Contents - Faperta

348 Biotechnological Approaches for Pest Management and Ecological Sustainability
toxicity towards A. mellifera (Belzunces et al., 1994). In vivo, trypsin inhibitor and WGA
caused a decrease in the amount of trypsin activity, but did not have a signifi cant effect on
esterase activity. In vitro, trypsin inhibitor inhibited about 80% of nonspecifi c protease
activity and 100% of trypsin activity. Serine proteases, but not the cystein proteases, play a
major role during protein degradation in honeybee ( Jimenez and Gilliam, 1989). In addition
to direct toxic effects, ingestion of PIs can affect the learning performance of the
honeybee. Such a detrimental effect has been reported for the serine-type PIs such as BBI
(Pham-Delègue et al., 2000) and CpTI (Picard-Nizou et al., 1997). However, cystein-type PIs
have no effect on the insects’ learning performance (Girard et al., 1998; Pham-Delègue
et al., 2000).
Genetically modifi ed oilseed rape, Brassica napus L., expressing heterologous chitinase
in somatic tissue for enhanced disease resistance did not cause any adverse effects on honeybee,
A. mellifera foraging behavior (Picard-Nizou et al., 1995). Insects do not discriminate
between conventional and transgenic oilseed rape resistant to glufosinate (Pierre et al.,
2003). The diversity and density of the foraging insects has been found to be similar on the
transgenic and nontransgenic cultivars, as was the foraging behavior. Honeybees fl ew
indifferently across these genotypes and no differences have been observed in nectar and
pollen between the transgenic and nontransgenic plants. Thus, we may assume that the
transgenic crops do not pose a major threat to the activity and abundance of pollinators.
Interaction of Transgenic Crops with Predators
Plant breeders have continued to breed for high levels of resistance to insects, and biocontrol
specialists have ignored the role of the host plant in ensuring successful foraging by
natural enemies. The new possibilities for controlling insect pests, which will combine
both “nature’s” own defenses with man’s ingenuity, may stack the odds in favor of natural
enemies and against insect pests (Poppy and Sutherland, 2004). Recombinant DNA technology
will allow plants to be designed that are well suited for use along with biological
control. However, transgenic crops have to be assessed for their effects on the environment,
including the possible impact on nontarget arthropods, many of which are important for
biological control of insect pests (Romeis et al., 2004). A framework for risk assessment on
transgenic crops to nontarget arthropods has been proposed by Romeis, Dutton, and Bigler
(2004). As a fi rst step, it is important to determine which entomophagous arthropods play
a major role in regulating the pest populations in an agroecosystem, and which ones may
be at risk. Because the risk that transgenic plants pose to entomophagous arthropods
depends on both their exposure and sensitivity to the insecticidal proteins, it is essential
to determine if, and at what level, organisms are exposed to the transgene product.
Exposure will be associated with the feeding behavior of phytophagous and entomophagous
arthropods and the tissue- and cell-specifi c temporal and spatial expression of the
insecticidal proteins. For organisms that are potentially being exposed to the insecticidal
protein, sensitivity tests should be performed to assess the toxicity. The testing procedure
adopted should depend on the feeding behavior under natural conditions.
It is diffi cult to assess the effects of transgenic plants on the abundance of generalist
predators, as their populations fl uctuate in repeat cycles of several generations. The test plots
have to be quite large (up to 1 ha or more) to measure such effects on mobile insects such
as lacewings, coccinellids, wasps, etc. Of the nontarget insects, the generalist predators are