Ash whitefly

Have you seen ash whitefly infestations?

Be on the lookout for symptoms and report them to Biosecurity Queensland.

Early detection is vital.

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  • Photo of an Ash whitefly on leaf
    Photo of an Ash whitefly on leaf

General information

Ash whitefly (Siphoninus phillyreae) is a pest of several horticultural crops and ornamental plants in Europe and north Africa. It has spread to the United States, New Zealand and several locations of Australia includes South Australia, New South Wales, Queensland, Tasmania, Northern Territory and Victoria (ref. CABI 2014).

When not under the control of its natural enemies, it can cause significant damage to host plants. Affected plants have unsightly sooty mould which grows on honeydew produced by the pest.

Overview

Regularly monitor common host plants:

  • Inspect first sign of an ash whitefly infestation is the small, white, winged adults resting on host plant leaves or fluttering around like tiny moths when disturbed. 
  • On an infested plant, the undersides of the leaves carry large numbers of adults and nymphs.
  • The fourth stage nymphs are distinctive with noticeable spines that are tipped with globules of white waxy material.
  • The whitefly is particularly noticeable on deciduous hosts when they are shedding leaves.   The adults swarm around the plant as they prepare to search for an evergreen host.
What does it look like?

The first sign of an ash whitefly infestation is the small (1-2mm), white, winged adults resting on host plant leaves or fluttering around like tiny moths when disturbed. On an infested plant, the undersides of the leaves carry large numbers of adults and nymphs. The fourth stage nymphs are distinctive with noticeable spines that are tipped with globules of white waxy material.

The whitefly is particularly noticeable on deciduous hosts when they are shedding leaves. The adults swarm around the plant as they prepare to search for an evergreen host.

Distribution

Native to Europe, the Mediterranean and northern Africa, the ash whitefly is found in numerous countries:  

  • Africa: Cameroon, Egypt, Ethiopia, Libya, Morocco, Sudan
  • Asia: India, Iran, Israel, Pakistan, Saudi Arabia, Syria
  • Europe: Austria, Corsica, Czech Republic, Cyprus, England, France, Germany, Hungary, Ireland, Italy, Poland, Romania, Spain, Switzerland, Yugoslavia
  • North America: United States (California, Florida)
  • Oceania: Australia (New South Wales, South Australia, Queensland, Victoria and Tasmania)
LifecycleS. phillyreae life cycle consists of three phases: post egg, nymph and pupae. The adult deposits eggs on the underside of the leaf that subsequently hatch into nymphs. The nymphs finally change into pupae. The immature pupa undergoes metamorphosis before it turns into an adult. The winged adults are the main dispersive stage. S. phillyreae breeds several generations per year.
Crops affectedCitrus, Crataegus (hawthorns), Fraxinus (ashes), Fraxinus excelsior (ash), Fraxinus velutina (velvet ash), Malus (ornamental species apple), Olea (olive), Olea europaea subsp. europaea (European olive), Phillyrea, Punica granatum (pomegranate), Pyrus (pears).
Hosts

Ash whitefly breeds on a range of ornamental hosts including ash species, crepe myrtle, privet, magnolia, buckthorn and hawthorn and on fruiting plants including pomegranate, olive, apricot, peach, pear, Japanese plum, apple, citrus and quince. The pest can also infest other small tree and shrub species when populations are high.

Symptoms and damage

Heavy infestations lead to premature leaf drop, wilting and smaller fruit. Whitefly infestations produce large quantities of honeydew on which black sooty mould grows. Damage includes loss of fruit and, at times, tree death.

Impacts

Ash whitefly can cause significant damage to host plants in absence of its natural enemies. The economic impact of this pest has been estimated in millions of dollars, most severely impacting the shade and fruit tree nursery industry and commercial pomegranate orchards.

Ash whitefly has the potential to become a serious pest in new environments. However, it has several natural enemies that can control its populations to under economic thresholds.

Spread 

Ash whitefly can be moved on plants from infested areas and can also be moved accidentally in vehicles and on clothes. It could appear in Queensland nurseries and home gardens at any time.

Adults are capable of flight, and can disperse over shorter distances. Adults participate in “swarming” in search of new hosts in Autumn.

Risk periodFlowering stage, fruiting stage and vegetative growing stage of hosts.
Monitoring and action

Regularly monitor common host plants:

  • Inspect first sign of an ash whitefly infestation is the small, white, winged adults resting on host plant leaves or fluttering around like tiny moths when disturbed.
  • On an infested plant, the undersides of the leaves carry large numbers of adults and nymphs.
  • The fourth stage nymphs are distinctive with noticeable spines that are tipped with globules of white waxy material.
  • The whitefly is particularly noticeable on deciduous hosts when they are shedding leaves.

The adults swarm around the plant as they prepare to search for an evergreen host

Control

There are no examples of eradication of ash whitefly in the world.

The pest can be suppressed through the introduction of its natural enemies such as Encarsia inaron. Ash whitefly has been brought completely under control in the USA through the use of this parasite.

A number of effective insecticidal controls are available.

Quarantine restrictions

Ash whitefly is already present in Queensland and other parts of Australian like South Australia, New South Wales, Victoria, Tasmania, Northern Territory.

Last updated 04 September 2017