Spiralling whitefly

Adult

• Like tiny white moths in appearance and in their mode of flight.
• 2-3mm in length.

Larvae

• There are 4 stages of development.
• The first larval stage is a crawler and is tiny (0.3mm long) and mobile as it feeds.
• The second and third larval stages range in size from 0.5 to 0.65mm in length, and secrete waxy tufts or rods from their back.
• The fourth stage is pre-pupal.

Pupae

• About 1mm long, oval, flattened, and colourless or yellowish in colour.
• Copious white secretions can form fluffy or waxy ribbons that extend outwards from the back.
• Adult whiteflies emerge from the pupae.

Egg

• Tiny, 0.3mm long and oval in shape, yellow to tan in colour, on a short stalk that is attached to the plant.
• Laid with deposits of waxy secretions in a spiral arrangement.

Plant stage and plant parts affected

The leaves of all stages of plant growth can be affected by spiralling whitefly. Fruit can also be affected.

Plant damage

Whiteflies mostly feed on the undersides of leaves.

Larvae and adults produce a sugary secretion or 'honeydew'. In heavy infestations mould grows on the honeydew giving leaves a black sooty appearance.

Sooty mould, in combination with leaf damage, reduces the plant's ability to photosynthesise. It also weakens, but rarely kills, the plant.

In the absence of natural predators spiralling whiteflies multiply very quickly, producing thousands of individuals on a single plant.

Spiralling whitefly looks like the closely related coconut whitefly that is found from New Britain to West Malaysia, Solomon Islands and Australia. Coconut whitefly occurs in Queensland and is a minor pest of some plants including coconut, custard apple, banana and acacia. Coconut whitefly is not considered a serious pest.

It is impossible to tell the difference between coconut and spiralling whiteflies by eye. An expert is needed to identify spiralling whitefly under a microscope.

Spiralling whitefly is believed to have originated in the wet tropics of Central and South America. It established in Hawaii in 1978 and spread rapidly through the Pacific. It is now found in most tropical countries of the world and some subtropical and temperate countries.

Spiralling whitefly was detected in Australia in the late 1990s and is now established in tropical coastal Queensland at locations from Torres Strait to Bundaberg. It is also known to occur in the Northern Territory.

Spiralling whitefly infests a broad range of horticultural plants including banana, citrus, papaya, mango, custard apple, guava, tomato, capsicum, eggplant and many ornamental species, shade trees and weeds. It has been recorded on more than 100 plant species. Spiralling whitefly is most commonly found on poinsettia and Acalypha.

Each spiralling whitefly egg hatches into a tiny active crawler, roughly the same size as the egg. This crawler moves out over the foliage of the host plant and then moults into a sedentary stage that attaches to the underside of the leaves where it sucks nutrients from the leaves. The second larval stage has no visible legs and grows progressively through a series of moults, each producing more 'wax' and sugar secretions. The final immature stage acts as a pupa, out of which the adult whitefly emerges. The time from egg to adult can be less than 3 weeks in summer, longer in cooler conditions. The female whitefly (which is identical to the male) can lay large numbers of eggs.

Whiteflies are pests of a wide range of host plants. Economic damage to crops can occur from direct feeding (where numbers are high) causing premature leaf drop and reduced plant vigour and yield. Cosmetic, indirect damage occurs from production of honeydew that encourages growth of sooty mould, and the white waxy material produced by the larvae, sticking to plants.

Spiralling whitefly can affect domestic and international market access for trade.

Backyard growers can also be affected by new whitefly infestations.

Whitefly are relatively weak flyers. Wind assisted flight can spread them further. They are known to hitch hike on clothing and equipment and can be easily spread on plant material such as pot plants.

Spiralling whiteflies are generally active during calm, still times of the day (e.g. at dawn and dusk) when they can be seen flying around host plants. Shaking an infested plant can cause whiteflies to fly then quickly resettle.

Check common host plants. If you find spiralling whitefly take close-up images (check to make sure that all images are in focus) and report it to Biosecurity Queensland on 13 25 23.

• Protect your farm from emergency plant pests
• Understand good farm biosecurity
• Visit the farm biosecurity website

A biological control agent (Encarsia dispersa) was originally established in Torres Strait in 1992 by entomologists from the Department of Agriculture and Fisheries (DAF). This agent is a microscopic, orange-coloured wasp that is host-specific to spiralling whitefly larvae and has already successfully managed pest populations in Torres Strait and mainland Queensland.

Controlling spiralling whitefly using insecticides is not recommended. Overseas experience indicates that spraying with insecticides has little long-term impact on the pest and usually increases the problem by destroying biological control agents and increasing insecticide resistance in whitefly populations.

There are no legal requirements for the movement of spiralling whitefly hosts within Queensland.

The presence of spiralling whitefly can affect the movement of plants and plant products interstate. Interstate movement restrictions may apply.

If you are moving plants and plant products from Queensland to other states and territories, please check with the destination state/territory prior to consigning. Various methods are available to meet the restrictions that may apply:

1. Having an inspection for pest freedom.
2. Having the product certified under an ICA arrangement.
3. Having the produce treated to meet the interstate destinations entry requirements.

Find out more about restrictions on moving plant material, soil and related equipment from Queensland to other states.