Population dynamics of natural enemies on bt / non bt cotton and their correlation with weather parameters

Abstract

The field study was carried out at Research Farm of cotton section, Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar, India to determine the effect of environmental factors and seven cotton genotypes (Bt and non Bt) on three natural enemies namely chrysoperla, coccinellids beetle and spi-ders. Natural enemies remained active throughout the crop season (with two peaks) with little differences among them. Chrysoperla and coccinellids both were remained active from 25th to 40th SMW (June to October, 2014) while spiders were active from 25th to 41st. It was observed that highest population of Chrysoperla (1.17 eggs/plant) and spiders (1.59 adult/plant) was observed on Bt cotton cultivar namely RCH-134 and JK-1947 respectively. However, coccinellids preferred non Bt genotype (HHH-223) for their population build-up. Chrysoperla and coccinellids popula-tion was significantly negatively correlated with maximum temperature (r = -0.527 at 5% and r = -0.626 at 1% re-spectively); positively correlated with RHm, RHe; negatively correlated with minimum temperature and wind speed without significance. While, spiders population showed negative correlation with all weather parameters except sun-shine hours. It was observed that population of the natural enemies fluctuated under different environmental conditions during cotton season.