Hyphantrophaga blanda Osten Sacken 1887

Hyphantrophaga blanda (Osten Sacken, 1887)

Host records ex. Choristoneura rosaceana: Wilkinson et al. 2004 (MI).

Hyphantrophaga blanda and H. virilis are, at best, uncommon parasitoids of Choristoneura species. They are included here rather than classed as accidental parasitoids of Choristoneura because a record each of H. blanda and H. virilis parasitizing different species of Choristoneura suggests that such parasitization is more opportunistic than accidental, and probably occurs occasionally. Both species are small to medium­sized tachinids (5– 8mm long), mostly gray with four black stripes on the thorax and a lightly banded abdomen. They are widely distributed throughout North America (O’Hara & Wood 2004).

Sellers (1930) examined reared specimens of H. blanda and H. virilis (both as species of Zenillia Robineau­Desvoidy) and described differences between the species in the puparium and both sexes of the adult. Thompson (1953) described and illustrated the egg, larval instars, and puparium of H. blanda.

Hyphantrophaga is a member of the Goniini, producing microtype eggs that are laid on foliage and consumed by a host (see Cyzenis incrassata above; also Thompson 1953). Records from a number of hosts indicate that the mature maggot of both H. blanda and H. virilis generally emerges from the host pupa but sometimes forms a puparium within the host (Sellers 1930). Similarly, Ciesla (1964) reported that H. blanda (as Eusisyropa blanda) emerges from the pupa of Ennomos subsignaria (Hübner) (Geometridae). However, Burgess and Crossman (1927) reported the emergence of H. blanda (as Zenillia blanda) from the larva of Leucoma salicis (L.) (as Stilpnotia salicis; Lymantriidae), and Evans (1962) reported the emergence of H. virilis (as Eusisyropa virilis) from the larva of Melanolophia imitata (Walker) (Geometridae). Sellers (1930) found that both H. blanda and H. virilis overwinter as larvae in the host pupa, and noted that “if parasitic on hosts producing adults in the same season, both parasites completed their development that season; but if parasitic on hosts that pass the winter in the pupal stage and emerge the following spring or summer, the flies likewise did not emerge until the following spring” (p. 574). There are usually two generations per year and multiparasitism can occur in larger hosts (Schaffner & Griswold 1934; Schaffner 1959).

Sellers (1930) examined the host records for H. blanda and H. virilis and found that only about one­third of the hosts known for these two species are shared. They are parasitoids of a wide variety of Lepidoptera, attacking hosts belonging to about 15 families. Hyphantrophaga blanda is a well known parasitoid of several tortricids, especially Archips species (Sellers 1930; Arnaud 1978, as Eusisyropa blanda).