Aquatic Plant Research > Invasives > Management and Control > Eurasian Watermilfoil (EWM) Control > Small Scale > Biological Control
Aquatic Plant Research
DNR Science Services researchers are studying the potential use of biological control as effective management of invasive aquatic species.
Researchers conducted an experiment to address efficacy of a biocontrol option for Eurasian watermilfoil. Specifically, could weevils, if present in large enough numbers, decrease Eurasian watermilfoil biomass. The study is still underway, but main findings to date are: 1) numbers of weevils per stem was highly variable among beds within lakes and among lakes, 2) augmentation of weevils only occasionally added substantially to the pre-existing background densities of weevils, 3) weevil numbers were not correlated with the change in biomass of Eurasian watermilfoil through the summer, and 4) there was ample evidence of Eurasian watermilfoil damage by weevils. In general there was lots of weevil damage observed, but no change in Eurasian watermilfoil biomass.