Pheromone Chemicals

(white rice borer) –also known as the paddy stem borer is a moth in the family Crambidae. Scirpophaga nivella has been reported as rice pest from Kerala, Tamil Nadu, Orissa and Punjab.

Life cycle :

Adult moths are creamy white in colour with crimson coloured anal tuft of hairs in females. Males are slightly smaller, with a wing span of 25-30 mm. Fecundity is 150-300 eggs per female. Eggs are dull white, oval, laid in overlapping clusters of about 30 eggs on the under surface of the leaf and covered with buff coloured hairs derived from the anal tuft of female. Incubation period is 5-7 days.
After hatching the larvae bore into the midrib and tunnel towards the stem for 24-48 hours and then enter the stem. Full grown larva is 25-30 mm long dull creamy white having shorter legs. Larval period is 25-40 days.
Pupation takes place inside the stem in a chamber constructed by the larva just above the node. Pupal period is 10-20 days depending on temperature. Hibernation takes place in the larval stage.

Host plants :

Rice, and species in the sedge family, Cyperaceae.

Damage :

The larvae do the damage, similar to other rice borer species. Rice plants can compensate for any damage caused by stem borers up to the stage of maximum tillering; however, infestation during panicle initiation and flowering causes loss in yield. Young larvae bore into the midrib, leaving red markings and small holes on the leaves. Then the larvae tunnel in the upper portion of the stem, resulting in drying of the central shoot, causing “dead heart”. With the death of central shoot, side branches start growing from a lower node, giving a characteristic “bunchy top” appearance to the plant. Older larvae tunnel to the growing point and into the internodes. A brown line and yellowy marks form on the underside of leaves even well after the moth has emerged. The tunnelling ends above the ground and runs almost to the epidermis where pupation occurs.Up to 25% mortality of shoots and 40% stunting has been recorded in northern India.