Eurasian Watermilfoil Management: Measuring Feasible Success of Biological Control

Abstract

Eurasian watermilfoil (Myriophyllum spicatum) is an aquatic invasive species whose infestation produces a variety of negative effects in North America. It was introduced to North America in the 1940s, and it was first identified in Minnesota in Lake Minnetonka in 1987. By 1992, the plant was found to have infested 60 Minnesota lakes, and according to most recent surveying, it now infests 160 Minnesota bodies of water. It is a submersed vascular plant that is highly prolific and grows in a vast range of temperatures and environmental conditions, with the potential of forming an entire new milfoil colony from a single plant segment. It is easily spread via watercraft, birds, other animals and vehicles and has therefore become incredibly difficult to control. Eurasian watermilfoil currently has confirmed existence in 45 U.S. States. Why is controlling Eurasian watermilfoil so imperative? As Eurasian watermilfoil spreads at incredibly rapid rates, it becomes a detriment to recreational water use such as boating, fishing, swimming, and other aquatic activities. It also inhibits the growth of native species, both plant and animal. The problematic consequences of milfoil infestation result in the accumulation of several costs; cost to manage, local business costs, declining property values, lost species variety, and possible lost area development opportunities. The key issue is that millions of dollars wind up being spent on controlling Eurasian watermilfoil in America every year. Efforts to control Eurasian watermilfoil are currently undertaken using the physical method of mechanical harvesting or by chemical control. These methods are temporary and must be repeated multiple times each growth season. The more novel approach of biological control, using the milfoil weevil (Euhrychiopsis lecontei), has the potential for long-term, and even permanent successful suppression of Eurasian watermilfoil. The goal of this research was to format a working model to estimate costs of management under certain probabilities of success using the biological method for controlling Eurasian watermilfoil.