Two-spotted mite: potato pest in Indonesia and Western Australia

Page last updated: Friday, 3 July 2020 - 2:05pm

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Two-spotted mite is a minor pest of potatoes 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 as well as 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 two-spotted mite’s Indonesian name is "tungau" and its scientific name is Tetranychus urticae.

Mites are related to spiders. Only the first immature stage called crawlers have six legs. All other stages have eight legs, not six legs like insects.

Two-spotted mite adults have a dark band on each side of their body and their eggs are spherical
Two-spotted mite adult and eggs

Actively feeding two-spotted mites are yellow to green with a prominent dark band on each side of the body. Adults are small — about 0.5mm long. Use a 10 times magnifier when looking for them. They usually occur on the lower side of leaves but as an infestation develops, they will feed on both sides of a leaf.

Eggs are spherical with a pearly lustre. Red eyespots are visible through the egg just prior to hatching.

Leaves heavily infested with two-spotted mite are mottled yellow-green and mites produce webbing
Leaves heavily infested with two-spotted mite

Feeding by two-spotted mites results in leaves becoming mottled yellow or silver. The presence of mites is first noticed by this change in colour to leaves.

If not controlled, mite infestation can be severe. The mites produce webbing and  eventually kill the leaves, which turn brown. This leaf loss reduces crop vigour and yield.

In cooler times of the year two-spotted mite adults enter an overwintering stage which is orange
An overwintering two-spotted mite adult

In cooler conditions, mites become dormant and are orange. These mites reactivate when warm weather returns. In temperate regions, overwintering commences in autumn and these adults become active again in early spring.

Contact information

Stewart Learmonth
+61 (0)8 9777 0167

Two-spotted mite: potato pest in Indonesia and Western Australia

Author

Stewart Learmonth