Aphids

Aphididae family

Aphids are a general term for a large number of insects from the Aphididae family.

Family: Aphididae

Order: Hemiptera

Description:

Adult

Colour - Black, browns and greens usually.

Body - Stout, soft bodied. Usually less than 2 mm long.

Legs - 6.

Wings - Winged and wingless forms.

Mouth Parts - Piercing stylet.

Nymphs

Biology:

Many species can reproduce without males or have two forms of reproduction - sexual and asexual.

Aphids can distinguish plant colour and are usually attracted to green and yellow. Pea aphids can also detect plant odours such as cut grass. Winged aphids appear to have a better sense of smell than their wingless counterparts.

They suck plant juices and produce honey dew which may be a food for ants. Some ants will farm aphids and move them between plants and protect them from predators.

Some species transmit viruses and the plant distortions often seen are due to these viruses. Direct effects of aphids can be wilting of plants or yellowing or reddening due to the aphids robbing the plant of water and nutrients.

Life Cycle:

They often survive harsh summer or winter conditions by shifting to protected locations or producing dormant resting forms or eggs that hatch when conditions improve. Winged forms often appear when overcrowding occurs or the plant or environment becomes stressful. They then move on to other plants, species or locations. They are usually most active in spring and autumn.

Habitats:

Origin and History:

Distribution:

Significance:

In canola the main species causing economic damage are

Cabbage Aphid (Brevicoryne brassicae)

Turnip Aphid (Lipaphis erysimi)

Green Peach Aphid (Myzus persicae)

Blue Green Aphid (Acyrthosiphon kondoi)

and occasionally the Potato Aphid (Macrosiphum euphorbiae).

Aphids in Canola can build up to very quickly within 2 weeks of their first appearance. They are most damaging at from the budding to early pod development stages of Canola. In WA they rarely get to levels that cause economic loss. Trials indicate that most stems need to have 25 mm of aphids on them before it is worth spraying and this rarely occurs. Damage appears to be worse on water stressed crops.

Aphids in Canola may be identified on the following features.


SpeciesAbdomen ColourBody lengthColony habitFeatures
Blue Green AphidWaxy blue-green2-3 mmOn growing tips.Long pale legs with black tips. 2 long "exhaust pipes" on tail.
Cabbage AphidGreyish to dull mid-green1.6-2.8 mmDense on tips of plants.Coated with white mealy wax.
Green Peach AphidWaxy green, but varies from shining yellow to pink or orange red.
Winged form has a black patch.
1.2-2.3 mmUsually scattered light colonies. Often on lower leaves. 
Potato AphidLight yellowish to pinkish green or bright green. Often with a darker green stripe down middle of the back1.7-3.6 mmSmall coloniesRed eyes.
Turnip AphidYellowish to olive-green, sometimes with dark bars.1.4-2.4 mmDense on tips of plants.Black legs. Small "exhaust pipes" on tail. Sometimes has a waxy dusting


Adapted from D. Eksteen, Agriculture WA

In cereals the main aphids causing damage are

Oat Aphid (Rhopalosiphum padi)

Corn Leaf Aphid (Rhopalosiphum maidis)

Rice Root Aphid.

See descriptions under Aphids; Cereal.

In Lupins the main aphids are

Green Peach Aphid (Myzus persicae)

Blue Green Aphid (Acyrthosiphon kondoi)

Cowpea Aphid (Aphis craccivora)

In Faba Beans the main aphids are

Green peach aphid (Myzus persicae)

Blue Green Aphid (Acyrthosiphon kondoi)

Cowpea Aphid (Aphis craccivora)

Pea Aphid (Acyrthosiphon pisum)

In pastures the main aphids are

Blue Green Aphid (Acyrthosiphon kondoi)

Cowpea Aphid (Aphis craccivora)

Spotted Alfalfa Aphid (Therioaphis trifolii)

Aphids damage plants directly by sucking the sap from the plant or indirectly by transmitting viruses or encouraging fungal growth on the 'honey dew' they excrete. Most aphids are quite specific to a particular plant or group of plants, and in some cases are only found on particular parts of the plant. Their ability to rapidly build up numbers makes them difficult to control both biologically and chemically. Common symptoms of aphid attack are clusters of the aphids, mottling or wilting of leaves or fruit, or symptoms of viral infection.

Management and Control:

There are a number of insects that feed on aphids such as lady birds, lace wings, hover flies and parasitic wasps. Choosing an insecticide that doesn't harm these species helps maintain control for a longer time or helps keep aphid numbers at lower levels.

Related Species:

Cherry aphid (Myzus cerasi) is an exotic pest. Please report if found.

Grape phylloxera (Daktulosphaira vitifolii) is an exotic pest. Please report if found.

Lettuce aphid (Nasonovia ribisnigri) is an exotic pest. Please report if found.

Similar Species:

References:

Hoffman & Botha (2006) Garden Note #206, DAFWA.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.