Contents - Faperta

10
Deployment of Insect-Resistant Transgenic Crops for
Pest Management: Potential and Limitations
Introduction
There is a continuing need to increase food production, particularly in the developing
countries of Asia, Africa, and Latin America. This increase in food production has to come
from increased productivity of major crops grown on existing cultivable lands. One practical
means of achieving greater yields is to minimize the pest-associated losses, which
are estimated at 14% of the total agricultural production (Oerke et al., 1994). Insect pests,
diseases, and weeds cause an estimated loss of US$243.4 billion in eight major fi eld crops
(42%), out of total attainable production of $568.7 billion worldwide. Among these, insects
cause an estimated loss of 90.4 billion, diseases 76.8 billion, and weeds 64.0 billion. Current
crop protection costs are valued at $31 billion annually ( James, 2007). Insects not only cause
direct loss to the agricultural produce, but also act as vectors of various plant pathogens.
In addition, there are extra costs in the form of insecticides applied for pest control, currently
valued at US$10 billion annually.
Massive application of pesticides to minimize losses due to insect pests, diseases, and
weeds results in adverse effects on the benefi cial organisms, leaves pesticide residues in
the food chain, and causes environmental pollution. A large number of insects have also
developed resistance to insecticides, and over 650 cases of insect resistance have been
documented. Helicoverpa armigera (Hubner) has shown resistance to several groups of
insecticides, resulting in widespread failure of pest control operations. The cotton whitefl
y, Bemisia tabaci (Genn.), tobacco caterpillar, Spodoptera litura (Fab.), green peach/potato
aphid, Myzus persicae (Sulzer), cotton aphid, Aphis gossypii Glover, and diamondback moth,
Plutella xylotella (L.) have developed high levels of resistance to insecticides. Development
of resistance to insecticides has necessitated the application of higher dosages of the same
pesticide or more number of pesticide applications. It is in this context that insect-resistant
transgenic plants can play a major role in integrated pest management (IPM) in the future
(Sharma et al., 2002a; Sharma, Sharma, and Crouch, 2004).