The lepidopteran stemborers and parasitic weeds, belonging to Striga spp., 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 farmers of eastern Africa. This strategy involved selection of plant species that could be employed as trap crops to attract stemborer colonization away from the cereal plants, or as 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 six hundred farmers in different agro-ecologies in Kenya have adopted this technology resulting in increased maize and milk production.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA