Contents - Faperta

350 Biotechnological Approaches for Pest Management and Ecological Sustainability
reported negative effects of Bt maize were prey-quality mediated rather than direct toxic
effects. No statistically signifi cant effects were observed on survival, aphid consumption,
development, or reproduction in Hippodamia convergens (Guerin-Meneville) fed on Myzus
persicae (Sulzer) reared on potatoes expressing d-endotoxin of B. thuringiensis subsp.
tenebrionis (Dogan et al., 1996). Presence of the cry1Ab gene showed no marked effects on
predation by the wolf spider, Pirata subpiraticus (Boes. and Str.) on the rice leaf folder,
Cnaphalocrocis medinalis (Gn.) and the brown planthopper, Nilaparvata lugens (Stal) (Z.C. Liu
et al., 2003). No signifi cant differences were observed in insect mortality from egg hatch
to adult eclosion, and total developmental period in Orius majusculus (Reuter) nymphs fed
on Anaphothrips obscurus (Muller), a thysanopteran pest of maize, reared on isogenic and
transgenic maize plants expressing cry1Ab (Zwahlen et al., 2000).
Lectins
Aphids fed on artifi cial diet containing GNA showed no deleterious effects on adult
longevity, but resulted in a consistent trend for improved fecundity of the ladybird beetle,
H. convergens. Egg production increased by 70%, suggesting that GNA is not deleterious to
ladybirds (Down et al., 2003). About 50% of the potential activity of Oryzacystatin I (OCI)
has been recovered in extracts of Perillus bioculatus Fab. feeding on L. decemlineata reared
on OCI-potato foliage, indicating that the predator was sensitive to OCI (Bouchard,
Michaud, and Cloutier, 2003). However, P. bioculatus survived on OCI prey and developed
normally, indicating its ability to compensate prey-mediated exposure to the OCI inhibitor.
Confi nement of P. bioculatus to potato foliage provided no evidence that potato plantderived
nutrition is a viable alternative to predation. Restriction to potato foliage was
inferior to free water for short-term survival of nonfeeding fi rst-instar larvae, suggesting that
OCI, an effective inhibitor of a fraction of digestive enzymatic potential in P. bioculatus,
may not interfere with its predation potential when expressed in potato plants fed to its
prey at a maximum level of 0.8% of total soluble proteins in mature foliage (Bouchard,
Michaud, and Cloutier, 2003). No signifi cant effects have been observed on development,
survival, and progeny production of ladybird larvae fed on aphids from transgenic plants
(Down et al., 2003).
Antagonistic Interactions
Bt Toxins
Sun et al. (2003) reported that the population density of the majority of natural enemies
(including predatory and parasitic enemies) was signifi cantly lower in transgenic cotton
than in normal cotton. The populations of P. japonica, Lysiphlebia japonica (Ashm.), and
Allothrombium ovatum (Zhang and Xin) in bivalent transgenic cotton were lower than in
univalent cotton by 30.4, 42.8, and 46.8%, respectively, whereas the density of the eggs of
Chrysopa sinica Tjeder and Araneida was lower by 20.0% and 27.4% (not signifi cant), and
that of C. sinica and O. minutus was higher by 27.0% and 8.9%, respectively. Signifi cantly
lower numbers of C. maculata larvae have been recorded in open as well as caged plots of
transgenic sweet corn with cry1Ab gene as compared with non-Bt treatments. No signifi -
cant effects were observed within a year on overall density of the benefi cial insect populations
between Bt and non-Bt sweet corn. However, long-term fi eld studies with larger
sample size should be conducted to characterize the effects of transgenic crops on natural
enemies in the fi eld (Wold et al., 2001). Abundance of Lebia grandis Dubrony has been found
to be lower in pure and mixed crops of transgenic potatoes than in pure nontransgenic