Temperature-Dependent Development in an Oregon Population ofHarmonia axyridis(Coleoptera: Coccinellidae)

The multicolored Asian lady beetle, Harmonia axyridis (Pallas), an aphidophagous coccinellid, was first seen in Benton County, OR, in 1993. Coincident with the 1st occurrence of H. axyridis , we initiated a study on its temperature-dependent survival and development. Survival from 1st instar to adult emergence ranged from 83–90% between 18 and 30°C, and at 10 and 34°C was 42 and 25%, respectively. Mean time for complete development ranged from 14.8 d at 30°C to 81.1 d at l4°C. No eggs hatched at 10° or 34°C and no 1st instars transferred to 10°C survived. The mean lower threshold for egg-to-adult development of 11.2°C is typical relative to other temperate aphidophagous Coccinellidae and was not significantly different from 10°C calculated for a French population of this beetle. Conversely, the mean number of degree-clays (DD) required for complete development was higher in the Oregon population (267.3 DD) than the French population (231.3 DD), although this may have been due in part to a different diet. Times for preimaginal development and values for thermal requirements suggest that the species is a thermal generalist in western Oregon.