EFFECTS OF TEMPERATURE ON DEVELOPMENTAL RATE, DISTRIBUTION, AND ESTABLISHMENT OF CALOPHASIA-LUNULA (LEPIDOPTERA, NOCTUIDAE), A BIOCONTROL AGENT FOR TOADFLAX (LINARIA SPP)

A degree-day model was developed for preimaginal development and ovipo sition of Calophasia lunula (Lepidoptera: Noctuidae), a European moth which has been introduced into North America for biological control of toadflax (Linaria spp.). Its developmental rate fits well to a linear model with a threshold of 13.5 degrees C, 418 degree-days required fo r preimaginal development, and an additional 124 degree-days for 95% o viposition. Parameters for two strains originating from Switzerland an d the former Yugoslavia are very similar, but the Yugoslav strain has a slightly higher degree-day requirement. The model predicts that two or more generations will occur in southern Europe, that one generation will occur in central Europe, and that the insect will be absent from northern Europe. Most locality records for C. lunula in Europe fall w ithin the predicted distribution. However, the insect extends further north in Scandinavia than predicted by the model, suggesting that a st rain adapted to a lower summer temperature may occur there. In North A merica it has become established only in areas predicted by the model to be within its range. According to the model, central and northern A lberta, where extensive unsuccessful releases have been made, are outs ide its potential range, Establishment may be possible in southern Bri tish Columbia, southeastern Alberta, and southern Saskatchewan. (C) 19 95 Academic Press, Inc.