Population dynamics of insect pests of cotton in Southern dry zone of Karnataka

Abstract

A field experiment was conducted during kharif season of 2019-20 at AICRP on Cotton scheme, Chamarajanagara, to study the seasonal variation of sucking pests incidence in non Bt cotton hybrid (DCH -32). From the data it is observed that the population of leafhopper was above ETL in almost all standard meteorological week (SMW) with peak population of 7.20 and 6.80/3 leaves during 35th and 36th SMW, respectively. While, the occurrence of aphids was noticed throughout the cropping season. The peak incidence was observed at 36th SMW (55.15/3leaves). Mirid bug incidence was started from 35th SMW and attained its peak during 42nd SMW and declined thereafter. The population of whiteflies and thrips didn't cross ETL during the entire cropping season. Correlation study revealed that the morning and evening relative humidity had a positive influence on the population of sucking insect pests including the activity of natural enemy (coccinellid beetles). Whereas, maximum and minimum temperature had a detrimental effect on the population of sucking insect pests.