Survival of Pectinophora Gossypiella (Saunders) on Transgenic Cotton Crop in Pakistan. Is It Resistance Development, Impact of High Temperature or Mixture of Non Bt. Cotton?

Cotton, "White gold” is the important fiber crop which shares 1% in GDP and 5.2% in Agriculture value addition of Pakistan. Among potential insect pests on non Bt. cotton, alone Pectinophora gossypiella caused the yield losses up to 20-30%. Pesticides remained the only major management tool in almost all the cotton production systems before the introduction of Bt. in Pakistan till 2005. Pink boll worm was found attacking all cotton varieties before the introduction of transgenic cotton. High infestation of Pink Boll worm was recorded from Pakistan i.e. 16.07%, 8.99%, 11.43% on flowers, squares and green bolls, respectively On non-transgenic cotton varieties. In 2004, boll damaged due to PBW on different conventional varieties was ranging from 15-31.67%. Due to increasing popularity of Bt cotton in farming community, its cultivation has been extended from 4% in 2006 up to 70% in 2009. In 2010, eight Bt. varieties were introduced officially in Pakistan with the objective to control boll worms, resulting in less dependence on pesticides sprays and ultimately resulting in increase of per hectare yield. However the problem of Boll worms infestation was built up in certain pockets on small scale in cotton growing areas. The cultivated area of Bt cotton increased gradually & reached up to 98% of the total cotton sown area.  Pink boll worm population starts increasing on Bt Cotton, Cry1Ac in 2014-15 and showed a decline of 27.8% yield due to this pest, which was the lowest in last fifteen years and loss were of Rs 125 billion. In 2017, PBW infestation in Province Punjab was observed 38.57%. The increasing population trend of PBW may be due to lack of refuge crop area and low level of Bt toxin protein in varieties or development of resistance in P. gossypiella.