Whitefly Control

Whiteflies are small, winged insects typically white or pale yellow in colour. The most common species in the UK is the greenhouse whitefly.

Whiteflies feed on plant sap which can cause leaf damage and stunted growth. They can transmit viruses and cause significant plant destruction or complete plant loss.

Whiteflies can also excrete honeydew which can attract dark sooty mould, further impacting plant health due to reduced photosynthesis ability.

Identifying Whitefly Damage

You may notice discoloured patches on sections of leaf where the whiteflies have been feeding. Leaves can wilt or drop completely as a result of whiteflies feeding, and edible produce can be spoiled through sticky honeydew deposits.

What is Biological Whitefly Control?

Agrigem sells two predator controls for whitefly management:

• Eretmocerus eremicus. Available in two pack sizes; 50m² and 100m².
• Encarsia formosa. Available in one pack size - up to 300m².

Both predators are tiny parasitic wasps. Eretmocerus eremicus is a very effective parasitic wasp predator. It lays its eggs inside the whitefly nymphs, which consume the host from within once hatched, causing their death and significantly reducing the whitefly population. A single female adult can parasitise up to 150 pest whitefly larvae.

Encarsia formosa wasp pupae will hatch out into adult female parasitic wasps once the temperatures reach 16°C. The adult wasps will search for whitefly larvae then parasitise the whitefly and lay an egg inside it, causing it to die. A new parasitic wasp will develop inside the dead whitefly larvae and will eventually emerge to search for more whitefly. The wasps will also feed on the younger larvae of whitefly in the 1st and 2nd larval stages of development.

Application

Conditions for optimal activity of Encarsia formosa require a minimum average greenhouse temperature of 18°C/64°F. The lifespan of Encarsia formosa is considerably reduced at termaratures above 30ºC/86ºF. Encarsia formosa do not like large whiteflycolonies as excessive honeydew can hamper its mobility.