Contents - Faperta

Evaluation of Transgenic Plants and Mapping Populations for Resistance to Insect Pests 61
FIGURE 3.10 A contained fi eld trial for evaluating transgenic plants for insect resistance under artifi cial
infestation.
The experiments can be performed using completely randomized design or any other
appropriate system. The plant residue and the insects used in bioassay should be properly
disposed of or burnt. The seeds of the transgenic material should be stored in a cool and
dry place under proper safeguards.
Transgenic events selected for insect resistance with optimum expression of the transgene
are tested under contained fi eld trials, after obtaining necessary permission from the
institutional and national biosafety regulatory bodies. The experimental area should be
fenced all around, and the plants covered with a nylon mesh to prevent the movement of
pollinators and the pollen from transgenic plants to nontransgenic plants (Figure 3.10). The
transgenic events to be tested along with the nontransgenic plants of the same cultivar
should be planted in a randomized block design with three to fi ve replications. A plot size
of 10 to 50 square meters should be maintained, depending on the resources and the material
to be tested. The nontransgenic plants of the same cultivar should be planted around
the test plots to monitor the movement of pollen, if any, through molecular techniques
(RT-PCR, ELISA, Southern blot, etc.). A nonhost crop should be planted all around the
boundary of the test plots to prevent movement of pollen from the test plants to the nontransgenic
plants of the same crop or closely related wild relatives of the transgenic plants
being tested. The test material is infested with a uniform number of neonates or third-instar
larvae at a density suffi cient to differentiate resistant and susceptible plants. The plant
material can also be brought to the laboratory and subjected to the bioassays described
above. The test material can also be infested with adults. In the case of lepidopteran insects
that are affected by light, infestation with adults does not lead to uniform infestation of the
test material. Once the transgenic events have been tested in contained fi eld trials for two
to three seasons for their effi cacy to control the target pests, yield potential, nutritional
quality, and environmental safety may be tested as per national biosafety guidelines. The
promising events thus identifi ed are tested in the target areas in an open fi eld in replicated
trials. The test material can be subjected to natural infestation or infested artifi cially with
insects reared in the laboratory. Once the effectiveness of the transgene, and the agronomic,
nutritional, and biosafety desirability of an event is proved across seasons and
locations, the institutions/scientists concerned can apply for the deregulation of the event
for use by farmers as a component of integrated pest management.