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2.
Implement Sci Commun ; 4(1): 84, 2023 Jul 24.
Article in English | MEDLINE | ID: mdl-37488632

ABSTRACT

BACKGROUND: The Systems Analysis and Improvement Approach (SAIA) is an evidence-based package of systems engineering tools originally designed to improve patient flow through the prevention of Mother-to-Child transmission of HIV (PMTCT) cascade. SAIA is a potentially scalable model for maximizing the benefits of universal antiretroviral therapy (ART) for mothers and their babies. SAIA-SCALE was a stepped wedge trial implemented in Manica Province, Mozambique, to evaluate SAIA's effectiveness when led by district health managers, rather than by study nurses. We present the results of a qualitative assessment of implementation determinants of the SAIA-SCALE strategy during two intensive and one maintenance phases. METHODS: We used an extended case study design that embedded the Consolidated Framework for Implementation Research (CFIR) to guide data collection, analysis, and interpretation. From March 2019 to April 2020, we conducted in-depth individual interviews (IDIs) and focus group discussions (FGDs) with district managers, health facility maternal and child health (MCH) managers, and frontline nurses at 21 health facilities and seven districts of Manica Province (Chimoio, Báruè, Gondola, Macate, Manica, Sussundenga, and Vanduzi). RESULTS: We included 85 participants: 50 through IDIs and 35 from three FGDs. Most study participants were women (98%), frontline nurses (49.4%), and MCH health facility managers (32.5%). An identified facilitator of successful intervention implementation (regardless of intervention phase) was related to SAIA's compatibility with organizational structures, processes, and priorities of Mozambique's health system at the district and health facility levels. Identified barriers to successful implementation included (a) inadequate health facility and road infrastructure preventing mothers from accessing MCH/PMTCT services at study health facilities and preventing nurses from dedicating time to improving service provision, and (b) challenges in managing intervention funds. CONCLUSIONS: The SAIA-SCALE qualitative evaluation suggests that the scalability of SAIA for PMTCT is enhanced by its fit within organizational structures, processes, and priorities at the primary level of healthcare delivery and health system management in Mozambique. Barriers to implementation that impact the scalability of SAIA include district-level financial management capabilities and lack of infrastructure at the health facility level. SAIA cannot be successfully scaled up to adequately address PMTCT needs without leveraging central-level resources and priorities. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03425136 . Registered on 02/06/2018.

3.
Pest Manag Sci ; 79(6): 2206-2219, 2023 Jun.
Article in English | MEDLINE | ID: mdl-36750418

ABSTRACT

BACKGROUND: Spodoptera frugiperda (J. E. Smith) is a widespread agricultural pest with several records of resistance to different insecticides and Bt proteins, including the neurotoxic insecticides chlorpyrifos (organophosphate) and lambda-cyhalothrin (pyrethroid). Here, we (i) characterized and monitored the susceptibility of field populations of S. frugiperda to chlorpyrifos (194 populations) and lambda-cyhalothrin (197 populations) collected from major maize-growing regions of Brazil from 2003 to 2016, and (ii) compared gene expression levels of laboratory-selected, chlorpyrifos- and lambda-cyhalothrin-resistant strains to a susceptible reference strain (Sf-ss) of S. frugiperda. RESULTS: The susceptibility monitoring detected average survival ranging from 29.3% to 36.0% for chlorpyrifos, and 23.1% to 68.0% for lambda-cyhalothrin. The resistance ratio of the chlorpyrifos-resistant strain (Clo-rr) was 25.4-fold and of the lambda-cyhalothrin-resistant strain (Lam-rr) was 21.5-fold. We identified 1098 differentially expressed genes (DEGs) between Clo-rr and Sf-ss, and 303 DEGs between Lam-rr and Sf-ss. Functional analyses of the DEGs revealed the up-regulation of several detoxification enzymes, mainly cytochrome P450 belonging to CYP3 and CYP6 clans. Genes associated with regulatory processes, such as the forkhead box class O (FoxO) transcription factor were also up-regulated. Variant analysis of target-site mutations for both pesticides identified the A201S and F290V mutations in acetylcholinesterase-1, both occurring in heterozigosis in the Clo-rr S. frugiperda strain. CONCLUSION: Our data show that the overexpression of the enzymatic detoxification machinery is the main difference to explain the resistance of Clo-rr and Lam-rr strains of S. frugiperda to chlorpyrifos and lambda-cyhalothrin, although a target-site mutation also contributes to the Clo-rr resistance to chlorpyrifos. © 2023 Society of Chemical Industry.


Subject(s)
Chlorpyrifos , Insecticides , Pyrethrins , Animals , Insecticides/pharmacology , Chlorpyrifos/pharmacology , Spodoptera/genetics , Acetylcholinesterase/genetics , Insecticide Resistance/genetics , Pyrethrins/pharmacology , Gene Expression
4.
Insects ; 14(2)2023 Jan 26.
Article in English | MEDLINE | ID: mdl-36835698

ABSTRACT

Susceptibility monitoring to insecticides is a key component to implementing insecticide resistance management (IRM) programs. In this research, the susceptibility to teflubenzuron in Spodoptera frugiperda (J.E Smith) was monitored in more than 200 field-collected populations from major corn-growing regions of Brazil, from 2004 to 2020. Initially, we defined a diagnostic concentration of 10 µg mL-1 of teflubenzuron using a diet-overlay bioassay for monitoring the susceptibility. A variation in the susceptibility to teflubenzuron in S. frugiperda was detected among populations from different locations. We also detected a significant reduction in the susceptibility to teflubenzuron throughout time in all the populations of S. frugiperda evaluated, with larval survival at diagnostic concentration varying from values of <5% in 2004 to up 80% in 2020. Thus, this research provides evidence of field-evolved resistance of S. frugiperda to teflubenzuron and reinforces that IRM practices are urgently needed to be implemented in Brazil.

6.
Rev. bras. cir. cardiovasc ; 37(6): 937-941, Nov.-Dec. 2022. tab, graf
Article in English | LILACS-Express | LILACS | ID: biblio-1407329

ABSTRACT

ABSTRACT The anomalous origin of one pulmonary artery from the ascending aorta is a rare congenital heart disease, generally diagnosed based on the clinical information and on echocardiographic and computed tomography angiography findings. Here we report two neonates successfully treated with surgery early in life.

7.
BMC Health Serv Res ; 22(1): 1422, 2022 Nov 28.
Article in English | MEDLINE | ID: mdl-36443742

ABSTRACT

BACKGROUND: Despite high coverage of maternal and child  health services in Mozambique, prevention of mother-to-child transmission of HIV (PMTCT) cascade outcomes remain sub-optimal. Delivery effectiveness is modified by health system preparedness. Identifying modifiable factors that impact quality of care and service uptake can inform strategies to improve the effectiveness of PMTCT programs. We estimated associations between facility-level modifiable health system readiness measures and three PMTCT outcomes: Early infant diagnosis (polymerase chain reaction (PCR) before 8 weeks of life), PCR ever (before or after 8 weeks), and positive PCR test result. METHODS: A 2018 cross-sectional, facility-level survey was conducted in a sample of 36 health facilities covering all 12 districts in Manica province, central Mozambique, as part of a baseline assessment for the SAIA-SCALE trial (NCT03425136). Data on HIV testing outcomes among 3,427 exposed infants were abstracted from at-risk child service registries. Nine health system readiness measures were included in the analysis. Logistic regressions were used to estimate associations between readiness measures and pediatric HIV testing outcomes. Odds ratios (OR) and 95% confidence intervals (95%CI) are reported. RESULTS: Forty-eight percent of HIV-exposed infants had a PCR test within 8 weeks of life, 69% had a PCR test ever, and 6% tested positive. Staffing levels, glove stockouts, and distance to the reference laboratory were positively associated with early PCR (OR = 1.02 [95%CI: 1.01-1.02], OR = 1.73 [95%CI: 1.24-2.40] and OR = 1.01 [95%CI: 1.00-1.01], respectively) and ever PCR (OR = 1.02 [95%CI: 1.01-1.02], OR = 1.80 [95%CI: 1.26-2.58] and OR = 1.01 [95%CI: 1.00-1.01], respectively). Catchment area size and multiple NGOs supporting PMTCT services were associated with early PCR testing OR = 1.02 [95%CI: 1.01-1.03] and OR = 0.54 [95%CI: 0.30-0.97], respectively). Facility type, stockout of prophylactic antiretrovirals, the presence of quality improvement programs and mothers' support groups in the health facility were not associated with PCR testing. No significant associations with positive HIV diagnosis were found. CONCLUSION: Salient modifiable factors associated with HIV testing for exposed infants include staffing levels, NGO support, stockout of essential commodities and accessibility of reference laboratories. Our study provides insights into modifiable factors that could be targeted to improve PMTCT performance, particularly at small and rural facilities.


Subject(s)
HIV Infections , Infectious Disease Transmission, Vertical , Infant , Female , Humans , Child , Infectious Disease Transmission, Vertical/prevention & control , Cross-Sectional Studies , Mozambique/epidemiology , HIV Testing , HIV Infections/diagnosis , HIV Infections/epidemiology , HIV Infections/prevention & control
8.
Braz J Cardiovasc Surg ; 37(6): 937-941, 2022 12 01.
Article in English | MEDLINE | ID: mdl-36112742

ABSTRACT

The anomalous origin of one pulmonary artery from the ascending aorta is a rare congenital heart disease, generally diagnosed based on the clinical information and on echocardiographic and computed tomography angiography findings. Here we report two neonates successfully treated with surgery early in life.


Subject(s)
Heart Defects, Congenital , Pulmonary Artery , Infant, Newborn , Humans , Pulmonary Artery/diagnostic imaging , Pulmonary Artery/surgery , Pulmonary Artery/abnormalities , Aorta/diagnostic imaging , Aorta/surgery , Heart Defects, Congenital/surgery , Echocardiography/methods , Angiography/methods
9.
Rev. bras. cir. cardiovasc ; 37(4): 534-545, Jul.-Aug. 2022. tab, graf
Article in English | LILACS-Express | LILACS | ID: biblio-1394728

ABSTRACT

ABSTRACT Introduction: Congenitally corrected transposition of the great arteries (CCTGA) is a rare anomaly. Current data available regarding adult cases is derived from small series, information simultaneously presented in pediatric publications, and one classical multicenter study. This review, not aimed to exhaust the subject, has the purpose to examine the literature addressing presentation, diagnostic methodology, and management of afflicted adult patients. Methods: A comprehensive search was undertaken in three major databases (PubMed, Cochrane, SciELO), using the keywords "congenitally corrected transposition of the great arteries" and "adults". Relevant articles in English, Spanish, and Portuguese were extracted and critically appraised in this review. Steps for study selection were: (1) identification of titles of records through databases searching, (2) removal of duplicates, (3) screening and selection of abstracts, (4) final inclusion in the study. Results: Four hundred sixty-five publications on CCTGA in adult patients were retrieved, and 166 were excluded; 299 studies were used for this review including 76 full-text articles, 70 studies related to general aspects of the subject, and, due to the small number of publications, 153 case reports. Sixty-one articles referring to combined experiences in pediatric and adult patients and judged to be relevant, but retrieved from another sources, were also included. Conclusion: Albeit clinical presentation and diagnostic criteria have been well stablished, there seems to be room for discussion related to clinical and surgical management of CCTGA in adults. Considering the rarity of the disease, well designed multicenter studies may provide answers.

10.
Braz J Cardiovasc Surg ; 37(4): 534-545, 2022 08 16.
Article in English | MEDLINE | ID: mdl-35895985

ABSTRACT

INTRODUCTION: Congenitally corrected transposition of the great arteries (CCTGA) is a rare anomaly. Current data available regarding adult cases is derived from small series, information simultaneously presented in pediatric publications, and one classical multicenter study. This review, not aimed to exhaust the subject, has the purpose to examine the literature addressing presentation, diagnostic methodology, and management of afflicted adult patients. METHODS: A comprehensive search was undertaken in three major databases (PubMed, Cochrane, SciELO), using the keywords "congenitally corrected transposition of the great arteries" and "adults". Relevant articles in English, Spanish, and Portuguese were extracted and critically appraised in this review. Steps for study selection were: (1) identification of titles of records through databases searching, (2) removal of duplicates, (3) screening and selection of abstracts, (4) final inclusion in the study. RESULTS: Four hundred sixty-five publications on CCTGA in adult patients were retrieved, and 166 were excluded; 299 studies were used for this review including 76 full-text articles, 70 studies related to general aspects of the subject, and, due to the small number of publications, 153 case reports. Sixty-one articles referring to combined experiences in pediatric and adult patients and judged to be relevant, but retrieved from another sources, were also included. CONCLUSION: Albeit clinical presentation and diagnostic criteria have been well stablished, there seems to be room for discussion related to clinical and surgical management of CCTGA in adults. Considering the rarity of the disease, well designed multicenter studies may provide answers.


Subject(s)
Congenitally Corrected Transposition of the Great Arteries , Adult , Humans , Multicenter Studies as Topic
12.
Int. j. cardiovasc. sci. (Impr.) ; 35(1): 136-139, Jan.-Feb. 2022. graf
Article in English | LILACS | ID: biblio-1356313

ABSTRACT

Abstract Isolated left ventricular apical hypoplasia is a rare cardiomyopathy, with a broad range of clinical presentations. Since this entity was already described in association with osteomuscular diseases, mutation in the Lamin A/C gene has been regarded as a possible cause of this disease. This study describes the case of an asymptomatic teenager with isolated left ventricular apical hypoplasia and arthrogriposis but with no mutations in the entire Lamin A/C gene.


Subject(s)
Humans , Male , Adolescent , Lamin Type A/genetics , Isolated Noncompaction of the Ventricular Myocardium/physiopathology , Arthrogryposis , Lamin Type A/deficiency , Isolated Noncompaction of the Ventricular Myocardium/diagnosis , Isolated Noncompaction of the Ventricular Myocardium/etiology
13.
ABC., imagem cardiovasc ; 35(3): eabc287, 2022. ilus
Article in Portuguese | LILACS | ID: biblio-1411754

ABSTRACT

Descreve-se o caso de um homem de 19 anos assintomático com fibroma de ventrículo esquerdo em acompanhamento por 15 anos, sem tratamento.(AU)


Here we describe a case of a 19-year-old asymptomatic man with a left ventricular fibroma on follow-up for 15 years with no treatment required.(AU)


Subject(s)
Humans , Male , Adult , Fibroma/diagnostic imaging , Heart Neoplasms/complications , Heart Ventricles/abnormalities , Myocardium/pathology , Echocardiography/methods , Magnetic Resonance Spectroscopy/methods , Radiography, Thoracic/methods , Tomography, X-Ray Computed/methods , Electrocardiography, Ambulatory/methods , Death, Sudden, Cardiac
14.
Endocr Pract ; 27(11): 1108-1113, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34153510

ABSTRACT

OBJECTIVE: To compare 2 ultrasound-based risk stratification systems in malignancy risk assessment of thyroid nodules and the clinical applicability of these guidelines in Brazil. METHODS: We retrospectively reviewed the ultrasound findings of 314 patients (473 thyroid nodules) who underwent fine-needle aspiration (FNA) biopsy and/or surgery between February 2018 and March 2019. All nodules were classified using 2 systems: the Thyroid Imaging, Reporting, and Data System (TIRADS) of the American College of Radiology (ACR-TIRADS) and the TIRADS of the European Thyroid Association (EU-TIRADS). Both risk stratification systems were analyzed. We identified the diagnostic predictive values that yielded optimal sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. RESULTS: Of the 473 nodules, all underwent FNA, and histopathology was performed for 332 nodules. The agreement between the ACR-TIRADS and EU-TIRADS results and that between cytology and histopathology findings was 92.6% (kappa = 0.84) and 86.7% (kappa = 0.73), respectively. The area under the curve for the ACR-TIRADS and EU-TIRADS was 0.871 and 0.828, respectively (P < .001). The EU-TIRADS had the best sensitivity and negative predictive value, whereas the ACR-TIRADS had the best specificity, positive predictive value, and accuracy. Of the 473 nodules studied, only 158 (33.4%) followed the FNA size criteria suggested by the ACR-TIRADS. CONCLUSION: ACR-TIRADS and EU-TIRADS had good diagnostic performances. However, most aspirated nodules did not follow the TIRADS indication; thus, the overuse of FNA as a diagnostic tool was observed.


Subject(s)
Thyroid Neoplasms , Thyroid Nodule , Brazil , Data Systems , Humans , Retrospective Studies , Thyroid Neoplasms/diagnostic imaging , Thyroid Nodule/diagnostic imaging , United States
15.
Physiol Rep ; 9(11): e14862, 2021 06.
Article in English | MEDLINE | ID: mdl-34057301

ABSTRACT

BACKGROUND: Lymphatic abnormalities play a role in effusions in individuals with a Fontan circulation. Recent results using near-infrared fluorescence imaging disclosed an increased contraction frequency of lymphatic vessels in Fontan patients compared to healthy controls. It is proposed that the elevated lymphatic pumping seen in the Fontan patients is necessary to maintain habitual interstitial fluid balance. Hyperthermia has previously been used as a tool for lymphatic stress test. By increasing fluid filtration in the capillary bed, the lymphatic workload and contraction frequency are increased accordingly. Using near-infrared fluorescence imaging, the lymphatic functional reserve capacity in Fontan patients were explored with a lymphatic stress test. METHODS: Fontan patients (n = 33) were compared to a group of 15 healthy individuals of equal age, weight, and gender. The function of the superficial lymphatic vessels in the lower leg during rest and after inducing hyperthermia was investigated, using near-infrared fluorescence imaging. RESULTS: Baseline values in the Fontan patients showed a 57% higher contraction frequency compared to the healthy controls (0.4 ± 0.3 min-1 vs. 0.3 ± 0.2 min-1 , p = 0.0445). After inducing stress on the lymphatic vessels with hyperthermia the ability to increase contraction frequency was decreased in the Fontan patients compared to the controls (0.6 ± 0.5 min-1 vs. 1.2 ± 0.8 min-1 , p = 0.0102). CONCLUSIONS: Fontan patients had a higher lymphatic contraction frequency during normal circumstances. In the Fontan patients, the hyperthermia response is dampened indicating that the functional lymphatic reserve capacity is depressed. This diminished reserve capacity could be part of the explanation as to why some Fontan patients develop late-onset lymphatic complications.


Subject(s)
Fontan Procedure/adverse effects , Lymphatic Diseases/etiology , Adult , Case-Control Studies , Female , Humans , Lymphatic Diseases/pathology , Lymphatic System/pathology , Lymphatic Vessels/pathology , Male , Spectroscopy, Near-Infrared
16.
J Econ Entomol ; 114(2): 903-913, 2021 04 13.
Article in English | MEDLINE | ID: mdl-33604658

ABSTRACT

Spodoptera frugiperda (J.E. Smith) is one of the key cross-crop pests in Brazilian agroecosystems. Field-evolved resistance of S. frugiperda to some conventional insecticides and Bt proteins has already been reported. Thus, the use of insecticides with new mode of action such as sodium channel blockers (indoxacarb and metaflumizone) could be an important tool in insecticide resistance management (IRM) programs. To implement a proactive IRM, we conducted baseline response and monitoring to indoxacarb and metaflumizone in 87 field populations of S. frugiperda collected from major maize-growing regions of Brazil from 2017 to 2020, estimated the frequency of resistance alleles to indoxacarb, and evaluated cross-resistance of indoxacarb and metaflumizone to some selected insecticides and Bt proteins. Low variation in susceptibility to indoxacarb (4.6-fold) and metaflumizone (2.6-fold) was detected in populations of S. frugiperda in 2017. The frequency of the resistance allele to indoxacarb was 0.0452 (0.0382-0.0527 CI 95%), by using F2 screen method. The mean survival at diagnostic concentration, based on CL99, varied from 0.2 to 12.2% for indoxacarb and from 0.0 to 12.7% for metaflumizone, confirming high susceptibility of S. frugiperda to these insecticides in Brazil. No cross-resistance was detected between sodium channel blocker insecticides and other insecticides (organophosphate, pyrethroid, benzoylurea, spinosyn, and diamide) and Bt proteins. These findings showed that sodium channel blocker insecticides are important candidates to be exploited in IRM strategies of S. frugiperda in Brazil.


Subject(s)
Insecticides , Sodium Channel Blockers , Spodoptera , Animals , Bacterial Proteins/pharmacology , Brazil , Insecticide Resistance , Insecticides/pharmacology , Larva , Sodium Channel Blockers/pharmacology , Zea mays
17.
Braz J Cardiovasc Surg ; 35(3): 254-264, 2020 06 01.
Article in English | MEDLINE | ID: mdl-32549096

ABSTRACT

OBJECTIVE: Description of adult congenital heart disease (CHD) outpatient characteristics has not been reported and several aspects regarding these patients require attention. We describe the 12-year experience of a Brazilian unit. METHODS: The main characteristics of 1168 patients were reviewed annotating for each patient age, gender, city of residence, main diagnosis, functional class at last examination, defect complexity and in-hospital referral pattern. RESULTS: Increasing workload was documented. Among the CHD patients, 663 (57%) were between 14 and 30 years old and 920 (79%) lived in the referral region. Referrals were made by hospital cardiologists for 611 (52%) patients, while 519 (45%) were referred by pediatric cardiologists. Regarding CHD severity, 637 (55%) had a defect of mild complexity. Of the patients analyzed, 616 (53%) had undergone an intervention, mainly atrial septal defect (ASD) closure, correction of tetralogy of Fallot, ventricular septal defect (VSD) closure and relief of coarctation of the aorta (CoAo). The main diagnosis of the 552 (47%) patients not submitted to an intervention were ASD, VSD, aortic stenosis, complex CHD and pulmonary stenosis. Regarding functional class, 1016 (87%) were in class I and 280 (24%) were lost to follow-up. Seventy-three patients had died, mainly due to cardiac death. CONCLUSION: In a unit were complex pediatric congenital heart surgery started twenty years ago, an increasing adult CHD workload was documented. Referral came predominantly from cities around the unit, most patients had low complexity defects and were in functional class I, a significant loss of follow-up was documented, and the death of patients was mainly due to the heart defect.


Subject(s)
Heart Defects, Congenital , Heart Septal Defects, Ventricular , Adolescent , Adult , Aged , Aged, 80 and over , Ambulatory Care Facilities , Brazil , Humans , Middle Aged , Outpatients , Young Adult
18.
Rev. bras. cir. cardiovasc ; 35(3): 254-264, May-June 2020. tab, graf
Article in English | LILACS, Sec. Est. Saúde SP | ID: biblio-1137274

ABSTRACT

Abstract Objective: Description of adult congenital heart disease (CHD) outpatient characteristics has not been reported and several aspects regarding these patients require attention. We describe the 12-year experience of a Brazilian unit. Methods: The main characteristics of 1168 patients were reviewed annotating for each patient age, gender, city of residence, main diagnosis, functional class at last examination, defect complexity and in-hospital referral pattern. Results: Increasing workload was documented. Among the CHD patients, 663 (57%) were between 14 and 30 years old and 920 (79%) lived in the referral region. Referrals were made by hospital cardiologists for 611 (52%) patients, while 519 (45%) were referred by pediatric cardiologists. Regarding CHD severity, 637 (55%) had a defect of mild complexity. Of the patients analyzed, 616 (53%) had undergone an intervention, mainly atrial septal defect (ASD) closure, correction of tetralogy of Fallot, ventricular septal defect (VSD) closure and relief of coarctation of the aorta (CoAo). The main diagnosis of the 552 (47%) patients not submitted to an intervention were ASD, VSD, aortic stenosis, complex CHD and pulmonary stenosis. Regarding functional class, 1016 (87%) were in class I and 280 (24%) were lost to follow-up. Seventy-three patients had died, mainly due to cardiac death. Conclusion: In a unit were complex pediatric congenital heart surgery started twenty years ago, an increasing adult CHD workload was documented. Referral came predominantly from cities around the unit, most patients had low complexity defects and were in functional class I, a significant loss of follow-up was documented, and the death of patients was mainly due to the heart defect.


Subject(s)
Humans , Adolescent , Adult , Middle Aged , Aged , Aged, 80 and over , Young Adult , Heart Defects, Congenital , Heart Septal Defects, Ventricular , Outpatients , Brazil , Ambulatory Care Facilities
19.
Pest Manag Sci ; 76(8): 2674-2680, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32133753

ABSTRACT

BACKGROUND: The use of spinosyn insecticides is one of the major control strategies of the fall armyworm, Spodoptera frugiperda (J. E. Smith) in Brazil. In this study, we selected a spinetoram-resistant strain from a field-population of S. frugiperda to characterize the inheritance of the resistance and cross-resistance relationship between spinosyn insecticides. RESULTS: The values of LC50 (95% CI) obtained from concentration-response bioassays were 0.63 (0.55-0.73) µg spinetoram mL-1 for the susceptible strain (SUS), and 1170.96 (1041.61-1323.89) µg spinetoram mL-1 for the strain resistant to spinetoram (SPT-R). These values resulted in a resistance ratio of 1844-fold. The SPT-R strain showed cross-resistance with spinosad (resistance ratio = 1196-fold). The reciprocal crosses showed LC50 values of 3.91 (2.97-5.84) and 5.37 (4.52-6.52) µg spinetoram mL-1 , suggesting that the resistance of S. frugiperda to spinetoram is autosomal and incompletely recessive. The backcrosses of the F1 progeny with the SPT-R strain suggest a resistance with polygenic effect. Estimates of the effective number of loci with equal contributions to the resistance effect were from 1.18 to 1.76, suggesting that resistance to spinetoram is associated with a few genes. CONCLUSION: The inheritance pattern of resistance of S. frugiperda to spinetoram was characterized as autosomal, incompletely recessive and polygenic. Cross-resistance between spinosyns was confirmed in S. frugiperda. The importance of this information for implementing insect resistance management strategies is discussed in this paper. © 2020 Society of Chemical Industry.


Subject(s)
Spodoptera , Animals , Bacterial Proteins , Brazil , Insecticide Resistance , Insecticides , Macrolides
20.
Pest Manag Sci ; 76(1): 169-178, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31106516

ABSTRACT

BACKGROUND: The use of Bt plants has been the main strategy for controlling the fall armyworm Spodoptera frugiperda (J. E. Smith) in Brazil. However, many resistance cases were already registered. The resistance of S. frugiperda to the Vip3Aa20 protein was recently characterized under laboratory conditions but it is still efficient under field conditions. Here, resistance monitoring studies were conducted using phenotypic (purified protein and Bt maize leaves) and genotypic (F1 and F2 screen) methods to support insect resistance management (IRM) programs and preserve Vip3Aa20 technology on maize. RESULTS: Phenotypic monitoring with purified protein showed two populations significantly different from the susceptible strain on the second crop season in 2016. This number increased for the first and second crop seasons in 2017 in several regions. The genotypic monitoring estimated a mean frequency of the resistance allele of 0.0027 for the F1 screen and 0.0033 for the F2 screen. Three new resistant strains to Vip3Aa20 were selected from F2 screen assays. Complementation tests on these new resistant strains were positive with the previous resistant strain. CONCLUSION: Here we showed that the resistance allele of S. frugiperda to Vip3Aa20 protein is widely distributed in maize-producing regions in Brazil and its frequency increases throughout crop seasons. © 2019 Society of Chemical Industry.


Subject(s)
Spodoptera/genetics , Animals , Bacterial Proteins , Brazil , Endotoxins , Gene Frequency , Hemolysin Proteins , Insect Proteins , Insecticide Resistance , Larva , Plants, Genetically Modified , Zea mays
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