Monday, 18 November 2002 - 9:36 AM

This presentation is part of : Ten-Minute Papers, Section E. Extension and Regulatory Entomology and F. Crop Protection Entomology

Habitat management strategies for control of cereal stemborers and striga weed in maize-based farming systems in eastern Africa

Zeyaur R. Khan1, William A. Overholt1, Ahmed Hassanali2, John A. Pickett3, and Lester J. Wadhams3. (1) International Centre of Insect Physiology and Ecology, Plant Health Division, Mbita Point Field Station, P. O. Box 30, Mbita Point, Kenya, (2) International Centre of Insect Physiology and Ecology, Biological and Chemical Ecology Department, P. O. Box 30772, Nairobi, Kenya, (3) Institute of Arable Crops Research-Rothamsted, Biological and Ecological Chemistry, Rothamsted, Harpenden, United Kingdom

The lepidopteran stemborers and parasitic striga weeds cause major yield losses in subsistence maize production throughout Sub Saharan Africa. A habitat management strategy for minimizing damage due to stemborers and striga weed has been developed in maize-based farming systems for small- and medium-scale African farmers. This strategy involves use of trap crops to attract stemborer colonization away from the cereal plants and intercrops to repel the pests. The two most successful trap crop plants Napier grass, Pennisetum purpureum, and Sudan grass, Sorghum vulgare sudanensis, attracted greater oviposition by stemborers, than cultivated maize. The intercrops giving maximum repellent effect were molasses grass, Melinis minutiflora and a legume species, silverleaf, Desmodium uncinatum. ‘Push-pull’ trials, using the trap crops and repellent plants, reduced stemborer attack and increased levels of parasitism of borers on protected plants, resulting in a significant increase in maize yield. The trap crop and intercrop plants also provide valuable forage for cattle, often reared in association with subsistence cereal production. The plant chemistry responsible for stemborer control involves release of attractant semiochemicals from the trap plants and repellent semiochemicals from the intercrops. With M. minutiflora, certain chemicals repellent to ovipositing adults also increased parasitism of stemborers. Intercropping maize with D. uncinatum not only reduced stemborer colonization on maize but also reduced parasitization of maize by Striga hermonthica. There has been considerable take-up of the habitat management system by farmers in eastern Africa and more than 1,500 farmers in different agro-ecologies in Kenya have adopted this technology.

Species 1: Lepidoptera Pyralidae Chilo partellus
Species 2: Lepidoptera Noctuidae Busseola fusca
Keywords: Push-pull, mixed farming

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