COMPARATIVE EFFICACY OF CHEMICAL INSECTICIDES AND BIOAGENTSAGAINST THRIPS (Thrips tabaci) AND TOBACCO STREAK VIRUS IN COTTON

Abstract

The present investigationoncomparative efficacy of chemical insecticides and bioagents against thrips (Thrips
tabaciLindeman) and tobacco streak virus in cotton was conductedat RARS, Warangal during kharif 2024 and 2025 to evaluate
the efficacy of selected insecticides and bioagents against thrips, their influence on TSV incidence under field conditions. Seven
treatments viz.,Metarhizium anisopliae @ 5g l-¹, Lecanicilliumlecanii@ 5g l-¹, Azadirachtin 1500 ppm @ 5ml l-¹, Spinetoram 11.7
SC @ 0.9ml l-¹, Fipronil 5 SC @ 2ml l-¹, Sulfoxaflor 21.8 SC @ 0.75ml l-¹, and an untreated control were evaluated.The pooled
results revealed that, Spinetoram 11.7 SC @ 0.9 ml l-¹ was the most effective against thrips, recording the lowest thrips population
of 2.33 thrips per three leaves at 10 days after second spray, with the highest 73.38 per cent reduction over control. It also
recorded the lowest Tobacco Streak Virus incidence (4.46%) with the highest (76.66 per cent) disease reduction andrealized the
maximum seed cotton yield (1968 kg ha-¹). Fipronil 5 SC and Sulfoxaflor 21.8 SC were the next best treatments, whereas
Azadirachtin 1500 ppm provided moderate suppression of thrips and disease. The entomopathogenic fungi,Metarhizium anisopliae
and Lecanicilliumlecanii, were comparatively less effective than the chemical insecticides, but performedsignificantly better than
the untreated control. However, Fipronil 5 SC @ 2ml l-¹ registered the highest incremental benefit ratio (8.85:1) owing to its lower
treatment cost.