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Greenhouse whitefly

Greenhouse whitefly adults are larger than Bemisia tabaci (silverleaf whitefly) but are not considered as serious a pest.

Scientific name

Trialeurodes vaporariorum

Description

Adults:

  • about 1.5mm long
  • hold their white powdery wings flat, almost parallel to and obscuring the body when viewed from above.

Nymphs:

  • pale yellow-green
  • scale-like
  • long hairs protruding all over the body
  • most nymph stages are immobile.

May be confused with

Distribution and habitat

Widespread; common in horticulture.

Hosts

Cotton, sunflower, soybean, navy bean.

Damage

  • Adults and nymphs suck on sap and excrete honeydew which interferes with photosynthesis and discolours the lint in cotton.
  • A secondary infection develops when a sooty black mould fungus grows on the sticky honeydew.
  • Under very heavy infestations, plants lose vigour causing leaf-wilting and failure to set seed.

Life cycle

The greenhouse whitefly breeds throughout the warm months with a life cycle of about 5–7 weeks. It can have up to 3 generations on a sunflower crop and 7 generations per year. Summer and autumn are risk periods, with outbreaks favoured by warm weather and host availability.

Monitoring and thresholds

  • Usually found on the lower leaf surface.
  • Affects all crop stages.

Natural enemies

Parasitic wasps (Encarsia formosa and Eretmocerus spp.) usually provide effective biological control.

Predators include small predatory bugs, lacewing larvae and ladybirds.

Control

A management strategy needs to preserve and promote the activity of predators and parasites. Avoid early season use of broad spectrum insecticides, particularly pyrethroids and organophosphates.

Further information