SYNCHRONY BETWEEN POPULATIONS OF THE TARNISHED PLANT BUG, LYGUS-LINEOLARIS (PALISOT-DE-BEAUVOIS) (HEMIPTERA, MIRIDAE), AND ITS EGG PARASITOIDS IN SOUTHWESTERN QUEBEC

The seasonal occurrence of four species of egg parasitoids of the tarnished plant bug (Lygus lineolaris) was determined in three different habitats: fields of mixed weeds, alfalfa (Medicago sativa L.), and crown vetch (Coronilla varia L.) in southwestern Quebec in 1991 and 1992. Parasitoids studied were the mymarids Anaphes iole Girault, Polynema pratensiphagum (Walley), and Erythmelus miridiphagus Dozier and a scelionid, Telenomus sp. Adult populations of these parasitoids showed three or four population peaks in all habitats throughout the season. Adult parasitoid activity started during the first egg-laying period of L. lineolaris at a temperature accumulation of 73 degree-days (DD). The overwintering period began in mid-October at 1277 and 1058 DD for 1991 and 1992, respectively. All the parasitoids had a strong synchrony with L. lineolaris populations; specifically, marked peaks in the adult population of all species were in synchrony with the egg-laying periods of L. lineolaris.