Contents - Faperta

278 Biotechnological Approaches for Pest Management and Ecological Sustainability
unlikely to be commercially viable. Another signifi cant barrier is deregulation by the
biosafety regulatory agencies and registration. Currently, regulatory oversight of genetically
modifi ed organisms (GMOs) is extremely cautious, and this has undoubtedly
extended development time, increased costs, and impacted commercial confi dence in an
early return on investment. To date, several prototype products, including rapid-action
NPVs, have been tested in the fi eld although none have been registered for commercial
use. The entire genome of H. armigera NPV has been sequenced, and this information can
now be used for matching gene(s) with virulence (Chen et al., 2002). It may be possible to
use molecular markers linked to virulence to study a range of NPV strains for use in
biopesticide formulations.
There is a need for consideration of biosafety aspects before releasing recombinant
baculoviruses into the environment, taking into consideration the nature of the genetic
material and the environment into which the recombinant baculoviruses are to be released.
Genes expressing insect-specifi c neurotoxic peptides augment the insecticidal activity of
baculoviruses and acquire altered host range. The data so far suggests that host range
determination is confi ned to a specifi c locus on the baculovirus genome. Therefore, probability
of horizontal mobilization of the toxin gene to nontarget insect populations or in
wild relatives in the fi eld may not be greater than occurs in nature. Baculoviruses sprayed
on fruits and vegetables are safe to human beings (Carter, 1984). Long-term exposure to
NPVs is safer for workers, and no antibodies have been observed in workers exposed to
products of H. zea SNPV (Ignoffo and Couch, 1981). Therefore, there is a possibility that the
recombinant baculovirus can be deployed for pest management in the future.
Hartig et al. (1989) evaluated the NPV of A. californica (AcNPV) by using in vitro test
systems for toxicity and transforming potential in mammalian cells. Mass cultures of CV-1
and W138 cells were unaffected by AcNPV. Human foreskin cells grew more slowly after
inoculation, but eventually produced healthy monolayers. The sensitivities of the inhibition
of reproductive survivability (IRS) assays indicated slight AcNPV toxicity to CV-1,
W138, and human fore-skin cells. Toxicity was not ameliorated when gradient-purifi ed or
inactivated virus was used, suggesting that the toxic component of the preparation is part
of the virion or copurifi es with it. AcNPV was not toxic to and did not transform BALB/c
3T3 cells or primary cell cultures derived from Syrian hamster embryo cells (SHE). Unlike
the BALB/c 3T3 transformation assay, the SHE assay detected no spontaneous transformants.
The SHE transformation assay can employ simian adenovirus 7 as a positive control.
The results suggested that in vitro assessment of viral pesticide toxicity should employ the
IRS assay and that transformation assessment is best done with the SHE-simian adenovirus
7 procedure.
Conclusions
Greater awareness of the problems associated with development of insect resistance to
insecticides, environmental hazards associated with synthetic pesticides, and pesticide
residues in food and food products has necessitated greater emphasis on use of biopesticides
for pest management in the future. There is a need to develop strategies for using
microorganisms alone or in combination with synthetic pesticides for pest management.
Considerable progress has been made in developing more virulent or effective strains of
entomopathogenic bacteria, viruses, fungi, and nematodes through genetic engineering.