Danos de Helicoverpa armigera (Hübner, 1809) (Lepdoptera: Noctuidae) na cultura da soja, Glycine max (L.)
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Data
2017-12-11
Autores
Zanardi Júnior, João Antonio
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Universidade Estadual Paulista (Unesp)
Resumo
A Helicoverpa armigera é uma praga importante no Brasil desde sua introdução em 2013. Pode provocar danos na cultura da soja desde a fase de emergência das plantas até o enchimento de grãos nas vagens. O objetivo deste trabalho foi quantificar os danos causados pelas lagartas de H. armigera no estádio vegetativo e reprodutivo da cultura da soja, em casa de vegetação e campo e determinar o nível de controle para praga no período reprodutivo da cultura. Foram conduzidos experimentos na safra 2014/2015 e 2015/2016. Safra 2014/2015: Foi realizada a quantificação dos danos no período vegetativo e reprodutivo da cultura da soja. Os experimentos foram conduzidos em casa de vegetação, o delineamento adotado foi de blocos ao acaso, com cinco tratamentos e quatro repetições. Cada parcela constou de um vaso retangular, com aproximadamente 50 cm de comprimento e volume aproximado de 13L de solo contendo sete plantas dispostas em linha. Os tratamentos constaram da infestação de uma, duas, três, cinco e nenhuma lagarta em 0,5m de linha da cultura. No período vegetativo, as plantas foram infestadas quando as lagartas atingiram o segundo instar e quando as plantas se encontravam no estádio de desenvolvimento V4. No período reprodutivo as plantas foram infestadas quando as lagartas atingiram o segundo ínstar e as plantas encontravam-se no estádio R4 de desenvolvimento. Para ambos os experimentos as avaliações foram realizadas a cada dois dias até o término do ciclo larva da praga. Ao término do ciclo da cultura foi realizado a avaliação de produtividade pelo peso de todos os grãos produzidos por parcela. Safra 2015/2016: Foi realizada a quantificação de danos proporcionada por lagartas de H. armigera apenas no período reprodutivo da cultura. Na primeira etapa do experimento foram infestadas 100 plantas de soja, conduzidas em vasos, quando as plantas encontravam-se no estádio R5 de desenvolvimento com lagartas de segundo instar. As plantas foram cobertas com sacos de tecido voil para evitar fuga de lagartas e a avaliação dos danos foi realizada apenas no término do ciclo larval da praga. A segunda etapa foi desenvolvida em campo, realizando-se o desbaste artificial de acordo com a média de ataque proporcionado pela H. armigera observado na primeira etapa. O delineamento adotado foi de blocos ao acaso. Cada parcela constou de 0,5m de linha da cultura, com sete plantas. Os tratamentos constaram da infestação de uma, duas, três, cinco e nenhuma lagarta por parcela. Ao término do ciclo da cultura foi realizado a avaliação de produtividade pelo peso de todos os grãos produzidos por parcela. Na safra 2014/2015, para infestação no período vegetativo de desenvolvimento das plantas constatou-se maior média de desfolha na infestação de três lagartas por 0,5m de linha da cultura plantada, proporcionando 3,6% de desfolha em um ciclo de vida da praga. Entretanto os danos causados pela espécie não provocaram redução significativa na produtividade de grãos da soja. No período reprodutivo da cultura, o tratamento que constituiu de cinco lagartas por 0,5m de linha da cultura proporcionou média de 23,25 vagens danificadas. Na safra 2015/2016 constatou-se que cada lagarta proporciona danos em seis vagens para completar seu desenvolvimento. A preferência alimentar de lagartas é por vagens que caracterizam o estádio R6 de desenvolvimento da cultura da soja. O nível de controle da espécie Helicoverpa armigera está entre uma e duas lagartas por metro da cultura quando detectadas na formação de grãos da cultura da soja.
Helicoverpa armigera has been important pest in Brazil since its introduction in 2013. The H. armigera species can cause damage to the soybean crop from the emergence of the plants at the filling of grain in the pods. The objective of this study was to quantify the damage caused by H. armigera caterpillars in the vegetative and reproductive phase of soybean crop in a greenhouse and field and to establish the level of control for the pest in the reproductive phase of the crop. Experiments were conducted in the 2014/2015 and 2015/2016 harvests. Harvest 2014/2015: Was quantification of the damages in the vegetative and reproductive period of the soybean crop. The experiments were conducted in greenhouse, the experimental design was randomized blocks with five treatments and four replications. Each plot consisted of a rectangular vase, approximately 50 cm long and with an approximate volume of 13L of soil containing seven plants in a row. Treatments consisted of infestation of one, two, three, five and no caterpillar on a half meter line of crop planted. In the vegetative period, the plants were infested with caterpillars of second instar and when the plants were in the V4 development stage. In the reproductive period the plants were infested with caterpillars of second instar and the plants were in the developmental stage R4. For both experiments the evaluations were carried every two days until the end of the pest larval cycle. At the end of the crop cycle, the yield was evaluated by the weight of all the grains produced per plot. Harvest 2015/2016: The damage quantification provided by H. armigera caterpillars was performed only during the reproductive period of the crop. In the first stage of the experiment, 100 potted soybean plants were infested when the plants were in the R5 development stage with caterpillars of second instar. The plants were covered with voil bags to prevent caterpillars from escaping and damage assessment was performed only at the end of the larval cycle. The second stage was developed in the field, the artificial thinning being carried out according to the attack average provided by H. armigera observed in the first stage. The design was randomized blocks. Each plot consisted of half meter line of crop planted in line, with seven plants. Treatments consisted of infestation of one, two, three, five and no caterpillar per plot. At the end of the crop cycle, the yield was evaluated by the weight of all the grains produced per plot. In the 2014/2015 harvest, for infestation in the vegetative period of plant development, the highest average of defoliation was observed in the infestation of three caterpillars of half meter line of the planted crop, providing 3.6% of defoliation in a life cycle of the pest. However, the damages caused by the species did not cause a significant reduction in soybean grain yield. In the reproductive period of the crop, the treatment consisting of five caterpillars of half meter line crop planted provided an average of 23.25 damaged pods. In the 2015/2016 harvest, was verified that each caterpillar provides damages in six pods to complete its development. The feeding preference of caterpillars is by pods which characterize the R6 stage of development of the soybean crop. The control level of the Helicoverpa armigera is between one and two caterpillars per meter of the crop when detected in the formation of soybean crop grains.
Helicoverpa armigera has been important pest in Brazil since its introduction in 2013. The H. armigera species can cause damage to the soybean crop from the emergence of the plants at the filling of grain in the pods. The objective of this study was to quantify the damage caused by H. armigera caterpillars in the vegetative and reproductive phase of soybean crop in a greenhouse and field and to establish the level of control for the pest in the reproductive phase of the crop. Experiments were conducted in the 2014/2015 and 2015/2016 harvests. Harvest 2014/2015: Was quantification of the damages in the vegetative and reproductive period of the soybean crop. The experiments were conducted in greenhouse, the experimental design was randomized blocks with five treatments and four replications. Each plot consisted of a rectangular vase, approximately 50 cm long and with an approximate volume of 13L of soil containing seven plants in a row. Treatments consisted of infestation of one, two, three, five and no caterpillar on a half meter line of crop planted. In the vegetative period, the plants were infested with caterpillars of second instar and when the plants were in the V4 development stage. In the reproductive period the plants were infested with caterpillars of second instar and the plants were in the developmental stage R4. For both experiments the evaluations were carried every two days until the end of the pest larval cycle. At the end of the crop cycle, the yield was evaluated by the weight of all the grains produced per plot. Harvest 2015/2016: The damage quantification provided by H. armigera caterpillars was performed only during the reproductive period of the crop. In the first stage of the experiment, 100 potted soybean plants were infested when the plants were in the R5 development stage with caterpillars of second instar. The plants were covered with voil bags to prevent caterpillars from escaping and damage assessment was performed only at the end of the larval cycle. The second stage was developed in the field, the artificial thinning being carried out according to the attack average provided by H. armigera observed in the first stage. The design was randomized blocks. Each plot consisted of half meter line of crop planted in line, with seven plants. Treatments consisted of infestation of one, two, three, five and no caterpillar per plot. At the end of the crop cycle, the yield was evaluated by the weight of all the grains produced per plot. In the 2014/2015 harvest, for infestation in the vegetative period of plant development, the highest average of defoliation was observed in the infestation of three caterpillars of half meter line of the planted crop, providing 3.6% of defoliation in a life cycle of the pest. However, the damages caused by the species did not cause a significant reduction in soybean grain yield. In the reproductive period of the crop, the treatment consisting of five caterpillars of half meter line crop planted provided an average of 23.25 damaged pods. In the 2015/2016 harvest, was verified that each caterpillar provides damages in six pods to complete its development. The feeding preference of caterpillars is by pods which characterize the R6 stage of development of the soybean crop. The control level of the Helicoverpa armigera is between one and two caterpillars per meter of the crop when detected in the formation of soybean crop grains.
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Palavras-chave
Nível de controle, Manejo integrado de pragas, Noctuidae, Integrated pest management, Control of level