''Encarsia perplexa'' is a tiny parasitic wasp, a

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

of the

citrus blackfly ''Aleurocanthus woglumi'' is a species of whitefly in the family Aleyrodidae. It is a pest of citrus crops, and is commonly known as the citrus blackfly because of its slate-blue colour. It originated in Asia, but has spread to other parts of t ...

, ''Aleurocanthus woglumi'', which is a global pest of

citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is native to ...

trees. It was originally misidentified as ''Encarsia opulenta'', but was recorded as a new species in 1998. It is a native of Asia but has been introduced to many other parts of the world as a means of controlling the citrus blackfly.

Distribution

This wasp is a native of India and Vietnam.Silvestri F. 1927. Contribuzione alla conoscenza degli Aleurodidae (Insecta: Hemiptera) viventi su citrus in Extremo Oriente e dei loro parasiti. Boll. Lab. Zool. Portici. 21: 1-60. It has been introduced to and has established itself in Barbados, Cuba, Jamaica, Mexico, Salvador, Venezuela, the USA (Florida, Texas and Hawaii), Kenya and Oman, for the purpose of controlling citrus blackfly.

Description

The female is just over one millimetre long with antennae 0.8 millimetre in length. The

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the c ...

is straw coloured, the wings are transparent with a smoky patch in the centre and the legs are whitish. The

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

is straw-coloured at the front and dark brown behind with a dark-coloured

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

0.5 millimetres long. The male is smaller, averaging 0.75 millimetres in length and is a uniform dark brown.

Life cycle

After mating, a female lays

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectiv ...

eggs in

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 ...

of the citrus blackfly. When available, a second

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...

nymph is selected and each egg will eventually produce a female adult. At 24 °C in the laboratory, it takes 30 to 35 days from egg-laying to adult emergence. Unmated females lay

haploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respective ...

eggs in the fully developed larvae of their own species. These hatch out into males, a process known as adelphoparasitism. The sex ratio among adults in the field is one male to every seven females. ''Encarsia perplexa'' is itself parasitized by '' Encarsia smithi'' which was accidentally introduced into Florida in the 1970s.

Use in biological control

The only hosts that have been identified for ''Encarsia perplexa'' are '' Aleurocanthus woglumi'' and '' Aleurocanthus incertus'', another whitefly. This means that introducing the species into a citrus growing area is unlikely to have adverse ecological side effects. '' Amitus hesperidum'' is another citrus blackfly parasitoid that has been used alongside ''E. perplexa'' to control the pest. It reproduces rapidly and can produce up to seventy progeny per female and is very successful at controlling heavy infestations. ''E. perplexa'' multiplies more slowly but is better at scouting for outlying blackflies and is more effective when populations of potential hosts are lower. In Hawaii, both species were introduced in 1999 after the citrus blackfly was discovered there for the first time the previous year. They rapidly became established and were soon controlling the pest on the island of Oahu. Later releases on other islands in the group have also been an effective, though not immediate, means of reducing infestations.

References

{{Taxonbar, from=Q5375319 Aphelinidae Biological pest control wasps Insects used as insect pest control agents Insects described in 1998