Trechnites Thomson 1876

Zuparko, Robert L., 2015, Annotated Checklist of California Encyrtidae (Hymenoptera), Zootaxa 4017 (1), pp. 1-126 : 52

Trechnites Thomson 1876

Hosts. Hemiptera : Psyllidae

insidiosus ( Crawford 1910: 89) (Psylledontus)

Type. USNM

Distribution. W (Alameda, Butte, Contra Costa, Inyo, Los Angeles, Marin, Mendocino, Mono, Napa, Orange, Placer, Riverside, San Bernardino, San Diego, Santa Barbara, Santa Clara, Santa Cruz, Shasta, Sonoma, Stanislaus, Tulare, Ventura)

Host/habitat. Cacopsylla pyri , C. pyricola , C. vasiljevi , Psylla pyrisuga , P. sp.

Remarks. Trechnites insidiosus was described in 1910 in New York, and at the time its only known host was Cacopsylla pyricola , an Old World species first found in the New World in 1832, and on the west coast in 1939 ( Clausen 1978b). The parasitoid was first recorded on the West Coast in 1962. During a biocontrol program against C. pyricola that ran from the 1960s to the 1980s, T. psyllae (Ruschka) was imported into California from Switzerland and southeastern Europe ( Unruh et al. 1995). Recently Guerrieri & Noyes (2009) synonymized T. psyllae under T. insidiosus (thereby increasing the host records of the latter). However it is not clear if the presence of T. insidiosus in California reflects the natural endemic range of a Holarctic species, if it is a Palearctic species that was introduced accidentally when C. pyricola expanded its range (as suggested by Unruh et al. 1995), or if it became established in California during the biocontrol program starting in the 1960s.