Potential for a Native Weevil to Serve as a Biological Control Agent for EurasianWatermilfoil

摘要

The potential of the North American weevil Euhrychiopsis lecontei to serve as abiological control agent for Eurasian watermilfoil (Myriophyllum spicatum) was evaluated. Attention has focused on E. lecontei because it was found associated with a watermilfoil population in Brownington Pond, Vermont, United States, which had declined from approximately 10 to 11 ha in 1986 to < 1 ha in 1989. Watermilfoil abundance was monitored in Brownington Pond from 1990 through 1992. Watermilfoil abundance increased from 1989 through 1991 and decreased again in 1992. Samples of weevils, water, and sediment chemistry suggested that this second decrease in watermilfoil abundance was caused by weevils and not changes in either water or sediment nutrient concentrations. Weevils significantly suppressed lateral stem and root production of watermilfoil in an enclosure experiment conducted in the pond. Damaged sterns also lost their buoyancy and settled out of the water column. Weevils were readily cultured in the laboratory. All life stages were produced, and under culture conditions, mean weevil generation time was approximately 1 month. Weevil eggs are laid on meristems; the first instar larvae burrow into and destroy the meristems; older larvae burrow through the stem; and pupation also occurs in the stem. Weevil adults feed and mate on the plants. Acentria, Eurasian watermilfoil, Biological control, Weevils Euhrychiopsis.