Effect of six cotton varieties and genotypes on natural mortality percentage of diapaused larvae of pink bollworm pectinophora gossypiella (Saund.) in subsequent of cotton and rate of infestation in the subsequent year

Document Type : Original Article

Abstract

The experiments were carried out during the cotton seasons of 2011 and 2012 in Sakha Agricultural Research Station, Kafr El-Sheikh Governorate to evaluate the effect of six cotton varieties and genotypes on percentage of natural mortality of diapaused larvae of pink bollworm, Pectinophora gossypiella (Saund.). Results during the five inspection dates (November, December, January, February and March) of both seasons of 2011 and 2012 were estimated. The percent reduction of diapaused pink bollworm larvae increased when the inspection date to be late of all six cotton varieties and genotypes. Also, the highest means of percent reduction were recorded in the Giza 86 x 10/229 and Giza 86 in the two seasons, while the lowest means percent reduction were recorded in the Giza 94 and Pima 56 x Giza 77. The differences of means percent reduction may be due to the differences of gossypol % in wall and wall thickness of green boll. The data over both seasons of PBW percent reduction were (29.17, 23.97, 23.52, 22.93, 20.97 and 17.51%) for Giza 86 x 10/229, Giza 86, Giza 92, Giza 88, Pima S6 x Giza 77 and Giza 94, respectively. The combined data over both seasons of gossypol % in green boll wall were (1.74, 1.15, 1.43, 1.77, 1.32 and 0.90%) and those of green boll's of wall thickness were (3.04, 2.79, 2.06, 2.76, 2.37 and 2.82 mm) for the six cotton varieties and genotypes, respectively. There were highly significant differences between data from the cotton varieties and genotypes in every character were studied.

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