01681nas a2200169   4500008004500000020001400045245007300059210006900132260001200201300001000213490000700223520113100230653002701361100001001388700002001398856009301418       1994                        Engldsh    a0146-662300aThe effect of two herbivorous insect larvae on Eurasian watermilfoil0 aeffect of two herbivorous insect larvae on Eurasian watermilfoil  cJanuary  a21-260 v323 aLarvae of the moth Acentria ephemerella (Denis and Schiffermuller) (=Acentria nivea (Olivier)) and the weevil Euhrychiopsis lecontei (Dietz) were associated with a population of Eurasian watermilfoil (Myriophyllum spicatum L.) that had declined. To determine if these herbivorous insect larvae played a role in the decline we conducted three experiments (Acentria alone, Euhrychiopsis alone, Acentria and Euhrychiopsis together) in outdoor pools which quantified their effects on watermilfoil growth. Acentria larvae significantly reduced watermilfoil growth in two experiments. Acentria damaged the plants by cutting the stem and removing leaves. Late instar Euhrychiopsis larvae significantly reduced watermilfoil growth in one experiment but not the other. Weevil larvae significantly reduced plant growth in the experiment in which watermilfoil exhibited a faster growth rate. Weevil larvae fed by burrowing through the stem and burrowed through approximately 6-8 mm of stem per day. These results suggest that these insect herbivores have potential as biological control agents for Eurasian watermilfoil in North America.10aEuhrychiopsis lecontei1 aCreed1 aSheldon, S., P.  uhttps://weevil.myspecies.info/effect-two-herbivorous-insect-larvae-eurasian-watermilfoil01792nas a2200157   4500008004500000020001400045245013700059210006900196260001200265300001000277490000700287520116600294653002901460100001001489856013501499       1998                        Engldsh    a0146-662300aA biogeographic perspective on watermilfoil declines: additional evidence for the role of herbivorous weevils in promoting declines?0 abiogeographic perspective on watermilfoil declines additional ev  cJanuary  a16-220 v363 aRecent research suggests that a native, herbivorous weevil (Euhrychiopsis lecontei (Dietz)) may play a major role in promoting or causing Eurasian watermilfoil (Myriophyllum spicatum L.) declines in North America. When the locations of all unexplained (i.e., not related to a specific management practice) North American Eurasian watermilfoil declines were plotted there was a non-random distribution of declines. The majority of declines have occurred in northern states in the USA and some Canadian provinces which is the original range of E. lecontei and its native host, northern watermilfoil (Myriophyllum sibiricum Komarov (=M. exalbescens Fernald)). If other factors were important in producing declines (e.g., competition with native species, accumulation of toxins, changes in water clarity or sediment chemistry) one would not expect to see such a latitudinal bias in the location of declines. This pattern of declines supports the hypothesis that E. lecontei is an important agent in promoting or causing Eurasian watermilfoil declines. Alternative factors (e.g., climate, other herbivores) that could have produced this pattern were also considered.10aEuhrychiopsis lecontei [1 aCreed  uhttps://weevil.myspecies.info/biogeographic-perspective-watermilfoil-declines-additional-evidence-role-herbivorous-weevils-promoti01680nas a2200169   4500008004500000020001400045245013200059210006900191260001200260300001000272490000700282520101600289653002701305100002401332700001901356856013501375       2009                        Engldsh    a0146-662300aDistribution and abundance of the milfoil weevil, Euhrychiopsis lecontei, in Lake Minnetonka and relation to milfoil harvesting0 aDistribution and abundance of the milfoil weevil Euhrychiopsis l  cJanuary  a21-250 v473 aThe milfoil weevil, Euhrychiopsis lecontei (Dietz), native to North America, is it potential biological control agent for Eurasian watermilfoil (Myriophyllum spicatum L.). The milfoil weevil has been shown to control the plant when sufficient densities are attained and maintained throughout the summer. Mechanical harvesting of Eurasian watermilfoil has been shown to locally reduce the density of weevils in harvested plots, but the effects of broad-scale harvesting have not been evaluated. We determined weevil densities in unharvested plots in early-, mid- and late-summer in nine bays of Lake Minnetonka that had a range of harvest levels. Weevil densities were significantly negitively related to proportion of the bay harvested (r2 = 0.55. p = 0.02). No relationship between shoreline habitat and weevil density was found. Our suggest that large-scale harvesting is detrimental to weevil populations and that harvesting and chemical control should be limited if the aim is to promote biological control.10aEuhrychiopsis lecontei1 aNewman, Raymond, M.1 aInglis, W., G.  uhttps://weevil.myspecies.info/distribution-and-abundance-milfoil-weevil-euhrychiopsis-lecontei-lake-minnetonka-and-relation-milfoi02322nas a2200193   4500008004500000020001400045245011700059210006900176260000900245300001200254490000700266520160900273653002701882100002301909700001901932700002101951700002101972856013501993       2008                        Engldsh    a0146-662300aBiological control of Eurasian watermilfoil by Euhrychiopsis lecontei: assessing efficacy and timing of sampling0 aBiological control of Eurasian watermilfoil by Euhrychiopsis lec  cJuly  a144-1490 v463 aThe milfoil weevil, Euhrychiapsis lecontei Dietz, is a biological control agent for Eurasian watermilfoil (EWM; Myriophyllum spicatum L.), a nuisance aquatic macrophyte. EnviroScience, Inc. (Stow, OH) rears and stocks E. lecontei for management of EWM infestations. Here, we analyze data collected by EnviroScience, Inc. from treatment (weevil-stocked) and control (unstocked) EWM beds in 30 Michigan and Wisconsin lakes over six years. Initial and final EWM and weevil densities were compared with lake-specific average and maximum lake depths, and lake surface area. The analyses showed substantive variability of weevil efficacy to control EWM. No significant associations were seen between average or maximum lake depth or lake surface area on final weevil densities or plant density changes. Only the number of days between initial and final surveys and timing of final data collection proved significant in determining final EWM densities. As more time passed between surveys, final EWM densities significantly decreased at treatment sites, possibly due to weevils, with a much smaller decrease at control sites. Also, EWM densities declined at both treatment and control sites when final survey data were collected after the start of September, a phenomenon not seen when final data were collected earlier in the year. These declines at control sites were likely due to plant senescence. Lake managers utilizing E. lecontei should consider the length of time between EWM surveys, as well as the timing of data collection, to avoid the confounding effect of plant senescence on data interpretation.10aEuhrychiopsis lecontei1 aReeves, Justin, L.1 aLorchi, P., D.1 aKershner, M., W.1 aHilovsky, M., A.  uhttps://weevil.myspecies.info/biological-control-eurasian-watermilfoil-euhrychiopsis-lecontei-assessing-efficacy-and-timing-sampli