Common Whitefly

Bemisia tabaci

1. Identification

• Common name: cotton whitefly
• Scientific name: Bemisia tabaci Gennadius
• Order: Hemiptera
• Family: Aleyrodidae

2. Description of the pest

• Adults: small winged insects (1–1.5 mm), with a pale-yellow body and white powdery wings; they fly rapidly when disturbed.
• Nymphs: flattened, oval, translucent; they adhere firmly to the underside of the leaves.
• Pupa (4th instar): oval structure, thicker and opaque.
• Eggs: very small, oval, initially whitish, darkening as they develop.

3. Main hosts

• Vegetables: tomato, pepper, cucurbits, bean, aubergine.
• Ornamentals: poinsettia, gerbera, hibiscus, chrysanthemum.
• Industrial crops: cotton, tobacco.
• Highly polyphagous species, with more than 600 recorded hosts.

4. Symptoms and damage

• Yellowing and weakening of the leaves due to the sucking of sap.
• Abundant production of honeydew, favouring the development of sooty mould.
• Reduction of photosynthesis and of plant vigour.
• Very serious indirect damage: transmission of viruses, including TYLCV (Tomato yellow leaf curl virus), ToCV (Tomato chlorosis virus) and others.
• In greenhouses, it can cause severe production losses.

5. Biological cycle

• Rapid cycle in hot conditions: 18–25 days.
• Eggs laid on the underside of the leaves.
• Nymphal development with 4 fixed instars.
• Adults live 1–2 weeks, with high reproductive capacity.
• Multiple generations per year; in greenhouses, a continuous cycle throughout the year.

6. Monitoring

• Direct observation of the underside of the leaves for nymphs and pupae.
• Counting of adults on yellow sticky cards.
• Frequent monitoring in greenhouses, especially in hot periods.
• Assessment of the presence of honeydew and sooty mould.
• Surveillance of viral symptoms in the host crops.

7. Management measures

• Cultural: elimination of crop remains; use of insect-proof netting; avoiding spontaneous host plants; appropriate management of greenhouse ventilation.
• Biological: release of beneficials such as Encarsia formosa, Eretmocerus eremicus, Amblyseius swirskii and A. montdorensis; conservation of natural predators.
• Integrated protection: intensive monitoring; use of sticky traps; rotation of modes of action to avoid resistance; judicious application of authorised insecticides.

Bibliographic references

• EPPO Global Database – Bemisia tabaci.
• CABI Invasive Species Compendium – Bemisia tabaci.
• Oliveira, M. R. V. et al. (2001). The worldwide spread of Bemisia tabaci.
• Horowitz, A. R. et al. (2005). Insecticide resistance in Bemisia tabaci.
• Byrne, D. N. et al. (1990). Biology and ecology of whiteflies.