Whitefly
Encarsia + Eretmocerus systems.
Whitefly control relies on parasitoids and sticky monitoring...
About Whitefly
Whiteflies are major pests in protected horticulture, especially glasshouse tomatoes, cucumbers, herbs and ornamentals. The two key UK species are the glasshouse whitefly (Trialeurodes vaporariorum) and the tobacco whitefly (Bemisia tabaci). Both feed by extracting plant sap, causing leaf yellowing, honeydew contamination and reduced crop quality. Bemisia is particularly serious due to virus transmission and insecticide resistance.
Symptoms of Whitefly Damage
- Clusters of white adults flying when foliage is disturbed
- Leaf yellowing, reduction in vigour and soft growth collapse
- Sticky honeydew coating leaves and fruit
- Sooty mould developing on the honeydew
- Presence of whitefly scale (nymphs and pupae) on leaf undersides
Why Biological Control Works
Whitefly biological control is well established in UK horticulture. Parasitoids such as Encarsia formosa and Eretmocerus eremicus target early nymphal stages, while predators like Macrolophus pygmaeus provide long-term suppression across all stages. When introduced early and supported with good climate and hygiene, these beneficials can maintain whitefly populations at very low levels throughout the season.
Common UK Whitefly Species
- Trialeurodes vaporariorum — Glasshouse whitefly
- Bemisia tabaci — Tobacco whitefly (quarantine concern)
IPM Recommendations
- Introduce Encarsia early at the first sign of adults
- Use Eretmocerus in warmer crops or where Bemisia is present
- Establish Macrolophus preventatively for season-long control
- Place yellow sticky traps to monitor adult movement
- Remove lower leaves where nymph stages accumulate
- Maintain good hygiene: clear crop debris and old yellow leaves
Preventative vs Curative Strategy
Preventative: Apply weekly introductions of Encarsia formosa as soon as the crop is established. Release Macrolophus pygmaeus early to build strong background predation.
Curative: Increase rates of Encarsia and add Eretmocerus where higher temperatures favour rapid whitefly development. Use Macrolophus for knockdown of high adult activity.
Environmental Notes
- Encarsia formosa performs best at 20–27°C
- Eretmocerus eremicus excels in warm summer crops
- Macrolophus pygmaeus requires early introduction to establish
- Lower leaves tend to harbour early infestations — remove if safe
Biological Controls for Whitefly
The options below are examples of beneficial insects and biological products commonly used against whitefly. Always refer to supplier guidance and product labels for crop safety and local registration status.
Encarsia formosa
Product: En-Strip
Environment: glasshouse
Temperature Range: 18.0 – 32.0°C
Rate: 1–3/m²
Frequency: Weekly x 3–6
Greenhouse whitefly
Eretmocerus eremicus
Product: Eretline
Environment: glasshouse
Temperature Range: 18.0 – 32.0°C
Rate: 1–3/m²
Frequency: Weekly x 3–6
Preventative
Amblyseius montdorensis
Product: Montyline
Environment: glasshouse
Temperature Range: 12.0 – 32.0°C
Rate: 100-150/m²
Frequency: 14 days
Preventative
Amblyseius swirskii
Product: Starskii
Environment: glasshouse
Temperature Range: 20.0 – 30.0°C
Rate: 100-150/m²
Frequency: 14 days
Preventative
Encarsia formosa
Product: Encarline
Environment: glasshouse
Temperature Range: 18.0 – 32.0°C
Rate: 1–3/m²
Frequency: Weekly x 3–6
Greenhouse whitefly
Eretmocerus eremicus
Product: Eretline
Environment: tunnel
Temperature Range: 18.0 – 32.0°C
Rate: 1–3/m²
Frequency: Weekly x 3–6
Tobacco Whitefly
Amblyseius montdorensis
Product: Montyline
Environment: tunnel
Temperature Range: 12.0 – 32.0°C
Rate: 100-150/m²
Frequency: 14 days
Preventative
Amblyseius swirskii
Product: Starskii
Environment: tunnel
Temperature Range: 20.0 – 30.0°C
Rate: 100-150/m²
Frequency: 14 days
Preventative
Encarsia formosa
Product: Encarline
Environment: tunnel
Temperature Range: 18.0 – 32.0°C
Rate: 1–3/m²
Frequency: Weekly x 3–6
Greenhouse whitefly
Related Biological Solutions
Growers dealing with whitefly often also monitor these pests as part of a complete IPM programme: