Potato tuber moth is a small grey brown moth. They are active at night, and rest under clods of earth or leaves during the daylight.
Tiny pearly white eggs are laid singly or in clusters of up to six on sheltered spots on the plants, on the ground near the plants, or on exposed potatoes. They are oval in shape and hatch in about a week.
Newly hatched larvae wander around briefly before eating their way into leaves, stems or tubers. The rest of the larval development (passing through four instars) takes place within the plant tissues, and takes up to three weeks (depending on temperature).
The caterpillars then leave the plant, moving down to the soil, and spin a loose cocoon to pupate.
Pupal development takes about a week, but may be much longer during winter. During the summer the whole cycle takes about a month but may extend to ten weeks during winter. Moths are short-lived
Other crops
Apart from potato this pest attacks tobacco “Apple of Peru” and Thornapple. There are occasional records of attack on brinjal and tomato.
Damage is caused by the tunnelling in leaves. The mines have a blotchy appearance, and are often associated with brown and dying bits of tissue.
One larva makes 3-4 tunnels, gradually filling them with excrement. They create twisting tunnels in fruits and tubers.
In potatoes, towards the end of the season, the caterpillars move down the plant towards the exposed tubers in the soil.
Here the first sign of infestation is the appearance of grey or whitish frass on the surface of the tubers, usually near the “eyes.”
Infestation can continue in the potato store room infested potatoes soon become filled with unsightly black tunnels.
Management
Controlling alternate weed hosts, clean harvesting of potatoes and careful ridging during and at the end of the growing season.
Where potatoes are grown all year round control measures may need to be taken early.
Releasing egg-larval parasitoid. Chelonus blackbumi at 30,000/ha twice, 40 and 70 days after planting helps in management.
N.D. Sunitha & S.B. Jagginavar
Assistant Professor of Entomology, College of Agriculture, Bijapur
