1. 5. Jute Stem Weevil: Apion corchori (Apionidae: Coleoptera)

Distribution and status: Jute tracts of India and Bangladesh.
 
Host range:  The weevil has a number of alternate host plants but the capsularis varieties are most preferred.

Bionomics

The small weevil is only 1.8 mm in length and 0.8 mm in breadth, brown or dull black and has small whitish setae on its body. In the active season, the weevils make holes in the stem and lay eggs. A single female lays as many as 675 eggs during its life-span of about 120 days. The eggs are generally laid at" the base of the petiole or in the basal region of the stem . Larva make a rough chamber in the stem and pupate. Larval period 8-11 days, pupal period 4-6 days. Although the adults may live for about 200 days, the normal life-cycle is completed in 15-24 days. A number of overlapping generations are completed during the jute season. The adult passes the winter in bushes, shrubs and hedges, and start laying eggs on the new crop next year.

Damage symptoms

The main damage to the quality of fibre is caused by weevils making oviposition holes. A female may make a number of holes before laying an egg and damages numerous stems in her life time. The fields suffering the most are those with nitrogen fertilizer and those which are sown early. The weevil has a number of alternate host plants but the capsularis varieties seem to be relished the most.

Management

• The pest may be suppressed by the removal and destruction of infested plants at the time of thinning the crop and by collecting and destroy.ing the stubble after harvest.
• Spray 2.5 kg of carbaryl 50WP in 625 L of water per ha.