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

Abstract

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 14°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 10.5°C calculated for a French population of this beetle. Conversely, the mean number of degree-days (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.