Mesochorus discitergus

(Say, 1835)

Mesochorus discitergus is a hyperparasitoid in the Ichneumonidae. It parasitizes primary —particularly braconid wasps such as Cotesia marginiventris—that are themselves developing inside lepidopteran caterpillars. This has been studied for its behavioral interactions with caterpillars, including the tactics it employs to overcome defensive and the evasive responses of different noctuid species. It has been recorded from both North and South America.

Pronunciation

How to pronounce Mesochorus discitergus: //ˌmɛsəˈkɔrəs ˌdɪsɪˈtɜrɡəs//

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Distribution

Recorded from Brazil (Pará, Paraná, Rio de Janeiro, Santa Catarina, São Paulo) and Canada (Alberta, British Columbia, Nova Scotia, Ontario, Saskatchewan); also present in the United States. GBIF records indicate presence in California (Gleichen, Moon Lake, Gull Lake).

Host Associations

Cotesia marginiventris - primary Braconid developing inside caterpillars; from this affect M. discitergus response to parasitized
Phryganidia californica - indirect (via caterpillar)California Oak Moth caterpillars recorded as for the ichneumon Mesochorus sp.
Helicoverpa zea - indirect (caterpillar)Corn earworm; behavioral interactions studied regarding evasive tactics and capture
Spodoptera frugiperda - indirect (caterpillar)Fall armyworm; behavioral interactions studied
Pseudoplusia includens - indirect (caterpillar)Soybean looper; behavioral interactions studied
Plathypena scabra - indirect (caterpillar)Green cloverworm; and defensive tactics specifically studied

Behavior

Females must physically capture caterpillars to oviposit into the primary developing within them. Capture success varies with defensive tactics: caterpillars using vigorous responses are captured approximately 68% of the time, while those dropping from leaves on silk threads are captured about 39% of the time, and those dropping unattached about 26% of the time. The 's response to parasitized caterpillars is influenced by from the primary parasitoid Cotesia marginiventris and its developmental stage.

Ecological Role

Hyperparasitoid; functions as a fourth consumer, parasitizing primary (ichneumonid and braconid wasps) within lepidopteran larvae. This role may influence of both primary parasitoids and their herbivorous .