COMPARISON OF 4 COTTON GENOTYPES FOR RESISTANCE TO HELIOTHIS-VIRESCENS

Heliothis spp. are major pests of cotton, Gossypium hirsutum L., in many cotton-producing countries of the world. Two strains of cotton putatively resistant to Heliothis virescens Fab., tobacco budworm, and two adapted cultivars, Deltapine 50 and DES 119, were grown in plots infested with tobacco budworm and in plots free of tobacco budworm (paired plots) for 2 yr. The difference in lint yield between each genotype grown in tobacco budworm-infested plots and in tobacco budworm-free plots was used as the measure of resistance. LA 850082 mas significantly more resistant each year than the other three. ST 69132 was significantly more resistant each year than DES 119 and more resistant than DPL 50 1 yr. Our results confirm the Heliothis resistance of strains LA 850082 and ST 69132. LA 850082 should be a good source of resistant germplasm to use in developing cultivars that resist infestations of tobacco budworm. In terms of agronomic characteristics, LA 850082 was significantly higher in yield than the two cultivars; however, it is known to have shorter and weaker fiber. Combining the delta-endotoxin gene from Bacillus thuringiensis with the resistance of LA 850082 is suggested as a strategy for development of cultivars with multiple mechanisms for resistance to Heliothis spp.