Chilo Polychrysus
Common name:
The Dark-headed Striped Borer
Order:
Lepidoptera
Family:
Pyralidae
Distribution:
Bangladesh, India (Assam, West Bengal, Kerala, Orissa and Tamil Nadu Pakistan Malaysia, Burma, Philippines, Sabah, Thailand, Laos, Vietnam and Indonesia
Host:
Rice, maize, sugarcane and several species of grasses.
The larva is yellowish white and has a black head capsule, and black thoracic plate and five longitudinal strips on its body. It measures 18-24 mm in length. The fore wings of male moth are brown ochreous with a cluster of dark spots covered with golden scales in the middle. The hind wings are white and the antennae are pectinate Female possesses non-pectinate antennae and is paler in colour. The wing span of male and female are 16-25 mm and 22-30 mm, respectively.
Life-cycle:
After mating, the female moth starts egg laying in rows of 2 to 4 or more arranged in groups of 30 to 200 on the underside of the leaves. The eggs are flat and scale like. A single female may lay upto 488 eggs during her oviposition period of 3 days. The incubation period is 4-7 days. The freshly hatched caterpillars bore into the outer leaf sheath, mid-rib or stem. The larval period is completed in 23-36 days after moulting five times. Before pupation, the larva makes an exit hole at the upper end and then pupates inside in thin silken web. The yellowish brown pupa has distinct abdominal strips measure 10 mm long and 2 mm wide. The adults emerge in 4-6 days. The longevity of adult is 4-6 days. The total development takes about 26-61 days. There are six generations in a year.
A braconid, Bracon albolineatus Cam. and an eulophid, Tetrasticus sp. are parasitic on larvae and pupae, respectively.
Damage:
The newly hatched caterpillar bores into the outer leaf and the leaf sheath first. Then, it moves into the inner whorl and bores through the central shoot for feeding. Due to the larval feeding, the central part of the whorl dry up first and finally the entire plant from its core. As many as seven larvae have been recorded in a single shoot.
Losses:
In case of severe attack by this pest, the losses up-to 60 per cent has been recorded in Southern India.
Control:
Same as mentioned under 'Yellow Stem Borer', S. incertulas.
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