Biologia de Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) exposta a inseticidas durante a fase larval
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Data
2004-08-27
Autores
Silva, Rosemery Ferraz da [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A localização das lagartas de Spodoptera frugiperda no interior do cartucho-do-milho, muitas vezes, dificulta a absorção da dose de inseticida necessária a sua morte, de tal forma que uma porcentagem significativa de insetos absorvem doses subletais, sofrendo evidentemente alterações na sua biologia e capacidade reprodutiva. Dessa forma, esse trabalho se propôs a verificar a ação de diferentes concentrações de clorpirifós, deltametrina e lufenuron no desenvolvimento larval e performance biológica de S. frugiperda em dieta artificial e natural (folhas de milho) sob condições controladas (em temperatura de 25 +/- 2ºC, umidade relativa de 70 % e fotofase de 14 horas). Folhas de milho foram mergulhadas em soluções contendo clorpirifós nas concentrações 0,15; 0,25; 0,35; 0,50; 0,75; 1,00; 2,00; 4,00; 8,00; 16,00 e 32,00 ppm, deltametrina nas concentrações 0,20 e 0,40 ppm e lufenuron nas concentrações 0,20; 0,50 e 1,00 ppm, em seguida fornecidas para as lagartas, 48 horas após a eclosão. Também foram preparadas dietas artificiais específicas para S. frugiperda contendo os mesmos inseticidas nas respectivas concentrações, onde foram inoculadas lagartas com 48 horas de idade. As observações de mortalidade e desenvolvimento foram realizadas em dias alternados e os dados comparados ao tratamento testemunha, sem tóxico. Verificou-se que as lagartas que se alimentaram tanto em dieta artificial quanto no alimento natural contaminado pelos inseticidas deltametrina e lufenuron não atingiram a fase de pupa, no entanto, muitas lagartas permaneceram vivas por mais tempo do que o período de duração da fase larval da testemunha. Os tratamentos com clorpirifós, apesar de provocarem uma alta mortalidade de lagartas só inviabilizaram a obtenção de adultos a partir da concentração 8,00 ppm. Mesmo nas doses menores,...
The localization of Spodoptera frugiperda larvae in the inner part of maize whorl, turns difficult the absorption of the necessary insecticide dosage to provoke insect mortality, what means that in field conditions, a significant percentage of the insects absorbs sub-lethal dosages, showing evident modifications on their biology and reproduction capacity. This way, the aim of this research was to verify the action of concentrations chlorpyrifos, deltamethrin and lufenuron on larval development and on the biological performance of S. frugiperda fed on artificial and natural diets. Maize leaves were dip in solutions of clorpyrifos at 0.15, 0.25, 0.35, 0.50, 0.75, 1.00, 2.00, 4.00, 8.00, 16.00 and 32.00 ppm, deltamethrin at 0.2 and 0.4 ppm and lufenuron at 0.2, 0.5 and 1.00 ppm. These leaves were immediately offered to 48 hours larvae. Artificial diets, specially developed for S. frugiperda, were also prepared containing the same insecticides at the same concentrations to receive larvae with 48 hours old. The observations of mortality and development were obtained every other day and the data were compared to a check treatment, with no insecticide. It was possible to verify that the larvae fed on artificial or natural diets containing deltamethrin and lufenuron, did not reach the pupal stage, however, many of them stayed alive for a period superior than that observed for the check treatment. The clorpyrifos treatment, dispite its high larval mortality, turned difficult the obtaining of adults from concentration of 8.00 ppm on. Even at low dosages, many survival larvae died during the pupal phase; only for 16.00 and 32.00 ppm the larval mortality reached 100%. When insects are exposed to sub-lethal dosages of insecticides during their larval period of development, they can increase their life cycle, even when they do not afford the insecticide action, nevertheless, those insects that reach the adult stage, do not show any life cycle modifications.
The localization of Spodoptera frugiperda larvae in the inner part of maize whorl, turns difficult the absorption of the necessary insecticide dosage to provoke insect mortality, what means that in field conditions, a significant percentage of the insects absorbs sub-lethal dosages, showing evident modifications on their biology and reproduction capacity. This way, the aim of this research was to verify the action of concentrations chlorpyrifos, deltamethrin and lufenuron on larval development and on the biological performance of S. frugiperda fed on artificial and natural diets. Maize leaves were dip in solutions of clorpyrifos at 0.15, 0.25, 0.35, 0.50, 0.75, 1.00, 2.00, 4.00, 8.00, 16.00 and 32.00 ppm, deltamethrin at 0.2 and 0.4 ppm and lufenuron at 0.2, 0.5 and 1.00 ppm. These leaves were immediately offered to 48 hours larvae. Artificial diets, specially developed for S. frugiperda, were also prepared containing the same insecticides at the same concentrations to receive larvae with 48 hours old. The observations of mortality and development were obtained every other day and the data were compared to a check treatment, with no insecticide. It was possible to verify that the larvae fed on artificial or natural diets containing deltamethrin and lufenuron, did not reach the pupal stage, however, many of them stayed alive for a period superior than that observed for the check treatment. The clorpyrifos treatment, dispite its high larval mortality, turned difficult the obtaining of adults from concentration of 8.00 ppm on. Even at low dosages, many survival larvae died during the pupal phase; only for 16.00 and 32.00 ppm the larval mortality reached 100%. When insects are exposed to sub-lethal dosages of insecticides during their larval period of development, they can increase their life cycle, even when they do not afford the insecticide action, nevertheless, those insects that reach the adult stage, do not show any life cycle modifications.
Descrição
Palavras-chave
Inseticidas, Inseticidas - concentração, Insecticides
Como citar
SILVA, Rosemery Ferraz da. Biologia de Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) exposta a inseticidas durante a fase larval. 2004. viii, 49 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agronômicas de Botucatu, 2004.