author(s)
Zunnu Raen Akhtar, Zain Saeed, Aqsa Noreen, Anjum Jabeen, Easha, Hasooba Hira, Arbab Ihsan and Saif Ullah

abstract
Transgenic cotton expressing cry1Ac gene was tested for its resistance against it target pink bollworm. Objective of this experiment was to observe either Bt protein is expressed in Bt cotton or not. If it is expressed in Bt cotton then how pink bollworm can react to its Bt host. Experiment was consisted of laboratory as well as field studies. Laboratory studies showed that pink boll worm was not having effect from Cry1Ac expressing cotton. Though there were numerical differences in the life cycle of the larvae but there was no significant difference in Bt and non-Bt cotton varieties. Field results were also in conjugation with field studies in which it was found that no significant difference was observed in population dynamics of pink boll worms on Bt and non-Bt varieties. These results confirm that pink bollworm are either transporting Bt protein to excrete outside body successfully or they have developed system to down regulate the cry1Ac gene from Bt plant, or pink bollworms have up regulated resistant gene by unknown mechanism which is resulting in more resistant pink bollworms progeny in the fields of transgenic cotton. Further research should be carried out to reduce or eliminate resistance development in pink bollworms against Bt cotton.