Contents - Faperta

4 Biotechnological Approaches for Pest Management and Ecological Sustainability
Pest Management Components
Management of insect pests on high-value crops relies heavily on insecticides, often to
the exclusion of other methods (Sharma and Veerbhadra Rao, 1995). With an increasing
restraint on insecticide use due to development of resistance in insect populations and
environmental contamination, integration of several management techniques has become
necessary to reduce the reliance on insecticides and prolong the utility of important molecules
(Reddy et al., 1997). In order to overcome the toxic and chronic effects of pesticides,
as well as pest resurgence, intensive research efforts are needed to develop a balanced
program for IPM. Various components of IPM are discussed below.
Economic Thresholds
The present methodology for assessing insect damage to undertake control measures is
cumbersome, and the grassroot-level fi eld workers and farmers are unable to understand
and practice them. Simple methods to assess insect damage and density would be useful for
timely application of appropriate control measures. Economic threshold levels (ETLs) are
available for a limited number of insect species. ETLs developed without taking into consideration
the potential of naturally occurring biological control agents and levels of resistance
in the cultivars grown to the target pests are of limited value. The ETLs have to be
developed for specifi c crop-pest-climatic situations. The ETLs developed in one region are
not applicable in other areas where the crop-pest and socioeconomic conditions are different.
Simple methods of assessing ETLs could help avoid unnecessary pesticide applications.
Biological Control
A large number of parasites, predators, bacteria, fungi, and viruses regulate populations
of insect pests under natural conditions. However, only a few biocontrol agents have been
exploited successfully for controlling insect pests. Identifi cation of potential biocontrol
agents would help to launch a successful battle against the crop pests. A more pragmatic
approach would be the conservation of biocontrol agents. Major improvements in biological
control of insect pests can be made through habitat management. Increasing genetic diversity
has been proposed as a means of augmenting natural enemy populations. However, the
response of natural enemies to genetic diversity varies across crops and cropping systems
(Andow, 1991). Hedgerows, cover crops, and weedy borders provide nectar, pollen, and
refuge to the natural enemies. Mixed planting and provision of fl owering plants at the fi eld
borders can increase the diversity of the habitat, and provide more effective shelter and
alternative food sources to predators and parasites. Inter- or mixed-cropping, which
involve simultaneous growing of two or more crops on the same piece of land, is one of the
oldest and most common cultural practices in tropical countries for risk aversion and pest
management. Densities of natural enemies have been found to be greater in 52.7% of the
species in polycultures, while 9.3% species had lower densities (Andow, 1991). Predators
and parasites have been found to result in higher mortality of herbivore arthropods in
polycultures in nine studies, lower rates of mortality in two studies, and no differences in
four studies (Russell, 1989). For biological control to be successful, it is important to ensure
that essential parasitoid resources and hosts coincide in time and space.
Further, technology available for mass rearing of some of the potential parasites, predators,
and pathogens is not satisfactory. An appropriate mass rearing or multiplication technology