Contents - Faperta

Evaluation of Transgenic Plants and Mapping Populations for Resistance to Insect Pests 45
Midge damage (%)
25
20
15
10
5
0
IR+IP IR IP Control
MD CS
FIGURE 3.1 Effect of planting infester rows (IR) inoculated with sorghum panicles having diapausing larvae
(IP) on sorghum midge, Stenodiplosis sorghicola damage under fi eld conditions. MD, Spikelets with midge
larvae (%); CS, midge-damaged chaffy spikelets (%).
should be removed after infestation of the test material has taken place so that it does not
compete with the test material.
Trap crops that are attractive to the target insect species can also be used to increase insect
infestation in the test material (Stern, 1969). The H. armigera infestations can be increased by
planting Solanum vairum Dunal in tomato (Talekar, Hau, and Chang, 1999), and sesame and
pigeonpea in cotton (Sharma et al., 2005a). Mustard planted in cabbage and caulifl ower can be
used to increase diamondback moth, Plutella xylostella (L.), infestation. Brassica juncea (L.) Czern.
can be planted in cotton to increase the infestation by Lygus lineolaris (Palisat de Beauvois)
(Laster and Meredith, 1974). When the main crops reach the susceptible stage, the trap crops
are either allowed to senesce or are chopped off so that the insects migrate to the test material.
Grouping the Material According to Maturity and Height
To screen for resistance to insect species that feed on reproductive structures, it is
important to group the test material according to maturity and height as there are large
FIGURE 3.2 Infester row fi shmeal technique to screen sorghum for resistance to shoot fl y, Atherigona soccata.