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.

Natural enemies of whitefly, Bemisia tabaci (Gennadius) on cotton in Punjab, India

“…Moreover, it also transmits more than 111 plant viruses (Jones, 2003) including cotton leaf curl virus (CLCuV) in American cotton (Hassan et al, 2016). Several bioagents from diverse groups have been recorded against whitefly across India (Rao et al, 1989;Natarajan 1990;Kedar et al, 2014;Boda and Ilyas 2017;Rawal et al, 2017). Huge populations of whiteflies were recorded during 2015 in Punjab, Haryana and Rajasthan leading to considerable economic losses to the farmers.…”

Influence of abiotic factor on incidence of Pink bollworm, Pectinophora gossypiella (SAUNDERS) on Bt cotton

“…The available literature revealed that the peak level of pink bollworm in Bt cotton was observed during 44 th SMW (21 WAS) to 52 nd SMW (29 WAS) (Ajmad et al, 2016) [1] . Rawal et al (2017) [8] reported that incidence of bollworms on squares started from 32 nd SMW (9 WAS) and continue till harvesting of crop. [10] revealed that the peak of flower resetting, green boll damage, pink bollworm larval population per 20 green bolls and locule damage in green bolls was observed during 45 th , 46 th and 47 th MW, respectively in Bt cotton.…”