Compatibilidade, efeitos letais e subletais de misturas de bioinseticidas à base de Bacillus thuringiensis e inseticidas em Chrysodeixis includens
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Data
2020-07-24
Autores
Gonçalves, Kelly Cristina
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Inseticidas e Bt bioinseticidas são utilizados em mistura em tanque principalmente para aumentar a eficiência de controle de pragas e otimizar as operações agrícolas. O presente estudo objetivou avaliar em laboratório a compatibilidade in vitro de inseticidas e Bt bioinseticidas e os seus efeitos letais e subletais em Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae), importante praga da cultura da soja. A compatibilidade in vitro dos Bt bioinseticidas Dipel SC® e Thuricide PM® e oito inseticidas (Ampligo SC®, Avatar CE®, Belt SC®, Curyom CE®, Exalt SC®, Lannate SL®, Larvin 800 WG® e Prêmio SC®) foi avaliada em 74 tratamentos (combinações) com 15 repetições cada. Os parâmetros crescimento vegetativo (cm2) e esporulação (esporos.mL-1) permitiram o cálculo de T, que classifica a interação em compatível, moderadamente tóxica, tóxica e muito tóxica. Posteriormente, para os testes de mortalidade uma suspensão contendo 3 x 108 esporos.mL-1 de 82 tratamentos (72 combinações entre inseticidas e os bioinseticidas e estes isoladamente) foi testada para lagartas de segundo ínstar de C. includens. A mortalidade foi avaliada um dia e sete dias após a aplicação dos tratamentos e relacionada com o índice T. A massa das lagartas sobreviventes foi avaliada nove, 11, 13, 15 e 19 dias após aplicação dos tratamentos, bem como a massa de pupa no segundo dia desse estágio. Todos os inseticidas foram compatíveis in vitro com o Thuricide PM® e 45% deles foram compatíveis para o Dipel SC®, enquanto oito foram moderadamente tóxicos e muito tóxicos e 10 tóxicos. O inseticida Exalt SC® apresentou maior compatibilidade in vitro com os bioinseticidas Thuricide PM® e Dipel SC®. A mortalidade no primeiro dia foi afetada por todos as misturas, enquanto no sétimo dia a influência dos tratamentos foi menor. Nem sempre foi constatada correlação positiva entre os parâmetros de T e a mortalidade, o que demonstra que a compatibilidade in vitro não prediz a mortalidade em laboratório. 1.805 (21,75%) lagartas sobreviveram em 41 misturas e somente 687 empuparam. Em seis das 31 misturas com três produtos a sobrevivência foi maior que 80%. Na primeira avaliação, as lagartas submetidas aos diferentes tratamentos apresentaram pesos maiores, mas também por vezes menores do que a testemunha; a maioria das mais pesadas empuparam antes do que a testemunha, e a maioria das menos pesadas morreram e, com algumas alogando o ciclo. Os efeitos subletais do tratamento Thuricide PM®+ Larvin WG 800® + Prêmio SC® em lagartas de C. includens foram menos severos, com 94,5% delas empupando, enquanto que em outros 16 tratamentos nenhuma lagarta empupou. A formulação granulo dispersível (WG) do inseticida Larvin WG 800®, favoreceu a sobrevivência dos indivíduos. Fatores como formulação dos produtos, especialmente a granulo dispersível, e seus inertes, bem como o modo de ação, afetam a eficiência da mistura de produtos químicos e biológicos
- Pesticides and Bt based biopesticides are used in tank mixes mainly to increase pest control efficiency and optimize agricultural operations. The present study aimed to evaluate in laboratory the in vitro compatibility of pesticides and Bt based biopesticides and their lethal and sublethal effects to Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae), an important pest in soybean. The in vitro compatibility of Bt based biopesticides Dipel SC® and Thuricide WP® and eight insecticides (Ampligo SC®, Avatar EC®, Belt SC®, Curyom EC®, Exalt SC®, Lannate LS®, Larvin 800 WG® and Prêmio SC®) was evaluated in 74 treatments (combinations) with 15 repetitions each. The vegetative growth (cm2 ) and sporulation (spores.mL-1 ) parameters allowed the calculation of T, which classified the interaction as compatible, moderately toxic, toxic and very toxic. Subsequently, for mortality tests, a suspension containing 3 x 108 spores.mL-1 from 82 treatments (72 combinations between pesticides and Bt based biopesticides and these alone) was tested for second instar C. includens larvae. Mortality was assessed one day and seven days after the treatments and related to the T index. The weight of the surviving larvae was evaluated nine, 11, 13, 15 and 19 days after application of the treatments, as well as the pupal weight on the second day of this stage. All pesticides were compatible in vitro with Thuricide WP® and 45% of them were compatible with Dipel SC®, while eight were moderately toxic and very toxic and 10 toxics. Exalt SC® was more compatible in vitro with both biopesticides. Mortality on the first day was affected by all mixtures while on the seventh day the influence of treatments was lesser. A positive correlation between T parameters and mortality has not always been found, which demonstrates that in vitro compatibility does not predict laboratory mortality. 1,805 (21.75%) larvae survived in 41 mixtures and only 687 pupate. In six of the 31 mixtures with three products, survival was higher than 80%. In the first evaluation between treatments, the larvae were more or less heavy than the control; the majority of the heavier ones pupate before the control, and the majority of those with lower weight died and, some extended the cycle until the end of the evaluation. The sublethal effects of the Thuricide PM® + Larvin WG 800® + Prêmio SC® treatment on C. includens larvae were less severe, with 94.5% of them pupate, while in the other 16 treatments no larvae became pupae. The dispersible granule (WG) formulation of the insecticide Larvin WG 800®, favored the survival of individuals. Factors such as product formulation, especially in water dispersible granules, and their inert as well as the mode of action affect the efficiency of mixing chemical and biological products.
- Pesticides and Bt based biopesticides are used in tank mixes mainly to increase pest control efficiency and optimize agricultural operations. The present study aimed to evaluate in laboratory the in vitro compatibility of pesticides and Bt based biopesticides and their lethal and sublethal effects to Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae), an important pest in soybean. The in vitro compatibility of Bt based biopesticides Dipel SC® and Thuricide WP® and eight insecticides (Ampligo SC®, Avatar EC®, Belt SC®, Curyom EC®, Exalt SC®, Lannate LS®, Larvin 800 WG® and Prêmio SC®) was evaluated in 74 treatments (combinations) with 15 repetitions each. The vegetative growth (cm2 ) and sporulation (spores.mL-1 ) parameters allowed the calculation of T, which classified the interaction as compatible, moderately toxic, toxic and very toxic. Subsequently, for mortality tests, a suspension containing 3 x 108 spores.mL-1 from 82 treatments (72 combinations between pesticides and Bt based biopesticides and these alone) was tested for second instar C. includens larvae. Mortality was assessed one day and seven days after the treatments and related to the T index. The weight of the surviving larvae was evaluated nine, 11, 13, 15 and 19 days after application of the treatments, as well as the pupal weight on the second day of this stage. All pesticides were compatible in vitro with Thuricide WP® and 45% of them were compatible with Dipel SC®, while eight were moderately toxic and very toxic and 10 toxics. Exalt SC® was more compatible in vitro with both biopesticides. Mortality on the first day was affected by all mixtures while on the seventh day the influence of treatments was lesser. A positive correlation between T parameters and mortality has not always been found, which demonstrates that in vitro compatibility does not predict laboratory mortality. 1,805 (21.75%) larvae survived in 41 mixtures and only 687 pupate. In six of the 31 mixtures with three products, survival was higher than 80%. In the first evaluation between treatments, the larvae were more or less heavy than the control; the majority of the heavier ones pupate before the control, and the majority of those with lower weight died and, some extended the cycle until the end of the evaluation. The sublethal effects of the Thuricide PM® + Larvin WG 800® + Prêmio SC® treatment on C. includens larvae were less severe, with 94.5% of them pupate, while in the other 16 treatments no larvae became pupae. The dispersible granule (WG) formulation of the insecticide Larvin WG 800®, favored the survival of individuals. Factors such as product formulation, especially in water dispersible granules, and their inert as well as the mode of action affect the efficiency of mixing chemical and biological products.
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Palavras-chave
Mistura em tanque, Lagarta falsa medideira, Controle microbiano, Controle químico, Parâmetros biológicos