Biological Control
Encarsia
Whitefly is a frequently occurring pest in vegetables and ornamental plants. The biological control for this pest is Encarsia, whitefly is an effective control for this pest.
Whitefly
Adult whiteflies are small, white, 'powderey' insects (about 1 mm.). They feed on plant sap, which stunts the growth of the plant. They also transmit several viruses that can cause plant disease. Larvae and adults secrete a sticky substance (honeydew). It makes the leaves (and fruits) dirty and sticky and causes fungal growth.
Parasitic Wasp
The parasitic wasp Encarsia measures about 0.6 to 0.7 mm and lays eggs into the whitefly larvae. After 10 days the whitefly parasitized pupae die and turn black. After another 10 to 14 days, new parasitic wasps leave the black pupae to infect further pupae.
The parasitic wasp is only active at 16°C or above. It survives at lower temperatures but is not active. The parasitic wasp will die if the temperature drops below 6°C.
Parasitic wasps are not harmful to humans, animals or plants and cannot survive without the presence of whitefly.
Application
The parasitic wasps are delivered as pupae (black) that are stuck on cards.
When the wasps arrive they have to be introduced as soon as possible. The cards can be torn loose carefully. See that your fingers do not touch the pupae while loosening and hanging the cards in the crop (to prevent from damage). The small hole on top of the card enables you to hang them up easily in the plants. Hang the cards 50 cm below the top of the plants, spreading them equally over the area to be treated.
If you are using yellow sticky traps, to minimise the risk of catching Encarsia, ensure that they are hung above the crop.