Contents - Faperta

7
Genetic Transformation of Crops for Resistance
to Insect Pests
Introduction
There is a continuing need to increase food production to meet food requirements in the
future, particularly in the developing countries of Asia, Africa, and Latin America. Several
biotic and abiotic constraints are a limiting factor in increasing the production and productivity
of food crops. Losses due to insect pests, which represent one of the largest constraints
in crop production, have been estimated at 14% of the total agricultural production
(Oerke et al., 1994). In addition, insects also act as vectors of various plant pathogens, and
the annual cost for controlling pest damage has been estimated to be US$10 billion. Largescale
application of insecticides for insect control results in toxic residues in food and food
products, in addition to adverse effects on the nontarget organisms in the environment.
Furthermore, the cost-benefi t ratio of such practices can easily become negative in marginal
cropping systems, particularly when other factors such as diseases or drought become
a limiting factor in crop production. The losses due to insect pests can be minimized effectively
through host plant resistance to insects through conventional plant breeding and use
of biotechnological approaches.
The ability to isolate and manipulate single genes through recombinant DNA technology
(Schnepf and Whiteley, 1981; Watson et al., 1987), together with the ability to insert specifi c
genes into cultivars with desirable agronomic traits, and adaptation to environmental conditions
in a particular region have opened up new vistas in crop improvement (Chilton,
1983). Signifi cant progress has been made over the past two decades in introducing foreign
genes into plants, and this has provided opportunities to modify crops to increase yields,
impart resistance to insect pests and diseases, and improve nutritional quality and yield
(H.C. Sharma et al., 2002, 2003). In this chapter, we focus on candidate genes with potential
to impart resistance to insect pests, review the progress in developing transgenic plants
with resistance to insects, and assess the future potential of this technology for making
host plant resistance an effective weapon in pest management.