Singla, NeenaChaudhary, Mithun2020-10-232020-10-232020Chaudhary, Mithun (2020). Diversity and Relative Abundance of Spiders on Cotton Crop (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810153705Present study was aimed to investigate diversity and relative abundance of spiders on Bt and non-Bt cotton crops. A total of 734 spiders of 11 species representing nine genera and six families namely Araneidae (36.4%), Salticidae (9.1%), Lycosidae (27.3%), Oxyopidae (9.1%), Thomisidae (9.1%) and Pisauridae (9.1%) were recorded from Bt and non-Bt cotton crops during the study period. Insects of 15 species including 10 phytophagous, one pollinator and four predators were found which were directly or indirectly affecting spider population. Field evidence for role of spider community in limiting insect pest and predator populations was also found. Diversity indices such as species evenness (0.71-0.80) and Shannon-Weiner index (1.27-1.43) for spiders of different families found on cotton crop were almost similar in Bt and non-Bt cotton crops and indicated rich biodiversity and less equitable distribution. No significant effect of Bt cotton was observed on spider population. Spider population was reported to be highest during September and October when there was severity of insect pests. Insecticides had direct or indirect affect on spider population. Climatic factors had a variable effect on spider population in different seasons and crop stages. Spider population generally had a positive correlation with sun shine and negative correlation with mean temperature, relative humidity, rain fall and wind velocity. Present study revealed diverse spider fauna and relative abundance on cotton crop thus suggesting their conservation and utilization in regulating insect pest population as part of IPM programme.EnglishThesis