Whiteflies
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Whiteflies

Whiteflies are homopterous insects of the order Hemiptera They are piercing and sucking insects: this activity begins at the 3rd larval stage.

Whitefly (Trialeurodes vaporariorum): adult
Whitefly (Trialeurodes vaporariorum): adult (Copyright Christiane METAY-MERRIEN, INRA-URIH).

One of the main pests on rose foliage, whiteflies are small insects (0.9 to 1.1mm), white or pale yellow.  Trialeurodes vaporariorum adults (see fig.1) are characterised by a triangular form and their wings (2 pairs) are covered with fine wax.
By shaking the foliage, adults are well visible but you need some training to detect the eggs, larvae and pupae.

Whieflies can cause direct damages by sucking the sap of crops and producing honeydew. There can also be indirect damages such as the possible transmission of viruses and the development of sooty mold (Cladosporium sphaerosporum).
Proliferation of whiteflies also interferes with the phosynthesis and the respiration.

Whiteflies can also be found on vegetables, other ornamental crops and citrus fruits.

Life cycle

There are 6 distinct developmental stages: eggs, 4 larval instars, imago.

Eggs of Whitefly (Trialeurodes vaporariorum)
Eggs of Whitefly (Trialeurodes vaporariorum) (Copyright Christiane METAY-MERRIEN, INRA-URIH).
Larvae and eggs of Whitefly (Trialeurodes vaporariorum)
Larvae and eggs of Whitefly (Trialeurodes vaporariorum) (Copyright Christiane METAY-MERRIEN, INRA-URIH).

Eggs are laid on the backside of the leaves (150 to 600 eggs depending on the host plant).

Whitefly early stage of larvae
Hatching of Whitefly (Trialeurode vaporariorum) - Early stage (x 35) (Copyright Christiane METAY-MERRIEN, INRA-URIH)
Moving larvae of Whitefly
Moving larvae of Whitefly (Trialeurode vaporariorum) (x 7,5) (Copyright Christiane METAY-MERRIEN, INRA-URIH).

Young larvae are translucent. They can be found on young leaves, whereas old larvae are located on older leaves, often at the foot of the plant.

Old larvae of Trialeurode vaporariorum Westwood
Old larvae of Trialeurode vaporariorum Westwood (Copyright Christiane METAY-MERRIEN, INRA-URIH).
Larvae of Whitefly (Trialeurode vaporariorum)
Larvae of Whitefly (Trialeurode vaporariorum) (x 50) (Copyright Christiane METAY-MERRIEN, INRA-URIH).

Once installed, they become motionless and adults emerge from the pupae by a hole. Adults are located at the top of the plants.

Pupal instar of Whitefly
Pupal instar of Whitefly (Trialeurodes vaporariorum) (x 30) (Copyright Christiane METAY-MERRIEN, INRA-URIH).

The last larval instar is called pupa.

Natural enemies

Pupae of Trialeurodes vaporariorum
Pupae of Trialeurodes vaporariorum (x 40). The black pupae is parasitised by the hymenopterous Encarsia formosa (Copyright Christiane METAY-MERRIEN, INRA-URIH).

Natural enemies are hymenopterous parasitoids and bugs. Parasitised larvae or pupae become black or yellow, depending on the parasitoid.

Date de modification : 25 avril 2023 | Date de création : 30 août 2013 | Rédaction : Roger BOLL, Christiane METAY-MERRIEN et Séverine DOISE (INRA-URIH)