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''Encarsia formosa'' is a species of chalcidoid
Females deposit 50-100 eggs individually inside the bodies of
wasp
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
and a well known parasitoid of greenhouse whitefly
''Trialeurodes vaporariorum'', commonly known as the glasshouse whitefly or greenhouse whitefly, is an insect that inhabits the world's temperate regions. Like various other whiteflies, it is a primary insect pest of many fruit, vegetable and or ...
, one of the first to be used commercially for biological pest control, from the 1920s. They can use at least 15 species of whitefly
Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described.
Description and taxonomy
The ...
as a host, including ''Bemisia tabaci
The silverleaf whitefly (''Bemisia tabaci'', also informally referred to as the sweet potato whitefly) is one of several species of whitefly that are currently important agriculture, agricultural pest (animal), pests. A review in 2011 concluded t ...
'' and '' Aleyrodes proletella.''
The tiny females (about 0.6 mm long) are black with a yellow abdomen and opalescent wings. This species reproduces asexually via thelytoky
Thelytoky (from the Greek ''thēlys'' "female" and ''tokos'' "birth") is a type of parthenogenesis in which females are produced from unfertilized eggs, as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in a ...
induced by Wolbachia
''Wolbachia'' is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproducti ...
infection. Males are produced only rarely. They are slightly larger than females and are completely black in coloration.
Life cycle
Females deposit 50-100 eggs individually inside the bodies of nymphs
A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ...
or pupa
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...
e 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.
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, a particularly difficult plant for predators to establish on.Clap and fling flight
''E. formosa'' utilizes the clap and fling mechanism often seen in sub-mm insects. The wings, at the apex, and nearly touching, fling apart and generate strong vortices along the leading edge and wing tips. This mechanism works well in low Reynolds number flight as the generated vortices remained attached through the stroke cycle. Flexible wings and bristles along the wing edges help mitigate the large drag forces that the insect must overcome. Unlike normal flight, this method would work in an entirely inviscid medium, as it does not rely on a starting vortex to create circulation about the wing.References