Resistência de genótipos de milho a Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae) e caracterização de injúrias de percevejos em plântulas de milho
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2019-05-28
Autores
Bueno, Nádia Maebara
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Universidade Estadual Paulista (Unesp)
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Percevejos fitófagos são insetos-praga que atacam diversas culturas de importância agrícola. Estes insetos, no geral apresentam preferência pela parte reprodutiva de leguminosas, porém, devido a mudanças no sistema produtivo brasileiro, têm sido comumente observados alimentando-se de plântulas de milho (Zea mays L.), especialmente quando este sucede a soja [Glycine max (L.) Merr.] no campo, causando danos significativos e variados. O percevejo-barriga-verde, Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae), é considerado praga-chave de período inicial na cultura do milho no Brasil. A espécie Euschistus heros (F.) (Hemiptera: Pentatomidae) é a espécie mais abundante no Brasil e também pode se alimentar de plântulas de milho. O percevejo-marrom-marmorizado, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) foi introduzido nos Estados Unidos da América na década de 1990 e tem se dispersado rapidamente pelo país, trazendo prejuízos de até 100% em culturas de importância econômica. Embora percevejos adultos tenham seu potencial de danos reconhecido, pouco se sabe sobre os prejuízos relacionados aos demais estágios de desenvolvimento. Formas de controle alternativas ao método químico, e que causem menos impacto ao ambiente e ao homem são altamente desejáveis. A resistência de plantas é uma tradicional ferramenta do Manejo Integrado de Pragas (MIP) e tem como principais vantagens a eficiência, menor impacto ambiental e a compatibilidade com outros métodos de controle. Diante do exposto, o presente trabalho teve como objetivos: i) caracterizar antixenose e/ou antibiose de genótipos de milho a D. melacanthus; ii) determinar os danos causados por todas as fases de vida de D. melacanthus e E. heros em plântulas de milho; e iii) determinar os danos causados por diferentes fases de H. halys em plântulas de milho-doce nos Estados Unidos. Observou-se que, após 24 horas, os genótipos IAC 8046, SCS 156 Colarado e IAC 8390 foram menos infestados por D. melacanthus, indicando ocorrência de antixenose. Os genótipos IAC 8390 e JM 2M60 afetaram parâmetros biológicos do percevejo barriga-verde, revelando a ocorrência de antibiose. Os genótipos indicados acima podem ser utilizados em programas de melhoramento visando a resistência de plantas. Ninfas de quinto instar de D. melacanthus foram as que mais afetaram negativamente o peso fresco e diâmetro de caule das plântulas de milho. O quarto instar de E. heros foi o que mais afetou negativamente peso fresco e seco, altura e diâmetro de caule das plântulas de milho. Plântulas de milho-doce servem como alimento ao percevejo H. halys, sendo os danos mais significativos quando as plantas são infestadas por ninfas de quarto instar. Em função do potencial de danos demonstrado, as fases jovens de percevejos devem ser consideradas para determinação de nível de dano econômico em milho, refletindo na tomada de decisão para controle desses insetos.
Phytophagous stink bugs are insect pests that attack several crops of agricultural importance. These insects generally have a preference for the reproductive parts of leguminous plants, but due to changes in the Brazilian agricultural system, they have been commonly observed feeding on corn seedlings (Zea mays L.), especially when it succeeds soybean [Glycine max (L.) Merr.] in the field, causing significant and varied damage to the corn. The green-belly stink bug, Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae), is considered a key pest of early-stage corn in Brazil. The neotropical brown stink bug Euschistus heros (F.) (Hemiptera: Pentatomidae) is the most abundant stink bug in Brazil and feeds on corn seedlings as well. Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) was introduced in the United States of America in the 1990’s and has quickly spread throughout the country, bringing yield losses of up to 100% in crops of economic importance. Thus, alternatives to chemical control which cause less impact to the environment and humans, are highly desirable. Plant resistance is a traditional Integrated Pest Management (IPM) tool and has advantages such as being efficient, having a lower environmental impact, and good compatibility with other control methods. Thus, the present work has the following objectives: i) to characterize antixenosis and/or antibiosis of corn genotypes to D. melacanthus; ii) to determine injury caused by different life stages of D. melacanthus and E. heros in corn seedlings iii) to determine the injury caused by different stages of H. halys in sweet corn seedlings in the United States. We observed that after 24 h D. melacanthus infested genotypes IAC 8046, SCS 156 Colorado and IAC 8390 significantly less than the others indicating antixenosis. The genotypes IAC 8390 and JM 2M60 affected biological parameters of the green-belly stink bug, revealing the occurrence of antibiosis. The genotypes indicated above may be used in breeding programs for plant resistance to stink bugs. Injuries caused by D. melacanthus caused greater injury to corn seedlings than injury from E. heros. Injury from fifth instars of D. melacanthus caused the shortest height, fresh weight, and stalk diameter in corn seedlings compared to other D. melacanthus life stages tested. Fourth instars of E. heros caused the smallest fresh and dry weight, shortest plant height, and smallest stalk diameter on corn seedlings compared to other E. heros life stages tested. H. halys fed on sweet corn seedlings and the most significant damage occured when plants were infested by fourth instars. Due to the injury potential demonstrated, the immature stages of stink bugs should be considered when determining the level of economic damage in corn, which is then reflected in decision-making about control of these insects.
Phytophagous stink bugs are insect pests that attack several crops of agricultural importance. These insects generally have a preference for the reproductive parts of leguminous plants, but due to changes in the Brazilian agricultural system, they have been commonly observed feeding on corn seedlings (Zea mays L.), especially when it succeeds soybean [Glycine max (L.) Merr.] in the field, causing significant and varied damage to the corn. The green-belly stink bug, Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae), is considered a key pest of early-stage corn in Brazil. The neotropical brown stink bug Euschistus heros (F.) (Hemiptera: Pentatomidae) is the most abundant stink bug in Brazil and feeds on corn seedlings as well. Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) was introduced in the United States of America in the 1990’s and has quickly spread throughout the country, bringing yield losses of up to 100% in crops of economic importance. Thus, alternatives to chemical control which cause less impact to the environment and humans, are highly desirable. Plant resistance is a traditional Integrated Pest Management (IPM) tool and has advantages such as being efficient, having a lower environmental impact, and good compatibility with other control methods. Thus, the present work has the following objectives: i) to characterize antixenosis and/or antibiosis of corn genotypes to D. melacanthus; ii) to determine injury caused by different life stages of D. melacanthus and E. heros in corn seedlings iii) to determine the injury caused by different stages of H. halys in sweet corn seedlings in the United States. We observed that after 24 h D. melacanthus infested genotypes IAC 8046, SCS 156 Colorado and IAC 8390 significantly less than the others indicating antixenosis. The genotypes IAC 8390 and JM 2M60 affected biological parameters of the green-belly stink bug, revealing the occurrence of antibiosis. The genotypes indicated above may be used in breeding programs for plant resistance to stink bugs. Injuries caused by D. melacanthus caused greater injury to corn seedlings than injury from E. heros. Injury from fifth instars of D. melacanthus caused the shortest height, fresh weight, and stalk diameter in corn seedlings compared to other D. melacanthus life stages tested. Fourth instars of E. heros caused the smallest fresh and dry weight, shortest plant height, and smallest stalk diameter on corn seedlings compared to other E. heros life stages tested. H. halys fed on sweet corn seedlings and the most significant damage occured when plants were infested by fourth instars. Due to the injury potential demonstrated, the immature stages of stink bugs should be considered when determining the level of economic damage in corn, which is then reflected in decision-making about control of these insects.
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Zea mays L., ninfas, resistência de plantas a insetos, potencial de danos