Insect pests, of which stem borers are the most widely distributed, affect a significant portion of the 96 million hectares of maize grown in developing countries (Pingali 2001). In Kenya, stem borers cause about 15% maize grain yield loss annually (De Groote et al. 2001). The major species in Kenya are Chilo partellus (Swinehoe), Busseola fusca (Fuller), Sessamia Calamistis (Hampson), and Eldana saccharina (Walker). The controls used to manage stem borer damage mainly consist of chemical, biological, cultural, and host plant resistance. Chemical control methods are the most effective, but they are also the most expensive for small-holder farmers. Pesticides also posses threats to humans, livestock, and the environment. Farmers can easily adapt host plant resistance as it is encapsulated in the seed. However, developing insect resistant maize using conventional means has been elusive due to limited genetic variation, difficulty in maintaining the quantitatively controlled traits, and the fact that the procedure deals with two organisms: pests and hosts. Using genetic engineering tools, modified novel genes from the soil dwelling bacterium Bacillus thuringiensis (Bt) have been introduced into crops, and hold great promise in controlling lepidopteran stem borers (National Academy of Science 2000). The genes encode delta-endotoxin proteins. On ingestion by the susceptible stem borer, these proteins are activated by the conducive environment in insect guts and the effects of their release result in larval mortality (Gill et al. 1992). The Bt toxins are active against lepidopteran pests but non-toxic to humans and livestock. The Insect Resistant Maize for Africa (IRMA) project was developed by three core partners, KARI, CIMMYT, and the Syngenta Foundation for Sustainable Agriculture, to meet the challenges in developing and deploying elite and adapted insect resistant maize germplasm, including Bt maize.

Global Maize Program|Socioeconomics Program

English

0311|AGRIS 0301|AL-Maize Program

Juan Carlos Mendieta

INT2512|INT2460

CIMMYT Staff Publications Collection