Green peach aphid: potato pest in Indonesia and Western Australia

Page last updated: Wednesday, 9 May 2018 - 11:20am

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Green peach aphid is a virus vector for potato crops in Indonesia and Western Australia, but a minor direct pest.

The Department of Primary Industries and Regional Development, Western Australia 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 the cabbage rotation crop.

Besides helping Indonesian farmers, this information will assist Western Australian seed potato exporters understand the challenges their Indonesian customers face.

Identification

Green peach aphid’s Indonesian name is "kutu daun" and its scientific name is Myzus persicae.

Wingless aphid adult with tube-like structures or cornicles which are on each side of the end of the abdomen and distinguish aphids from similar insects
Arrows point to tube-like structures called cornicles that are diagnostic for all aphids

Aphids differ from similar insects because they have two tubes called cornicles on the end of the body. Use a 10 times magnifier to see them to positively identify aphids.

Aphid adults can be wingless or winged. Green peach aphid on the left and potato aphid
Aphid adults can be winged or wingless. Green peach aphid is on the left next to potato aphid.

Adult aphids can be winged or wingless. Winged adults invade crops and produce live nymphs which grow to become wingless adults.  When populations on leaves are high, nymphs become winged adults.

Green peach aphid adults are 2mm long. Nymphs and wingless adults are usually green but can be yellow to pale brown. Winged adults have black patches.

Another species, the potato aphid (Macrosiphum euphorbiae) also breeds in potato crops. It is green and up to 3mm long.

Aphids reproduce by producing live young called nymphs
Adult aphids produce live young or nymphs

Winged adults invade crops and produce live nymphs which grow to become wingless adults.

Management

Green peach aphids damage potato crops by:

  • sucking sap (but many aphids must be present before they affect plant vigour)
  • spreading viruses.
Aphids can introduce and spread potato leafroll virus to potato crops. Diseased plants are stunted and have rolled leaves
Aphids can introduce and spread potato leafroll virus in potato crops

Minimise virus infestion levels by:

  • removing nearby sources of virus particularly plants in the potato family such as self-sown potatoes, tomatoes, chilli, tobacco and the weed nightshade
  • planting seed that has low levels of virus, for example certified seed
  • remove virus infected plants and any associated tubers growing within a crop.

Aphids can invade crops from emergence onwards.

Seed potato crops must be protected from the green peach aphid because it introduces and spreads viruses. Apply systemic insecticide in the planting furrow.

Wingless adult and immature nymphs of aphids feeding on the underside of a potato leaf
Aphids feed on the underside of potato leaves that are in the bottom half of the canopy

Monitor crops weekly after emergence by checking the underside of 100 lower leaves across the crop; include crop edges.

Aphids are most abundant at the change of seasons such as winter to spring and summer to autumn. Aphids are less likely in hot weather of summer and cold weather of winter.

For seed crops, spray when 5% of leaves are infested with nymphs and adults (five of 100 leaves).

A wasp has emerged from the aphid body after chewing a hole in the skin of the aphid
Wasps can kill many aphids in potato crops

For non-seed crops, some aphid infestation can be tolerated because a wide range of natural enemies help control the aphids.

The most common beneficial insects are wasps. Adult wasps lay an egg inside the aphid. After the wasp grows, the aphid body swells up and is called a "mummy". The adult wasp chews a hole in the mummy to emerge.

Other natural enemies feed on aphids directly - hover fly maggots, ladybirds and lacewings. When humidity is high, fungal disease can kill aphids.

Acknowledgments

Funding for this work to support Indonesian potato farmers and WA seed potato exports was provided by ACIAR (Australian Centre for International Agricultural Research) and the Department of Primary Industries and Regional Development, Western Australia.

Contact information

Stewart Learmonth
+61 (0)8 9777 0167

Author

Stewart Learmonth