Developmental Performance of the Milfoil Weevil (Coleoptera: Curculionidae) on Watermilfoils in Washington State

Abstract

Abstract The milfoil weevil, Euhrychiopsis lecontei Dietz, is a North American herbivore associated with declines of Eurasian watermilfoil (Myriophyllum spicatum L.) in the United States. The weevil is a watermilfoil specialist and northern watermilfoil (M. sibiricum Komorov) is its native host plant. Previous studies have reported better developmental performance (egg to adult development) on Eurasian watermilfoil (exotic host) than on northern watermilfoil (native host). The reported difference in performance between host plants and the weevil’s occurrence in two distinct geographical regions in Washington State (eastern and western Washington) led us to conduct laboratory experiments to compare the developmental performance between weevil and host plant populations. No significant differences were detected in the egg to adult development time for eastern and western Washington weevils reared on Eurasian or northern watermilfoil from both regions. Regional differences, however, were found in egg to pupa...