Pod weevil Apion clavipes Gerst. (Apionidae: Coleoptera) infestation on pigeonpea in West Bengal

Field biology, infestation pattern and damage to seeds by Apion clavipes Gerst. on pigeonpea were studied in West Bengal during 2001-2003. Top tier of the plant irrespective of the date of sowing between July and August was preferred by the larva for feeding. The variability of infestation between top, middle and bottom tiers of plant canopy was moderate (V=16.08%). The morphology of the pods i. e., bigger, softer and light green pods of 20/105 (Rabi) and smaller, harder and brown pods of UPAS 120 did not show much difference in infestation level and late sown crops were more prone to infestation irrespective of the variety. Significant correlation was found between seed damage and pod infestation. From regression equations Y=0.745 x-0.529 (UPAS 120 in 2001-2002), Y=0.658 x - 0.542 (UPAS 120 in 2002-2003) and Y=0.676 x -1.055 (20/105) (Rabi ) in 2002-2003), it could be deduced that 14% pod infestation caused 10% of seed damage.