Encarsia formosa (Parasitic Wasp): Biological Control of Whitefly

Whitefly control with the parasitic wasp Encarsia formosa

Encarsia formosa is a parasitic wasp belonging to the family Aphelinidae, widely recognized for its role in biological control, particularly in the management of whitefly populations in various agricultural and horticultural settings. This parasitic wasp, native to temperate and subtropical regions, has become an important natural enemy for farmers and gardeners aiming to reduce the reliance on chemical pesticides.

Encarsia formosa is used for the control of the following pests:

Greenhouse whitefly (Trialeurodes vaporariorum)
Tobacco whitefly (Bemisia tabaci)

The parasitic wasp Encarsia formosa is available at Koppert as En-Strip.

Encarsia formosa products

En-Strip

Enermix

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Best conditions for Encarsia formosa

The parasitic wasp Encarsia formosa is most effective at temperatures between 20°C and 25°C (68 and 77°F). At a 24 hours average temperature below 17°C/63°F the control of whiteflies may be insufficient.

How to use Encarsia formosa

The parasitic wasp Encarsia formosa is available on cardboard strips as single species (En-Strip) and in combination with Eretmocerus eremicus (Enermix).

Open package carefully inside the greenhouse
Bend and tear off the strips opposite to the mounting hole
Make sure not to touch the pupae during handling
Suspend the cards in the crop, if possible approximately 75 cm under the plant head
Avoid to hang cards at places exposed to direct sunlight

The dosage of En-Strip or Enermix depends on climate, crop and whitefly density and should always be adjusted to the particular situation. Start introduction preventively soon after planting of the crop. Introduction rates typically range from 1-10 per m²/release. Releases should be repeated until control is achieved. At increasing temperatures it may be better to switch to the use of Enermix or Ercal. Consult a Koppert advisor or a recognized distributor of Koppert products for advice on the best strategy for your situation.

Behaviour of the parasitic wasp Encarsia formosa

Encarsia formosa is a parasitic wasp renowned for its effectiveness in controlling whitefly populations, particularly the greenhouse whitefly (Trialeurodes vaporariorum). The female wasp lays her eggs inside the whitefly nymphs, which are then consumed from the inside out by the developing larvae. The larvae feed on the internal tissues of the host, leading to its death and thereby contributing to the reduction of whitefly numbers. Encarsia formosa is highly adaptable and can adjust its parasitism based on the density of the whitefly population, making it a valuable tool in integrated pest management. The wasps themselves do not feed on whiteflies but rely on nectar and honeydew produced by other insects for their sustenance. Their presence in greenhouses and other controlled environments helps maintain balance and reduce the reliance on chemical pesticides.

Life cycle and appearance of Encarsia formosa

The development of E. formosa consists of six stages: the egg, three larval instars, a pupal instar, and the adult wasp. All these stages except the adult insect are found inside the host (i.e. larval and pupal whiteflies). The female can deposit her egg in any larval stage of whitefly, but preferably selects the third and young fourth larval instars. This offers the best chance of successful development. The egg is 0.08 mm long and 0.03 mm wide. About halfway through the parasitoid’s development, the host pupa turns black. Parasitized pupae are thus easily recog nized. However, this blackening can be delayed, in which case the larva remains visible throughout its development. Once the tobacco whitefly has been parasitized, the pupa remains transparent to brown in colour. The pupa of E. formosa is unique among the species of Encarsia, in that it is formed immediately beneath and in contact with the whitefly pupal cuticle, whereas in other Encarsia species it can be seen clearly that the pupa develops freely within the host pupa. When the parasitic wasp is fully grown, it eats a round hole in the pupal cuticle. It takes several hours before the wasp frees itself from its case. The female parasitic wasp is approximately 0.6 mm long, with a head that is dark brown to black in colour, a dark brown to black thorax, and a yellow abdomen. The male is entirely black.