Pragas e inimigos naturais na soja e no milho cultivados em sistemas diversificados
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Data
2002-12-01
Autores
Cividanes, Francisco Jorge [UNESP]
Yamamoto, Fábio Takeshi
Título da Revista
ISSN da Revista
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Editor
Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ)
Resumo
A consorciação de culturas e o plantio direto podem influenciar a dinâmica populacional de insetos, aumentando ou diminuindo a densidade populacional de pragas e de inimigos naturais. Deste modo, avaliaram-se os efeitos de sistemas de plantio direto e da consorciação soja [Glycine max (L.) Merrill] e milho (Zea mays L.) sobre as populações de insetos-pragas e inimigos naturais. Os tratamentos constituíram um fatorial 3x2 (monocultura de soja, monocultura de milho, consorciação soja-milho em plantio direto e plantio convencional). Os insetos foram amostrados pelo método do pano, rede entomológica e procura visual. No milho, a ocorrência de insetos-pragas da parte aérea e insetos predadores não foi influenciada pelo manejo do solo. Lagartas de Helicoverpa zea ocorreram em maior número (5,1) no milho em consorciação. Na soja, adultos de Anticarsia gemmatalis e do predador Cycloneda sanguinea foram mais abundantes em plantio direto, respectivamente, 0,4 e 2,4 insetos. Observou-se maior número do sirfídeo Toxomerus sp. em plantio convencional (1,3). Nas condições de consorciação, verificou-se baixo número de Diabrotica gracilenta (11,5) na soja, enquanto que Maecolaspis sp. (5,0) e Megascelis sp. (17,0) e os predadores C. sanguinea (2,3), Doru sp. (0,8), Geocoris sp. (1,5) e Toxomerus sp. (1,4) ocorreram em alta densidade.
Intercropping and no-tillage systems can affect the population dynamics of insects, increasing or decreasing the population density of pests and natural enemies. The objective of this study was to evaluate the effects of no-tillage and strip intercropping of soybean [Glycine max (L.) Merrill] and corn (Zea mays L.) on the abundance of insect pests and their natural enemies. Plots were arranged in a randomized complete block design in a 3 x 2 factorial experiment (soybean monoculture, corn monoculture, strip intercropping of soybean-corn under no-tillage and conventional tillage). Insects were sampled using sweep net, ground cloth and by visual search. For corn, the occurrence of insect pests and predators was not affected by soil management practices. Larvae of Helicoverpa zea occurred in higher number (5.1) for corn under strip intercropping. For soybean, adults of Anticarsia gemmatalis and of the predator Cycloneda sanguinea were more abundant for the no-tillage plots, respectively, 0.4 and 2.4 insects. A higher number of the syrphid Toxomerus sp. was observed for the conventional tillage plots (1.3). Under strip intercropping conditions, low numbers of Diabrotica gracilenta (11.5) were observed, while Maecolaspis sp. (5.0) and Megascelis sp. (17.0), and the predators C. sanguinea (2.3), Doru sp. (0.8), Geocoris sp. (1.5) and Toxomerus sp. (1.4) occurred in high densities.
Intercropping and no-tillage systems can affect the population dynamics of insects, increasing or decreasing the population density of pests and natural enemies. The objective of this study was to evaluate the effects of no-tillage and strip intercropping of soybean [Glycine max (L.) Merrill] and corn (Zea mays L.) on the abundance of insect pests and their natural enemies. Plots were arranged in a randomized complete block design in a 3 x 2 factorial experiment (soybean monoculture, corn monoculture, strip intercropping of soybean-corn under no-tillage and conventional tillage). Insects were sampled using sweep net, ground cloth and by visual search. For corn, the occurrence of insect pests and predators was not affected by soil management practices. Larvae of Helicoverpa zea occurred in higher number (5.1) for corn under strip intercropping. For soybean, adults of Anticarsia gemmatalis and of the predator Cycloneda sanguinea were more abundant for the no-tillage plots, respectively, 0.4 and 2.4 insects. A higher number of the syrphid Toxomerus sp. was observed for the conventional tillage plots (1.3). Under strip intercropping conditions, low numbers of Diabrotica gracilenta (11.5) were observed, while Maecolaspis sp. (5.0) and Megascelis sp. (17.0), and the predators C. sanguinea (2.3), Doru sp. (0.8), Geocoris sp. (1.5) and Toxomerus sp. (1.4) occurred in high densities.
Descrição
Palavras-chave
Glycine max, Zea mays, insect population dynamics, No-tillage, intercropping, Glycine max, Zea mays, dinâmica populacional de insetos, Plantio direto, consorciação de culturas
Como citar
Scientia Agricola. São Paulo - Escola Superior de Agricultura Luiz de Queiroz, v. 59, n. 4, p. 683-687, 2002.