Contents - Faperta

Deployment of Insect-Resistant Transgenic Crops for Pest Management 319
FIGURE 10.2 Performance of Bt transgenic and nontransgenic cotton hybrids with and without insecticide
protection.
pink bollworm, Pectinophora gossypiella (Saunders) (Wilson et al., 1992), cabbage looper,
Trichoplusia ni (Hubner), tobacco caterpillar, Spodoptera exigua (Hubner), and cotton bollworms,
Helicoverpa zea Boddie/Heliothis virescens (F.) (Benedict et al., 1996), and H. armigera
(Hubner) (Guo et al., 1999). Field trials in the Andalusian region of Spain have also
confi rmed the effectiveness of Bt transgenic cotton in providing protection against
H. armigera, P. gossypiella, and Earias insulana (Boisd). In addition to reduction in the
number of insecticidal sprays, the transgenic cotton was also relatively safe to benefi cial
arthropods (Novillo, Soto, and Costa, 1999).
In China, transgenic cotton cultivars Shiyuan 321, Zhongmiansuo 19, 3517, and 541
resulted in up to 96% mortality of cotton bollworm, H. armigera (Guo et al., 1999). Sukang
102 exceeded the nontransgenic control and Simian 3 in boll weight (Xu et al., 2000). New
cotton hybrids derived from cross- pollination between Bt-transgenic cotton as a donor
parent and traditionally bred cotton cultivars possessing high yield and resistance to
cotton diseases and insect pests have shown competitive and transgressive dominances,
and the lint output increased by 11.7% to 54.6% (Z.B. Wu et al., 2003). Dong et al. (2004)
reported that yield increase in Bt-transgenic cotton varieties under good agronomic management
and pesticide application was only marginal. However, the hybrids resulted in
20% increase in productivity over the conventional cultivars. Rapid increases in adoption
of Bt cotton have been attributed to hybrid seed production, seedling transplanting, and
low planting densities.
In India, the cotton hybrids (Mech 12, Mech 162, Mech 184, RCH 2) carrying the cry1Ac
gene have been approved for cultivation (Mohan and Manjunath, 2002). Since then, many
hybrids have been released for cultivation in different regions in the country (Table 10.1).