| Causal Organism: Trialeurodes vaporariorum (greenhouse whitefly – GFW)); Bemisia tabaci (sweetpotato whitefly); Bemisia argentifolia (silverleaf whitefly)
- The specific species present may vary by region
Crops Affected: Wide host range (250+ species) – a range of greenhouse vegetable crops (e.g. tomatoes, cucumbers), as well as ornamentals (poinsettia, cut flowers, bedding plants, house plants, etc.)
Life Cycle:
- True bugs – feed on plant sap by piercing and sucking
- May cause a reduction in plant vigour and some secondary sooty moulds (due to sticky honeydew)
- Life stages include eggs, nymphs (crawlers), pupae, adults
- Life cycle is affected by temperatures, with shorter times at warmer temperatures
- Sensitive to cold temperatures
- Adults
- Small (1.5-2mm), powdery white winged insects
- GWF has the wings held flat and parallel to the resting surface, and the overall body shape is triangular
- B have the wings in a tented fashion above the body, and the overall body shape is more linear
- Difficult to see with the naked eye
- Adults lay 100-300 eggs (over a 3-5 week lifetime) along the undersides of younger leaves
- Eggs are sometimes laid in circular “fairy-ring” patterns
- Eggs start off a creamy-white, darkening within a day or so
- Nymphs
- Eggs hatch in 5-10 days to produce a flat, scale-like, largely immobile nymphal stage, referred to as “crawlers”
- Nymphs pass through 3 instars before pupation
- Pupae
- Pupation lasts about 1 week, with no feeding taking place
- GWF pupae are somewhat raised off of the surfaces of the leaves, and may be surrounded by a fringe of hairs
- B pupae sit flat on the leaf surface and have no hairy fringe
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Multiple life stages of Greenhouse Whitefly
(Trialeurodes vaporariorum) | Adult Silverleaf Whitefly (Bemisia argentifolia) |
Photo by Whitney Cranshaw, Colorado State University, Bugwood.org | Photo by Scott Bauer, USDA Agricultural Research Service, Bugwood.org |
Symptoms:
- A decline in plant vigour
- Stunting, yellowing of leaves and premature leaf drop
- The observation of the insects stages may be indicative of presence
- Some species transmit plant viruses, which produce other symptoms
Management:
- Monitor / inspect plants regularly for pests
- Quarantine new plants to ensure they are not bringing in a problem
- Use pest-attractive plants as trap or monitoring sites (e.g. eggplants)
- Apply controls quickly to prevent populations from increasing rapidly
- Control alternative hosts (e.g. weeds) in adjacent areas
- Use clean, virus-free plants (to avoid virus transmission)
- Biological controls can be effective at managing populations of whitefly, including specific parasitic wasps, ladybeetles, predatory bugs and a couple of different fungal biocontrol products.
- Yellow sticky traps or yellow sticky tape can be used broadly and/or in population hotspots to draw whiteflies
(and other insects) out of the crop
- Vacuuming adults from hotspots can work to quickly bring a population in one area down, however this is not effective in larger areas
- Install fine-meshed screens over vents and doorways, to prevent entry and movement between areas, and from outside to inside a greenhouse
- Registered chemical controls may be applied at specific stages to reduce populations
- Use these with care to prevent the development of resistance
- Certain products are more effective on certain life stages (e.g. horticultural oils are best for immobile, immature stages
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