Potato tuber moth

(Lepidoptera: Gelechiidae)

Potato tuber moth is indigenous in South America and is now distributed all over the world. Potato is the main host plant of the potato tuber moth. However, it also attacks other Solanaceae plants such as tomato, tobacco, chilli, aubergine and cape gooseberry. It has also been reported to attack several related wild host plant species. Other common names of the potato tuber moth include potato moth, tobacco leaf miner and tobacco splitworm.

Nozibusiso Maphumulo

IPM-PROGRAM, NORTH-WEST UNIVERSITY POTCHEFSTROOM e-mail:mashimanenozi03@gmail.com

Potato tuber moth classification:

Class: Insecta (Insects) Order: Lepidoptera (moths and butterfIies) Family: Gelechiidae Genus: Phthorimaea Species: Operculella

EGGS OF THE POTATO tuber moth are oval in shape and yellowish, iridescent in colour. Larvae are about 15 mm long when fully grown. The body is greyish-white or pale greenish-grey with a dark brown head. The pupa has a yellowish or reddish brown colour. Adults are small and elonga- ted with a length of 8-10 mm. They are pale brown in colour with darker marbling and brown antennae. Potato tuber moth lays its eggs either singly or in batches on the leaves or exposed tubers of the host plant. It lays between 40 to 290 eggs. Egg laying is completed within 3 days. Eggs hatch within 3 to 15 days in summer, and it may take up to 58 days before hatching occurs in winter. After hatching, the larvae bores into the petiole or young shoot or the main leaf vein, where it mines the leaf, resulting in the formation of a blotch. It then bores into a tuber at a later stage and forms a long irregular gallery (passage). The larval stage takes approximately between 13 and 33 days to complete. Pupation occurs in the soil and the pupal stage ranges between 6- 29 days. Moths can survive for a period of up to 10 days. They are nocturnal and are attracted to light. Its life cycle can be completed within 17 - 125 days. Potato tuber moth can have up to 13 generations per year where climatic conditions are favourable. Potato tuber moth is a major pest of potatoes, more especially in areas where climatic conditions are favorable. It is also an important post-harvest pest of potatoes. Feeding damage can be observed as mines in the leaves, leaf stalks and stems. Tunnels inside the tubers are a clear indication of infestations by the potato tuber moth. The larvae of the potato tuber moth mines potato leaves during the growing season and tunnels through the tubers while feeding on them and filling them with their frass. Damage inside tubers is only noticeable during harvest time. Prevention and control measures can be achieved by using specific chemicals. Cultural control can also be used to control this pest by using healthy tubers during planting to minimise infestation levels, because re-infestation occurs as a result of using infested seed tubers. Integrated pest management (IPM) is the best solution towards tackling this pest.

Figure 1: Potato tuber moth. https://cropserve.co.zw/potato-tuber-moth/ Figure 2: Potato tuber moth larva inside the potato tuber and its inflicted damage. https://news.cornell.edu/stories/2016/05/potato-plants-get-defensive-after-underground-attacks

Figure 3: Signs of potato tuber worm damage on the potato tuber. http://entnemdept.ufl.edu/creatures/veg/potato/potato_tuberworm.htm