Contents - Faperta

94 Biotechnological Approaches for Pest Management and Ecological Sustainability
application have been estimated to be 3.7 to 3.8 on Annigeri and ICCC 37 (susceptible
cultivars) as compared to 2.7 larval days on ICC 506, a resistant cultivar (Wightman et al.,
1995). HPR has a great infl uence on EILs, and this information is very important in cropping
systems involving insect resistant cultivars as a component of pest management. One
of the fi rst and most important adjustments to crop management recommendations that
must be made relates to economic thresholds or action thresholds in relation to host plant
resistance (Sharma and Teetes, 1995). In some cases, there are several cultivars of a crop
with different levels of resistance. Experimental and empirical data should be generated to
determine the level of resistance of a cultivar, which is critical in deciding the nature and
timing of the intervention (insecticide application or release of natural enemies) needed to
suppress an increasing pest population.
Host Plant Resistance in Integrated Pest Management
Host plant resistance as a method of insect control in the context of IPM has a greater potential
than any other method of pest suppression. In general, the use of insect-resistant varieties
is not subjected to the vagaries of nature, unlike chemical and biological control methods.
HPR along with natural enemies and cultural practices is a central component of any pest
management strategy (Painter, 1951, 1958; Maxwell and Jennings, 1980; Smith, 1989; Sharma,
2002; Sharma and Ortiz, 2002). Plant resistance as a method of pest control offers many
advantages, and in some cases, it is the only practical and effective method of pest management.
However, there may be some problems if we rely exclusively on plant resistance for
insect control, for example, high levels of resistance may be associated with low yield potential
or undesirable quality traits, and resistance may not be expressed in every environment
where a variety is grown. Therefore, insect-resistant varieties need to be carefully fi tted into
the pest management programs in different agroecosystems. The nature of deployment,
alone or in combination with other methods of insect control, depends on the level and
mechanisms of resistance, and the cropping system (Kennedy et al., 1987).
High levels of plant resistance are available against a few insect species only. However,
very high levels of resistance are not a prerequisite for use of HPR as a component in integrated
pest management. Varieties with low to moderate levels of resistance or those that
can avoid insect damage can be deployed for pest management in combination with other
components of pest management. Deployment of insect-resistant cultivars should be
aimed at conservation of the natural enemies and minimizing the number of insecticide
applications. Use of insect-resistant cultivars also improves the effi ciency of other pest
management practices, including the synthetic insecticides (Adkisson and Dyck, 1980;
Heinrichs, 1988; Sharma, 1993; Panda and Khush, 1995). HPR can be used as:
• A principal component of pest control.
• An adjunct to cultural, biological, and chemical control.
• A check against the release of susceptible cultivars.
HPR as a Principal Method of Insect Control
HPR has often been used for the management of several insect species. However, only a
few insect species can be controlled by the use of resistant varieties alone. Insect-resistant