Dr. S.K. Dutta & Dr. Badal Bhattacharyya Department of Entomology

Dr. S.K. Dutta & Dr. Badal BhattacharyyaDepartment of Entomology

Assam Agricultural University,Jorhat-13

Identification, symptoms and nature of damage: potato tuber moth and cut worm

Potato Tuber Moth

The larvae are pinkish-white or greenish in colour with dark brown head

They are about 20 mm in length

The adult moth is very small (about 13 mm) and dark brown in colour

Identification:

Larva Adult

Fig. Larva of potato tuber moth

Source:http://www.fwi.co.uk/assets/getAsset.a spx?ItemID=5225298

Fig. Adult of potato tuber moth

Source:http://4.bp.blogspot.com/0UlluG7ZKE0/TeeOgqQ7NFI/AAAAAAAAAYs/j7XtDbecb0/s1600/1+Potato+tuber+moth+phthorimaea_operculella_male.gif

Symptoms:

In Field: Mined leaves and drooping twigs of the plants are the main symptoms of attack in field

In Store: Tunnelling by larva leads to rotting and foul smelling of tubers due to bacterial infection

Fig. Field infestation of potato plants by potato tuber mothSource: http://www.infonet-biovision.org/default/images/139/crops

Fig. Potato tubers damaged by the potato tuber moth.

Source: http://www.infonet-biovision.org/default/images/139/crops

Nature of Damage:

Larvae mine the younger leaves and feed on the tubers

Larvae penetrate the leaves and feed within leaf veins or stems of the plant

Larvae make irregular galleries and tunnel deep inside the tuber in storage

The field infestation is caused either by the moths escaping from godowns or by infested seed tubers

Larval Damage Adult Damage

Fig. Potato field damaged by the larvae

Source: www.googleimages.co.in

Fig. Potato tuber damaged by the larvae

Source: www.googleimages.co.in

Cut worm:

Larvae are dark grey or dull green with smooth and greasy

skin . The full-grown larva is 40-50mm in length

The adult is a heavy bodied, greyish-brown or wheat coloured moth and measures 5.0-6.2 cm in length. The adults are strong fliers, found on the hills (in summer) and plains (in winter)

Identification:

1 2 3 4Fig. Different life stages of cutworm 1: Egg 2: Larva 3: Pupa 4: Adults

Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Symptoms:

Cutting down the young potato plants just above or slightly below the surface of the soil

Fig. Cut worm infested potato seedlings

Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Nature of Damage:

Larvae spend the day hiding near the bases of potato plants (5-10 cm of top soil) and at night they come out and cut the young plants just above or slightly below the surface of the soil

Larvae are voracious feeders and they cut or fell more plants than they can consume

After tuber formation, they nibble and bore into the tubers affecting both tuber yield and market value

Fig. Cut worm infested potato seedlings and tubers

Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13