Encarsia formosa

Encarsia formosa is a species of chalcidoid wasp and a well known parasitoid of greenhouse whitefly, one of the first to be used commercially for biological pest control, from the 1920s. Its use fell with commercial pesticides in the 1940s, but rose again from the 1970s.

Description

The tiny females are black with a yellow abdomen and opalescent wings. The species reproduces asexually via thelytoky induced by Wolbachia infection. Males are produced but are unable to inseminate the females.
The adults use the clap and fling flight mechanism often seen in sub-mm insects.

Life cycle

Females deposit 50-100 eggs individually inside the bodies of nymphs or pupae of the host species. The wasp larvae develop through four instars in about two weeks at optimum temperatures. Parasitized greenhouse whitefly pupae turn black in about 10 days, while parasitized sweet potato whiteflies turn amber brown. Both are easily distinguished from unparasitized host pupae. Wasp pupation occurs within the whitefly body. Adult wasps emerge about 10 days later. E. formosa can use at least 15 species of whitefly as its host, including Bemisia tabaci and ''Aleyrodes proletella.''

Use in biological control

Encarsia formosa has been used as a natural pesticide to control whitefly populations in greenhouses since the 1920s. Use of the insect fell out of fashion due to the increased prevalence of chemical pesticides and was essentially non-existent by the 1940s. Since the 1970s E. formosa has seen something of a revival, with renewed usage in European and Russian greenhouses. In some countries, such as New Zealand, it is the primary biological control agent used to control greenhouse whiteflies, particularly on crops such as tomato which is a difficult plant for predators to establish themselves on.