Contents - Faperta

356 Biotechnological Approaches for Pest Management and Ecological Sustainability
Protease Inhibitors
Soybean Kunitz inhibitor (SKTI) fed to L. oleracea larvae in an artifi cial diet has been detected
in hemolymph of the parasitoid, Eulophus pennicornis (Nees) larvae, indicating that proteinase
inhibitors in the host diet can be delivered to a parasitoid via the host hemolymph
(Down et al., 1999). If transgenic plants expressing proteinase inhibitors for protection
against insect pests are to form a component of integrated pest management systems, possible
adverse effects, whether direct or indirect, of transgene expression on parasitoids
should be taken into consideration. The success of the parasitic wasp, E. pennicornis was
reduced by the presence of CpTI in host diet and on transgenic potato expressing the transgene
for resistance to L. oleracea (Bell et al., 2001a). Parasitoid progeny that developed on
L. oleracea reared on CpTI-containing diets, however, were not adversely affected.
Lectins
The success of the parasitic wasp, E. pennicornis was not reduced by the presence of GNA
in any of the diets or by the length of feeding of the host prior to parasitism (Bell et al.,
1999). However, the mean numbers of E. pennicornis wasps that developed on L. oleracea
reared from the third-instar on the GNA-containing maize diet was signifi cantly higher
than on the controls, although the differences were not signifi cant. Progeny of E. pennicornis
that developed on L. oleracea reared on GNA-containing diets showed little or no alteration
in size, longevity, egg load, and fecundity when compared with wasps that had developed
on hosts fed on respective control diets. The results suggested that expression of GNA in
transgenic crops will not adversely affect the ability of the ectoparasitoid, E. pennicornis to
utilize L. oleracea as a host (Bell et al., 1999). GNA-containing artifi cial diet has a detrimental
effect on aphid parasitoids. Effects of GNA appeared to be host-quality mediated rather
than constituting direct toxic effects of GNA (Couty et al., 2001a; Couty, Clark, and Poppy,
2001). GNA delivered via artifi cial diet to the aphid, M. persicae can be transferred through
the trophic levels and has a dose-dependent effect on the parasitoid, A. ervi (Couty et al.,
2001b). Parasitoid larvae excreted most of the ingested GNA in the meconium, but some
of it was detected in the pupae. Although A. ervi development was not affected when
developing within hosts feeding on transgenic potato leaves, this probably refl ected
suboptimum expression of the toxin in the transgenic potato line used. Bell et al. (2001b)
suggested that GNA-expressing potatoes and E. pennicornis were compatible for controlling
L. oleracea. GNA expressed in tomato enhanced the parasitism by E. pennicornis on
tomato moth in the greenhouse.
Interactions of Transgenic Plants with Fauna and Flora in the Rhizosphere
Potential effects of genetically transformed crops on nontarget species are not restricted
only to the environment above ground, but also on those inhabiting the soil rhizosphere
( Jepson, Croft, and Pratt, 1994). Some genetically engineered crops affect soil ecosystems
(Griffi ths, Geoghegan, and Robertson, 2000), but the long-term signifi cance of any of these
changes is unclear. Effects of transgene products on non target organisms may decrease
the rate of plant decomposition, and of carbon and nitrogen levels, thus affecting soil fertility.
Similarly, declining species diversity of soil microorganisms in some cases can cause