Effects of crop diversification levels and fertilization regimes on abundance of Brevicoryne brassicae (L.) and its parasitization by Diaeretiella rapae (M’Intosh) in broccoli

Authors

  • Luigi Ponti,

    1. * Division of Organisms and Environment and Division of Ecosystem Science, Department of Environmental Science, Policy, and Management, University of California, 137 Mulford Hall, Berkeley, CA 94720-3114, U.S.A.
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  • Miguel A. Altieri,

    Corresponding author
    1. * Division of Organisms and Environment and Division of Ecosystem Science, Department of Environmental Science, Policy, and Management, University of California, 137 Mulford Hall, Berkeley, CA 94720-3114, U.S.A.
      Miguel A. Altieri, Division of Organisms and Environment, University of California, 137 Mulford Hall, Berkeley, CA 94720-3114, U.S.A. Tel.: +1 510 642 9802; fax: +1 510 643 5438; e-mail: agroeco3@nature.berkeley.edu
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  • Andrew Paul Gutierrez

    1. * Division of Organisms and Environment and Division of Ecosystem Science, Department of Environmental Science, Policy, and Management, University of California, 137 Mulford Hall, Berkeley, CA 94720-3114, U.S.A.
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Miguel A. Altieri, Division of Organisms and Environment, University of California, 137 Mulford Hall, Berkeley, CA 94720-3114, U.S.A. Tel.: +1 510 642 9802; fax: +1 510 643 5438; e-mail: agroeco3@nature.berkeley.edu

Abstract

1 The effects of intercropping via competition on crop yields, pest [cabbage aphid Brevicoryne brassicae (L.)] abundance, and natural enemy efficacy were studied in the Brassica oleracea L. var. italica system.

2 From May to December 2004, insect populations and yield parameters were monitored in summer and autumn in broccoli monoculture and polyculture systems with or without competition from Brassica spp. (mustard), or Fagopyrum esculentum Moench (buckwheat), with addition of organic (compost) or synthetic fertilizer.

3 Competition from buckwheat and mustard intercrops did not influence pest density on broccoli; rather, aphid pressure decreased and natural enemies of cabbage aphid were enhanced in intercropping treatments, but this varied with the intercropped plant and season (summer vs. autumn).

4 In compost-fertilized broccoli systems, seasonal parasitization rates of B. brassicae by Diaeretiella rapae (M’Intosh) increased along with the expected lower aphid pressure compared with synthetically fertilized plants.

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