Stem girdling beetle Nupserha bicolor postbrunnea Dutt (Lamiidae:Coleoptera)

Distribution: Corchorus olitorius and C. capsularis are the two species of Jute cultivated in Assam, West Bengal, Orissa, Tripura and Uttar Pradesh which are attacked by this pest. It is particularly serious on C. olitorius.

Nature of damage: The adult beetle girdles the stem at two levels before it starts oviposition. This causes withering, drooping and death of the portion above the lower girdle to a length varying from 5 - 50 cm thus resulting in loss of fibre yield.

Management strategies

• Spray application of phosalone 0.07% or endosulfan 0.07 % at fortnightly interval.
• Removal and destruction of drooping stem portions and stem casings containing the larvae in diapause.
• Growing of C. capsularis jute which is not preferred by the insect.

Jute weevil Apion corchori Mshll. (Apionidae: Coleoptera)

Distribution: The insect occurs in a serious form on jute in Bihar and U.P.

Nature of damage: The adult weevil excavates a small hole on the stem and oviposits. The grubs tunnel into the pith. Due to damage a gall-like swelling is formed. C. capsularis is more susceptible to attack than C. olitorius.

Life history: The weevil is dull black or dark brown in colour and a female is capable of laying up to 675 eggs during an oviposition period of about 4 months. The egg, larval and pupal periods last for 3 – 5, 8 – 18 and 4 days respectively. Management strategies:

Spray application of phosalone 0.07% or endosulfan 0.07 or cypermethrin 0.005%.

Spodoptera exigua (Noctuidae: Lepidoptera)

Distribution: Has worldwide distribution which includes Europe, South Africa, America and the oriental region. In India, it is quite widespread, found attacking jute, indigo, Lucerne, lentil, cabbage, maize, cotton and gram.

Nature of damage: The caterpillars, on hatching, gather on the leaf surface, the epidermis of which they eat. At this young stage, they are also in the habit of webbing together either several leaflets or the margin of the same large leaf. At times, these webs give a shabby look to the crop. Within these webs the young larvae live gregariously only for two or three days and thereafter they separate and spread out.The feeding activity of grown up larva is generally confined to a few morning hours i.e. 9 to 11 a.m. and then again after 4 p.m. or so. They are very voracious and quite large patches of foliages are quickly stripped.

Management strategies:

• Collection and destruction of egg masses.
• Spray application of phosalone 0.07% or endosulfan 0.07% or cypermethrin 0.005%.