The two species of whitefly that affect many crops are Bemisia tabaci or tobacco whitefly and Trialeurodes vaporariorum or glasshouse whitefly. The main morphological difference that enables these to be distinguished from one another is the position of the wings. In B. tabaci, these are joined to the body and in T. vaporariorum they are parallel to the surface of the leaf. Furthermore, the adult and pupa of T. vaporariorum usually has a greater quantity of waxy powder than B. tabaci.
About the pest in short
- What are Whiteflies?
- Whiteflies are hemipterous insects belonging to the Aleyrodidae family. They can cause considerable damage and loss of production.
- What can you see?
- Discolored patches on the parts of the leaf when they have been feeding.
- What can you do?
- One of the main objectives when controlling whitefly is to avoid the crop being infected by a virus that the insect can carry.
Biological cycle of Whitefly
The full life cycle of the whitefly lasts between 15 to 40 days, depending on environmental conditions, particularly the temperature, as eggs will turn into adults more quickly when the temperature is higher. The whitefly usually lays its eggs on the underside of the leaves and the eggs stick to them.
Symptoms of a pest
The direct damage is caused to the plant as the whitefly feed. The sucking of the sap leaves discolored patches on the parts of the leaf when they have been feeding. Furthermore, as they suck out the sap, they release toxic substances into the phloem, which then spread throughout the plant. This leads to metabolic imbalances in the plant which leads to overall weakening, chlorosis and changes to the flowers and fruit. In terms of indirect damage, the molasses excreted by the nymphs enables fungi such as sooty mold (Capnodium sp.) to form on the leaves.
This mold acts as a screen and reduces the photosynthetic capacity of the plant. However, the most serious damage that the whitefly can cause to crops is the transmission of viruses.
How to prevent the pest?
One of the main objectives when controlling whitefly is to avoid the crop being infected by a virus that the insect can carry. Therefore, any weeds or remains of other plants that are near the crop should be removed as these can act as a habitat for the whitefly. Furthermore, if a whitefly feeds off a weed that contains a virus and then reaches your crop, the virus can easily be spread. The use of protective barriers such as nets and covers are also a good option for preventing infestations.
Solutions to control the pest
A range of entomophagus insects, parasites, and some entomopathogenic fungi are used to control whitefly. Most of the predators feed on the eggs and nymphs of the whitefly. This category includes the Delphastus catalinae beetle. The chrysopidae larva and some bedbugs are also good biological controllers of this pest. The small wasps of the Aphelinae family are parasites of the whitefly larva, where the wasps lay their eggs and they develop by feeding off their host.