Transgenic cotton varieties have expanded their demand in Delicias, Chih., México. Cotton growers planted 18 ha of Bt cotton varieties in 1998. In 1999, they planted 841.50 ha of Bt cotton varieties from a total of 2121.50 ha. This was due to both the presence of insect pests as tobacco budworm and pink bollworm and the improvement of conventional cotton varieties.