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Doctoral Thesis
DOI
10.11606/T.97.2012.tde-07102013-092237
Document
Author
Full name
Fernanda Menezes França Salgueiro
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Lorena, 2012
Supervisor
Committee
Paiva, Teresa Cristina Brazil de (President)
Ferreira, Jose Roberto
Grisolia, Cesar Koppe
Hipolito, Marcio
Mostério, Cláudia Maris Ferreira
Title in Portuguese
Avaliação da toxicidade de agrotóxicos utilizados na cultura do arroz irrigado para girinos de Lithobates catesbeianus
Keywords in Portuguese
Ecotoxicologia
Hematologia
Micronúcleo
Rã-touro
Abstract in Portuguese
Os girinos de rã-touro, Lithobates catesbeianus, podem ser bons bioindicadores de condições ambientais. O objetivo desse trabalho foi determinar o potencial de toxicidade para L. catesbeianus de alguns dos principais agrotóxicos utilizados no cultivo de arroz irrigado. Foram realizados testes de toxicidade aguda para a determinação da CL50-96h do bentazon, penoxsulam, óleo vegetal, permetrina e carbofuran, separadamente, e da mistura desses agrotóxicos. Com esses resultados foram estimados os índices de segurança dos produtos. Girinos em fase pré-metamorfose foram expostos aos agrotóxicos na própria lavoura de arroz e em laboratório por 21 dias, para avaliar os possíveis efeitos crônicos destas substâncias, separadamente e da mistura, sobre o quadro hematológico, metamorfose (regulada pelo eixo tiroideano), e também o possível potencial mutagênico através do teste do micronúcleo. A CL50-96h para girinos foi de 4530 mg/L para o bentazon; 7,52 mg/L para o penoxsulam + 145,66 mg/L do óleo vegetal; 81,57 mg/L para o óleo vegetal, 0,10 mg/L para a permetrina, 29,90 mg/L para o carbofuran (ingredientes ativos) e, 38,79 vezes a dose utilizada no campo para a mistura desses produtos. Foi determinado risco ambiental apenas para o inseticida permetrina. Nos testes in situ, as águas de irrigação não apresentaram toxicidade aguda para os girinos. A taxa de metamorfose não diferiu entre os tratamentos, demonstrando que os agrotóxicos utilizados nas doses indicadas não tem ação desreguladora do eixo tiroideano. As análises do micronúcleo mostraram aumento significativo de eritrócitos micronúcleoados para os testes in situ e, no laboratório, para o herbicida bentazon e para a mistura dos agrotóxicos. As análises hematológias mostraram diminuição da hemoglobina e número de eritrócitos no teste de campo, retornado aos padrões normais na semana seguinte. No laboratório houve queda na contagem de eritrócitos para o bentazon, aumento do VCM e HCM para o bentazon e penoxsulam; aumento do CHCM para o penoxsulam e para a mistura dos agrotóxicos. Para a série branca não houve diferenças no teste in situ, mas obtivemos aumento dos números de neutrófilos dos girinos tratados com o bentazon.
Title in English
Evaluation of toxicity of pesticides used in irrigated rice crops to Lithobates catesbeianus tadpoles
Keywords in English
Bullfrog
Ecotoxicology
Hematology
Micronuclei
Abstract in English
American bullfrogs, Lithobates catesbeianus could be good environmental indicators. The aim of this study was evaluate the potential toxicity of some principal pesticides used in irrigated rice crops to L. catesbeianus tadpoles. The pesticides Bentazon, Penoxsulam, Vegetable oil, Permetrina, Carbofuran and the mixture of them were assessed. Pre-metamorphose tadpoles were exposed to all of these agrochemicals in the laboratory to determinate de LC50-96h and so estimate the index of security by each product. Animals in the same phase were exposed to these pesticides on the rice crops, in situ and in laboratory per 21 days to evaluate the possible chronic effects of the substances, separated and in the mixture of them. The hematological results, red and white series, the mutagenic potential (micronucleous test), and the metamorphose rate (regulated by thyroid axis) were evaluated. The LC50-96h to tadpoles was 4530 mg/L to Bentazon; 7.52 + 145.66 mg/L to Penoxsulam + vegetable oil; 81.57 mg/L to vegetable oil; 0.10 mg/L to Permetrina; 29.90 mg/L to Carbofuran (active ingredients) and 38.79 times to the dose used in the field to the mixture of the products. Only to Permetrina insecticide was observed environmental risk. The metamorphose rate showed no difference between the treatments suggesting that these pesticides, used on indicated doses did not promote deregulated action on the thyroid axis. In situ tests the irrigated waters showed low mortality to the animals. The red series showed in situ, a decrease in the haemoglobin tax and in the counting of erytrocyte's number however return to the normal values in the follow week. In laboratory tests showed a decrease in the counting of erytrocyte's number to the animals exposed to Bentazon, an increase in the MCV and MCH to the animals exposed to Bentazon and Penoxsulam, an increase in the MCHC to those exposed to Penoxsulam and to the "mixture". The white series showed no difference in situ test however an increase in the neutrophils number was observed to the animals exposed to Bentazon in laboratory. The micronucleous analyze showed significant increase in the erytrocyte's micronucleated number in situ and in laboratorial tests to animals exposed to Bentazon and to the "mixture".
 
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Publishing Date
2013-10-07
 
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