Anticarsia gemmatalis (Lepidoptera: Erebidae): resistência de genótipos de soja, caracterização de movimentação larval e interação intraguilda com Chrysodeixis includens (Lepidoptera: Noctuidae)
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Data
2021-06-02
Autores
Ongaratto, Sabrina [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A produtividade da soja é frequentemente reduzida devido a injurias causadas por inúmeras pragas. Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae) é uma dessas pragas e é considerada um dos mais importantes insetos desfolhadores da cultura. Além disso, Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae) tem se tornado um sério problema fitossanitário para a cultura, com vários surtos ocorrendo isolados ou associados a A. gemmatalis. Além da ocorrência no Brasil, essas espécies também ocorrem em diferentes regiões produtoras de soja dos Estados Unidos. O uso de materiais resistentes é uma ferramenta valiosa para o manejo desses lepidópteros em substituição ou em associação aos inseticidas sintéticos. Porém a rápida adoção de culturas Bt (soja geneticamente modificada) pelo mundo tem ocasionado uma contínua pressão de seleção das proteínas Cry sobre esses lepidópteros, o que pode resultar em populações resistentes, com consequentes falhas de controle. Assim, considerando a importância da soja, a expansão do cultivo com culturas Bt e o respectivo impacto na entomofauna, um entendimento mais profundo sobre o comportamento larval tem se tornado cada vez mais necessário. Os objetivos desta pesquisa foram: i) caracterizar a possível resistência de 30 genótipos de soja a A. gemmatalis por meio de testes em casa de vegetação e laboratório; ii) caracterizar o movimento larval de A. gemmatalis “na planta” e “entre plantas” de soja não Bt a campo e; iii) investigar as interações intra e interespecífica envolvendo A. gemmatalis e C. includens em laboratório. Os resultados dos ensaios de resistência a A. gemmatalis revelaram a expresssão de antixenose (oviposição, atratividade e/ou consumo) nos genótipos 'TMG 133' RR, 'TMG 1179' RR, 'IAC 19', 'IAC 17', 'IAC 100', D75-10169 e IAC 78-2318. Os genótipos IAC 74-2832, 'IAC 19', 'IAC 17', 'IAC 100' e PI 274454 afetaram o comportamento e também impactaram negativamente a viabilidade larval, indicando a expresssão de antixenose e/ou antibiose. 'TMG 7062' IPRO afetou negativamente o desenvolvimento e a viabilidade larval, indicando uma possível expresssão de antibiose, além de baixo grau de antixenose. Os genótipos ‘IAC 19’, ‘IAC 24, ‘IAC 17’ e ‘IAC 100’ expressaram antibiose por comprometer diferentes parâmetros biológicos, principalmente o desenvolvimento larval, viabilidade e reduzir o peso de pupas. Devido à redução da ingestão foliar por larvas em confinamento, a antixenose foi também caracterizada em 'IAC 24'. Os testes de movimentação na planta mostraram que A. gemmatalis tem um comportamento bastante ativo durante o dia, especialmente em instares avançados de desenvolvimento. Verificou-se que as lagartas variam quanto à posição em que são encontradas na planta e na folha ao longo do período de observação. Quanto à movimentação entre plantas, lagartas de A. gemmatalis podem mover-se por longas distâncias (até 2 m) a partir da planta infestada de uma maneira não direcional. Os resultados do teste de fitness e de rastreamento por vídeo, mostraram que A. gemmatalis tem vantagem competitiva sobre C. includens. Nosso estudo apresenta relevantes descobertas envolvendo a interação dos dois lepidópteros em soja. Os genótipos com indicativo de resistência podem ser utilizados em programas de melhoramento visando à resistência de genótipos a A. gemmatalis e possivelmente a outros insetos desfolhadores. Os resultados obtidos nos testes de movimentação poderão auxiliar na escolha do momento ideal para pulverizações com inseticidas, entomopatógenos e liberação de organismos biológicos, além de auxiliar na escolha de estratégias de manejo mais assertivas. Ainda, a interação entre A. gemmatalis e C. includens poderá contribuir para um melhor entendimento do comportamento e da dinâmica de populações. Esse conjunto de informações podem auxiliar nos programas de Manejo Integrado de Pragas (MIP) e no Manejo de Resistência de Insetos (MRI) na cultura da soja.
Soybean yield is often reduced because of the injury caused by numerous pests. Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae) is one such pest and is considered one of the most important defoliating insects of the crop. In addition, Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae) has recently become a serious phytosanitary problem for the crop, with several outbreaks occurring in isolation or associated with A. gemmatalis. Besides the ocurrence in Brazil, these species also occur in different United States soybean production regions. The use of resistant materials is a valuable tool for the management of these lepidopterans in replacement or being used in association with synthetic insecticides. However, the rapid widespread adoption of Bt crops (genetically modified soybean) worldwide has caused a continuous selection pressure by Cry proteins on these lepidopteran pests, which may result in the resistant populations, with unsucessfull control. Thus, considering the importance of soybean, the expansion of the cultivation Bt crops and its impact on entomofauna, a deeper understanding of larval behavior has become increasingly necessary. The objectives of this research were to: i) to characterize the possible resistance of 30 soybean genotypes to A. gemmatalis through greenhouse and laboratory tests; ii) to characterize larval "on-plant" and "plant-to-plant" movement of A. gemmatalis on non-Bt soybean in the field and; iii) to investigate intra and interspecific interactions involving A. gemmatalis and C. includens in the laboratory. The resistance results showed antixenosis expression (oviposition, attractiveness and foliar intake) in genotypes ‘TMG 133’ RR, ‘TMG 1179’ RR, ‘IAC 19’, ‘IAC 17’, ‘IAC 100’, D75-10169, and IAC 78-2318. The genotypes IAC 74-2832, ‘IAC 19’, ‘IAC 17’, ‘IAC 100’, and PI 274454 affected behavior and also negatively impacted larval viability, indicating antixenosis and/or antibiosis expression. ‘TMG 7062’ IPRO negatively affected larval development and viability, indicating a possible antibiosis expression, in addition to low degree of antixenosis. Genotypes ‘IAC 19’, ‘IAC 24, ‘IAC 17’, and ‘IAC 100’ were shown to express antibiosis resistance by compromising several biological parameters, mainly larval development and viability, and reducing pupal weight. Due to the reduction of foliar intake by confined larvae, antixenosis was also characterized in ‘IAC 24’. On-plant movement tests showed that A. gemmatalis has a very active behavior during the day, especially in advanced instars. It was found that larvae vary according to the position in which they are found on the plant and leaf thoughout the observation period. Regarding plant-to-plant movement, A. gemmatalis larvae can move long distances (up to 2 m) from the infested plant in a nondirectional manner. The results of the fitness test and video tracking showed that A. gemmatalis has a competitive advantage over C. includens. Our study provides relevant findings involving the interaction of the two lepidopterans in soybean. Genotypes with indications of resistance might be used in breeding programs aimed at finding genotypes resistant to A. gemmatalis and possibly to other leaf-feeding insects. The results obtained in the movement tests may help in choosing the better time for insecticide, entomopathogens and releasing of biological enemy application, besides assisting in the choice of more assertive management strategies. Furthermore, the interaction between A. gemmatalis and C. includens could contibute to a better understanding of behavior and populations dynamics. This body of information can assist Integrated Pest Management (IPM) and Insect Resistance Management (IRM) programs for soybean.
Soybean yield is often reduced because of the injury caused by numerous pests. Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae) is one such pest and is considered one of the most important defoliating insects of the crop. In addition, Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae) has recently become a serious phytosanitary problem for the crop, with several outbreaks occurring in isolation or associated with A. gemmatalis. Besides the ocurrence in Brazil, these species also occur in different United States soybean production regions. The use of resistant materials is a valuable tool for the management of these lepidopterans in replacement or being used in association with synthetic insecticides. However, the rapid widespread adoption of Bt crops (genetically modified soybean) worldwide has caused a continuous selection pressure by Cry proteins on these lepidopteran pests, which may result in the resistant populations, with unsucessfull control. Thus, considering the importance of soybean, the expansion of the cultivation Bt crops and its impact on entomofauna, a deeper understanding of larval behavior has become increasingly necessary. The objectives of this research were to: i) to characterize the possible resistance of 30 soybean genotypes to A. gemmatalis through greenhouse and laboratory tests; ii) to characterize larval "on-plant" and "plant-to-plant" movement of A. gemmatalis on non-Bt soybean in the field and; iii) to investigate intra and interspecific interactions involving A. gemmatalis and C. includens in the laboratory. The resistance results showed antixenosis expression (oviposition, attractiveness and foliar intake) in genotypes ‘TMG 133’ RR, ‘TMG 1179’ RR, ‘IAC 19’, ‘IAC 17’, ‘IAC 100’, D75-10169, and IAC 78-2318. The genotypes IAC 74-2832, ‘IAC 19’, ‘IAC 17’, ‘IAC 100’, and PI 274454 affected behavior and also negatively impacted larval viability, indicating antixenosis and/or antibiosis expression. ‘TMG 7062’ IPRO negatively affected larval development and viability, indicating a possible antibiosis expression, in addition to low degree of antixenosis. Genotypes ‘IAC 19’, ‘IAC 24, ‘IAC 17’, and ‘IAC 100’ were shown to express antibiosis resistance by compromising several biological parameters, mainly larval development and viability, and reducing pupal weight. Due to the reduction of foliar intake by confined larvae, antixenosis was also characterized in ‘IAC 24’. On-plant movement tests showed that A. gemmatalis has a very active behavior during the day, especially in advanced instars. It was found that larvae vary according to the position in which they are found on the plant and leaf thoughout the observation period. Regarding plant-to-plant movement, A. gemmatalis larvae can move long distances (up to 2 m) from the infested plant in a nondirectional manner. The results of the fitness test and video tracking showed that A. gemmatalis has a competitive advantage over C. includens. Our study provides relevant findings involving the interaction of the two lepidopterans in soybean. Genotypes with indications of resistance might be used in breeding programs aimed at finding genotypes resistant to A. gemmatalis and possibly to other leaf-feeding insects. The results obtained in the movement tests may help in choosing the better time for insecticide, entomopathogens and releasing of biological enemy application, besides assisting in the choice of more assertive management strategies. Furthermore, the interaction between A. gemmatalis and C. includens could contibute to a better understanding of behavior and populations dynamics. This body of information can assist Integrated Pest Management (IPM) and Insect Resistance Management (IRM) programs for soybean.
Descrição
Palavras-chave
Host plant resistance, Antixenosis, Antibiosis, Fitness, Larval behavior, Lepidoptera, Resistência de plantas a insetos, Antixenose, Antibiose, Comportamento larval