Contents - Faperta

Transgenic Resistance to Insects: Interactions with Nontarget Organisms 343
TABLE 11.1
Assessment of Biosafety of Transgenic Crops to Nontarget Organisms
Assessment of Biosafety of Transgenic Crops Organisms/Tests
Which nontarget organism should be included in
the assessment?
Coccinellids, lacewings, hymenopteran parasitoids,
pollinators, bacteria, fungi, and earthworms in the soil
What kind of nontarget tests should be carried out? Acute and chronic toxicity effects
How should the biosafety tests be carried out? Laboratory, contained fi eld trials, and long-term fi eld trials
testing for chronic, lethal, sublethal, and acute toxicity effects (Table 11.1). Basing ecological
studies solely on bitrophic studies that provide the highly processed toxin protein directly
to the nontarget organisms may not be suffi cient as such studies may not provide
information on synergistic interaction between plants, insects, and the natural enemies.
Routes of exposure should include the natural situation, where the toxin is actually entering
the food, and then delivered to the higher trophic level. Test organisms should include
ecologically relevant species, and consider all the multitrophic interactions involved
(Table 11.2). There is a need for detailed information on Hymenoptera, which also includes
honeybees, bumble bees, and wild bees because of their role in pollination. Diptera and
Coleoptera also contain some important parasites and predators, and it is crucial to have
information on the effects of transgenic plants on these insects. It is important to differentiate
between different life stages as only the larval stages act as parasites or predators in
several species, while the adults feed on pollen and nectar. In some species, such as coccinellids,
both adults and larvae feed on the herbivore insects. There is a need to generate
information on predator-prey ratio, and population dynamics of the insect host and its prey.
Such information is essential for learning about existing biological control mechanisms,
their effectiveness, ecological effects, and potential changes in the future. First, the attention
should be focused on important species. If important species have been identifi ed, a tiered
testing procedure from laboratory to fi eld should be followed to assess the risk that the
deployment of a specifi c transgenic crop would pose to key nontarget organisms, similar to
the testing procedure used in ecotoxicology (Dutton, Romeis, and Bigler, 2003a) (Table 11.3).
Use of insecticide treatments often leads to signifi cant differences in treatment effects.
However, the potential adverse effects of transgenic plants on benefi cial insects are likely
to be more sublethal and chronic in nature, and the long-term intergenerational effects on
population dynamics in the fi eld may persist over many years. Quite often, on becoming
adults, the insects migrate away from the fi eld in search of food, mating, and oviposition.
Different habitats provide different sets of conditions for the insects. One-year small plot
studies may not provide adequate information on such complex interactions. Therefore,
long-term monitoring should be carried out wherever transgenic crops are deployed.
TABLE 11.2
Nontarget Organisms Likely to Get Exposed to Transgenic Crops under Natural Conditions
Category of Organisms Test Organisms
Species of ecological importance in the ecosystem Natural enemies of crop pests
Species of economic importance in the ecosystem Pollinators
Species likely to get exposed to insecticidal proteins Nontarget herbivores and natural enemies
Species that are rare or endangered Protected Lepidoptera, Collembola, etc.