Respostas fisiológicas e espectrais de plantas de milho infestadas por Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) e Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae)
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2023-07-10
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Universidade Estadual Paulista (Unesp)
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O sensoriamento remoto vem se tornando uma alternativa relevante na otimização do monitoramento de pragas agrícolas. Contudo, antes de propor o uso de sensores como uma solução a detecção de ataque insetos, é essencial conhecer a resposta espectral de plantas sob diferentes tipos de estresses. Neste estudo foram determinados parâmetros de trocas gasosas e o comportamento espectral de plantas de milho em casa de vegetação infestadas por Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) e Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), a fim de investigar respostas fisiológicas e bandas espectrais sensíveis às diferentes injúrias causadas por estes insetos. Para isso, plantas de milho em estádio de desenvolvimento V5 foram aleatoriamente distribuídas em quatro tratamentos: plantas não infestadas, plantas infestadas por D. saccharalis, plantas infestadas por S. frugiperda e plantas infestadas por ambas as espécies. As medições da reflectância espectral foram realizadas por meio do sensor hiperespectral configurado para adquirir imagens em 50 bandas entre 500 e 900 nm. Ainda, a resposta fisiológica, dado por parâmetros de assimilação, concentração de CO2 subestomatal, condutância estomática, déficit de vapor entre folha e ar e eficiência de uso da água fotossintética também foram obtidos utilizando sistema portátil de medição de fotossíntese. As leituras espectrais e fisiológicas foram realizadas em seis dias distintos durante o período de 14 dias de desenvolvimento larval. Ao final deste período, todas as plantas foram seccionadas para constatação de sucesso de infestação e somente as plantas infestadas foram consideradas nas análises. Modelos de classificação criados a partir dos espectros de reflectância médios permitiram a discriminação de plantas sadias e plantas com os estressores, sobretudo na região do visível (666,36 nm) para plantas com S. frugiperda e infravermelho próximo (866,05 nm) para plantas com D. saccharalis. Não houve diferença relevante nos parâmetros de troca gasosa entre plantas sadias e infestadas durante o período avaliado. Esses resultados indicam que o sensor imageador hiperespectral tem potencial para ser utilizado em atividades de monitoramento dessas pragas. Como não houve alterações significativas nos parâmetros de trocas gasosas, as mudanças espectrais provavelmente ocorreram por modificações estruturais internas das folhas ocasionadas pelas injúrias desses insetos.
Remote sensing is becoming a relevant alternative in optimizing the monitoring of agricultural pests. However, before proposing the use of sensors as a solution for insect detection, it is essential to know the spectral response of plants under different types of stress. In this study, gas exchange parameters and the spectral behavior of maize plants in the greenhouse infested by Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) and Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) were determined in order to investigate physiological responses and spectral bands sensitive to the different injuries caused by these insects. For this, maize plants at V5 developmental stage were randomly assigned to four treatments: non-infested plants, plants infested by D. saccharalis, plants infested by S. frugiperda and plants infested by both species. Spectral reflectance measurements were performed using hyperspectral sensor configured to acquire images in 50 bands between 500 and 900 nm. The physiological response given by parameters of assimilation, substomatal CO2 concentration, stomatal conductance, vapor deficit between leaf and air and photosynthetic water use efficiency were also obtained using a portable photosynthesis system. Spectral and physiological readings were performed on six different days during the 14-day period of larval development. At the end of this period, all plants were sectioned to verify successful infestation and only infested plants were considered in the analyses. Classification models created from the average reflectance spectra allowed the discrimination of healthy plants and plants with stressors, especially in the visible region (666.36 nm) for plants with S. frugiperda and near infrared (866.05 nm) for plants with D. saccharalis. There was no relevant difference in gas exchange parameters between healthy and infested plants during the evaluated period. These results indicate that the hyperspectral imaging sensor has the potential to be used in monitoring activities for these pests. As there were no significant changes in the gas exchange parameters, the spectral changes probably occurred due to internal structural changes in the leaves caused by the injuries of these insects.
Remote sensing is becoming a relevant alternative in optimizing the monitoring of agricultural pests. However, before proposing the use of sensors as a solution for insect detection, it is essential to know the spectral response of plants under different types of stress. In this study, gas exchange parameters and the spectral behavior of maize plants in the greenhouse infested by Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) and Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) were determined in order to investigate physiological responses and spectral bands sensitive to the different injuries caused by these insects. For this, maize plants at V5 developmental stage were randomly assigned to four treatments: non-infested plants, plants infested by D. saccharalis, plants infested by S. frugiperda and plants infested by both species. Spectral reflectance measurements were performed using hyperspectral sensor configured to acquire images in 50 bands between 500 and 900 nm. The physiological response given by parameters of assimilation, substomatal CO2 concentration, stomatal conductance, vapor deficit between leaf and air and photosynthetic water use efficiency were also obtained using a portable photosynthesis system. Spectral and physiological readings were performed on six different days during the 14-day period of larval development. At the end of this period, all plants were sectioned to verify successful infestation and only infested plants were considered in the analyses. Classification models created from the average reflectance spectra allowed the discrimination of healthy plants and plants with stressors, especially in the visible region (666.36 nm) for plants with S. frugiperda and near infrared (866.05 nm) for plants with D. saccharalis. There was no relevant difference in gas exchange parameters between healthy and infested plants during the evaluated period. These results indicate that the hyperspectral imaging sensor has the potential to be used in monitoring activities for these pests. As there were no significant changes in the gas exchange parameters, the spectral changes probably occurred due to internal structural changes in the leaves caused by the injuries of these insects.
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Broca-da-cana-de-açúcar, Lagarta-do-cartucho, Estresse biótico, Manejo integrado de pragas, Monitoramento, Sensoriamento remoto, Sugarcane borer, Fall armyworm, Biotic stress, Integrated pest management, Remote sensing