Whitefly, Tobacco Whitefly

Bemisia tabaci

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Changed on: 24.06.2019
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Adulte Weiße Fliege, Tabakmottelschildlaus (Bemisisa tabaci)
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Adulte Weiße Fliege, Tabakmottelschildlaus (Bemisisa tabaci)

The tobacco whitefly (Bemisia tabaci) is very similar in appearance and biology to its close relative the greenhouse whitefly (Trialeurodes vaporariorum). It was imported to Austria about 35 years ago and is found occasionally on ornamental plants (poinsettia) and, on rare occasions, on greenhouse vegetables.

One of this organism’s most harmful characteristics is that it serves as a vector for over 100 plant viruses of the genus begomovirus, crinivirus, carlavirus and ipovirus, in addition to extracting plant sap for nourishment. Given the risk of transmitting viruses, non-European populations of Bemisia tabaci are listed as quarantine pests in line with EU Regulation 2000/29/EC and are, therefore, subject to legal regulations on the prevention of importing and spreading of such pests to and within the Member States.

Adulte Weiße Fliege, Tabakmottelschildlaus (Bemisisa tabaci)
caption
Adulte Weiße Fliege, Tabakmottelschildlaus (Bemisisa tabaci)

The tobacco whitefly (Bemisia tabaci) is very similar in appearance and biology to its close relative the greenhouse whitefly (Trialeurodes vaporariorum). It was imported to Austria about 35 years ago and is found occasionally on ornamental plants (poinsettia) and, on rare occasions, on greenhouse vegetables.

One of this organism’s most harmful characteristics is that it serves as a vector for over 100 plant viruses of the genus begomovirus, crinivirus, carlavirus and ipovirus, in addition to extracting plant sap for nourishment. Given the risk of transmitting viruses, non-European populations of Bemisia tabaci are listed as quarantine pests in line with EU Regulation 2000/29/EC and are, therefore, subject to legal regulations on the prevention of importing and spreading of such pests to and within the Member States.

Symptoms


Plants that are severely affected show yellowing on their leaves and are damaged by the sugary excretions of the insect. Similar to aphids, whiteflies excrete sticky honeydew which drips onto the leaves and fruit below. This shiny coat can, on the one hand, induce the growth of sooty moulds, which soil the fruit (additional rinsing necessary), and the affected leaves lose their assimilation surface, weakening the plants, on the other.

Host plants

Bemisia tabaci was known as a farm crop pest in tropical and subtropical countries, affecting crops such as manioc, cotton, sweet potato, tobacco and tomatoes, until recently. However, its range of hosts encompasses more than 900 host plants from over 60 families (such as Asteraceae, Brassicaceae, Cucurbitaceae, Convolvulaceae, Euphorbiaceae, Fabaceae, Malvaceae, Solanaceae, etc.).
The development of the extraordinarily polyphagous subtype B made Bemisia tabaci a notorious greenhouse pest, infesting peppers, courgettes, cucumbers, lettuces and tomatoes, as well as hibiscus, gerbera, gloxinia and poinsettia (Euphorbia pulcherrima) in many parts of the world. It is quite likely that international trade with poinsettia plants is the largest propagator of this pest.

Diagnosis

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Eggs of the tobacco whitefly (Bemisia tabaci)
Eier der Tabakmottenschildlaus (Bemisia tabaci)

The tobacco whitefly (Bemisia tabaci) is very similar in appearance and biology to its close relative the greenhouse whitefly.

Specialists can differentiate adult insects of Trialeurodes by looking at the bristles of their hind legs, while the insect’s pseudo pupae can even be differentiated by laymen, as they are shield-like in form, unlike those of Trialeurodes.

Enzymatic detection methods have been used for the past few years to  differentiate between a number of different subspecies of Bemisia tabaci. The most commonly known subspecies, Subtype B -- the silver-leaf whitefly, Bemisia argentifolii – has caused severe damage to vegetable crops in California, is particularly fertile and highly resistant to insecticides.

 

 

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Tobacco whitefly larva (Bemisia tabaci)
Larve der Tabakmottenschildlaus (Bemisia tabaci)
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Empty egg skin (exuviae) of the tobacco whitefly (Bemisia tabaci)
Abgelegte Eihaut (Exuvie) der Tabakmottenschildlaus (Bemisia tabaci)

Control

Plants should be checked for the presence of whitefly or suspicious damage symptoms (e.g. yellow, chlorotic spots, honeydew, sooty mould) when they arrive at the greenhouse or farm, when bought from external sources.

Monitoring using yellow whitefly traps before and during culture growth. Poinsettia and tomatoes are at risk. Regular infestation checks – older leaves are ideal to look for pseudo pupae.
Proper hygiene measures, in particular before and after growing the plants, are highly recommended.

Treatment with plant protection products to fight whitefly and licensed for use in Austria (See BAES register for authorised plant protection products in Austria).
Use of natural predators, such as Encarsia, Eretmocerus or Macrolophus (Heteroptera).



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