Use of a native insect as a biological control for an introduced weed

• Published in: Ecological applications 1995-11, Vol.5 (4), p.1122-1132
• Main Authors: Sheldon, Sallie P., Creed, Robert P.
• Format: Article
• Language: English
• Subjects: Annuals; Aquatic plants; AQUATIC WEEDS; AUGMENTATION; AUXILIAIRE DE LUTTE BIOLOGIQUE; BIOLOGICAL CONTROL; BIOLOGICAL CONTROL ORGANISMS; Coleoptera; CONTROL BIOLOGICO; CURCULIONIDAE; ESPECE; ESPECIES; ESTANQUES; ETANG; Euhrychiopsis lecontei; FEEDING PREFERENCES; Freshwater; HERBIVORE; HERBIVORES; HERBIVOROS; INTRODUCED VARIETIES; Invertebrates; LAC; LAGOS; LAKES; LUTTE BIOLOGIQUE; Macrophytes; MALEZAS ACUATICAS; MAUVAISE HERBE AQUATIQUE; Military engineering; MYRIOPHYLLUM; MYRIOPHYLLUM SPICATUM; Native plants; NONTARGET ORGANISMS; ORGANISMOS PARA CONTROL BIOLOGICO; Plants; PONDS; PREFERENCE ALIMENTAIRE; PREFERENCIAS ALIMENTARIAS; SPECIES; VARIEDADES NATURALIZADAS; VARIETE INTRODUITE; VERMONT; Waterways; Weevils
• ISSN: 1051-0761; 1939-5582
• DOI: 10.2307/2269359

We have evaluated the potential of a North American aquatic weevil, Euhrychiopsis lecontei, to serve as an agent of biological control for an exotic weed, Eurasian watermilfoil (Myriophyllum spicatum), which is currently found throughout much of the United States and in some southern provinces of Canada. We have found this weevil on M. spicatum in lakes where populations of the exotic weed have declined. We introduced weevils into enclosures in two lakes dominated by M. spicatum. In both lakes there was 50% less M. spicatum biomass in enclosures with weevils than in enclosures without weevils. Also, in control enclosures, M. spicatum formed a canopy on the water surface as it did outside the enclosures, while there was no plant canopy in any of the weevil enclosures. In laboratory feeding trials we quantified the effects of weevils on ten native aquatic plants including a native watermilfoil, Myriophyllum sibiricum. Weevils did not have a significant effect on the increase in plant length or final dry mass of any native plant, however the weevils did feed on the native watermilfoil. All native plants added new leaves, leaf whorls, or side branches under all weevil densities. The results from these studies suggest that a North American insect may be a suitable control agent for this introduced aquatic weed. Native biological control agents, when they can be found, offer potential advantages over classical biological control agents; they may have little impact on non-target native species that have coexisted with the control agent, and may save the time and expense of foreign research and quarantine procedures.