Life history and developmental performance of the Eurasian milfoil weevil, Eubrychius Velutus (Coleoptera: Curculionidae)

Eubrychius velutus Beck is an aquatic weevil distributed throughout Europe and Asia. It is closely related to Euhrychiopsis lecontei Dietz, which is native to North America and is a potential biological control agent of Eurasian watermilfoil (Myriophyllum spicatum L.). Both weevils are watermilfoil (Myriophyllum) specialists and complete all life stages submersed on the plants. Eubrychius velutus has recently expanded its host range to include the exotic M. heterophyllum Michaux, introduced to Europe from North America. We describe the life history and developmental performance of E. velutus. Developmental rates and survival of E. velutus were similar on the exotic host (M. heterophyllum) when compared to the native hosts (M. spicatum and M. verticillatum L.) and also were similar to developmental rates of E. lecontei. At 23°C, eggs hatched in three days, larval and pupal development each lasted about 10 days and total development from egg to adult was completed in 23 days. Both species have very similar life histories and developmental performance. However, E. velutus develops in the meristem and outer portions of the plant and pupates in a cocoon on the top 5 cm of the plant, whereas E. lecontei larvae mine the stems and also pupate there.