Contents - Faperta

294 Biotechnological Approaches for Pest Management and Ecological Sustainability
TABLE 9.1
Applications of Biotechnology to Improve Arthropod Natural Enemies
Characteristics References
Modify the genome of natural enemies Handler and O’Brochta (1991)
Change sex ratio of parasitoids Bownes (1992)
Cryopreservation Mazur et al. (1992)
Develop genetic linkage maps Sobral and Honeycutt (1993)
Identify biotypes Ballinger-Crabtree, Black, and Miller (1992)
Improve artifi cial diets Thompson (1990)
Monitor establishment and dispersal Edwards and Hoy (1993)
Parentage analysis and genetic changes Scott and Williams (1993)
to improve rearing of natural enemies for biological control (Table 9.1). Selection for resistance
to pesticides, lack of diapause, and enhanced temperature tolerance has been successful.
However, most research has been focused on selection for resistance to pesticides
(Hoy, 1990a). Genetic improvement has proved to be practical and cost effective when the
trait(s) limiting the effi cacy can be identifi ed, and the improved strain retains the fi tness
(Headley and Hoy, 1987). Biotechnological interventions can also be used to broaden the
host range of natural enemies or enable their production on artifi cial diet or nonhost insect
species that are easy to multiply under laboratory conditions. Some of the desirable characteristics
for transgenic insects include pathogen resistance, environmental hardiness,
increased fecundity, and improved host-seeking ability (O’Brochta and Atkinson, 1998).
There is tremendous scope for developing natural enemies with genes for resistance to
pesticides and ability to withstand adverse weather conditions (Hoy, 1992a). Genetically
modifi ed natural enemies can be used more effectively in pest management programs in
combination with the conventional insecticides. Pesticide-resistant predators and parasitoids
have been evaluated in the fi eld and are being used in several integrated pest management
(IPM) programs (Hoy, 1990a). The transgenic predatory mite, Metaseiulus occidentalis Nesbitt
has been used for the control of spider mite, Tetranychus uirticae Koch (Presnail et al., 1997).
If the natural populations of predatory mites can be replaced with the one that is resistant
to pesticides, then there will be considerable reduction in pesticide use as the pesticide
application would only affect the crop pests, but not the pesticide-resistant predatory mites.
Another potential application of biotechnology could be the use of insects as a delivery
vehicle for vaccines (Crampton et al., 1999). A blood-sucking insect can be transformed to
express an antigen and deliver it through saliva that the insect would inject into the vertebrate
host during feeding (Coates et al., 1999; Crampton et al., 1999). Genetic transformation
can also be used to modify commercial production of materials such as silk, honey,
lac, and biomaterials (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 quite diffi cult to develop transgenic individuals incapable of transmitting
different pathogens. 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 single major gene.