Estratégia de mistura de sementes em eventos de milho bt “piramidado” a Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae)
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Data
2018-11-09
Autores
Nogueira, Luciano [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os eventos de milho Bt que expressam as proteínas de Bacillus thuringiensis (Bt) Berliner são importantes ferramentas para o manejo da lagarta-docartucho, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Um dos problemas associados ao cultivo de plantas Bt, tem sido a ausência de nãoconformidade dos refúgios e eventos que não apresentam alta dose da proteína inseticida. A estratégia de mistura de sementes tem sido utilizada como uma ferramenta para tentar reduzir a baixa adoção de áreas de refúgio. No entanto, existe uma grande preocupação com relação a sua eficácia em retardar a evolução da resistência, principalmente em relação a movimentação e sobrevivência da praga. Assim, o presente trabalho teve como objetivo avaliar: 1) em condições de laboratório, a sobrevivência e o desenvolvimento de lagartas de S. frugiperda expostas ao longo da fase larval em milho Bt piramidado e não-Bt; 2) em casa de vegetação, a mobilidade das lagartas em quatro esquemas de plantio e, 3) em campo, avaliar a estratégia de mistura de sementes, em quatro proporções de mistura de sementes (2,5; 5,0; 7,5; e 10,0%) (Bt: não-Bt), nas safras (verão e inverno) em dois anos agrícolas em 2016 e 2017. Para a condução dos experimentos foram utilizadas as tecnologias de milho Agrisure Viptera 3110 e YieldGard VT Pro 3 e suas respectivas linhas isogências (não-Bt). Na avaliação de sobrevivência e desenvolvimento, as lagartas de S. frugiperda expostas no milho Agrisure Viptera 3110 não completaram o desenvolvimento. As lagartas expostas ao longo do desenvolvimento no milho YieldGard VT Pro 3 sobreviveram, demonstrando que as proteínas Cry não controlam eficientemente as lagartas nos estágios finais de desenvolvimento. As lagartas de S. frugiperda foram capazes de se dispersar por até 1,20 m da planta de infestação nos esquemas de plantio com plantas não-Bt, tanto na linha de infestação, quanto nas linhas adjacentes. Quando dispostas no plantio com apenas plantas Bt, as lagartas foram eficientemente controladas pelos eventos de milho Bt. Os resultados de campo evidenciaram que a estratégia de mistura de sementes com Agrisure Viptera 3110 controla eficientemente as lagartas. No milho Yeldgard VT Pro 3 foi verificado alta incidência de plantas com injúrias causadas por S. frugiprerda, principalmente nas safras de inverno. Os resultados de sobrevivência, movimentação e a alta incidência de injúrias nas plantas Bt em campo, com YeldGard VT Pro 3 demonstram que a estratégia de mistura de sementes pode não ser efetiva como uma estratégia de MRI para retardar a evolução da resistência a S. frugiperda. Os resultados observados neste estudo fornecem informações importantes em relação a estratégia de mistura de sementes para o manejo de resistência de S. frugiperda em áreas de milho Bt.
Maize events expressing Bacillus thuringiensis (Bt) Berliner proteins are important tools for the management of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) (J.E. Smith). One problem associated with the cultivation of Bt plants is the difficulty in complying with refuge regulations by implementing events that do not produce high doses of insecticidal protein. The seed mixture strategy has been used as a tool to try to increase the adoption of refuge areas. However, there is great concern about their effectiveness in slowing the evolution of resistance, especially in relation to movement and pest survival. Thus, the objective of the present study was to evaluate the following: 1) the survival and development of S. frugiperda larvae exposed along the larval stage in “pyramided” Bt maize under laboratory conditions, 2), the mobility of larvae in four planting patterns under greenhouse conditions, and 3) the strategy of seed mixture under field conditions, in four Bt proportions (2.5, 5.0, 7.5, and 10.0%) (Bt: non-Bt), for two seasons (summer and winter crop) in 2016 and 2017. Agrisure Viptera 3110 and YieldGard VT Pro 3 maize hybrids and their respective isolines (non-Bt) were used to conduct the experiments. In the evaluation of survival and development, the S. frugiperda larvae exposed to Agrisure Viptera 3110 maize did not survive. Some larvae exposed to YieldGard VT Pro 3 throughout their development survived, demonstrating that Cry proteins do not efficiently control the larvae in late stages of development. S. frugiperda larvae were dispersed up to 1.20 m from the central plant in the planting patterns with non-Bt plants, both in the infestation line and adjacent lines. In the planting patterns with only Bt plants, fall armyworm larvae were efficiently controlled by the Bt maize hybrids. The field results showed that the seed mixture strategy with Agrisure Viptera 3110 efficiently controls larvae. There were incidences of S. frugiperda survival in Yeldgard VT Pro 3, with higher incidences in the winter crops under farm conditions in both years. The results of survival, movement, and high field incidence of injuries in field Bt plants with the Yeldgard VT Pro 3 hybrid demonstrate that the seed mixture strategy may not be effective as an insecticide resistance management (IRM) strategy to delay the evolution of resistance to S. frugiperda. The results of this study provide important information regarding the seed mixture strategy for the resistance management of S. frugiperda.
Maize events expressing Bacillus thuringiensis (Bt) Berliner proteins are important tools for the management of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) (J.E. Smith). One problem associated with the cultivation of Bt plants is the difficulty in complying with refuge regulations by implementing events that do not produce high doses of insecticidal protein. The seed mixture strategy has been used as a tool to try to increase the adoption of refuge areas. However, there is great concern about their effectiveness in slowing the evolution of resistance, especially in relation to movement and pest survival. Thus, the objective of the present study was to evaluate the following: 1) the survival and development of S. frugiperda larvae exposed along the larval stage in “pyramided” Bt maize under laboratory conditions, 2), the mobility of larvae in four planting patterns under greenhouse conditions, and 3) the strategy of seed mixture under field conditions, in four Bt proportions (2.5, 5.0, 7.5, and 10.0%) (Bt: non-Bt), for two seasons (summer and winter crop) in 2016 and 2017. Agrisure Viptera 3110 and YieldGard VT Pro 3 maize hybrids and their respective isolines (non-Bt) were used to conduct the experiments. In the evaluation of survival and development, the S. frugiperda larvae exposed to Agrisure Viptera 3110 maize did not survive. Some larvae exposed to YieldGard VT Pro 3 throughout their development survived, demonstrating that Cry proteins do not efficiently control the larvae in late stages of development. S. frugiperda larvae were dispersed up to 1.20 m from the central plant in the planting patterns with non-Bt plants, both in the infestation line and adjacent lines. In the planting patterns with only Bt plants, fall armyworm larvae were efficiently controlled by the Bt maize hybrids. The field results showed that the seed mixture strategy with Agrisure Viptera 3110 efficiently controls larvae. There were incidences of S. frugiperda survival in Yeldgard VT Pro 3, with higher incidences in the winter crops under farm conditions in both years. The results of survival, movement, and high field incidence of injuries in field Bt plants with the Yeldgard VT Pro 3 hybrid demonstrate that the seed mixture strategy may not be effective as an insecticide resistance management (IRM) strategy to delay the evolution of resistance to S. frugiperda. The results of this study provide important information regarding the seed mixture strategy for the resistance management of S. frugiperda.
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Palavras-chave
Lagarta-do-cartucho, Manejo de resistência, Refúgio na sacaria, Movimentação larval, Piramidação de genes