The Elm Leaf Beetle, Pyrrhalta luteola1 , in Southern California: Its Host Preference and Host Impact

Abstract

Five groups of 20 elm leaf beetle (ELB) larvae, Pyrrhalta luteola (Müller) and 20 prs (♂ and ♀) of ELB adults were reared on leaves from 4 elm species: one group each on American elm ( Ulmus americana L.), English elm ( U. procera Salisb.), Siberian elm ( U. pumila L.), and on new (currently growing) and old leaves of Chinese elm ( U. parvifolia Jacq.). English elm leaves produced the highest larval survivorship (70%), but the shortest adult life expectancy; Siberian and American elm leaves produced low larval survivorship (25 and 15%, respectively), but caused the longest life expectancy of adults. ELB larvae failed to survive when fed old leaves of Chinese elm, while those fed new leaves exhibited low levels of larval and adult survivorship. Thus, the 4 species may be ranked from most to least susceptible as follows: English, Siberian, American, and Chinese elm. These results generally reflect those reported previously with the exception of Chinese elm. The most important host in southern California is Siberian elm because it is so widely planted. English elm, although more vulnerable, is an infrequently planted species in the area.