Diversity and Relative Abundance of Spiders on Cotton Crop
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
Present 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.
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Citation
Chaudhary, Mithun (2020). Diversity and Relative Abundance of Spiders on Cotton Crop (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.