Contents - Faperta

504 Biotechnological Approaches for Pest Management and Ecological Sustainability
Genetic Improvement of Natural Enemies
Some of the major problems in using natural enemies in pest control are the diffi culties
involved in mass rearing and their inability to withstand adverse conditions in the fi eld.
Traditional approaches have been used successfully to select natural enemies for resistance
to pesticides and enhanced tolerance to high temperatures. Genetic improvement
can be useful when the natural enemy is known to be a potentially effective biological
control agent, except for one limiting factor; the limiting trait is primarily infl uenced by a
major gene; and the gene can be obtained by selection, mutagenesis, or cloning. The manipulated
strain should be fi t, effective, and able to be maintained in some form of reproductive
isolation (Headley and Hoy, 1987). Some of the desirable characteristics for transgenic
insects include resistance to pathogens, adaptation to different environmental conditions,
high fecundity, and improved host-seeking ability (Atkinson and O’Brochta, 1999).
Biotechnological interventions can also be used to broaden the host range of natural
enemies and enable their production on artifi cial diet or nonhost insect species that are
easy to multiply under laboratory conditions. There is a tremendous scope for developing
natural enemies with genes for resistance to pesticides (Hoy, 1992). Genetic transformation
can also be used to improve commercial production of materials such as silk, honey, and
lac (Mori and Tsukada, 2000), or production of pharmaceuticals and biomolecules (Yang
et al., 2002). However, release of genetically modifi ed insects might have a potential risk to
the environment (Spielman, Beier, and Kiszewski, 2002). This is of particular concern when
the same vector transmits several disease-causing pathogens, as it might be diffi cult to
develop transgenic individuals incapable of transmitting different pathogens. Future
research on genetic manipulation of insects should focus on:
• Production of insects for improved silk, honey, lac, and biomaterials;
• Genetically modifying insect vectors for disease control;
• Production of robust natural enemies with resistance to pesticides or adaptation to
extremes of climatic conditions;
• Increased host range and effi cient rearing systems;
• Mechanisms to drive the gene of interest (such as sex-linked sterility or lethal
genes) through natural populations; and
• Procedures for testing, deployment, and risk management of genetically modifi ed
insects.
Genetic Improvement of Entomopathogenic Microorganisms
Entomopathogenic bacteria, viruses, fungi, nematodes, and protozoa have a good potential
as a component of integrated pest management. However, they still account for 3% of
the total pesticide market, and formulations based on the bacterium, Bacillus thuringiensis
(Berliner) account for 80 to 90% of the commercial microbial pesticides. The major constraint
to the use of biopesticides for pest management is the need for simultaneous
management of three biological systems: the pathogen, the prey, and the crop. Despite several
advantages of biological insecticides, many factors have hindered their commercial