Triaspis

Triaspis is a of in the Braconidae. within this genus are agents that parasitize weevil larvae and , particularly those of agricultural pests. The genus includes species such as T. thoracicus, an egg-larval parasitoid of pea weevils, and T. aequoris, a larval parasitoid of sunflower seed weevils.

Triaspis fiskei by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Triaspis: /ˈtraɪ.əs.pɪs/

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Images

Habitat

Agricultural , particularly fields of legumes and sunflower . Laboratory rearing occurs in controlled environments including jars, bottles, desiccators, crystallizers, and Petri dishes.

Distribution

Western Europe, North America (including North Dakota and South Dakota, USA), Czechoslovakia, Moravia, Transcaucasia, Georgia, and Azerbaijan. T. thoracicus was introduced from the USA to Europe in 1938 for of bruchid pests.

Seasonality

activity occurs primarily in the first half of the day. Peak of T. thoracicus occurs on day 5 after flight initiation.

Host Associations

Bruchus pisorum - -larval primary ; pea weevil, most dangerous pest of pea crops
Bruchus atomarius - -larval reported in literature, though polyphagy claims disputed
Bruchus lentis - -larval reported in literature, though polyphagy claims disputed
Bruchus rufimanus - -larval reported in literature, though polyphagy claims disputed
Smicronyx fulvus - larval red sunflower seed weevil; sole reared from cultivated sunflowers in some studies
Acanthoscelides obtectus - alternative bean weevil; used for laboratory rearing but with low rates

Life Cycle

-larval development spanning two developmental phases. One of T. thoracicus averages 30 days at 28-39°C. emerge from host after approximately 30 days.

Behavior

activity occurs primarily in the first half of the day with no regular pattern in flight dynamics observed. Females can parasitize laid on developing green pods.

Ecological Role

Natural enemy of weevil pests in agricultural systems. Part of a complex (approximately 20 ) regulating pea weevil . Serves as a alternative to chemical in programs.

Human Relevance

Used as a agent against agricultural pests. T. thoracicus was introduced from the USA to Europe in 1938 specifically for bruchid control. Laboratory rearing programs have been developed for mass release, though natural field appear low based on survey data.