Contents - Faperta

60 Biotechnological Approaches for Pest Management and Ecological Sustainability
resistance through diet impregnation assay, the test material can be grown in the greenhouse
or fi eld conditions (Kumari, Sharma, and Jagdishwar Reddy, 2008). No insecticide
should be applied on the test material, but care should be taken that there is no heavy incidence
of any disease or nontarget insect species.
• The plant material (leaves at the beginning of fl owering in chickpea, pigeonpea,
and cotton; fl owers at petal opening; or pods/bolls at 10 to 15 days after fl owering)
should be harvested and immediately placed in an icebox.
• The test material should be brought to the laboratory and placed in a freeze-drier
until the material is completely dry. If freeze-drying equipment is not available,
the test material can be placed in paper bags and placed in an oven at 55°C and
dried to a constant weight (in about four to fi ve days).
• The dried material should be powdered in a pestle and mortar or in a Willey mill,
placed in sealed packets or paper bags, and stored in desiccators until used in diet
incorporation assay.
• Take 10 to 20 g of the powdered material (10 g leaf or pod powder in case of chickpea
and pigeonpea) and add it to diet ingredients to prepare 250 mL of diet. Pour
7 to 10 mL of diet in 15- to 20-mL glass vials or plastic cups, allow the diet to
solidify, and release neonate larvae singly or in groups in each vial. Keep the vials
at 27 2°C or at room temperature.
• Record data on larval survival and larval weight at 10 days after initiating the
experiment, number of larvae pupated, adult emergence, fecundity, larval and
pupal development periods, and pupal weights.
A relative assessment of the adverse effects of different genotypes on the survival and
development of insects will give an idea of the antibiosis component of resistance because
of the presence or absence of secondary metabolites and/or poor nutritional quality
of food.
Bioassay of Transgenic Plants for Resistance to Insects
Evaluation of transgenic plants should be carried out in contained facilities (P 2 level greenhouse
or in the laboratory) with the approval of the institute’s biosafety committee or as
per guidelines of the national regulatory bodies, with proper control over pollen movement,
and disposal of plant residues, water, and soil used for growing the plants. The
transgenic events along with the nontransgenic plants of the same cultivar should be
grown under similar conditions. If possible, susceptible and resistant checks (identifi ed
through conventional host plant resistance evaluations) of the same crop should also be
included as controls. The material can be tested using leaf disc assay, detached leaf assay,
no-choice cage screening in the greenhouse, feeding preference assays, and consumption
and utilization of food. The bioassay can be performed with neonate larvae or nymphs,
third-instar larvae, and adults as per the feeding behavior of the insect, and the reliability
of the testing procedure. There should be 5 to 10 replications for each transgenic plant or
event depending on the availability of the plant material and the experimental requirements.