Maize stem borer colonization, establishment and crop damage levels in a maize-leucaena agroforestry system in Kenya

The effect of resource concentration on the population of stem-borers of maize in the maize-leucaena agroforestry system was evaluated. The studies covered six cropping seasons from October 1992 to August 1995, and were conducted at Mtwapa and Amoyo in coastal and western Kenya, respectively. Treatments included monocropped and intercropped (maize, leucaena) plots, weeded and unweeded plots, mulched and unmulched plots, and three spacing (1.5, 2.25 and 3.0 m) regimes for leucaena hedgerows. Maize was interplanted at the onset of the rainy season. Abundance of adult and larval/pupal stages of maize stem borers, oviposition preference, foliar damage, borer entry/exit holes, maize plant mortality and stem breakage because of borer damage,were significantly greater in the maize monocrop than in the maize-leucaena intercrops. The reduced pest numbers were associated with reduced yield loss per plant, and the 3.0 m leucaena hedgerow spacing plots yielded more than the maize monocropped plots despite having 25% fewer initial maize plants. (C) 1999 Elsevier Science B.V. All rights reserved.