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Bemisia tabaci

EPPO code 

BEMITA

Common names

English names: Tobacco Whitefly, Sweet Potato Whitefly, Cotton Whitefly
Nordic names: Bomuldsmellus (DK), Etelänjauhiainen (FI), Bomullsmellus (NO), Bomullsmjöllus (SE) 

Major host plants

The host range includes 600 plant species belonging to Asteraceae, Brassicaceae, Convolvulaceae, Cucurbitaceae, Euphorbiaceae, Fabaceae, Malvaceae, Solanaceae, etc. B. tabaci has been spreading into new regions and become a pest of glasshouse crops in many parts of the world, especially Capsicum, courgettes, cucumbers, Hibiscus, Gerbera, Gloxinia, lettuces, poinsettia and tomatoes. 

Symptoms

Numerous chlorotic spots develop on the leaves of affected plants, which may also be disfigured by honeydew and associated sooty moulds. A close observation of the underside of the leaves will show tiny yellow/white larval scales and in severe infestations, when the plant is shaken, numerous small white adult whiteflies will flutter out and quickly resettle.

Bemisia-tabaci
Bemisia tabaci. Courtesy: EPPO/Agroscope FAW Wädenswil, Switzerland

See more pictures on EPPO´s website

Distribution

A map can be downloaded from EPPO´s website. See instructions here.

Biology

Adult females lay oval-shaped eggs either singly or in scattered groups on the underside of leaves. The larvae hatch one – two weeks after oviposition, depending upon the temperature and humidity.
B. tabaci has four nymphal stages, of which only the first (called the “crawler”) is mobile. The last stage is known as puparium. The total nymphal period lasts two to four weeks according to temperature.

The adult emerges about six days after pupation through a T-shaped rupture in the dorsal surface of the pupal case. Mating begins 12 – 20h after emergence and it happens several times a year. A female may live for 60 days and is able to lay up to 160 eggs in her lifetime.

Major pathway(s)

Adults do not fly very efficiently but, once airborne, they can be transported quite large distances by the wind. All stages of the pest are liable to be carried on planting material and cut flowers of host species.

Detection and inspection

White adults, about 2-3 mm, are easily seen underside of leaves. When the plant is shaken, numerous small white adult whiteflies will flutter out and quickly resettle. A close observation of the underside of the leaves will show the tiny yellow/white larval scales. 

B. tabaci is difficult to distinguish from ordinary white fly Trialeurodes vaporariorum.

Pest status and importance

The risk to the EPPO region is principally to the glasshouse industry in northern countries. Since its recent introduction to several of these countries, the pest has proved particularly difficult to combat because of its polyphagy, its resistance to many insecticides and its disruption of biological control programs. 

B. tabaci is considered among the most invasive and economically damaging insects to both field and greenhouse agricultural crops and ornamental plants. Three types of damage are observed. Direct feeding damage by adults and nymphs may reduce host vigour and growth. Indirect damage is caused by the sooty moulds that develop on honeydew. The mould reduces photosynthesis and decreases the yield and market value of the plant. The third type of damage is due to plant virus transmission property of B. tabaciB. tabaci vectors more than 60 plant viruses, including geminiviruses (e.g. tomato yellow leaf curl bigeminivirus (TYLCV), which are very important agriculturally, since they cause yield losses, ranging from 20 to 100% depending upon the crop and season. Several of these geminiviruses are quarantine pests for the EPPO region.

Source of information

See further information here: 

EPPO

Author: Jorma Rautapää
Editor: Elise T. Yamamoto Buch

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