The Gram Pod Borer
Host: This is a polyphagous pest that feeds on pulses, Bengal gram, soya beans, black gram, pea, cotton, maize, tomato, cotton bolls, sun flower and a variety of vegetables.
Damage: Caterpillars cause a variety of damage to different crops. They feed on leaves and tender shoots and bore into the fruits. In pulses, they bore into the pod to feed on seeds, sometimes half of the body remains outside the pod if the pod is small. Fungus and other diseases follow in the damaged fruits. One larva may feed on several fruits before completing development.
Life cycle: Adult moths are medium sized, with a wing span of 3-4 cm. They are extremely variable in colour from buff to light brownish to greyish-brown, marked with dark greyish irregular lines on the fore wing and a broad blackish band near the outer margin. Hind wing is dull whitish in colour, with outer margin broadly black. Sometimes there is a dark spot in the middle of fore wing. Eggs are spherical, dome-shaped with a flat base, 0.5 mm in diameter, yellowish and turn brownish as the embryo develops. They are laid singly on tender leaves and take 2-4 days for hatching. Full grown larva may be green, pale yellow, pale brown or greyish but always with a dark stripe on the lateral sides of the body. Body also bears inconspicuous tubercles and scattered small hairs. There are 6 larval instars and the entire larval development takes 20-25 days. Pupation takes place in the soil. Pupal period is 10-15 days. Moths emerge and make their way through the soil.
Distribution: Widely distributed in the tropics, subtropics and warmer temperate areas of the old world, up to
Germany and Japan.
Control: The pest can be controlled by spraying 0.02% malathion, endosulphan, endrin, monocrotophos or carbaryl at 15 day interval commencing flowering stage. Dusting with BHC or carbaryl 10-15% also helps.
Ploughing of the field after harvesting kills and exposes the pupae in soil.