Acroclisoides sinicus

(Huang & Liao, 1988)

Acroclisoides sinicus is a small pteromalid described from China in 1988. It is an obligate hyperparasitoid that exploits the pupal stage of scelionid primary , particularly Trissolcus , within pentatomid . Laboratory studies demonstrate extreme selectivity, with strong preference for Trissolcus mitsukurii over T. japonicus and no exploitation of eupelmid parasitoids. The species has recently expanded to Europe and North America, likely following of its primary parasitoid hosts. Its presence raises concerns for programs targeting stink bugs like Halyomorpha halys.

Pronunciation

How to pronounce Acroclisoides sinicus: /ˌækroʊklaɪˈsɔɪdiːz ˈsaɪnɪkəs/

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Identification

Distinguished from by morphological features visible in detailed habitus and views; molecular analysis supports delineation and synonymy with A. solus. Separation from other pteromalid hyperparasitoids requires examination of antennal structure, body proportions, and genital .

Habitat

Associated with agricultural and semi-natural where pentatomid stink bugs occur; found in field-collected masses of Halyomorpha halys and other pentatomids in northern Italy. Laboratory rearing successful at 26°C, 60% relative humidity, and 16:8 light:dark .

Distribution

Native to Asia (described from China); now present across the Holarctic with confirmed records in Europe (northern Italy, Switzerland, Germany) and North America (USA: Georgia, Alabama, Maryland; Canada). Recent detection in invaded regions suggests introduction linked to movement of Trissolcus agents.

Diet

feed on honey. Larvae develop as obligate hyperparasitoids by consuming pupae of scelionid primary (Trissolcus and Telenomus ) within pentatomid .

Host Associations

Trissolcus mitsukurii - primary (preferred)exploitation rate 96.2% in no-choice tests
Trissolcus japonicus - primary (low preference)exploitation rate 4.0% in no-choice tests
Trissolcus euschisti - primary
Trissolcus edessae - primary
Trissolcus basalis - primary
Telenomus podisi - primary
Halyomorpha halys - of primary masses containing parasitized eggs
Acrosternum heegeri - of primary laboratory rearing
Dolycoris baccarum - of primary laboratory rearing

Life Cycle

Females parasitize only the pupal stage of scelionid , which occurs approximately 7-9 days after primary oviposition. load increases over first 6 days post-, with mature located at end of or in lateral . development characterized through systematic dissection at 2, 3, 6, 9, and 12 days after host exposure. Sex ratio strongly female-biased (80-95% female in successful parasitizations).

Behavior

Shows strong olfactory attraction to volatiles emitted by masses parasitized by Trissolcus mitsukurii, but no response to those parasitized by T. japonicus or unparasitized eggs. Uses probing (>1 minute) to confirm suitability. Demonstrates aggressive intraspecific behavior: females kill other females when confined together. Host recognition is highly selective, with clear preference demonstrated in two-choice experiments.

Ecological Role

Occupies the highest as an obligate hyperparasitoid in multitrophic systems involving pentatomid stink bugs and their . Potential threat to efficacy by limiting of effective primary parasitoids, particularly Trissolcus mitsukurii. Minimal predicted impact on Trissolcus japonicus. May alter composition of parasitoid guilds in invaded regions.

Human Relevance

Emerging concern for programs targeting Halyomorpha halys (brown marmorated stink bug) and other pentatomids. Its strong preference for T. mitsukurii over T. japonicus suggests differential impacts on candidate biological control agents. Management strategies may need to account for hyperparasitoid-mediated suppression of primary effectiveness.

Similar Taxa

Acroclisoides solusProposed as junior synonym of A. sinicus based on morphological and molecular analysis; originally described from USA
Anastatus bifasciatusEupelmid also associated with pentatomid ; A. sinicus does not exploit this , distinguishing their ecological roles