Yield loss assessment and establishment of economic threshold level of Maruca vitrata in pigeonpea

Yield loss assessment using insect density and chemical protection method was carried out along with establishing the economic injury level (EIL) and economic threshold level (ETL) for M. vitrata in pigeonpea under field conditions. Using the insect density method, the highest avoidable loss of 79.05 per cent was recorded in the treatment with eight larvae per plant and lowest (29.75%) in the treatment with two larvae per plant. The correlation between the larval infestation level and the pod damage, as well as with the seed damage was significantly positive (r=0.98). However, the correlation between larval infestation level per plant and seed yield, as well as with 100 seed weight was significantly negative (r=0.98 and 0.95, respectively). Using the chemical protection method, the avoidable yield losses due to M. vitrata in pigeonpea varied from 39.55–84.68 per cent, with the determinate var. ‘MN-1’ registering the highest (84.68%) avoidable loss and the lowest (39.55%) being in the indeterminate var. ‘PAU 881’. On the basis of regression analysis and gain threshold, the EIL and ETL of M. vitrata in pigeonpea were determined as 5.58 and 4.19 webs per plant, respectively.