2. Pseudostem borer

2. Pseudostem borer - Odoiporus longicollis (Curculionidae: Coleoptera)

    Damage
    • The first instar larvae feed on the tissues around the air chamber of the leaf sheath.
    • The second instar larva bores into the inner sheaths of the pseudostem and moves across in a horizontal or slight oblique direction.
    • The third and fourth instar larvae feed voraciously and riddle the pseudo stem cutting a thin hole on the out surface of the pseudostem for better aeration.
    • The infested part of pseudostem decomposes as a result of which plants become very weak and break easily in wind.
    • Exudation of plant sap from leaf sheath, yellowing and withering of leaves, immature ripening of fruits, destroying of flower primordia, decaying of leaf sheath and corm and finally falling of whole plant are the symptoms of damage.
    • The severity of pest notices in ratoon crop compre to first year crop
    Bionomics
    • The adult weevil is reddish brown and black measuring 1.3 cm long. It thrusts the eggs within the air chamber of leaf sheath through oviposition slit made by rostrum at the rate of one egg per air chamber.
    • Eggs are laid in the area of the pseudostem about 1 - 1.5 metres above the ground level.
    • The incubation period is 3-5 days in summer and 5-8 days winter.
    • The grubs are apodous and have duration of 26.2 days in summer and 68.1 days in winter with five larval instars.
    • It pupates in the tunnel towards the periphery.
    • The pupal period last for 20-24 days in summer and 37- 44 days in winter. Adult feeds on tissue of leaf sheath from its inner surface and also on decaying tissues.
    • Infective for up to 13 days after feeding on infected material.
    Management
    • Adopt good husbandry practices such as weeding, manuring and mulching which improve weevil tolerance.
    • Remove dried leaves periodically and keep the field clean.
    • Prune the side suckers every month.
    • Use healthy and pest free suckers to check the pest incidence.
    • Spray monocrotophos 36WSC at 1 ml / litre of water.
    • Do not dump infested materials into manure pit.
    • Uproot infested trees, chop into pieces and burn.
    • Spray methyl parathion 50 EC 2 ml/1 or monocrotophos 36 WSC 1 ml/1 on trunk. Alternatively, dilute 50 ml of monocrotophos 36 WSC with 350 ml of water and inject 4 ml (2ml at 45 cm from ground level, another 2 ml 150 cm from ground level) using banana injector’ or long needle in the pseudostem at monthly intervals from 5th to 8th month. Do not follow stem injection after 8 months of growth.

Last modified: Monday, 6 February 2012, 11:01 PM