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 tarn ished plant bug (Lygus lineolaris) was determined in three different h abitats: fields of mixed weeds, alfalfa (Medicago sativa L.), and crow n vetch (Coronilla varia L.) in southwestern Quebec in 1991 and 1992. Parasitoids studied were the mymarids Anaphes iole Girault, Polynema p ratensiphagum (Walley), and Erythmelus miridiphagus Dozier and a sceli onid, Telenomus sp. Adult populations of these parasitoids showed thre e or four population peaks in all habitats throughout the season. Adul t 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 wi th L. lineolaris populations; specifically, marked peaks in the adult population of all species were in synchrony with the egg-laying period s of L. lineolaris.