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Onion aphid (276) Print Fact Sheet

Common Name

Onion aphid

Scientific Name

Neotoxoptera formosana. Two other species, Neotoxoptera violae (violet aphid) and Neotoxoptera olieri (marigold aphid) are closely related.

Distribution

Worldwide. It was first recorded in Taiwan, but now occurs widely in the tropics and sub-tropics, and occasionally in Europe. Asia, Africa (St. Helena), North and South America, Europe (restricted), Oceania. It is recorded from Australia, New Zealand, and the highlands of Papua New Guinea.

Hosts

Members of the onion (Allium) family, including chives, leeks, onion, shallot, leeks, and weed relatives of onion.

Symptoms & Life Cycle

The aphid lives on onions and their relatives, either on the leaves (Photo 1) or on the bulbs in storage. Populations increase rapidly to damaging levels and plants wilt, yellow, collapse, and dry (Photo 2).

Eggs are unknown, and so are males. Females give birth to living young without fertilization. The nymphs pass through four stages before they become winged or wingless adults. The body length is 1.5-2.5 mm, and the antennae are approximately the same length as the body. Adults are dark red to black. Winged individuals occur occasionally, and they have distinctive wide black veins.

It is thought that this aphid is attracted to the compounds in Allium species that give them their distinctive smell.

Spread over short distances occurs by adults walking between plants, and over long distances on air currents, and on bulbs traded on domestic or international markets. Survival occurs on volunteer plants from the previous crop or on bulbs in storage.

Impact

Damage occurs in two ways: directly as the aphids suck the sap of plants causing them to collapse, and indirectly through the spread of viruses. The latter are reported in Japan. The extent of either kind of damage is not well documented, but the fact that populations increase quickly and cause the collapse of plants suggests that it can be considerable. Serious rots in storage are reported from Australia.

Detection & Inspection

Look for dark red or black aphids, mostly wingless, but some winged with broad veins on the wings.  individuals.

Management

NATURAL ENEMIES
Predators [ladybird beetles and their larvae, hover (syrphid) flies and lacewing larvae], and parasites (wasps) usually keep onion aphid populations low; however, the rapid population increase of the onion aphid may mean that the smell of onions, and other Allium species, keeps natural enemies away.

CULTURAL CONTROL

Before planting:

During growth:

After harvest:

CHEMICAL CONTROL
If ants are present, find the nest, and if not too close to the plants with aphids, destroy the nest with boiling water; alternatively, use ant baits or spray with synthetic pyrethroids.Without ants, predators and parasites will bring about natural control.

If insecticides are necessary against aphids, use any of the following:

Alternatively, use:


AUTHOR Grahame Jackson
Information from MacLeod A (2007) CSL Pest risk Analysis for Neotoxoptera formosana. Central Science Laboratory, Sand Hutton, York. (https://secure.fera.defra.gov.uk/phiw/riskRegister/plant-health/documents/neotoxoptera.pdf).

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 of the Pacific Community.  

 



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