Susceptibility of six cotton varieties and genotypes to infestation by the pink bollworm, Pectinophora gossypiella (Saund.) in Kafr El-Sheikh governorate, Egypt

Trials were carried out during 2012 and 2013 cotton seasons at Sakha Agricultural Research Station Farm, Kafr El-Sheikh governorate, Egypt to evaluate the efficiency of six cotton varieties and genotypes on infestation by pink bollworm, Pectinophora gossypiella (Saund.) throughout the season. Results during the two experiments showed that infestation % of PBW to six cotton varieties and genotypes in both seasons were (14.90, 9.82, 21.56, 10.54, 10.66 and 13.34%) for Giza 86, Pima S6 x, Giza 77, Giza 92, Giza 94, Giza 86 x 10/229 and Giza 88, respectively.
The higher means of infestation % were recorded in the G.92, G.86 and G.88 in both seasons, while the lower means of infestation % were recorded in the Pima S6 x G.77 and G.94 in both seasons. The differences among means of infestation % may be due to the differences in gossypol % in wall and wall thickness of green bolls. The means of gossypol % in green boll wall were (1.78, 1.32, 1.44, 0.91, 1.75 and 1.16%) and the means of wall thickness were (2.77, 2.38, 2.07, 2.82, 3.04 and 2.94 mm) for above mentioned cotton varieties and genotypes during both seasons, respectively. There were highly significant differences among the cotton varieties and genotypes in some characters.