Marigold (Tagetes erecta L.) as an attractive crop to natural enemies in onion fields
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Data
2009-12-01
Autores
Silveira, Luís Cláudio Paterno
Berti Filho, Evoneo
Pierre, Leonardo Santa Rosa
Peres, Fernanda Salles Cunha [UNESP]
Louzada, Julio Neil Cassa
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Editor
Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ)
Resumo
A cebola é a terceira hortaliça mais cultivada em São Paulo, cujo cultivo orgânico tende a crescer devido ao grande mercado consumidor existente. O manejo das pragas na cebolicultura orgânica baseia-se nos extratos de plantas inseticidas que, além de terem eficiência não comprovada, podem afetar negativamente os inimigos naturais. A utilização de plantas atrativas a inimigos naturais no entorno dos cultivos de cebola pode ser uma boa opção para os produtores, pois potencialmente aumentam a diversidade da artropodofauna e podem regular naturalmente as populações de espécies pragas. Verificou-se o efeito de linhas de cravo-de-defunto (Tagetes erecta L.) como cultura atrativa a inimigos naturais em campos de cebola. O experimento foi realizado em propriedade orgânica certificada, instalando-se linhas de cravo-de-defunto nas bordaduras de dois campos de cebola. Os tratamentos foram definidos coletando-se amostras nas plantas de cebola próximas às linhas da atrativa (5m) e distante das linhas (30 m). de maneira geral, observou-se maior quantidade de artrópodes fitófagos nas plantas de cebola longe da faixa atrativa e, inversamente, maior quantidade de inimigos naturais próximos à faixa. A riqueza de espécies também foi maior nas coletas próximas, o mesmo valendo para o índice de diversidade de Shannon. Portanto, a manutenção de linhas de cravo-de-defunto próximas ao cultivo de cebola promoveu maior riqueza e diversidade de artrópodes, bem como maior número de entomófagos, resultando em menor presença de fitófagos nas plantas, auxiliando na regulação natural das pragas da cultura.
Onion is the third most grown vegetable crop in São Paulo state, Brazil. Organic onion farming is expected to increase in the state due to the increasing demand. Pest management in organic onion farming is based on plant extracts with insecticide effects. However, the efficacy of such plant extracts has not been proved yet, and it was observed that they do negatively affect natural enemies. Plants surrounding onion fields, and that are attractive to natural enemies, may be a good option to farmers, since they may lead to increased diversity of arthropod species and, consequently, the natural control of pest populations. This study deals with the effect of marigold plants as a resource plant to natural enemies in onion fields. The experiment was set in a certified organic farm using marigold rows at a center of an onion field. Samples were taken from marigold and the onion plants 5 m (near) and 30 m (far) from the flowering strips. Higher numbers of arthropod pests were observed in onion plants 30 m from the marigold strip, while higher numbers of predators and parasitoids were found at 5 m distance. Species richness and Shannon's diversity index were higher at 5 m from marigold. Therefore, marigold rows next to onion fields resulted in higher number of entomophagous species, potentially enhancing the natural control of onion pests. In the study field, marigold strips may be an alternative to crop sprays for organic control of onion pests.
Onion is the third most grown vegetable crop in São Paulo state, Brazil. Organic onion farming is expected to increase in the state due to the increasing demand. Pest management in organic onion farming is based on plant extracts with insecticide effects. However, the efficacy of such plant extracts has not been proved yet, and it was observed that they do negatively affect natural enemies. Plants surrounding onion fields, and that are attractive to natural enemies, may be a good option to farmers, since they may lead to increased diversity of arthropod species and, consequently, the natural control of pest populations. This study deals with the effect of marigold plants as a resource plant to natural enemies in onion fields. The experiment was set in a certified organic farm using marigold rows at a center of an onion field. Samples were taken from marigold and the onion plants 5 m (near) and 30 m (far) from the flowering strips. Higher numbers of arthropod pests were observed in onion plants 30 m from the marigold strip, while higher numbers of predators and parasitoids were found at 5 m distance. Species richness and Shannon's diversity index were higher at 5 m from marigold. Therefore, marigold rows next to onion fields resulted in higher number of entomophagous species, potentially enhancing the natural control of onion pests. In the study field, marigold strips may be an alternative to crop sprays for organic control of onion pests.
Descrição
Palavras-chave
natural control, Conservation, Predator, Parasitoid, controle natural, Conservação, Predador, Parasitóide
Como citar
Scientia Agricola. São Paulo - Escola Superior de Agricultura Luiz de Queiroz, v. 66, n. 6, p. 780-787, 2009.