Contents - Faperta

Genetic Engineering of Natural Enemies for Integrated Pest Management 305
et al., 1990; Hadrys, Balick, and Schierwater, 1992). The RAPD-PCR method is also of potential
value for monitoring, establishment, and dispersal of specifi c biotypes of arthropod
natural enemies (Chapco et al., 1992; Edwards and Hoy, 1993). Green fl uorescent protein
(GFP) has been expressed in insects, and can be used as a marker to identify the transformants
(Berghammer, Klingler, and Wimmer, 1999). The GFP can be linked with different
promoters that allow expression in different tissues and in different insects. Peloquin et al.
(2000) used the GFP in pink bollworm, Pectinophora gossypiella (Saunders), pre-blastoderm
embryos and analyzed in vivo the expression of DNA that encodes the enhanced GFP. PCR
has also been also used to amplify the expected 579bp enhanced GFP DNA fragment from
protein-positive pink bollworm.
Identifi cation of transformed individuals could also be achieved by using a pesticide
resistance gene, such as the opd gene as a selectable marker. Another option is to use the
neomycin (neo) antibiotic resistance gene, which functions in both Drosophila and mosquitoes,
and is less likely to provoke concern about risks of releasing transgenic arthropods
into the environment. Use of insecticide resistance genes as selection markers might lead
to unintended genetic selection for resistance to insecticides, and horizontal transfer of the
transgene may lead to some complications in the environment. Pesticide resistance genes
have been used in arthropods when the goal is to develop insecticide-resistant strains of
insects for biological control. Another marker is the b-galactosidase gene (lacZ) isolated
from E. coli and regulated by the Drosophila hsp70 promoter, which has been expressed in
both Drosophila and the phytoseiid predator, M. occidentalis (Presnail and Hoy, 1992). If an
appropriate selectable marker is not available, identifying transformed lines can be accomplished
with PCR and subsequent analysis by Southern blot hybridization or an immunological
procedure.
Environmental Release and Potential Risks
Experience indicates that the probability that a new organism will become established is
small. Risk assessment should include questions about survival, reproduction, and dispersal
of transgenic species, and their effects on other species. Questions may also be raised
about the inserted DNA, its stability, and possible effect on other species should the genetic
material move from one species to another. Historical examples of biological invasions or
classical biological control have demonstrated lack of predictability, low level of successful
establishment, and the importance of scale, specifi city, and the speed of evolution (Ehler,
1990). The greater the genetic novelty, the greater is the possibility of surprising results.
Molecular markers can be used to understand dispersal and interactions between the
species (Williamson, 1992).
Transgenic insects may not pose a greater threat than the ones selected through conventional
approaches. Release of insects modifi ed through conventional approaches has occurred
for many years (Braig and Yan, 2002). Hoy (2000) has given a list of assays that may be
considered for risk assessment of genetically modifi ed organisms. The major concerns
include: (1) attributes of the species (potential for gene fl ow to other species, role in ecosystem,
mobility, longevity, and fecundity), (2) the nature of the transgene (function and
stability), (3) the environment (alternate hosts, presence of species in the environment,
and possibilities for indirect dissemination), and (4) comparison of the transgenic with
nontransgenic phenotype. Very little attention has been paid to evaluate intentional or