Life History and Developmental Performance of the Eurasian Milfoil Weevil, Eubrychius velutus (Coleoptera: Curculionidae)

Abstract

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 238C, 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. ZusammenfassungEubrychius velutus Beck ist ein aquatischer Rüsselkäfer, der über Europa und Asien verbreitet ist. Er ist eng mit dem nordamerikanischen Euhrychiopsis lecontei Dietz verwandt, einem potenziellen biologischen Antagonisten des Ä hrigen Tausendblatts (Myriophyllum spicatum L.). Beide Arten sind Myriophyllum-Spezialisten und durchlaufen alle Entwicklungsstadien submers an der Pflanze. Eubrychius velutus hat erst kürzlich sein Wirtspflanzenspektrum erweitert und besiedelt auch das von Nord-Amerika nach Europa eingeführte Myriophyllum heterophyllum Michaux. Hier beschreiben wir den Lebenszyklus und Entwicklungsstadien von E. velutus. Entwicklungs-und Ü berlebensraten von E. velutus auf dem exotischen Wirt M. heterophyllum waren vergleichbar mit denen auf den einheimischen Arten M. spicatum und M. verticillatum L.; auch war die Entwicklungsrate von E. velutus ähnlich der von E. lecontei. Bei 238C schlüpften die Larven nach drei Tagen aus den Eiern, Larven-und Puppenstadium dauerten jeweils 10 Tage, und die komplette Entwicklung vom Ei zur Imago wurde innerhalb von 23 Tagen durchlaufen. Beide

Ecology and Environmental Impact of Myriophyllum heterophyllum, an Aggressive Invader in European Waterways

“…Several Curculionidae have been described feeding on Myriophyllum species in man-made lakes in Northern Germany; Bagous collignensis, Eubrychius velutus and Phytobius leucogaster were found on M. heterophyllum [72]. No differences in development times for eggs and larvae until the adult stage were found for E. velutus reared on four different Myriophyllum species (M. alterniflorum, M. heterophyllum, M. spicatum and M. verticillatum) [73].…”

“…In Europe, the effect of native herbivores on M. heterophyllum should receive more attention. The European milfoil weevil E. velutus could be a suitable target organism, as it is highly specific to Myriophyllum species [72,73].…”

Annotated checklist of Indian Ceutorhynchinae (Coleoptera: Curculionidae)

“…Ceutorhynchus adults gnaw leaves, stems, buds and flowers of the cruciferous plants (Korotyaev, 2006). Some Ceutorhynchinae species feed on weeds and therefore are used or considered as biological control agents against weeds (Peschken and Wilkinson, 1981;Burki et al, 2001;Colpetzer et al, 2004;Korotyaev, 2006;Newman et al, 2006;Gerber et al, 2007;Visalakshy, 2007). There are some interesting biological and morphological peculiarities that occur in subgroups of Ceutorhynchinae and noteworthy is the ability to leap, expressed to a varying degree in several tribes of Ceutorhynchinae, which is not developed to a comparable extent in other Curculionidae except for Rhamphini (Curculioninae) and has been newly acquired within the Ceutorhynchinae (Korotyaev, 2006).…”