Psyllaephagus

Ashmead, 1900

Species Guides

2

Psyllaephagus is a large of chalcid wasps in the Encyrtidae, containing approximately 245–246 described as of 2019, with greatest diversity in Australia (~100 described species, possibly ~1,000 total). The genus was established by William Harris Ashmead in 1900. Most species are primary of psylloids (Hemiptera: Psylloidea), with some secondary parasitoids. Three Australian species—P. pilosus, P. bliteus, and P. yaseeni—have been successfully deployed as agents against psylloids in California, Europe, Hawaii, and southeast Asia.

Psyllaephagus arbuticola by the Smithsonian. Used under a CC0 license.Psyllaephagus arbuticola by the Smithsonian. Used under a CC0 license.Psyllaephagus arbuticola by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Psyllaephagus: //sɪˌliːəˈfeɪɡəs//

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Identification

Distinguished from similar Encyrtidae by combination of: punctiform or slightly elongated (shorter than stigmal ), metallic green/blue-green coloration, 11-segmented with 6-segmented funicle, and hidden to exserted ovipositor. Mesopleuron clearly separated from metasoma base by propodeum visible in lateral view. Male antennae with variable funicle structure (whiplike to flattened) differ from females.

Images

Habitat

Associated with psylloid : leaves, twigs, and stems of host plants bearing nymphs. Rearing conducted in laboratory settings using nylon mesh bags containing infested plant material.

Distribution

. Greatest in Australia (~100 described , possibly ~1,000 total). Also abundant in Palaearctic region (~57 species), India (~20), Africa (~30). Documented from China (Ningxia, Shandong, Tianjin, Xinjiang, Guangxi), Russia (Tajikistan, Kazakhstan, Mongolia, Turkmenistan, Uzbekistan), Rica, Hawaii, southeast Asia, California, New York, England, Indonesia, Brazil, Mexico, and European countries.

Seasonality

Activity synchronized with psylloid . Some exhibit facultative in pupal stage, within mummified hosts. Diapause induced by short and low temperature during larval development.

Host Associations

Life Cycle

develop as larvae within psylloid nymphs, emerging as after at least one month in rearing conditions. occurs as pupa within mummified . Facultative induced by short and low temperature during larval stage; diapause termination temperature-dependent but chilling unnecessary.

Behavior

Females use plant volatiles and honeydew for host location. Infested host plant leaves are most attractive; honeydew stimulates increased searching activity, antennal drumming, and ovipositor probing, serving as directional cue to retain in favorable patches. Host-stage selection and oviposition adapted to psylloid nymphal instars.

Ecological Role

Primary regulating psylloid ; agent of pests. Some act as secondary parasitoids.

Human Relevance

Major agents for pests. P. pilosus introduced to California and Europe for control of Ctenarytaina eucalypti. P. bliteus introduced to California, Mexico, and Brazil for control of Glycaspis brimblecombei, achieving up to 90% natural control in Mexico City. P. yaseeni introduced to Hawaii and southeast Asia for control of Heteropsylla cubana. P. pistaciae is the major biocontrol agent of common pistachio psylla in pistachio . pipientis endosymbiont detected in some .

Similar Taxa

  • TorymusAlso of gall-forming insects including psyllids; distinguished by different wing venation and non-metallic coloration in most
  • Other Encyrtidae generaPsyllaephagus distinguished by combination of punctiform , metallic coloration, and psylloid specialization

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Sources and further reading