''Comperiella bifasciata'' is a parasitic wasp species in the genus ''

Comperiella ''Comperiella'' is a genus of parasitic wasps in the family Encyrtidae Encyrtidae is a large family of parasitic wasps, with some 3710 described species in about 455 genera. The larvae of the majority are primary parasitoids on Hemiptera, thou ...

'' in the family

Encyrtidae Encyrtidae is a large family of parasitic wasps, with some 3710 described species in about 455 genera. The larvae of the majority are primary parasitoids on Hemiptera, though other hosts are attacked, and details of the life history can be variab ...

. It is used in

biological control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or o ...

California red scale ''Aonidiella aurantii'' or red scale is an armored scale insect and a major pest of citrus. It is thought to be a native of South China but has been widely dispersed by the agency of man through the movement of infected plant material. In the U ...

and yellow scale of

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

Description

''Comperiella bifasciata'' is a tiny black wasp with two white bars on the head. These are more prominent in females, which also have dark patches on the wings, giving them the appearance of having a forked tail; the wings of males are unblotched.

History

''C. bifasciata'' is a parasite of the red scale (''Aonidiella aurantii''), a major insect pest of citrus. This pest was accidentally brought into the United States in the second half of the nineteenth century, and is known there as California red scale. In attempts to try to control the red scale, in 1908 ''Comperiella bifasciata'', and two other parasitic wasps, were introduced into California from Japan. It failed to become established on red scale but was found by 1931 to have become established on yellow scale (''Aonidiella citrina''). It was later established that an error had been made and that it was not parasitising ''Aonidiella aurantii'' in Japan, but rather ''

Aonidiella taxus ''Aonidiella'' is a genus of scale insects in the family Diaspididae, the armored scale insects. Several species are pests of citrus.Ben-Dov, Y. (2006)Taxonomy of ''Aonidiella yehudithae'' sp. nov. and ''Lindingaspis misrae'' (Laing) comb. nov. w ...

'' and ''

Chrysomphalus bifasciculatus ''Chrysomphalus'' is a genus of armoured scales in the family Diaspididae. There are about 17 described species in ''Chrysomphalus''. Species These 17 species belong to the genus ''Chrysomphalus'': * '' Chrysomphalus aberrans'' Mamet, 1951 * '' ...

''. When imports of a different biological race were made from China between 1947 and 1949, the parasite did become established on red scale in California. These two types are identical in appearance and will hybridise in the laboratory, but maintain their separate identities in the field. In the

San Joaquin Valley The San Joaquin Valley ( ; Spanish language in California, Spanish: ''Valle de San Joaquín'') is the southern half of California's Central Valley (California), Central Valley. Famed as a major breadbasket, the San Joaquin Valley is an importa ...

, wasps reared from yellow scale are always of the Japanese type while those raised from red scale are the Chinese type. It seems that the hybrid is not so well adapted as either of its parents, so

natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the Heredity, heritable traits characteristic of a population over generation ...

eliminates it, thereby preserving the two distinct types.

Ecology

The larva of ''C. bifasciata'' is an

endoparasite Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

. The adult female seeks out third

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

and fourth instar female scale insects, but is prepared to

oviposit 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 ...

in any stage except females that have already produced crawlers. Each egg is laid singly and the developing larva feeds inside its host as it grows. When it pupates, black

meconium Meconium is the earliest stool of a mammalian infant resulting from defecation. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the uterus: intestinal epithelial cells, lanugo, mucus, am ...

pellets are deposited and get pushed to one side under the scale. When it emerges, the wasp chews a jagged-edged hole through the scale's body and scale. The mummified corpse of the scale insect, with black meconium deposits inside, usually remains stuck to the host plant.

Use in biological control

In California, the most important parasite of yellow scale is ''C. bifasciata''. The California red scale is most easily controlled by using the ectoparasite ''

Aphytis Aphytis (), also Aphyte (Ἀφύτη) and Aphytus or Aphytos (Ἄφυτος), was an ancient Greek city in Pallene, the westernmost headland of Chalcidice. Around the middle of the 8th century BC colonists from Euboea arrived. The city became ...

'', with ''C. bifasciata'' being unable to compete with ''Aphytis'' because the latter consumes the scale larvae including any developing ''C. bifasciata'' larvae that happens to be inside. However, in inland climates, such as in the

, ''Aphytis'' is less suitable for use and ''C. bifasciata'' is more effective.

References

{{Taxonbar, from=Q13474848 Encyrtidae Insects described in 1906 Endoparasites