Laboratory Performance of Two Polyphagous Invasive Weevils on the Predominant Woody Plant Species of a Northern Hardwood Community

Abstract

A complex of invasive weevils that consume roots as larvae and foliage as adults have become established in northern hardwood forests in North America. We evaluated adults of the two most prominent species, Phyllobius oblongus and Polydrusus sericeus, for longevity, foliage consumption, and egg production on several putative hosts commonly found in this ecosystem. Adult pairs were monitored in no-choice laboratory assays for the duration of their lifespans on basswood, Tilia americana, ironwood, Ostrya virginiana, sugar maple, Acer saccharum, raspberry, Rubus spp., or leatherwood, Dirca palustris. Overall, P. sericeus lived more than twice as long as P. oblongus and lived longer on all hosts. P. sericeus consumed more total leaf area than P. oblongus on basswood, ironwood, and raspberry, but P. oblongus had a higher leaf consumption rate on sugar maple. Basswood was a very good host for P. sericeus. Leatherwood was not a suitable host for either weevil species. The higher longevity and fecundity of P. sericeus than P. oblongus did not agree with that expected from population data, in that the latter species is substantially more abundant. This likely reflects P. oblongus ' superior performance on sugar maple, the dominant flora in the study area. These data provide a basis for estimating the broader impacts of adult weevil feeding.