Contents - Faperta

52 Biotechnological Approaches for Pest Management and Ecological Sustainability
FIGURE 3.5 Headcage technique to screen sorghum for resistance to sorghum midge, Stenodiplosis sorghicola.
(A) sorghum panicle at anthesis infested with sorghum midge females, (B) reaction to midge of a susceptible
sorghum cultivar, CSH 1, and (C) reaction to midge of a resistant sorghum cultivar, ICSV 745.
(Figure 3.5) or infl orescences of cotton, pigeonpea, etc. (Sharma et al., 1992, 2005a; Sharma,
Pampapathy, and Kumar, 2005). Cage size and shape are determined by the type and number
of test plants needed for evaluation. For valid comparisons, resistant and susceptible
checks of appropriate maturity should also be included and infested at the same time as
the test genotypes.
Greenhouse Screening
Screening for resistance to some insects can be carried out at the seedling stage in the
greenhouse under no-choice, dual-choice, or multi-choice conditions, and has been utilized
successfully in case of sorghum (Starks and Burton, 1977; Nwanze and Reddy, 1991;
Sharma et al., 1992), rice (Medrano and Heinrichs, 1985; Heinrichs, Medrano, and Rapusas,
1985), wheat (Webster and Smith, 1983), soybean (Fehr and Caviness, 1977; All, Boerma,
and Todd, 1989), alfalfa (Sorenson and Horber, 1974), pearl millet (Sharma and Youm, 1999;
Sharma and Sullivan, 2000), groundnut (Sharma, Pampapathy, and Kumar, 2002), and
chickpea (Sharma et al., 2005a, 2005b; Sharma, Pampapathy, and Kumar, 2005) (Table 3.3).
Screening can be carried out under no-choice (Figures 3.6 and 3.7) or multi-choice conditions.
The test material can also be infested with insects under multi-choice, dual-choice,
or no-choice conditions using cages of appropriate size. The test material can also be
infested with insects at the susceptible stage without a cage. This approach is more appropriate
to evaluate seedlings or small-sized plants, such as those of chickpea, saffl ower,
cruciferous vegetables, etc. However, it may be a bit cumbersome to use the cage technique
on plants with a large canopy, such as those of cotton and pigeonpea. The following procedure
may be adopted to screen for resistance to insects under greenhouse conditions.
• Raise the plants in the greenhouse as per recommended package of practices. Infest
the test plants at the susceptible stage of the crop, for example, for chickpea, the
plants can be infested with neonate larvae of H. armigera at 30 days after seedling
emergence or at the 50% fl owering and pod setting stages; while for sorghum, the
infestation should be carried out at 10 days after seedling emergence for A. soccata,
and 20 days after seedling emergence with C. partellus, Mythimna Separeta (Walk.),