Phryxe pecosensis Townsend 1926

Phryxe pecosensis (Townsend, 1926), Fig. 49

Host records ex. Choristoneura conflictana: Prentice 1955 (SK, MB); Schaffner 1959, ex. Archips conflictana (northeastern United States); † Arnaud 1978 (SK, MB, ME); † Huber et al. 1996 (America north of Mexico).

Host records ex. Choristoneura fumiferana: Johannsen 1913, as Exorista vulgaris ex. Tortrix fumiferana (ME); Tothill 1913, as Exorista vulgaris ex. Tortrix fumiferana (QC); † Winn & Beaulieu 1915, as Exorista vulgaris ex. Tortrix fumiferana (QC); Wilkes & Anderson 1947, ex. Archips fumiferana (ON, QC); Daviault 1950 (QC); Dowden et al. 1951, ex. Archips fumiferana (NY); Jaynes & Drooz 1952 (NY, ME); Raizenne 1952 (ON); Dowden et al. 1953 (ME); Miller 1955 (NB); McGugan & Blais 1959 (ON); Schaffner 1959, as Phryxe vulgaris (northeastern United States); Blais 1960 (QC); MacDonald & Webb 1963 (NB); † Miller 1963 (NB); Blais 1965 (QC); † Arnaud 1978, as Phryxe vulgaris (MA, QC, ME); † Tilles & Woodley 1984 (ME); Hébert et al. 1989 (QC); Huber et al. 1996 (NB); † Huber et al. 1996, as Phryxe vulgaris (America north of Mexico); Cappuccino et al. 1999 (QC).

Host records ex. Choristoneura fumiferana and/or Choristoneura occidentalis: Brown 1941, as Zenillia vulgaris ex. Cacoecia fumiferana (Canada); Sellers 1943, ex. Archips fumiferana (North America); Dowden et al. 1948, ex. Archips fumiferana (North America); † Zwolfer 1961, ex. C. fumiferana (North America); † Arnaud 1978, ex. C. fumiferana (BC, OR, ON, QC, NB, NF, ME, NY).

Host records ex. Choristoneura fumiferana, Choristoneura occidentalis and/or Choristoneura pinus: † Ross 1952, ex. spruce and/or jack pine budworm (Canada).

Host records ex. Choristoneura occidentalis: McKnight 1974 (CO); Harris & Dawson 1979 (BC).

Host records probably ex. Choristoneura occidentalis: Wilkes et al. 1949, ex. C. fumiferana (BC); Carolin & Coulter 1959, ex. C. fumiferana (OR); † Coppel 1960, ex. C. fumiferana (BC).

Host records ex. Choristoneura pinus: Benjamin & Drooz 1954 (MI); Drooz & Benjamin 1956 (MI); Kulman & Hodson 1961 (MN); Dixon & Benjamin 1963 (WI); Allen et al. 1969 (MI); † Arnaud 1978 (MN, WI, MI); † Huber et al. 1996 (America north of Mexico).

Host records ex. Choristoneura rosaceana: Raizenne 1952, ex. Archips rosaceana (ON); † Arnaud 1978 (ON); † Huber et al. 1996 (America north of Mexico).

Phryxe pecosensis ranges from Alaska to Newfoundland, and south to California and New Mexico in the West and Virginia in the East. It is a dark coloured species about 4.0–7.5mm long. The adult and puparium resemble those of the related Madremyia saundersii, and the puparia of the two species (Figs. 24–25) are not always easily distinguished. Phryxe pecosensis was included in a key to the puparia of dipterous parasitoids of Choristoneura species by Ross (1952) and in a key to the adults of dipterous parasitoids of C. occidentalis (as C. fumiferana) in British Columbia by Coppel (1960). The egg, larval instars and puparium were described by Maw and Coppel (1953).

Phryxe vulgaris (Fallén) is a widely distributed Holarctic species that is very similar in appearance to P. pecosensis. This similarity has resulted in frequent misidentifications of P. pecosensis as P. vulgaris in the literature. Sellers (1943) provided useful characters by which to separate the species, but the differences between the species are so subtle that misidentifications continue to occur. Sellers (1943) considered host records of P. v u l g a r i s from C. fumiferana (as Archips fumiferana) to be based on misidentifications of P. pecosensis, and I agree with his assessment.

Phryxe pecosensis is an eryciine tachinid that develops mature eggs within the female reproductive system. In a study of the biology of this species, Maw and Coppel (1953) found that eggs are deposited directly on the host. The first instar usually emerges soon after egg deposition, exiting through the ventral surface of the egg and burrowing into the host. Maw and Coppel (1953) observed a maximum deposition of 32 eggs in the laboratory but found many more eggs in the reproductive systems of dissected females, so females probably deposit close to 100 eggs under natural conditions. Females have a preoviposition period of about 10 days and adults live up to about 50 days (Maw & Coppel 1953). Phryxe pecosensis attacks late instar larvae of Choristoneura species and emerges from the sixth instar or pupa (Dowden et al. 1948; Carolin & Coulter 1959; Allen et al. 1969; McKnight 1974). The fully mature maggot leaves the host to pupariate elsewhere (Sellers 1943; Maw & Coppel 1953). Adults are active from May to October, there are two or more generations per year, and the parasitoid overwinters as a larva in an alternate host (Schaffner & Griswold 1934; Schaffner 1959).

Phryxe pecosensis is a commonly recorded parasitoid of Choristoneura species that is generally responsible for low levels of parasitism but occasionally has been found at higher levels. Parasitism of C. pinus was reported as low (less than 3% parasitism of late larvae) in Michigan by Benjamin and Drooz (1954) and Allen et al. (1969) and in Wisconsin by Dixon and Benjamin (1963). In Quebec, Daviault (1950) reported spruce budworm parasitism as high as 7.4% in larvae and 1% in pupae, whereas Blais (1960) reported relative parasitism as high as 15%. In New York, Dowden et al. (1951) reported parasitism of spruce budworm larvae as high as 18% and of pupae as high as 6%. Jaynes and Drooz (1952) found up to 24% parasitism of mature larvae of spruce budworm in New York and up to 12% parasitism of budworm larvae in Maine. Tilles and Woodley (1984) included P. pecosensis as one of five tachinids in their manual of spruce budworm parasitoids in Maine. Parasitism in the West has been reported as low. Wilkes et al. (1949) ranked P. pecosensis fifteen among the 15 dominant dipterous and hymenopterous parasitoids of C. occidentalis (as C. fumiferana) in British Columbia.

The hosts from which P. pecosensis has been reported are many and varied: a species of Tenthredinidae (Hymenoptera), a species each in Danaidae, Hesperiidae, Pieridae, and Saturniidae, two species of Pyralidae, several species in each of Geometridae and Noctuidae, and about ten species of Tortricidae (Arnaud 1978).