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tissue cultures. All have contributed to improved yields, developed resistance to
specific diseases and pests, environmental adaptations and improved quality
demanded by the food industry and consumers. Cell culture and molecular biology
advances have culminated in the genetic modification of crops. Currently, genetic
modification of plants is a powerful, widespread but controversial application of
biotechnology (Conner et al. 2003 ; Mendelsohn et al. 2003 ; Sanahuja et al. 2011 ).
GM crops have reduced, and continue to reduce herbicide, insecticide and overall
pesticide use (Benbrook 2012 ). Despite the potential benefits, environmental and
food safety concerns have been raised about GM crops. It is feared that GM crops
will harm the human population with undesired impacts on the environment.
Concerns regarding the introduction of GM crops into the environment include the
effects on biodiversity, becoming agricultural weeds, direct and indirect effects on
non-target organisms, and food safety (Conner et al. 2003 ).

4.6.1 Impact on Insect Pests

The area under Bacillus thurengiensis (Bt) crops increased from 1.1 million to 66
million hectares from 1996 to 2011 with a cumulative total of more than 420 million
hectares. Insects have a remarkable ability to adapt insecticides and other control

Direct observation

Population census

Feeding studies

Gut analysis

Reduce direct mortality

Provide resources

Control secondary enemies

Manipulate host-plant

attributes

Correlation

Addition

Exclusion/inclusion

Interference/removal

Feeding activity

Life tables

Survey & identify potentially-important

natural enemies

Study of biology & ecology; determine factors

that disrupt or enhance biological control

Implementation and evaluation

Fig. 1 Components and approaches of conservation biological control

A. Nawaz et al.