Impact analysis of genetically modified (Bt) cotton cultivars on natural enemies

摘要

The response of six genotypes I e. two Bt hybrids (RCH 134 and RCH 317) two non-Bt hybrids (RCH 134 and RCH 317), one hybrid (HHH-223) and one variety (H-1226) to natural enemies was evaluated at Research Farm of Haryana Agricultural University, PlantBreeding Department, Hisar during the kranif season of 2006. Spiders, coccinellids, green lacewings and others (yellow wasp, dragonflies, damselfiies, etc.) were main natural enemies observed on cotton genotypes. Natural enemies population /plant in different genotypes did not vary significantly throughout the period of study. However, the population was more in Bt genotypes in comparison with the non-Bt genotypes. Under unsprayed conditions, maximum mean population was recorded on RCH-134 Bt (0.22/plant), followed by RCH-317 Bt (0.20/plant) and HHH-223 (0.20/plant) and minimum on RCH-317 non-Bt (0.15/plant). While under sucking pests sprayed condition maximum population was recorded on RCH-134 Bt (0.28/plant) and minimum on H-1226 (0.17/plant). On the other hand under both sucking and bollworm pests sprayed conditions, the maximum population was recorded in RCH-317 non-Bt (0.33/plant) and RCH-134 Bt (0.33/plant) and minimum on H-1226 (0.22/plant). The correlation analysis of mean of following seasonrevealed that the natural enemies population was positively correlated with temperature (r= 0.76), relative humidity (r=0.35), rainfall (r=0.14), wind speed (r=0.57) and leafhopper population (r= 0.19) while negatively correlated with sunshine hours (r=-0.06) and whitefly population (r=-0.76).