Thrips: potato pest in Indonesia and Western Australia

Page last updated: Friday, 3 July 2020 - 2:13pm

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Thrips are a relatively minor pest of potato crops in both Indonesia and Western Australia.

The Department of Primary Industries and Regional Development has worked with the Indonesian potato industry to increase the productivity of Indonesian crops planted with WA seed potatoes.

Improved productivity requires accurate identification of pests in potatoes and also in the cabbage rotation crop.

As well as helping Indonesian farmers this information will assist Western Australian seed potato exporters understand the challenges their Indonesian customers face.

Identification

The Indonesian name for thrips is "trips" and they are in the insect family Thripidae.

Thrips are small, cigar-shaped insects up to 2mm long that feed on potato leaves and flowers by sucking/scraping. Adult thrips vary from grey to yellow, brown to black. Adults have a pair of thin wings held over their backs. Nymphs are pale-white to yellow and do not have wings.

Thrips feed on both leaf surfaces, but are more common on the underside. They are so small they are usually found only after the effects of their feeding is noticed on leaves - distorted or silvery grey leaves (see photo below). A 10x magnifier is needed to see the insects clearly.

Palm thrips adult. Photo courtesy IPM Images USA
Palm thrips adult. Photo courtesy IPM Images USA
Onion thrips adult and immature nymph (pale insect). Photo courtesy IPM Images USA
Onion thrips adult and nymph. Photo courtesy IPM Images USA

Although palm thrips (Thrips palmi) is a common insect in potato crops in Indonesia, and onion thrips (Thrips tabaci) is a common insect in Western Australian crops, they rarely cause damage.

Adults of onion thrips, left, and western flower thrips, right. Photo courtesy IPM Images USA
Adults of onion thrips, left, and western flower thrips, right. Photo courtesy IPM Images USA
Tomato thrips aduilt blck) and nymph yellow)
Tomato thrips adult (black) and nymph (yellow)

Other thrips that occurs in potato crops are western flower thrips (Frankliniella occidentalis) and tomato thrips (Frankliniella schultzei). While western flower thrips is very similar to onion thrips (see photo), tomato thrips adults are black and their nymphs are yellow.

Thrips damage to leaves in young potato crop - left damaged, right unaffected.
Thrips damage to leaves - left damaged, right unaffected
Thrips feeding causes silvering on underside of a potato leaf
Thrips feeding causes silvering on underside of a potato leaf

Feeding initially causes silvering of leaves, especially on the under surface. With continued feeding, leaves become distorted or cupped and may start wilting. If thrips invade crops soon after emergence, plant growth is retarded.

Tomato spotted wilt virus symptoms on potato leaf
Tomato spotted wilt virus symptoms on potato leaf

Some species of thrips are vectors for tomato spotted wilt virus, with western flower thrips the most efficient vector for the virus.  Only the immature nymph stage of thrips can acquire the virus and only adults can spread it in crops.

Do not use seed potatoes from crops that have been infected with tomato spotted wilt virus. The virus is important in non-seed crops because it reduces crop yield and tuber quality.

Contact information

Stewart Learmonth
+61 (0)8 9777 0167

Thrips: potato pest in Indonesia and Western Australia

Author

Stewart Learmonth