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Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

Melon aphid (038)

Photo 1. Aphids on the underside of a taro leaf. Aphis gossypii is common on taro.

Photo 2. Curly-top symptom on basil caused by large numbers of aphids feeding on the underside of young leaves.

Photo 3. Crazy ants tending aphids for their honeydew. The ants keep predators and parasitoids away and defend the aphids from their natural enemies. Winged aphids can be seen in the lower part of the photo.

Photo 4. Ladybird beetles feeding on aphids on maize. The yellow "worm-like" creature in the centre is a syrphid larva - the adults are hoverflies.

Photo 5. Ladybird beetle larvae feeding on aphids on taro.

Photo 6. Ladybird beetle larva.

Photo 7. Syrphid larvae feeding on large numbers of aphids on maize. They are the larvae of hoverflies

Photo 8. Aphid 'mummies' on a chilli leaf.

Summary

Worldwide distribution. Small (1-2mm) greenfly on backs of young leaves or tips of shoots. In tropics, females only: they give birth to living young. Populations increase rapidly. A major pest.
Damage results from sucking sap, spreading viruses, moulds that grow on honeydew excreta, blackening leaves.
Natural enemies: syrphids (hoverfly larvae), lacewing larvae, ladybird beetle adults and larvae, and parasitoid wasps. Note, ants take honeydew from the aphids, and in so doing protect them from natural enemies.
Cultural control: check plants in nursery; plant away from crops with aphids; inspect crops regularly: remove infested shoots/leaves; weed, use reflective mulches.
Chemical control: soap, white or horticultural oils; PDPs: derris, pyrethrum, or chilli; synthetic pyrethroids, but these will kill predators and parasitoids. Removing ants will allow natural enemies to control aphid populations. Use hot water or pyrethroids.

Common Name

Melon or cotton aphid. There are many aphids attacking a wide range of crops; Aphis gossypii, described here, is common in Pacific island countries.

Scientific Name

Aphis gossypii

AUTHORS Helen Tsatsia & Grahame Jackson
Information from Waterhouse DE (1998) Biological control of Insects: Southeast Asian Prospects. ACIAR Monograph no. 51, 548pp. Photo 6 Graham Teakle. Canberra, Australia. Photo 8 Caroline Smith. University of Tasmania, Australia.

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat for the Pacific Community.

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