Eficácia de antiparasitários sobre Amblyomma sculptum in vitro e no semicampo: Estudo comparativo a Ripicephalus microplus
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Data
2022-06-02
Autores
Sousa, Gustavo Avelar
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Universidade Estadual Paulista (Unesp)
Resumo
O carrapato da espécie Amblyomma sculptum é o principal vetor do agente etiológico da Febre Maculosa Brasileira - FMB, provocando até mesmo casos letais desta enfermidade. Por isso, as ações preventivas dessa zoonose devem ser constantes. O carrapato bovino da espécie Rhipicephalus microplus é responsável por enormes perdas econômicas na pecuária nacional, especialmente devido à resistência que as populações adquiriram frente aos acaricidas químicos. Diante da importância de ambas as espécies, faz-se necessária a busca por métodos mais eficientes de controle, mais seguros e de menor impacto ambiental. Assim, este estudo teve por objetivo avaliar a eficácia de antiparasitários no controle de A. sculptum in vitro e em diferentes gramíneas (semicampo), por meio de metodologia adaptada. Foram executados testes de pacote com larvas (TPL) para determinação das CL50 e CL99 para a A. sculptum e R. microplus. Foram avaliados os antiparasitários Butox®, Colosso®, Triatox®, Demand®, Plenoway Top®, Regent®, Vertimec®. Demand®, Plenoway Top® e Vertimec® também foram avaliados quanto à sua ecotoxicidade sobre o nematoide da espécie Caenorhabditis elegans e no semicampo em Brachiaria brizantha cv. Marandu para A. sculptum, e em B. brizantha, Panicum maximum cv. BRS Zuri e Cynodon cv. Tifton 85 para R. microplus. Foi feita a infestação de cada parcela com 3 g de larvas, as quais foram coletadas das extremidades do capim pela técnica da bandeira de flanela para posterior contagem e determinação da eficácia larvicida. Para os produtos químicos avaliados no TPL, as CL50 e CL99 obtidas para A. sculptum, em mg/mL, foram 0,00003 e 0,0024, 0,00019 e 0,0026, 0,000069 e 0,030, 0,00046 e 0,014, 0,00005 e 0,0086, 0,00006 e 0,0081, e 0,025 e 1,39 para os produtos Butox®, Colosso® e Triatox®, Demand®, Plenoway Top® SC, Regent® e Vertimec®, respectivamente. Para R. microplus, em mg/mL, foram 0,0026 e 0,02, 0,007 e 0,04, 0,0054 e 0,095, 0,030 e 0,35, 0,035 e 0,26, 0,0015 e 0,009, e 0,040 e 0,56 para os mesmos produtos, respectivamente. No semicampo, Demand®, Plenoway Top® e Vertimec® apresentaram eficácia de 93,1%, 96,4% e 97,0%, respectivamente, sobre larvas de A. sculptum em Brachiaria. Para R. microplus, Demand® obteve eficácia de 80,8%, 95,1% e 75,2%, Plenoway Top® 87,8%, 97,9% e 88,8%, Vertimec® 40,7%, 56% e 6,2% para Brachiaria, Tifton e Zuri, respectivamente. As condições de macro e microclima não variaram entre gramíneas e favoreceram a sobrevivência das larvas, exceto pela ação da chuva em A. sculptum. Demand® e Plenoway Top® tiveram algum impacto na recuperação, crescimento e fertilidade de C. elegans no ensaio de ecotoxicidade. Este trabalho servirá de base para outras pesquisas que busquem alavancar o uso e o aperfeiçoamento do controle ambiental de larvas de ixodídeos, como também terá importância na saúde pública, no desenvolvimento de medidas de controle seguras e com mínimo impacto ambiental para a prevenção de doenças como a FMB.
The tick of the Amblyomma sculptum species is the main vector of the etiologic agent of the Brazilian Spotted Fever - BSF, causing even lethal cases of this disease. Therefore, preventive actions of this zoonosis must be constant. The bovine tick of the Rhipicephalus microplus species is responsible for enormous economic losses in national livestock, especially due to the resistance that populations have acquired against chemical acaricides. Given the importance of both species, it is necessary to search for more efficient methods of control, safer and with less environmental impact. Thus, this study aimed to evaluate the efficacy of antiparasitics in the control of A. sculptum in vitro and in different pastures (“semi-field”), through an adapted methodology. The results were also compared to those obtained with R. microplus. Larval package tests (LPT) were performed in order to determine the LC50 and LC99 for A. sculptum and R. microplus. The antiparasitics Butox®, Colosso® Pulverização,Triatox®, Demand®, Plenoway Top®, Regent® and Vertimec® were evaluated. Demand®, Plenoway Top® and Vertimec® were also evaluated for their ecotoxicity on nematodes of the species Caenorhabditis elegans and in the semi-field on Brachiaria brizantha cv. Marandu for A. sculptum, and in B. brizantha, Panicum maximum cv. BRS Zuri and Cynodon cv. Tifton 85 for R. microplus. Each plot was infested with 3 g of larvae, which were collected from the top of the grass using the flannel flag technique for later counting and determination of larvicidal efficacy. For the chemicals evaluated in the LPT, the LC50 and LC99 obtained for A. sculptum, in mg/mL, were 0.00003 and 0.0024, 0.00019 and 0.0026, 0.000069 and 0.030, 0.00046 and 0.014, 0.00005 and 0.0086, 0.00006 and 0.0081, and 0.025 and 1.39 for the products Butox®, Colosso®, Triatox® Demand® 10CS, Plenoway Top®, Regent® and Vertimec® 1.8%, respectively. For R. microplus, in mg/mL, they were 0.0026 and 0.02, 0.007 and 0.04, 0.0054 and 0.095, 0.030 and 0.35, 0.035 and 0.26, 0.0015 and 0.009, and 0.040 and 0.56 for the same products, respectively. In the semi-field with R. microplus, Demand® obtained efficacy of 80.8%, 95.1% and 75.2%, Plenoway Top® 87.8%, 97.9% and 88.8%, Vertimec® 40.7%, 56% and 6.2% for Brachiaria, Tifton and Zuri, respectively. The macro and microclimate conditions did not varied among grasses and favored the larvae survival, except for the action of rain on A. sculptum. Demand® and Plenoway Top® had some impact on recovery, growth and fertility of C. elegans in the ecotoxicity assay.This study will serve as a basis for other research that seeks to leverage the use and improvement of environmental control of ixodid larvae, as well as being important in public health, in the development of safe control measures with minimal environmental impact for the prevention of diseases such as the BSF.
The tick of the Amblyomma sculptum species is the main vector of the etiologic agent of the Brazilian Spotted Fever - BSF, causing even lethal cases of this disease. Therefore, preventive actions of this zoonosis must be constant. The bovine tick of the Rhipicephalus microplus species is responsible for enormous economic losses in national livestock, especially due to the resistance that populations have acquired against chemical acaricides. Given the importance of both species, it is necessary to search for more efficient methods of control, safer and with less environmental impact. Thus, this study aimed to evaluate the efficacy of antiparasitics in the control of A. sculptum in vitro and in different pastures (“semi-field”), through an adapted methodology. The results were also compared to those obtained with R. microplus. Larval package tests (LPT) were performed in order to determine the LC50 and LC99 for A. sculptum and R. microplus. The antiparasitics Butox®, Colosso® Pulverização,Triatox®, Demand®, Plenoway Top®, Regent® and Vertimec® were evaluated. Demand®, Plenoway Top® and Vertimec® were also evaluated for their ecotoxicity on nematodes of the species Caenorhabditis elegans and in the semi-field on Brachiaria brizantha cv. Marandu for A. sculptum, and in B. brizantha, Panicum maximum cv. BRS Zuri and Cynodon cv. Tifton 85 for R. microplus. Each plot was infested with 3 g of larvae, which were collected from the top of the grass using the flannel flag technique for later counting and determination of larvicidal efficacy. For the chemicals evaluated in the LPT, the LC50 and LC99 obtained for A. sculptum, in mg/mL, were 0.00003 and 0.0024, 0.00019 and 0.0026, 0.000069 and 0.030, 0.00046 and 0.014, 0.00005 and 0.0086, 0.00006 and 0.0081, and 0.025 and 1.39 for the products Butox®, Colosso®, Triatox® Demand® 10CS, Plenoway Top®, Regent® and Vertimec® 1.8%, respectively. For R. microplus, in mg/mL, they were 0.0026 and 0.02, 0.007 and 0.04, 0.0054 and 0.095, 0.030 and 0.35, 0.035 and 0.26, 0.0015 and 0.009, and 0.040 and 0.56 for the same products, respectively. In the semi-field with R. microplus, Demand® obtained efficacy of 80.8%, 95.1% and 75.2%, Plenoway Top® 87.8%, 97.9% and 88.8%, Vertimec® 40.7%, 56% and 6.2% for Brachiaria, Tifton and Zuri, respectively. The macro and microclimate conditions did not varied among grasses and favored the larvae survival, except for the action of rain on A. sculptum. Demand® and Plenoway Top® had some impact on recovery, growth and fertility of C. elegans in the ecotoxicity assay.This study will serve as a basis for other research that seeks to leverage the use and improvement of environmental control of ixodid larvae, as well as being important in public health, in the development of safe control measures with minimal environmental impact for the prevention of diseases such as the BSF.
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Palavras-chave
Carrapatos, antiparasitários, residuos, Gramíneas forrageiras, Pecuária