Fundação Oswaldo Cruz, Centro de Pesquisa Aggeu Magalhães, Departamento de Parasitologia, Pernambuco, Brazil.,Universidade de Pernambuco, Instituto de Ciências Biológicas, Pernambuco, Brazil
| |
Collapse
|
6
|
Menezes HSG, Chalegre KDDM, Romão TP, Oliveira CMF, de-Melo-Neto OP, Silva-Filha MHNL. A new allele conferring resistance to Lysinibacillus sphaericus is detected in low frequency in Culex quinquefasciatus field populations. Parasit Vectors 2016; 9:70. [PMID: 26846600 PMCID: PMC4743420 DOI: 10.1186/s13071-016-1347-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 01/28/2016] [Indexed: 12/03/2022] Open
Abstract
Background The Cqm1 α-glucosidase of Culex quinquefasciatus larvae acts as the midgut receptor for the binary toxin of the biolarvicide Lysinibacillus sphaericus. Mutations within the cqm1 gene can code for aberrant polypeptides that can no longer be properly expressed or bind to the toxin, leading to insect resistance. The cqm1REC and cqm1REC-2 alleles were identified in a laboratory selected colony and both displayed mutations that lead to equivalent phenotypes of refractoriness to L. sphaericus. cqm1REC was first identified as the major resistance allele in this colony but it was subsequently replaced by cqm1REC-2, suggesting the better adaptive features of the second allele. The major aim of this study was to evaluate the occurrence of cqm1REC-2 and track its origin in field populations where cqm1REC was previously identified. Methods The screening of the cqm1REC-2 allele was based on more than 2000 C. quinquefasciatus larvae from five localities in the city of Recife, Brazil and used a multiplex PCR assay that is also able to identify cqm1REC. Full-length sequencing of the cqm1REC-2 and selected cqm1 samples was performed to identify further polymorphisms between these alleles. Results The cqm1REC-2 allele was found in field samples, specifically in two heterozygous individuals from a single locality with an overall frequency and distribution much lower than that observed for cqm1REC. The full-length sequences from these two cqm1REC-2 copies were almost identical to the cqm1REC-2 derived from the resistant colony but displayed more than 30 SNPs when compared with cqm1 and cqm1REC. The cqm1REC and cqm1REC-2 resistant alleles were found to be associated with two distinct sets of wild-type cqm1 variants found in field populations. Conclusions The cqm1REC-2 allele occurs in populations in Recife and was probably already present in the samples used to establish the laboratory resistant colony. The data generated indicates that cqm1REC-2 can be selected in field populations, although its low frequency and distribution in Recife suggest that cqm1REC-2 presents a lower risk of selection compared to cqm1REC. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1347-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
| | | | - Tatiany Patrícia Romão
- Department of Entomology, Centro de Pesquisas Aggeu Magalhães-FIOCRUZ, Recife, PE, 50740-465, Brazil.
| | | | | | | |
Collapse
|
7
|
Regis LN, Acioli RV, Silveira JC, Melo-Santos MAV, Souza WV, Ribeiro CMN, da Silva JCS, Monteiro AMV, Oliveira CMF, Barbosa RMR, Braga C, Rodrigues MAB, Silva MGNM, Ribeiro PJ, Bonat WH, de Castro Medeiros LC, Carvalho MS, Furtado AF. Sustained reduction of the dengue vector population resulting from an integrated control strategy applied in two Brazilian cities. PLoS One 2013; 8:e67682. [PMID: 23844059 PMCID: PMC3701045 DOI: 10.1371/journal.pone.0067682] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 05/20/2013] [Indexed: 11/30/2022] Open
Abstract
Aedes aegypti has developed evolution-driven adaptations for surviving in the domestic human habitat. Several trap models have been designed considering these strategies and tested for monitoring this efficient vector of Dengue. Here, we report a real-scale evaluation of a system for monitoring and controlling mosquito populations based on egg sampling coupled with geographic information systems technology. The SMCP-Aedes, a system based on open technology and open data standards, was set up from March/2008 to October/2011 as a pilot trial in two sites of Pernambuco -Brazil: Ipojuca (10,000 residents) and Santa Cruz (83,000), in a joint effort of health authorities and staff, and a network of scientists providing scientific support. A widespread infestation by Aedes was found in both sites in 2008-2009, with 96.8%-100% trap positivity. Egg densities were markedly higher in SCC than in Ipojuca. A 90% decrease in egg density was recorded in SCC after two years of sustained control pressure imposed by suppression of >7,500,000 eggs and >3,200 adults, plus larval control by adding fishes to cisterns. In Ipojuca, 1.1 million mosquito eggs were suppressed and a 77% reduction in egg density was achieved. This study aimed at assessing the applicability of a system using GIS and spatial statistic analysis tools for quantitative assessment of mosquito populations. It also provided useful information on the requirements for reducing well-established mosquito populations. Results from two cities led us to conclude that the success in markedly reducing an Aedes population required the appropriate choice of control measures for sustained mass elimination guided by a user-friendly mosquito surveillance system. The system was able to support interventional decisions and to assess the program's success. Additionally, it created a stimulating environment for health staff and residents, which had a positive impact on their commitment to the dengue control program.
Collapse
Affiliation(s)
- Lêda N Regis
- Departameto de Entomologia, Fundação Oswaldo Cruz-Fiocruz-Pe, Recife-PE, Brazil.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Correia JC, Barbosa RMR, Oliveira CMFD, Albuquerque CMRD. Residential characteristics aggravating infestation by Culex quinquefasciatus in a region of Northeastern Brazil. Rev Saude Publica 2013; 46:935-41. [PMID: 23380836 DOI: 10.1590/s0034-89102013005000010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE Analyse how basic sanitation conditions, water supply and housing conditions affect the concentration of Culex quinquefasciatus METHODS Populations of C. quinquefasciatus in 61 houses in the municipality of Olinda, PE, were monitored between October 2009 and October 2010. Observations were carried out in homes without the presence of preferred breeding sites in order to identify characteristics that may be aggravating factors for the development of the mosquito. Five aggravating factors were analysed: vegetation cover surrounding the home, number of residents/home, water storage, sewage drainage and water drainage. These characteristics were analysed in terms of presence or absence and as indicators of the degree of infestation, which was estimated through monitoring the concentration of eggs (oviposition traps - BR-OVT) and adults (CDC light traps). RESULTS Sewage drainage to a rudimentary septic tank or to the open air was the most frequent aggravating factor in the homes (91.8%), although the presence of vegetation was the only characteristic that significantly influenced the increase in the number of egg rafts (p = 0.02). The BR-OVT achieved positive results in 95.1% of the evaluations, with the presence of at least one egg raft per month. A total of 2,366 adults were caught, with a mosquito/room/night ratio of 32.9. No significant difference was found in the number of mosquitoes caught in the homes. CONCLUSIONS Although the sanitation and water supply influence the population density of C. quinquefasciatus, residence features that are not usually considered in control measures can be aggravating factors in sustaining the mosquito population.
Collapse
Affiliation(s)
- Juliana Cavalcanti Correia
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, 52011-330 Recife, PE, Brasil.
| | | | | | | |
Collapse
|
9
|
Kamareddine L. The biological control of the malaria vector. Toxins (Basel) 2012; 4:748-67. [PMID: 23105979 PMCID: PMC3475227 DOI: 10.3390/toxins4090748] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/29/2012] [Accepted: 09/03/2012] [Indexed: 02/05/2023] Open
Abstract
The call for malaria control, over the last century, marked a new epoch in the history of this disease. Many control strategies targeting either the Plasmodium parasite or the Anopheles vector were shown to be effective. Yet, the emergence of drug resistant parasites and insecticide resistant mosquito strains, along with numerous health, environmental, and ecological side effects of many chemical agents, highlighted the need to develop alternative tools that either complement or substitute conventional malaria control approaches. The use of biological means is considered a fundamental part of the recently launched malaria eradication program and has so far shown promising results, although this approach is still in its infancy. This review presents an overview of the most promising biological control tools for malaria eradication, namely fungi, bacteria, larvivorous fish, parasites, viruses and nematodes.
Collapse
Affiliation(s)
- Layla Kamareddine
- Department of Biology, American University of Beirut, Bliss Street, Beirut 11072020, Lebanon.
| |
Collapse
|
10
|
Barbosa RMR, Regis LN. Monitoring temporal fluctuations of Culex quinquefasciatus using oviposition traps containing attractant and larvicide in an urban environment in Recife, Brazil. Mem Inst Oswaldo Cruz 2012; 106:451-5. [PMID: 21739033 DOI: 10.1590/s0074-02762011000400011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 03/25/2011] [Indexed: 11/21/2022] Open
Abstract
The use of attractants and larvicides in oviposition traps is of practical interest for the surveillance and control of urban mosquitoes. In addition to increasing the safety of the traps, this combination is essential for an attract-and-kill control strategy based on trapping mosquito eggs. The combination of Bacillus thuringiensis var. israelensis (Bti) and grass infusion (GI) vs. GI alone were tested for their ability to attract in paired BR-OVT traps in the backyards of 10 houses in Recife, Brazil, for a period of 45 days. Results show that females prefer to oviposit in traps containing Bti (363 compared with 251 egg rafts over 45 days). Results from a one-year trial on the efficacy of BR-OVT traps loaded with GI and Bti as a sampling tool to monitor temporal fluctuations in the population densities of Culex quinquefasciatus in an urban environment are also reported. From December 2006-January 2007, one trap per home was installed and maintained for 348 consecutive days in 134-151 houses located in three urban blocks. Throughout the one-year field trial a total of 43,151 Culex egg rafts were collected in the traps. The data show that BR-OVT loaded with GI and Bti is sensitive enough to demonstrate continuous reproductive activity of Cux. quinquefasciatus in the study area throughout the year and to monitor temporal fluctuations in population density.
Collapse
|
11
|
Cartaxo MF, Ayres CF, Weetman D. Loss of genetic diversity in Culex quinquefasciatus targeted by a lymphatic filariasis vector control program in Recife, Brazil. Trans R Soc Trop Med Hyg 2011; 105:491-9. [DOI: 10.1016/j.trstmh.2011.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 05/09/2011] [Accepted: 05/09/2011] [Indexed: 10/18/2022] Open
|
12
|
Regis L, Monteiro AM, Melo-Santos MAVD, Silveira JC, Furtado AF, Acioli RV, Santos GM, Nakazawa M, Carvalho MS, Ribeiro PJ, Souza WVD. Developing new approaches for detecting and preventing Aedes aegypti population outbreaks: basis for surveillance, alert and control system. Mem Inst Oswaldo Cruz 2008; 103:50-9. [PMID: 18368236 DOI: 10.1590/s0074-02762008000100008] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 02/11/2008] [Indexed: 11/22/2022] Open
Abstract
A new approach to dengue vector surveillance based on permanent egg-collection using a modified ovitrap and Bacillus thuringiensis israelensis(Bti) was evaluated in different urban landscapes in Recife, Northeast Brazil. From April 2004 to April 2005, 13 egg-collection cycles of four weeks were carried out. Geo-referenced ovitraps containing grass infusion, Bti and three paddles were placed at fixed sampling stations distributed over five selected sites. Continuous egg-collections yielded more than four million eggs laid into 464 sentinel-ovitraps over one year. The overall positive ovitrap index was 98.5% (over 5,616 trap observations). The egg density index ranged from 100 to 2,500 eggs per trap-cycle, indicating a wide spread and high density of Aedes aegypti (Diptera: Culicidae) breeding populations in all sites. Fluctuations in population density over time were observed, particularly a marked increase from January on, or later, according to site. Massive egg-collection carried out at one of the sites prevented such a population outbreak. At intra-site level, egg counts made it possible to identify spots where the vector population is consistently concentrated over the time, pinpointing areas that should be considered high priority for control activities. The results indicate that these could be promising strategies for detecting and preventing Ae. aegypti population outbreaks.
Collapse
Affiliation(s)
- Lêda Regis
- Instituto Nacional de Pesquisas Espaciais, São José dos Campos, SP, Brasil.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Lacey LA. Bacillus thuringiensis serovariety israelensis and Bacillus sphaericus for mosquito control. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2007; 23:133-63. [PMID: 17853604 DOI: 10.2987/8756-971x(2007)23[133:btsiab]2.0.co;2] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Since the discovery of Bacillus thuringiensis (Berliner) serovariety israelensis de Barjac (Bti) and efficacious isolates of Bacillus sphaericus Neide, formulations of these bacteria have become the predominant non-chemical means employed for control of mosquito larvae at several locations in the United States and other countries. An overview of developments in the past 20 years is presented in this chapter regarding the toxins of Bti and B. sphaericus, their modes of action, efficacy and factors that affect larvicidal activity, development of resistance, safety, and their roles in integrated mosquito control. The efficacy of Bti formulations has been demonstrated in a variety of habitats against a multitude of species of mosquitoes. B. sphaericus formulations have been utilized predominantly in organically enriched habitats against Culex species, but they are also active in a variety of habitats having low organic enrichment, against numerous species, and across several genera. Stegomyia spp. are not susceptible to practical doses of B. sphaericus formulations. B. sphaericus has been shown to persist longer than Bti in polluted habitats and, under certain circumstances, can recycle in larval cadavers. A disadvantage of B. sphaericus has been the development of resistance in certain populations of Cx. quinquefasciatus Say and Cx. pipiens Linnaeus. Biotic and abiotic factors that influence the larvicidal activity of Bti and B. sphaericus include species of mosquito and their respective feeding strategies, rate of ingestion, age and density of larvae, habitat factors (temperature, solar radiation, depth of water, turbidity, tannin and organic content, presence of vegetation, etc.), formulation factors (type of formulation, toxin content, how effectively the material reaches the target, and settling rate), storage conditions, production factors, means of application and frequency of treatments. Due to their efficacy and relative specificity, both Bti and B. sphaericus can be ideal control agents in integrated programs especially where other biological control agents, environmental management, personal protection and the judicious use of insecticides are combined.
Collapse
Affiliation(s)
- Lawrence A Lacey
- Yakima Agricultural Research Laboratory, USDA-ARS, 5230 Konnowac Pass Road, Wapato, WA 98951, USA
| |
Collapse
|
14
|
Romão TP, de Melo Chalegre KD, Key S, Ayres CFJ, Fontes de Oliveira CM, de-Melo-Neto OP, Silva-Filha MHNL. A second independent resistance mechanism to Bacillus sphaericus binary toxin targets its alpha-glucosidase receptor in Culex quinquefasciatus. FEBS J 2006; 273:1556-68. [PMID: 16689941 DOI: 10.1111/j.1742-4658.2006.05177.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The entomopathogen Bacillus sphaericus is an important tool for the vector control of Culex sp., and its effectiveness has been validated in field trials. The appearance of resistance to this bacterium, however, remains a threat to its use, and attempts have been made to understand the resistance mechanisms. Previous work showed that the resistance to B. sphaericus in a Culex quinquefasciatus colony is associated with the absence of the approximately 60-kDa binary toxin receptor in larvae midgut microvilli. Here, the gene encoding the C. quinquefasciatus toxin receptor, Cqm1, was cloned and sequenced from a susceptible colony. The deduced amino-acid sequence confirmed its identity as an alpha-glucosidase, and analysis of the corresponding gene sequence from resistant larvae implicated a 19-nucleotide deletion as the basis for resistance. This deletion changes the ORF and originates a premature stop codon, which prevents the synthesis of the full-length Cqm1. Expression of the truncated protein, however, was not detected when whole larvae extracts were probed with antibodies raised against an N-terminal 45-kDa recombinant fragment of Cqm1. It seems that the premature stop codon directs the mutated cqm1 to the nonsense-mediated decay pathway of mRNA degradation. In-gel assays confirmed that a single alpha-glucosidase protein is missing from the resistant colony. Further in vitro affinity assays showed that the recombinant fragment binds to the toxin, and mapped the binding site to the N-terminus of the receptor.
Collapse
Affiliation(s)
- Tatiany Patrícia Romão
- Department of Entomology, Centro de Pesquisas Aggeu Magalhães/Fundação Oswaldo Cruz, Recife-PE, Brazil
| | | | | | | | | | | | | |
Collapse
|
15
|
Silva-Filha MHNL, Oliveira CMFD, Regis L, Yuan Z, Rico CM, Nielsen-LeRoux C. TwoBacillus sphaericusbinary toxins share the midgut receptor binding site: implications for resistance ofCulex pipienscomplex (Diptera: Culicidae) larvae. FEMS Microbiol Lett 2004; 241:185-91. [PMID: 15598531 DOI: 10.1016/j.femsle.2004.10.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 08/27/2004] [Accepted: 10/11/2004] [Indexed: 10/26/2022] Open
Abstract
This work demonstrates that Bin1 and Bin2 toxins, produced by Bacillus sphaericus strains IAB59 and 2362, respectively, share a binding site in midgut brush border membranes (BBMF) from Culex pipiens complex larvae. However, a colony selected with strain IAB59, displaying a resistance ratio of only 42-fold to IAB59, but a 162,000-fold resistance to strain 2362, was found to miss receptors for Bin2 in the BBMF. This correlates with results showing that Bin1, produced in strain IAB59, failed to bind specifically to BBMF from other colony highly resistant to strain 2362. Data indicate the loss of the BBMF bound receptor as a general mechanism of resistance to binary toxins in mosquito.
Collapse
|
16
|
Braga C, Albuquerque MDFPM, Morais HMD. A produção do conhecimento científico e as políticas de saúde pública: reflexões a partir da ocorrência da filariose na cidade do Recife, Pernambuco, Brasil. CAD SAUDE PUBLICA 2004; 20:351-61. [PMID: 15073614 DOI: 10.1590/s0102-311x2004000200002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
O artigo discute a relação entre a produção científica sobre a ocorrência da filariose bancroftiana no Brasil e o processo de formulação e implementação da política de saúde voltada ao seu controle. Para tanto, realiza uma revisão da produção do conhecimento e das políticas específicas, no período compreendido desde a criação do Programa de Combate à Filariose, em meados do século passado, até a criação do SUS, no marco da descentralização do controle das endemias. Centrando suas observações empíricas na ambiência da cidade do Recife, espaço urbano no qual ainda prevalece a filariose, ressalta os processos institucionais e destaca o papel dos distintos atores neles envolvidos. Partindo da hipótese de que se até à primeira metade do século vinte faltavam o conhecimento científico e o desenvolvimento tecnológico para o controle do problema, a seguir, quando esses avanços são disponibilizados, outros requerimentos, agora do campo da política, irão se impor, atuando como determinantes da persistência da endemia na cidade.
Collapse
Affiliation(s)
- Cynthia Braga
- Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Recife, Brasil.
| | | | | |
Collapse
|
17
|
Oliveira CMF, Silva-Filha MH, Nielsen-Leroux C, Pei G, Yuan Z, Regis L. Inheritance and mechanism of resistance to Bacillus sphaericus in Culex quinquefasciatus (Diptera: Culicidae) from China and Brazil. JOURNAL OF MEDICAL ENTOMOLOGY 2004; 41:58-64. [PMID: 14989346 DOI: 10.1603/0022-2585-41.1.58] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Investigations on the inheritance and mechanism of resistance to Bacillus sphaericus Neide in Culex quinquefasciatus Say colonies, selected with strains C3-41 (RLCq1/C3-41) and 2362 (CqRL1/2362), were performed in China and Brazil, respectively. The progeny of reciprocal F1 crosses (susceptible female x resistant male and vice versa) from both resistant colonies responded alike in bioassays, indicating recessive inheritance. Data on larvae susceptibility from the backcross offspring between F1 and their respective susceptible and resistant parental colonies are consistent with a monofactorial and autosomal mode of inheritance. In vitro binding assays between 125I binary (Bin2) toxin and the brush border membrane fractions (BBMF) from CqRL1/2362 and RLCq1/C3-41 larvae showed that resistance, in both colonies, is caused by a failure in the binding step of the B. sphaericus Bin2 toxin to its specific midgut receptor. The specific and saturable binding of Bin2 toxin to BBMF from F1 larvae (CqRL1/2362 X susceptible counterpart) confirms the recessive inheritance of the resistance gene. Further studies are needed to advance understanding of B. sphaericus resistance.
Collapse
Affiliation(s)
- Cláudia M F Oliveira
- Centro de Pesquisas Aggeu Magalhães-FIOCRUZ, Departamento de Entomologia, Av. Moraes Rêgo s/n Recife-PE 50670-420, Brazil
| | | | | | | | | | | |
Collapse
|
18
|
Fillinger U, Knols BGJ, Becker N. Efficacy and efficiency of new Bacillus thuringiensis var israelensis and Bacillus sphaericus formulations against Afrotropical anophelines in Western Kenya. Trop Med Int Health 2003; 8:37-47. [PMID: 12535249 DOI: 10.1046/j.1365-3156.2003.00979.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We evaluated the efficacy of new water-dispersible granular (WDG) formulations of Bacillus thuringienis var. israelensis (Bti; VectoBac) and B. sphaericus (Bs; VectoLex), Valent BioScience Corp., Illinois, USA) for the control of larval Anopheles gambiae sensu lato Giles mosquitoes in a malaria-endemic area around Lake Victoria, Western Kenya. WDG and powder formulations were compared in laboratory bioassays and followed by efficiency and residual effect assessments of both WDG formulations in open field experiments. LC50 and LC95 values for the Bti/Bs strains and their formulations show high susceptibility of A. gambiae sensu stricto under laboratory conditions. The larvae proved more susceptible to Bs than to Bti and the WDG formulations were slightly superior to the powder formulations. High efficiency was also shown in the open field trials, and a minimum dosage of 200 g/ha Bti WDG, representing the LC95 of the laboratory tests, was sufficient to fully suppress emergence of mosquitoes when applied at weekly intervals. Bti WDG did not show a residual effect, irrespective of the concentration applied. The Bs WDG formulation, however, showed significant larval reductions up to 11 days post-treatment at application doses of either 1 or 5 kg/ha. We conclude that the main malaria vector in our study area is highly susceptible to these microbial control agents. Minimum effective dosages to achieve elimination of the larval population in a given habitat are extremely low and environmental impact is negligible. Microbial products for larval control have therefore great potential within Integrated Vector Management programmes and may augment control efforts against adult vector stages, such as the use of insecticide-treated bednets, in many parts of Africa.
Collapse
Affiliation(s)
- Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (ICIPE), Mbita Point, Kenya.
| | | | | |
Collapse
|
19
|
Regis L, Silva-Filha MH, Nielsen-LeRoux C, Charles JF. Bacteriological larvicides of dipteran disease vectors. Trends Parasitol 2001; 17:377-80. [PMID: 11685898 DOI: 10.1016/s1471-4922(01)01953-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The apparent success in vector control observed between 1950 and 1970 was followed by worldwide resistance to organosynthetic insecticides wherever they were used intensively. Insect resistance to one or more categories of insecticides has limited the effectiveness of these compounds, and their non-selective mode of action adversely affects non-target organisms. This scenario highlights the need for selective agents in integrated vector control programs. This article gives an overview of the main fundamental and applied research topics on entomopathogenic bacteria in relation to their role in vector control.
Collapse
Affiliation(s)
- L Regis
- Fundação Oswaldo Cruz-Fiocruz, CPqAM, Dept Entomology, Av Moraes Rego s/n 50670.420 Recife, PE, Brazil.
| | | | | | | |
Collapse
|
20
|
Regis L, da Silva SB, Melo-Santos MA. The use of bacterial larvicides in mosquito and black fly control programmes in Brazil. Mem Inst Oswaldo Cruz 2001; 95 Suppl 1:207-10. [PMID: 11142716 DOI: 10.1590/s0074-02762000000700035] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bacillus spp. based larvicides are increasingly replacing, with numerous advantages, chemical insecticides in programmes for controlling black fly and mosquito populations. Brazil was among the pioneers in adopting Bacillus thuringiensis israelensis (B.t.i) to control black flies. However, the major current mosquito control programme in Brazil, the Programme for Eradication of Aedes aegypti launched in 1997, only recently decided to replace temephos by B.t.i based larvicides, in the State of Rio de Janeiro. In the last decade, works developed by research groups in Brazilian institutions have generated a significant contribution to this subject through the isolation of B. sphaericus new strains, the development of new products and the implementation of field trials of Bacillus efficacy against mosquito species under different environmental conditions.
Collapse
Affiliation(s)
- L Regis
- Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães-Fiocruz, Caixa Postal 7472, 50670-420 Recife, PE, Brasil.
| | | | | |
Collapse
|