Trialeurodes vaporariorum (Greenhouse Whitefly)
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Image 1: Trialeurodes vaporariorum
Trialeurodes vaporariorum, commonly known as the greenhouse whitefly, is a small herbivorous insect belonging to the family Aleyrodidae of the order Homoptera. It affects many crops worldwide and is considered one of the most important entomological pests due to its adaptability to various environments, multiple generations per year, and rapid spread, making its eradication challenging. This article presents the insect's bioecology, the damage it causes, and ways to control and reduce its population.
Morphology of Greenhouse Whitefly
Its body length is about 1 mm, with a light-yellow color, and it is covered with a white waxy powder.
Image 2: Adult stage of the insect (Tsolakos P. Avgoustos, 2018)
Host Plants of Greenhouse Whitefly
It is mainly found in greenhouses. It infests ornamental plants, herbaceous crops, solanaceous and cucurbitaceous plants, wild flora, and other species.
Life Cycle and Biology
The greenhouse whitefly has six life stages: egg, 1st, 2nd, 3rd, and 4th nymphal instars, and adult. The nymphs are oval-shaped and located on the underside of young leaves. First-instar nymphs are mobile, while the later stages remain stationary on the foliage. The 4th instar nymph develops inside a white, oval casing with vertical wax rods around it. This is the pupal stage, typically found on the older leaves of the plant. The adult emerges from the pupal case through a T-shaped slit. Adults are usually found at the top of the plant and on the undersides of young leaves, where they lay their eggs. When infested plants are disturbed, the adults will fly away briefly and then return to the underside of the leaves. The adult's mouthparts pierce the plant and begin feeding on sap immediately after emergence. The insect is covered in a white waxy substance.
Crop Damage Caused by Whiteflies
The whitefly feeds on plant sap, causing plant weakening. This feeding leads to discoloration at the feeding sites, leaf curling, fruit and flower drop, and wilting. Additionally, it causes indirect damage, as its honeydew secretions support the development of sooty mold, which reduces the plant's photosynthetic capacity.
Chemical Control of T. vaporariorum
In cases of severe infestation, foliar spray applications can be used with the chemicals mentioned below. However, it is essential to note that chemical treatments should only be considered as a last resort, particularly in cases of high pest pressure. Preference should always be given to biological and integrated pest management approaches. Before applying any chemical product, growers must consult a local agronomist or crop protection specialist to assess the situation and determine the most appropriate strategy properly. It is also crucial to use only registered and approved products, strictly following the instructions on the label. The substances mentioned above are based on literature sources and serve as general guidance; expert consultation is necessary for safe and effective pest control.
- Neonicotinoids (acetamiprid, thiacloprid, thiamethoxam)
- Insect Growth Regulators (pyriproxyfen, teflubenzuron)
- Pyrethroids (deltamethrin)
- Pyrethrins
- Triazinones (pymetrozine)
- Potassium salts of fatty acids
- Cyclic ketoenols (spiromesifen) (Source: Ministry of Rural Development & Food, 2012)
Additionally, a carbamate or organophosphate insecticide can be applied in combination with a neonicotinoid (e.g., imidacloprid) along the planting line via drip irrigation.
Biological Control
- Yellow sticky traps
- Beneficial insects and mites
Image 3: Beneficial insects and mites (BIO-INSECTA)
Preventive Measures
It is recommended that crop residues as well as wild host plants be destroyed.
References
- Image 1: https://www.koppert.gr/parasita-fyton/aleyrodeis/aleyrodis-toythermokipioy/
- Image 2: https://garden-for-all.com (Panagiotis Tsolakos, August 27, 2018)
- Image 3: https://www.bioinsecta.gr/pests/%CE%B1%CE%BB%CE%B5%CF%85%CF%81%CF%8E%CE%B4%CE%B5%CE%B9%CF%82
- Entomology, Navrozidis I. Emmanouil & Andreadis S. Stefanos, Thessaloniki 2012